Title of Invention	"A COMPOSITION FOR MAKING CEMENTITIOUS BINDERS BASED ON HIGH FLY ASH CONTENT, CLAY POZZOLANA AND OTHER MINERAL OR INDUSTRIAL WASTES FOR USE IN CEMENT MORTARS AND CONCRETE"
Abstract	Over 150 million tonnes of industrial wastes are produced from various agro-industrial processes per annum in India. The major solid industrial wastes have been identified are fly ash, phosphogypsum, fluorogypsum, lime sludge, red mud, mine tailings etc. These materials require immediate attention to reduce environmental pollution and health hazards and at the same time to mitigate disposal problems associated with them. Investigations were, therefore, undertaken to formulate cementitious binders by judicious blending of the ground fly ash with the gypsum anhydrite (Fluorogypsum or by-product gypsum), hydrated lime sludge, calcined clay, portland cement including a chemical activator. It was found that cementitious binder of high compressive strength may be produced by admixing 10-15 wt.% gypsum anhydrite (fluorogypsum), 5-20 wt.% calcined clay pozzolana, 15-20 wt.% lime sludge, 10-15 wt.% portland cement and 1-2 wt.% chemical activator (Na2SO4.1OH2O) with 50-60 wt. % of fly ash. The cementitious binders were produced with and without addition of portland cement. The strength development of binders take place through formation of ettringite (C3A. 3CaSO4. 32H2O), C-S-H and C4AH,3. The binders are emminently suitable for making cement mortar of high compressive strength and high workability properties. Cost - wise, these binders are cheaper than the portland cement and conform to the strength characteristics of BS : 6610-1991, Specification for pulverized fuel ash pozzolanic cement.The findings further infer that fly ash can be used in the range 50-60% in formulating these binders along with other wastes to alleviate environmental pollution.

Title of Invention

"A COMPOSITION FOR MAKING CEMENTITIOUS BINDERS BASED ON HIGH FLY ASH CONTENT, CLAY POZZOLANA AND OTHER MINERAL OR INDUSTRIAL WASTES FOR USE IN CEMENT MORTARS AND CONCRETE"

Abstract

Over 150 million tonnes of industrial wastes are produced from various agro-industrial processes per annum in India. The major solid industrial wastes have been identified are fly ash, phosphogypsum, fluorogypsum, lime sludge, red mud, mine tailings etc. These materials require immediate attention to reduce environmental pollution and health hazards and at the same time to mitigate disposal problems associated with them. Investigations were, therefore, undertaken to formulate cementitious binders by judicious blending of the ground fly ash with the gypsum anhydrite (Fluorogypsum or by-product gypsum), hydrated lime sludge, calcined clay, portland cement including a chemical activator. It was found that cementitious binder of high compressive strength may be produced by admixing 10-15 wt.% gypsum anhydrite (fluorogypsum), 5-20 wt.% calcined clay pozzolana, 15-20 wt.% lime sludge, 10-15 wt.% portland cement and 1-2 wt.% chemical activator (Na2SO4.1OH2O) with 50-60 wt. % of fly ash. The cementitious binders were produced with and without addition of portland cement. The strength development of binders take place through formation of ettringite (C3A. 3CaSO4. 32H2O), C-S-H and C4AH,3. The binders are emminently suitable for making cement mortar of high compressive strength and high workability properties. Cost - wise, these binders are cheaper than the portland cement and conform to the strength characteristics of BS : 6610-1991, Specification for pulverized fuel ash pozzolanic cement.The findings further infer that fly ash can be used in the range 50-60% in formulating these binders along with other wastes to alleviate environmental pollution.

Full Text	The present invention relates to a "Compositions for Making Cementitious Binders Based on High Fly ash content, Clay Pozzolana and Other Minerals or Industrial Wastes for Use in Cement Mortar and Concrete". The Compositions can be used for preparing cementitious binder based on fly ash, calcined clay, gypsum anhydrite ( by-product gypsum or natural gypsum) and lime or lime sludge, portland cement and small quantity of a chemical activator. The production of cementitious binder will consume sizeable quantities of industrial solid wastes and may help in reducing threat to environment. Fly ash is produced as finely divided by-product from the combustion of pulverised coal in suspension fired furnaces of thermal, power plants. It is collected by electrical or mechanical precipitators or cyclones or bag filters. It is normally, finer than portland cement and comprises of rounded glassy particles of variable chemicals and mineralogical compositions. The properties of fly ash show variation and depend upon numerous factors, such as the composition of coal (bitumenous, sub-bitumenous and lignite coals), fineness of coal, flame temperature, oxidation conditions and mode of collection of fly ash. Several countries and organisations have their own standard specifications and requirements for fly ash to be used as mineral admixture or as pozzolana. ASTM C 618-89, defines the pozzolana as "siliceous or siliceous and aluminuous materials which is themselves possess little or no cementitious value but in finely divided form and in the presence of moisture chemically react with Ca(OH)2 at ordinary temperature to form compounds possessing cementitious properties". ASTM C 618-89 classify the pozzolana into class N, F, C and S. Class N refers to raw or calcined natural pozzolana such as some diatomacious earths, opline, shales or cherts, and volcanic or pumicites. Class S refers to processed, pumicites which are porous forms of volcanic glass and to certain calcined and ground diatomites, clays & shales. Classs F and C pozzolanas refer to fly ash derived from the burning of different coals. Physical and chemical properties of fly ash play an important role in imparting the pozzolanic reactivity and in the production of cement mortar and concrete. Most of the fly ash particles are glassy or amorphous. Yet the minerals like quartz, mullite, silimanite, crysto-bellite, haematite and calcium compounds including calcium sulphate may be present as crystalline compounds constituting about 15.0 percent by weight of the fly ash. Some of the carbon in coal particles does not burn properly and thus fly ashes also possess unburnt carbon. Over 500 million tonnes of fly ash is produced annually by thermal power plants all over the world (R.C. Joshi and R.P.Lohtia, Types and Properties of Fly ash, Progress in Cement & Concrete - Mineral Admixtures in Cement and Concrete, Vol. 4, 1st Edn., 1993, Academia Books International, New Delhi, p. 121). In India 70 percent power is generated through coal based thermal power plants which throw 70 million tonnes of fly ash per annum. Not more than 10.0 per cent of fly ash is being used in India at present. The major reasons for limited utilization of fly ash may be non-availability of quality grade fly ash complying with IS:3812 (Part-I)-1981, specification of fly ash for use as pozzolana in solid form and due to its less reactivity compared to foreign fly ashes. However, the utilization of fly ash is an important building material which has been accepted as an engineering fact in the technologies in advanced countries. Extensive work has been accomplished abroad as well as in India regarding effective utilization of fly ash in areas such as factory produced portland pozzolana cement, ready mixed fly ash concrete for use as structural concrete in the manufacture of precast building products (S.S.Rehsi, Ready mixed fly ash concrete, Engineers and Planners Journal, Vol. 2, No. 7, Feb. 1974, National Workshop on Utilization of Fly ash, May 19-20, 1988, Roorkee, pp B-75-B-78); As a part replacement of portland cement in mortars and concrete (S.S.Rehsi and S.K.Garg, Use of fly ash in masonry mortars, National Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1988, pp B-l 11 - B-l 16; Abdun-Nur and A.Edward, Fly ash in concrete, An Evaluation, Highway Research Board Bullentin, 28th Washington, D.C., 1961, p. 138; S.S.Reshi and S.K.Garg, Production of precast concrete building units using fly ash, J. of the Association of Engineers, India, Vol. 48, No.4, Oct.-Dec. 1973, pp 125-131), Manufacture of Sintered lightweight fly ash aggregate (S.K.Chopra and Kishan Lai, Sintered lightweight aggregate from Indian fly ashes, The Indian Concrete J. Vol. 35, No.5, 1961, pp 150-153), in the production of cellular concrete (S.K.Chopra, C.A.Taneja and S.P.Tehri, Development of cellular concrete based on lime and fly ash, Research and Industry, Vol. 13, 1968, pp 189- 191), production of clay fly ash building bricks (C.Raj Kumar, S.C.Aluwalia and Rattan Lai, Bricks from fly ash - A technical appraisal, National Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1998, pp A-135- A-136; J.M.Bhatnagar et. al., National Seminar on New Materials and Technology in Building Industry, New Delhi, India, July 24-25, 1998, p 123), production of fly ash-sand-lime bricks (Mohan Rai, Dinesh Chandra, R.L.Gupta and S.K.Jain, Production of calcium silicate bricks from fly ash, National Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1988, pp A-59 - A-62) and in road & soil stabilization works (P.K.Dhavan, N.K.Goswani & N.K.Bhasin, Utilization of fly ash in construction, National Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1988, pp A-73 A-76; Arjun Das and S.K.Malhotra, Lime stabilized soil as a building material - Preliminary investigations, N.B.O.J., Vol. 24, Oct. 1979, pp 29- 33). Apart from these applications of fly ash in building sector, the use of fly ash has been made substantially in the manufacture of cementitious binders in conjunction with calcined gypsum, cement and chemical retarders (Manjit Singh and Mridul Garg, Investigations of durable gypsum binder for building materials, Construction and Building Materials (U.K.), Vol. 6, No.l, March 1992, pp 52-56; Manjit Singh and Mridul Garg, Studies on the formation of cementitious compounds using phosphogypsum and fly ash, NCB Quest (India), Vol. 4, 1991, pp 42-54; Manjit Singh and Mridul Garg, Phosphogypsum-fly ash cementitious binder-its hydration and strength development, Cement and Concrete Research (U.S.A.), Vol. 25, No.4, 1995, pp 752-758; Manjit Singh and Mridul Garg, Alternative binders and components from industrial by-products, Civil Engineering and Construction Review (India), Vol. 8, No. 10, October 1995, pp 332-338; Mridul Garg, Manjit Singh and Rakesh Kumar, Some aspects of the durability of a phosphogypsum-lime-fly ash binder, Construction and Building Materials (U.K.), Vol. 10, No.4, 1996, pp 273-279; Manjit Singh and Mridul Garg, Durability of cementitious binder derived from industrial waste, Materials and Structure Journal (France), RILEM, Vol. 30, December, 1997, pp 607- 612; Manjit Singh, Phosphogypsum-cement-pozzolana binder for use in construction work, International Conference on 'Low Cost Housing for Developing Countries, CBRI, Roorkee, Vol. 1, March 8-12, 1985, pp 233- 237; Manjit Singh and Mridul Garg, Microstructure of glass fibre reinforced water resistant gypsum binder composites, Cement and Concrete Research (USA), Vol. 23, 1993, pp 213-220; Manjit Singh and Mridul Garg, An alternative to timber, The Indian Concrete J., Feb. 1993, pp 78-84. J. Beretka L. Santaro and G.L. Valenti, New and durable building materials based on ettringite, Fourth-International Conference on Durability of Building Materials & Components, Singapore 1987, pp 64-70). In these binders, 15 to 50 per cent fly ash was used both in moist cold blending and hot curing environments and the durability of systems was established.Thus, binders based on fly ash have been produced in combination with other wastes as cited above but very limited work has been done on the activation of fly ashses. Generally, fly ash is activated by (1) addition of chemical additives to fly ash concrete (2) mechanical grinding of fly ash and by (3) curing fly ash concrete at elevated temperature respectively (Caijun, Shi and L.Day Robert, Cement and Concrete Research, Vol. 25, No.l, 1995, pp 15-21; G.G.Carett, V.M.Malhotra, C.Bedard. V.De Benedictis, and M. Plumet Proc. 2nd International Conference on Fly ash Silica Fume, Slag and Natural Pozzolana in Concrete, SP-91, American Concrete Institute, Farmington Hills, Mich., Vol. 1, 1986, pp 249-272; J.Paya, J.Monjo, M.V.Borrachero and E.Peris - Mora, Mechanical treatment of fly ashes, Part 1 : Physicochemical characterization of ground fly ashes, Cement & Concrete Research, Vol. 25, No. 7, 1995, pp 1469-1479; A katz, Microscopic study of alkaliactivated fly ash, Cement and Concrete Research, Vol. 28, No.2, 1998, pp 197-208, B.C. Francis et. al., Fly ash based compositions, US Patent 0543 9518, Jan 6, 1993. Activation of fly ash hydrated lime blends (80 and 20 percent by mass) by Na2SO4 or CaCl2.2H2O chemicals at 50°C has been claimed (Caijun Shi, Pozzolanic reaction and microstructure of chemical activated lime-fly ash pastes, ACI Materials J., Sept. - Oct. 1998, pp 537 - 545) which establish the understanding of chemical activation of reactivity of fly ashes. Besides fly ash, several other industrial solid wastes such as phosphogypsum, fluorogypsum, lime sludges etc. are produced from the phosphoric acid, hydrofuoric acid, acetylene/sugar/paper industries respectively. In India over 5.0 million tonnes of phosphogypsum as well as lime sludge and about 0.2 million tonnes of fluorogypsum are produced annually which require judiceous disposal and utilization. Enormous work has been done on these wastes throughout the world regarding their beneficiation and utilization as potential building material (R.K.Collings, Evaluation of phosphogypsum for gypsum products, Canadian Institute of Mining and Metallurgy Bulletin, Vol. 65, Sept. 1972, pp 41-51; Manjit Singh et. al., An improved process for the purification of phosphogypsum, Construction and Building Materials (U.K.), Vol. 10., No.6-1996, pp 597- 600; Manjit Singh, Physico-Chemical Studies on Phosphogypsum for Use as Building Materials, Ph.D Thesis, University of Roorkee, Roorkee, India 1980; I.Masood et. al. High strength activated Lime pozzolana mixture. National Seminar on Building Materials - Their Science and Technology New Delhi, 15-16 April 1982; 11 B, pp 1-4. Several cements and cementitious materials are being produced through out the world using fly ash. In India fly ash being used in the range of 10 to 25 percent (by mass) in the manufacture of portland pozzolana cement as per 18:1489-1976, Specification for Portland pozzolana cement. The properties of PPC are at par with the properties of ordinary portland cement (OPC) of 33 grade as per 18:269-1989, Specification for 33 grade ordinary portland. The quantity of fly ash differs from country to country for making PPC. Various European standards have now permitted large quantities of fly ash to be blended with cement for its uses in construction activities. In BS:6610-1991, Specification for pozzolanic fuel ash cement; the fly ash has been allowed to be incorporated in the range 41 to 53 percent and the compressive strength of cement prescribed is > 12.0 and 22.5 N/mm2 at 7 and 28 days respectively. In continuation of these cements, two cementitious binders (1) containing 60 percent fly ash, 5.0 percent calcined clay pozzolana, 10.0 percent each of gypsum anhydrite (fluorogypsum, by-product gypsum or natural gypsum) and portland cement, 15.0 percent calcined hydrated lime sludge and 1.0 percent sodium sulphate (Na2SO4.10H2O) activator and (2) the binder containing 50.0 percent fly ash, 20.0 percent calcined clay pozzolana, 10.0 percent gypsum anhydrite ( by-product gypsum or natural gypsum), 20.0 percent calcined hydrated lime sludge and 1.0 percent sodium sulphate activator have been produced at CBRI, Roorkee conforming to strength requirements (7 and 28 days) of BS:6610-1991, specification for pozzolanic pulverized fuel ash cement have been claimed for the first time. The development of cementitious binders from fly ash and other industrial wastes, such as gypsum anhydrite (by-product gypsum or natural gypsum), calcined clay, hydrated lime sludge to give strength and other characteristics similar to strength requirements as per 18:6610-1991 are the novel features which were not possible to achieve earlier just by blending gypsum anhydrite ( by-product gypsum or natural gypsum) or hydrated lime with the fly ash. The main objective of the present invention is to provide a Composition for making cementitious binders based on high fly ash content, clay pozzolana and other industrial wastes. Another object is to provide cement mortar and concrete made from the novel compositions containing industrial solid wastes. Accordingly, the present invention provides a 'composition for making cementitious binders based on high fly ash content, clay pozzolana and other industrial wastes for use in cement mortar and concrete which comprises: Pulverised fly ash (400 to 520 m2/kg) in the range of 50 to 65 wt. %; gypsum anhydrite ( by-product gypsum or natural gypsum) (350 to 450 m2/kg) in the range of 15 to 15 wt. %; Calcined clay pozzolana (400 to 530 m2/kg) in the range of 5 to 20 wt. %; lime sludge (350 to 430 m2/kg) in the range of 10 to 25 wt. %; Portland cement (300 to 330 m2/kg) in the range of 10 to 15 wt. %; and Sodium Sulphate activator (350 to 400 m2/kg) in the range of 1 to 2 wt.%. In an embodiment of the present invention, fly ashes of lime reactivity 3.0 to 5.0 N/mm2 may be used to form binders. In another embodiment of the present invention the pozzolanic clay may be obtained by calcining the clay at a temperature in the range of 700 to 1000°C for a period of 15 minutes to 200 minutes. In yet another embodiment of the present invention the lime may be produced by calcining the lime sludge /stone at a temperature in the range of 950 to 1100°C for a period of 15 minutes to 4.0 hours. In yet another embodiment of the present invention, the fly ash may have SiO2 in the range of 50-60 wt. %, A12O3 + Fe2O3 in the range of 20 to 33 wt.%, loss on ignition, in the range of 0.5 to 5.0 wt. % and lime reactivity 3.0 to 5.0 N/mm2. In still another embodiment of the present invention the gypsum anhydrite (by-product gypsum or natural gypsum) may have SO3 in the range of 50 to 56 wt. %, loss on ignition in the range of 0.40 to 0.92 wt.%, and fluoride in the range of 1.0 to 2.0 wt.%. In yet another embodiment of the present invention the pozzolanic clay may have SiO2 in the range of 40 to 50 wt.%, and A12O3 + Fe2O3 in the range of 35.0 to 40.0 wt.%. In yet another embodiment of the present invention the lime sludge may have cotamination of P2O5 and F in the range of 1.0 to 3.5 wt.% and 1.0 to 2.0 wt. % respectively. In still another embodiment of the present invention, the fly ash may be ground to a fineness of 400 to 520 m2/kg (Blaine) in a ball mill or a pulverizer. In still another embodiment of the present invention commercial grade chemical activator such as sodium sulphate (Na2SO4. 10H2O) may be used. In yet another embodiment of the present invention, various consituents are first uniformally blended in a blender followed by grinding in a ball mill or pulverizer to achieve a fineness of 500 to 530 m2/kg (Blaine). All these ingredients are mixed parts by weight except activator which is mixed by wt.% of the total wt. of the binder. Accordingly, the present invention provides composition of cementitious binders which can be produced by intimately mixing 50 to 60 percent ground fly ash (400 to 520 m2/kg) (Blaine) with the ingredients such as 5 to 20% calcined clay pozzolana (400 to 530 m2/kg, (Blaine) produced at 700 to 1000°C), 10 to 15% gypsum anhydrite ( by-product gypsum or natural gypsum) (350 to 450 m2/kg (Blaine), and lime sludge (350 to 430 m2/kg (Blaine) calcined at 950 to 1100°C) and 10 - 15% portland cement (300 to 330 m2/kg (Blaine) and 1 - 2% sodium sulphate activator (350 to 400 m2/kg Blaine) followed by grinding in the ball mill to a fineness of 500 to 530 m2/kg (Blaine) to form uniformally blended binder which is hardened to give a strong mass through formation of ettringite (C3A.3CaSO4.32H2O), tobermorite C-S-H and tetracalcium aluminium hydrate (C4AHi3) conforming to BS:661 0-1 991. The process for making cementitious binders from fly ash and other industrial wastes consists of calcining the clay (700 - 1000°C) and lime sludge (950- 1 100°C) whereby clay is transformed into reactive pozzolana of high lime reactivity (8-12 N/mm2) and lime sludge into lime. The lime is converted into hydrated lime by sprinkling l/3rd (by mass) of the water on the lime. The calcined clay pozzolana and the gypsum anhydrite (by-product gypsum or natural gypsum) ground to the requisite finenesses are then blended with ground fly ash (50-60%), portland cement and the sodium sulphate activator followed by grinding to form cementitious binders. The fly ash, clay, gypsum anhydrite ( by-product gypsum or natural gypsum) , lime sludge and portland cement samples are analysed for their chemical constituents as per standard test procedures and subjected to DTA and XRD to identify the composition of the materials. The clay pozzolana is produced by heating the clay sample in a furnace or rotary kiln at 700- 1000°C for a period of 15 minutes to 200 minutes. The lime sludge (sugar/paper/acetylene industries) is heated at 950-1100°C in a furnace or rotary calciner for a period of 15 minutes to 4.0 hours to get lime. After cooling, the calcined lime sludge is crushed to coarser powder and then slaked. About l/3rd of water by the weight of lime is sprinkled over the lime powder gradually and is thoroughly mixed. After 15-20 minutes, the hydration/slakening occurs with heat liberation and the slaking is completed in a period of one hour. After cooling, the finely divided white hydrated lime is screened through 300 micron sieve and the coarse fruction is discarded. The samples of fly ash, calcined clay, gypsum anhydrite (fluorogypsum,byproduct gypsum or natural gypsum), hydrated lime, portland cement and Na2SO4.10H2O activator dried at 42 + 2°C are ground to the fineness of 400 to 520 nr/kg, 400 to 530 nr/kg, 350 to 450 nr/kg, 300 to 330 m2/kg and 350 to 400 m2/kg (Elaine) respectively. After grinding, the fly ash, calcined clay, gypsum anhydrite (fluorogypsum,by-product gypsum or natural gypsum) hydrated lime, portland cement and Na2SO4.10H2O activator are blended in two proportions (1) 60% fly ash, 5.0% calcined clay pozzolana, 10.0% each of gypsum anhydrite (by-product gypsum or natural gypsum), and portland cement, 15.0% calcined hydrated lime and 1.0% Na2SO4.10H2O activator and (2) 50% fly ash, 20% clay pozzolana, 10.0% gypsum anhydrite (fluorogypsum,by-product gypsum or natural gypsum), 20% hydrated lime and 1.0% Na2SO4.10H2O activator (by wt.%) respectively followed by grinding in a ball mill to form an uniform cementitious binder. The cementitious binder is then ready for packing. The chemistry of cementitious binder is predominently is based on the reactivity of fly ash and clay pozzolana. Fly ash is a pozzolanic material which shows reactivity when interacted with lime in presence of water and produce insoluble stable cementitious products. The reactivity of fly ash is due to amorphous SiO2, A12O3 and Fe2O3 constituents. Similarly, calcined clay contains amorphous SiO2 and A12O3 including Fe2O3. The quantities of these constituents vary with the type of the clay mineral used. The metastable silicate present in fly ash and clay pozzolana reacts with Ca2+ ions contributed by the hydration of portland cement and lime and form water insoluble calcium silicates (C-S-H), C4AH13 and aluminate hydrate compounds. Besides fly ash and clay pozzolanas, the cementitious binders contain gypsum anhydrite ( by-product gypsum or natural gypsum) which on addition of water releases SO4 2" ions which further combiness with A12O3 and CaO available in the aqueous phase and form ettringite (C3A.3CaSO4.32H2O). The development of C-S-H, C4AH13 and ettringite compounds have been amply demonstrated by differential thermal analysis (DTA) and scanning, electron microscopy of the hydrated cementitious binder. The interaction of fly ash and clay pozzolana with the moist lime and gypsum to form cementitious materials is shown below: CaO + fly ash + clay pozzolana + H2O -> CaaAlb.CH2O + CaxSiy.2H2O (1) Calcium aluminate Calcium silicate hydrate hydrate Caa Alb.CH2O + CaSO4.2H2O -» C3A.3CaSO4.32H2O (2) Calcium aluminate Gypsum Ettringite hydrate In the above equations a, b, c, x, y and z are the variables that are dependent on the temperature, pressure and molar ratios of the reactants. It may be noted here that transformation of gypsum anhydrite (by-product gypsum or natural gypsum) which is an anhydrite (CaSCU) into gypsum dihydrate is a slow process, the addition of Na2SO4.10H2O activator facilitates rapid transformation of anhydrite into gypsum and also accelerate the interaction of SiO2, A12C>3 and Fe2O3 of fly ash and clay pozzolana to precipitrate cementitious compounds. The following example is given by way of illustration of the present invention and should not be construted to limit the scope of the present invention. Example 1 The sample of fly ash, gypsum anhydrite (fluorogypsum), lime sludge and portland cement were procured from M/s Nasik Thermal Plant, Mumbai, M/s Navin Fluorine Industries, Bhestan, M/s Rashtriya Chemicals & Fertilizers Co. Ltd., Mumbai and Orissa Cement Ltd., Rajgangpur respectively. The sample of clay was collected from Gujarat. These materials were analysed for various chemical constituents (Table 1) as per Indian Standard IS: 1727- 1967, Method of test for pozzolanic materials, Indian Standard 18:1288-1983, Methods of test for mineral gypsum, Indian Standard 18:6932-1973, Methods of test for building limes and Indian Standard 18:4032-1989, Methods of test for chemical analysis of hydraulic cements respectively. The fly ash, calcined clay pozzolana, gypsum anhydrite (fluorogypsum), hydrated lime sludge, portland cement and Na2SO4.10H2O activator were ground to the fineness of 400-520 m /kg, 400-530 m /kg, 350-450 m2/kg, 350-430 m2/kg, 300-330 m2/kg and 350-400 m2/kg (Elaine) respectively. These materials were then blended in different proportions (Table 2)and ground in the ball mill to a fineness of 500-530 m2/kg (Elaine) to produce uniformally mixed cementitious binder. Table -1 Chemical Composition of Fly ash, Clay, gypsum anhydrite (fluorogypsum), Lime Sludge and Portland Cement (Basis - Oven dried) (Table Removed) Table - 2 Mix Composition of Cementitious Binders Based on Fly ash, Calcined clay, gypsum anhydrite (fluorogypsum), (Table Removed) tested and evaluated for various physical properties. The test results are depicted in Table 3. Table - 3 Physical Properties of Cementitious Binder Prepared from Ground Fly ash, Calcined Clay, gypsum anhydrite (fluorogypsum), Hydrated Lime and Portland Cement Physical Properties (Table Removed) The results show that mix composition ^B' i.e. fly ash : calcined clay : gypsum anhydrite (fluorogypsum): hydrated lime : Na2SO4.10H2O :: 50 : 20 : 10 : 20 : 1.0 and mix composition 'D' i.e. fly ash : calcined clay : gypsum anhydrite (fluorogypsum) : hydrated lime : portland cement : Na2SO4.10H2O :: 60 : 5 : 10: 15 : 10 : 1 ( by wt. %) gave maximum compressive strength complying with the strength requirements of BS:6610- 1991. The Cementitious binders were found sound as the cold expansion was within the maximum specified value of 5.0 mm laid down in IS:6909- 1983, specification for super-sulphated cement. Hence, these two mix compositions are recommended for commercialization. The suitability of optimum mix composition of cementitious binders i.e. 'B' and 'D' were tested and evaluated for making masonry mortars. The results are listed in Tables 4 and 5.Data show that masonry mortars 1:3 and 1:4 binder-sand (P.M. 2.20 and P.M. 1.26) have much higher strength and water-retentivity than the conventionally used 1:6, cement-sand mortars and comply with the minimum specified strength of 2.5 and 5.0 N/mm2 at 7 and 28 days and water-retentivity of 60.0 percent laid down in Indian Standard 18:2250-1981, Code of practice for preparation and use of masonry mortars. Table - 4 Properties of Masonry Mortars produced using Cementitious Binder B' Physical Properties Mix Proportion Compressive strength (MPa) Water retentivity (Table Removed) Table - 5 Physical Properties of Cement Mortars produced using Cementitious Binder 'D' (Table Removed) Suitability of cementitious binders 'B' and 'D' was examined as part replacement of portland cement.In this context, concrete cubes(10 cm) were cast according to IS : 516-1991, Methods of tests for strength of concrete using 15% and 25% replacement of portland cement by the cementitious binder, gravel(40% passing 3/8 inch and passing 3/16 inch IS sieves) and Badarpur sand(fmeness modulus 2.2) in the proportions 1:2:4 and l:3:6.The water cement ratio was fixed at 0.5.The concrete cubes were cured in water and tested for compressive strength.The results are given in Table 6. It can Table 6 - Compressive Strength of Concrete SI. Cementitious Mix Proportion (Wt.%) Compressive Strength No. Binder Cement: Binder : Sand : Coarse (MPa) (Table Removed) seen that by replacing the cement with 15.0% and 25.0% by the cementitious binder, the compressive strength of the concrete reduced than the plain 1:2:4 and 1:3:6 concrete. However, 28 days strength of 15.0 and 10.0 MPa are for the concrete 1:2:4 and 1:3:6 respectively given in IS : 456-1988, code of practice for plain and reinforced concrete. Example 2 The samples of fly ash and gypsum anhydrite (fluorogypsum) were procured from M/s Indraprastha. Thermal Power Plant Delhi and M/s Sri Ram Fibres Ltd., Bhewari. The samples of lime sludge, clay and portland cement were collected from the same sources as cited in Example 1. The chemical composition of fly ash and gypsum anhydrite (fluorogypsum) was analysed and is reported in Table 7. Table - 7 Chemical composition of Delhi Fly ash and Bhewari gypsum anhydrite (fluorogypsum) (Table Removed) Data show that fly ash complied with the requirements of Indian Standard 18:3812-1981, specification for fly ash for use as pozzolana and admixture whereas gypsum anhydrite (fluorogypsum) possess main impurity of F (fluoride) and show low pH. The low pH denotes acidic nature of gypsum anhydrite (fluorogypsum) . The acidity of gypsum anhydrite (fluorogypsum) is automatically adjusted when hydrated lime is mixed in the binder. The chemical composition of other materials is same as reported in Table 1 (Example 1). The fly ash, clay pozzolana, gypsum anhydrite (fluorogypsum), hydrated lime sludge, portland cement and Na2SO4.10H2O activator were ground to the fineness of 512 m2/kg, 515 m2/kg, 415 m2/kg, 408 m2/kg, 315 m2/kg and 351 m2/kg (Elaine) respectively. These materials were then blended in different proportions as cited in Table 2 (Example 1) for a period of one hour followed by grinding in the ball mill to a fineness of 516 nT/kg (Elaine) to formulate cementitious binder. The cementitious binders were then tested and evaluated for various properties. The test results are shown in Table 8. Table - 8 Physical Properties of Cementitious binders (Table Removed) Data show that binders 'B' and 'D' conform to the requirements laid down in BS: 6610 - 1991. The binders were sound as they complied with the maximum specified value of 5.0 mm in 18:6909-1983. Hence, these binders corroborate the results obtained in Example 1. These cementitious binders ('B' and 'D') were tested for their suitability for making masonry mortars. The results are shown in Tables 9 and 10. The results conclude that mortar mixes 1:3 and 1:4, binder-sand Table - 9 Properties of Masonry Mortal's produced using Cementitious Binder VB' Based on Delhi Fly ash. (Table Removed) Table -10 Properties of Masonry Mortars produced using Cementitious Binder 'C' Based on Delhi Fly ash. (Table Removed) (P.M. 2.20 and 1.26) show higher strength and higher water retentivity than the 1:6, cement-sand -mortar and complied with the strength requirement of Indian Standard 18:3466-1981. Suitability of cementitious binders 'B' and 'D' was examined as part replacement of portland cement.In this context, concrete cubes(10 cm) were cast according to IS : 516-1991, Methods of tests for strength of concrete using 15% and 25% replacement of portland cement by the cementitious binder, gravel(40% passing 3/8 inch and passing 3/16 inch IS sieves) and Badarpur sand(fmeness modulus 2.2) in the proportions 1:2:4 and l:3:6.The water cement ratio was fixed at 0.5.The concrete cubes were cured in water and tested for compressive strength.The results are given in Table 11. It can Table 11 - Compressive Strength of Concrete SI. Cementitious Mix Proportion (Wt.%) Compressive Strength (Table Removed) seen that by replacing the cement with 15.0% and 25.0% by the cementitious binder, the Compressive strength of the concrete reduced than the plain 1:2:4 and 1:3:6 concrete. However, 28 days strength of 15.0 and 10.0 MPa are for the concrete 1:2:4 and 1:3:6 respectively given in IS : 456-1988, code of practice for plain and reinforced concrete. The main advantages of the present invention are : 1. The composition of cementitious binders consume 50 to 60% fly ash plus 5 to 20% of calcined clay against the maximum specified value of 53.0% fly ash specified in 88:6610-1991. 2. The fly ash, gypsum anhydrite (by-product fluorogypsum) and lime sludge used as raw materials are industrial waste products. 3. The cementitious binders are cheaper than the conventional cements such as portland pozzolana cement or portland slag cement. 4. The production of cementitious binders may be eco-friendly as it will consume sizeable quantities of industrial wastes & may help in their disposal. We claim : 1. A composition for making cementitious binders based on high fly ash content, clay pozzolana and other industrial wastes for use in cement mortar and concrete which comprises: Pulverised fly ash (400 to 520 m2/kg) in the range of 50 to 65 wt. %; gypsum anhydrite ( by-product gypsum or natural gypsum) (350 to 450 m2/kg) in the range of .5 to 15 wt. %; Calcined clay pozzolana (400 to 530 m2/kg) in the range of 5 to 20 wt. %; lime sludge (350 to 430 m2/kg) in the range of 10 to 25 wt. %; Portland cement (300 to 330 m2/kg) in the range of 10 to 15 wt. %; and Sodium Sulphate activator (350 to 400 m2/kg) in the range of 1 to 2 wt.%. 2. A novel composition as claimed in claim 1, wherein the waste by products is selected from pulverized fly ash from thermal power plants, gypsum anhydrite ( by-product gypsum or natural gypsum), lime sludge from sugar, paper and acetylene plants used in formulating the cementitious binders. 3. A novel composition as claimed in claims 1-2, wherein the pozzolanic clay used is obtained by calcining the clay at a temperature in the range 700 to 1000°C for a period of 15 minutes to 200 minutes. 4. A novel composition as claimed in claims 1-3, wherein the lime used is obtained by calcining the lime sludge at a temperature in the range 950 to 1100°C for a period of 15 minutes to 4.0 hours. 5. A novel composition as claimed in claims 1-4, wherein the fly ash used may have SiO2 in the range of 50 to 60 wt.%, A12O3 + Fe2O3 in the range of 20 to 33 wt.%, loss on ignition in the range of 0.5 to 5.0 wt.% and lime reactivity 3.0 to 5.0 N/mm2. 6. A novel composition as claimed in claims 1-5, wherein the gypsum anhydrite (by-product gypsum or natural gypsum), used is having SO3 in the range of 50.0 to 56.0 wt.%, loss on ignition in the range of 0.40 to 0.92 wt.% and fluoride in the range of 1.0 to 2.0 wt.%. 7. A novel composition as claimed in claims 1-6, wherein the clay used is having SiO2 in the range of 40.0 to 50.0 wt.% and A12O3 + Fe2O3 in the range of 35.0 to 40.0 wt.%. 8. A novel composition as claimed in claims 1-7, wherein the lime sludge is having P2O5 and F in the range of 1.0 to 3.5 wt.% and 1.0 to 2.0 wt.% respectively. 9. A novel composition as claimed in claims 1-8, wherein the fly ash used is ground to a fineness of 400 to 520 m2/g (Blaine) in a ball mill or pulverizer. 10. A novel composition as claimed in claims 1-9, wherein chemical activator - Na2SO4.10H2O used is in the range of 1.0 to 2.0 wt.%. 11. A process for the preparation of novel composition which comprises all the ingredients used are first blended in the blender followed by grinding in a ball mill or pulverizer to achieve a fineness of 500 to 530 m2 /kg (Blaine). 12. Cement mortars concrete made from the novel composition as claimed in claims 1-11, by known methods. 13. A novel cementatious binder composition substantially as herein described with reference to the examples.

Full Text

The present invention relates to a "Compositions for Making Cementitious
Binders Based on High Fly ash content, Clay Pozzolana and Other Minerals
or Industrial Wastes for Use in Cement Mortar and Concrete".
The Compositions can be used for preparing cementitious binder
based on fly ash, calcined clay, gypsum anhydrite ( by-product gypsum or
natural gypsum) and lime or lime sludge, portland cement and small
quantity of a chemical activator. The production of cementitious binder will
consume sizeable quantities of industrial solid wastes and may help in
reducing threat to environment.
Fly ash is produced as finely divided by-product from the combustion
of pulverised coal in suspension fired furnaces of thermal, power plants. It is
collected by electrical or mechanical precipitators or cyclones or bag filters.
It is normally, finer than portland cement and comprises of rounded glassy
particles of variable chemicals and mineralogical compositions. The
properties of fly ash show variation and depend upon numerous factors, such
as the composition of coal (bitumenous, sub-bitumenous and lignite coals),
fineness of coal, flame temperature, oxidation conditions and mode of
collection of fly ash. Several countries and organisations have their own
standard specifications and requirements for fly ash to be used as mineral
admixture or as pozzolana. ASTM C 618-89, defines the pozzolana as
"siliceous or siliceous and aluminuous materials which is themselves possess
little or no cementitious value but in finely divided form and in the presence
of moisture chemically react with Ca(OH)2 at ordinary temperature to form
compounds possessing cementitious properties". ASTM C 618-89 classify
the pozzolana into class N, F, C and S. Class N refers to raw or calcined
natural pozzolana such as some diatomacious earths, opline, shales or cherts,
and volcanic or pumicites. Class S refers to processed, pumicites which are
porous forms of volcanic glass and to certain calcined and ground
diatomites, clays & shales. Classs F and C pozzolanas refer to fly ash
derived from the burning of different coals. Physical and chemical properties
of fly ash play an important role in imparting the pozzolanic reactivity and in
the production of cement mortar and concrete. Most of the fly ash particles
are glassy or amorphous. Yet the minerals like quartz, mullite, silimanite,
crysto-bellite, haematite and calcium compounds including calcium sulphate
may be present as crystalline compounds constituting about 15.0 percent by
weight of the fly ash. Some of the carbon in coal particles does not burn
properly and thus fly ashes also possess unburnt carbon. Over 500 million
tonnes of fly ash is produced annually by thermal power plants all over the
world (R.C. Joshi and R.P.Lohtia, Types and Properties of Fly ash, Progress
in Cement & Concrete - Mineral Admixtures in Cement and Concrete, Vol.
4, 1st Edn., 1993, Academia Books International, New Delhi, p. 121). In
India 70 percent power is generated through coal based thermal power plants
which throw 70 million tonnes of fly ash per annum. Not more than 10.0 per
cent of fly ash is being used in India at present. The major reasons for
limited utilization of fly ash may be non-availability of quality grade fly ash
complying with IS:3812 (Part-I)-1981, specification of fly ash for use as
pozzolana in solid form and due to its less reactivity compared to foreign fly
ashes. However, the utilization of fly ash is an important building material
which has been accepted as an engineering fact in the technologies in
advanced countries. Extensive work has been accomplished abroad as well
as in India regarding effective utilization of fly ash in areas such as factory
produced portland pozzolana cement, ready mixed fly ash concrete for use
as structural concrete in the manufacture of precast building products
(S.S.Rehsi, Ready mixed fly ash concrete, Engineers and Planners Journal,
Vol. 2, No. 7, Feb. 1974, National Workshop on Utilization of Fly ash, May
19-20, 1988, Roorkee, pp B-75-B-78); As a part replacement of portland
cement in mortars and concrete (S.S.Rehsi and S.K.Garg, Use of fly ash in
masonry mortars, National Workshop on Utilization of Fly ash, Roorkee,
May 19-20, 1988, pp B-l 11 - B-l 16; Abdun-Nur and A.Edward, Fly ash in
concrete, An Evaluation, Highway Research Board Bullentin, 28th
Washington, D.C., 1961, p. 138; S.S.Reshi and S.K.Garg, Production of
precast concrete building units using fly ash, J. of the Association of
Engineers, India, Vol. 48, No.4, Oct.-Dec. 1973, pp 125-131), Manufacture
of Sintered lightweight fly ash aggregate (S.K.Chopra and Kishan Lai,
Sintered lightweight aggregate from Indian fly ashes, The Indian Concrete J.
Vol. 35, No.5, 1961, pp 150-153), in the production of cellular concrete
(S.K.Chopra, C.A.Taneja and S.P.Tehri, Development of cellular concrete
based on lime and fly ash, Research and Industry, Vol. 13, 1968, pp 189-
191), production of clay fly ash building bricks (C.Raj Kumar, S.C.Aluwalia
and Rattan Lai, Bricks from fly ash - A technical appraisal, National
Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1998, pp A-135-
A-136; J.M.Bhatnagar et. al., National Seminar on New Materials and
Technology in Building Industry, New Delhi, India, July 24-25, 1998, p
123), production of fly ash-sand-lime bricks (Mohan Rai, Dinesh Chandra,
R.L.Gupta and S.K.Jain, Production of calcium silicate bricks from fly ash,
National Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1988, pp
A-59 - A-62) and in road & soil stabilization works (P.K.Dhavan,
N.K.Goswani & N.K.Bhasin, Utilization of fly ash in construction, National
Workshop on Utilization of Fly ash, Roorkee, May 19-20, 1988, pp A-73
A-76; Arjun Das and S.K.Malhotra, Lime stabilized soil as a building
material - Preliminary investigations, N.B.O.J., Vol. 24, Oct. 1979, pp 29-
33). Apart from these applications of fly ash in building sector, the use of fly
ash has been made substantially in the manufacture of cementitious binders
in conjunction with calcined gypsum, cement and chemical retarders (Manjit
Singh and Mridul Garg, Investigations of durable gypsum binder for
building materials, Construction and Building Materials (U.K.), Vol. 6,
No.l, March 1992, pp 52-56; Manjit Singh and Mridul Garg, Studies on the
formation of cementitious compounds using phosphogypsum and fly ash,
NCB Quest (India), Vol. 4, 1991, pp 42-54; Manjit Singh and Mridul Garg,
Phosphogypsum-fly ash cementitious binder-its hydration and strength
development, Cement and Concrete Research (U.S.A.), Vol. 25, No.4, 1995,
pp 752-758; Manjit Singh and Mridul Garg, Alternative binders and
components from industrial by-products, Civil Engineering and Construction
Review (India), Vol. 8, No. 10, October 1995, pp 332-338; Mridul Garg,
Manjit Singh and Rakesh Kumar, Some aspects of the durability of a
phosphogypsum-lime-fly ash binder, Construction and Building Materials
(U.K.), Vol. 10, No.4, 1996, pp 273-279; Manjit Singh and Mridul Garg,
Durability of cementitious binder derived from industrial waste, Materials
and Structure Journal (France), RILEM, Vol. 30, December, 1997, pp 607-
612; Manjit Singh, Phosphogypsum-cement-pozzolana binder for use in
construction work, International Conference on 'Low Cost Housing for
Developing Countries, CBRI, Roorkee, Vol. 1, March 8-12, 1985, pp 233-
237; Manjit Singh and Mridul Garg, Microstructure of glass fibre reinforced
water resistant gypsum binder composites, Cement and Concrete Research
(USA), Vol. 23, 1993, pp 213-220; Manjit Singh and Mridul Garg, An
alternative to timber, The Indian Concrete J., Feb. 1993, pp 78-84. J. Beretka
L. Santaro and G.L. Valenti, New and durable building materials based on
ettringite, Fourth-International Conference on Durability of Building
Materials & Components, Singapore 1987, pp 64-70). In these binders, 15 to
50 per cent fly ash was used both in moist cold blending and hot curing
environments and the durability of systems was established.Thus, binders
based on fly ash have been produced in combination with other wastes as
cited above but very limited work has been done on the activation of fly
ashses. Generally, fly ash is activated by (1) addition of chemical additives
to fly ash concrete (2) mechanical grinding of fly ash and by (3) curing fly
ash concrete at elevated temperature respectively (Caijun, Shi and L.Day
Robert, Cement and Concrete Research, Vol. 25, No.l, 1995, pp 15-21;
G.G.Carett, V.M.Malhotra, C.Bedard. V.De Benedictis, and M. Plumet Proc.
2nd International Conference on Fly ash Silica Fume, Slag and Natural
Pozzolana in Concrete, SP-91, American Concrete Institute, Farmington
Hills, Mich., Vol. 1, 1986, pp 249-272; J.Paya, J.Monjo, M.V.Borrachero
and E.Peris - Mora, Mechanical treatment of fly ashes, Part 1 : Physicochemical
characterization of ground fly ashes, Cement & Concrete Research,
Vol. 25, No. 7, 1995, pp 1469-1479; A katz, Microscopic study of alkaliactivated
fly ash, Cement and Concrete Research, Vol. 28, No.2, 1998, pp
197-208, B.C. Francis et. al., Fly ash based compositions, US Patent 0543
9518, Jan 6, 1993. Activation of fly ash hydrated lime blends (80 and 20
percent by mass) by Na2SO4 or CaCl2.2H2O chemicals at 50°C has been
claimed (Caijun Shi, Pozzolanic reaction and microstructure of chemical
activated lime-fly ash pastes, ACI Materials J., Sept. - Oct. 1998, pp 537 -
545) which establish the understanding of chemical activation of reactivity
of fly ashes. Besides fly ash, several other industrial solid wastes such as
phosphogypsum, fluorogypsum, lime sludges etc. are produced from the
phosphoric acid, hydrofuoric acid, acetylene/sugar/paper industries
respectively. In India over 5.0 million tonnes of phosphogypsum as well as
lime sludge and about 0.2 million tonnes of fluorogypsum are produced
annually which require judiceous disposal and utilization. Enormous work
has been done on these wastes throughout the world regarding their
beneficiation and utilization as potential building material (R.K.Collings,
Evaluation of phosphogypsum for gypsum products, Canadian Institute of
Mining and Metallurgy Bulletin, Vol. 65, Sept. 1972, pp 41-51; Manjit
Singh et. al., An improved process for the purification of phosphogypsum,
Construction and Building Materials (U.K.), Vol. 10., No.6-1996, pp 597-
600; Manjit Singh, Physico-Chemical Studies on Phosphogypsum for Use as
Building Materials, Ph.D Thesis, University of Roorkee, Roorkee, India
1980; I.Masood et. al. High strength activated Lime pozzolana mixture.
National Seminar on Building Materials - Their Science and Technology
New Delhi, 15-16 April 1982; 11 B, pp 1-4. Several cements and
cementitious materials are being produced through out the world using fly
ash. In India fly ash being used in the range of 10 to 25 percent (by mass) in
the manufacture of portland pozzolana cement as per 18:1489-1976,
Specification for Portland pozzolana cement. The properties of PPC are at
par with the properties of ordinary portland cement (OPC) of 33 grade as per
18:269-1989, Specification for 33 grade ordinary portland. The quantity of
fly ash differs from country to country for making PPC. Various European
standards have now permitted large quantities of fly ash to be blended with
cement for its uses in construction activities. In BS:6610-1991, Specification
for pozzolanic fuel ash cement; the fly ash has been allowed to be
incorporated in the range 41 to 53 percent and the compressive strength of
cement prescribed is > 12.0 and 22.5 N/mm2 at 7 and 28 days respectively.
In continuation of these cements, two cementitious binders (1) containing 60
percent fly ash, 5.0 percent calcined clay pozzolana, 10.0 percent each of
gypsum anhydrite (fluorogypsum, by-product gypsum or natural gypsum)
and portland cement, 15.0 percent calcined hydrated lime sludge and 1.0
percent sodium sulphate (Na2SO4.10H2O) activator and (2) the binder
containing 50.0 percent fly ash, 20.0 percent calcined clay pozzolana, 10.0
percent gypsum anhydrite ( by-product gypsum or natural gypsum), 20.0
percent calcined hydrated lime sludge and 1.0 percent sodium sulphate
activator have been produced at CBRI, Roorkee conforming to strength
requirements (7 and 28 days) of BS:6610-1991, specification for pozzolanic
pulverized fuel ash cement have been claimed for the first time.
The development of cementitious binders from fly ash and other
industrial wastes, such as gypsum anhydrite (by-product gypsum or natural
gypsum), calcined clay, hydrated lime sludge to give strength and other
characteristics similar to strength requirements as per 18:6610-1991 are the
novel features which were not possible to achieve earlier just by blending
gypsum anhydrite ( by-product gypsum or natural gypsum) or hydrated
lime with the fly ash.
The main objective of the present invention is to provide a
Composition for making cementitious binders based on high fly ash
content, clay pozzolana and other industrial wastes.
Another object is to provide cement mortar and concrete made from
the novel compositions containing industrial solid wastes.
Accordingly, the present invention provides a 'composition for
making cementitious binders based on high fly ash content, clay pozzolana
and other industrial wastes for use in cement mortar and concrete which
comprises:
Pulverised fly ash (400 to 520 m2/kg) in the range of 50 to 65 wt. %;
gypsum anhydrite ( by-product gypsum or natural gypsum) (350 to 450
m2/kg) in the range of 15 to 15 wt. %; Calcined clay pozzolana (400 to
530 m2/kg) in the range of 5 to 20 wt. %; lime sludge (350 to 430
m2/kg) in the range of 10 to 25 wt. %; Portland cement (300 to 330
m2/kg) in the range of 10 to 15 wt. %; and Sodium Sulphate activator
(350 to 400 m2/kg) in the range of 1 to 2 wt.%.
In an embodiment of the present invention, fly ashes of lime reactivity
3.0 to 5.0 N/mm2 may be used to form binders.
In another embodiment of the present invention the pozzolanic clay
may be obtained by calcining the clay at a temperature in the range of 700 to
1000°C for a period of 15 minutes to 200 minutes.
In yet another embodiment of the present invention the lime may be
produced by calcining the lime sludge /stone at a temperature in the range of
950 to 1100°C for a period of 15 minutes to 4.0 hours.
In yet another embodiment of the present invention, the fly ash may
have SiO2 in the range of 50-60 wt. %, A12O3 + Fe2O3 in the range of 20 to
33 wt.%, loss on ignition, in the range of 0.5 to 5.0 wt. % and lime reactivity
3.0 to 5.0 N/mm2.
In still another embodiment of the present invention the gypsum
anhydrite (by-product gypsum or natural gypsum) may have SO3 in the
range of 50 to 56 wt. %, loss on ignition in the range of 0.40 to 0.92 wt.%,
and fluoride in the range of 1.0 to 2.0 wt.%.
In yet another embodiment of the present invention the pozzolanic
clay may have SiO2 in the range of 40 to 50 wt.%, and A12O3 + Fe2O3 in the
range of 35.0 to 40.0 wt.%.
In yet another embodiment of the present invention the lime sludge
may have cotamination of P2O5 and F in the range of 1.0 to 3.5 wt.% and 1.0
to 2.0 wt. % respectively.
In still another embodiment of the present invention, the fly ash may
be ground to a fineness of 400 to 520 m2/kg (Blaine) in a ball mill or a
pulverizer.
In still another embodiment of the present invention commercial grade
chemical activator such as sodium sulphate (Na2SO4. 10H2O) may be used.
In yet another embodiment of the present invention, various
consituents are first uniformally blended in a blender followed by grinding
in a ball mill or pulverizer to achieve a fineness of 500 to 530 m2/kg
(Blaine).
All these ingredients are mixed parts by weight except
activator which is mixed by wt.% of the total wt. of the binder.
Accordingly, the present invention provides composition of
cementitious binders which can be produced by intimately mixing 50 to 60
percent ground fly ash (400 to 520 m2/kg) (Blaine) with the ingredients such
as 5 to 20% calcined clay pozzolana (400 to 530 m2/kg, (Blaine) produced at
700 to 1000°C), 10 to 15% gypsum anhydrite ( by-product gypsum or
natural gypsum) (350 to 450 m2/kg (Blaine), and lime sludge (350 to 430
m2/kg (Blaine) calcined at 950 to 1100°C) and 10 - 15% portland cement
(300 to 330 m2/kg (Blaine) and 1 - 2% sodium sulphate activator (350 to 400
m2/kg Blaine) followed by grinding in the ball mill to a fineness of 500 to
530 m2/kg (Blaine) to form uniformally blended binder which is hardened to
give a strong mass through formation of ettringite (C3A.3CaSO4.32H2O),
tobermorite C-S-H and tetracalcium aluminium hydrate (C4AHi3)
conforming to BS:661 0-1 991.
The process for making cementitious binders from fly ash and other
industrial wastes consists of calcining the clay (700 - 1000°C) and lime
sludge (950- 1 100°C) whereby clay is transformed into reactive pozzolana of
high lime reactivity (8-12 N/mm2) and lime sludge into lime. The lime is
converted into hydrated lime by sprinkling l/3rd (by mass) of the water on
the lime. The calcined clay pozzolana and the gypsum anhydrite (by-product
gypsum or natural gypsum) ground to the requisite finenesses are then
blended with ground fly ash (50-60%), portland cement and the sodium
sulphate activator followed by grinding to form cementitious binders.
The fly ash, clay, gypsum anhydrite ( by-product gypsum or natural
gypsum) , lime sludge and portland cement samples are analysed for their
chemical constituents as per standard test procedures and subjected to DTA
and XRD to identify the composition of the materials. The clay pozzolana is
produced by heating the clay sample in a furnace or rotary kiln at 700-
1000°C for a period of 15 minutes to 200 minutes. The lime sludge
(sugar/paper/acetylene industries) is heated at 950-1100°C in a furnace or
rotary calciner for a period of 15 minutes to 4.0 hours to get lime. After
cooling, the calcined lime sludge is crushed to coarser powder and then
slaked. About l/3rd of water by the weight of lime is sprinkled over the lime
powder gradually and is thoroughly mixed. After 15-20 minutes, the
hydration/slakening occurs with heat liberation and the slaking is completed
in a period of one hour. After cooling, the finely divided white hydrated lime
is screened through 300 micron sieve and the coarse fruction is discarded.
The samples of fly ash, calcined clay, gypsum anhydrite (fluorogypsum,byproduct
gypsum or natural gypsum), hydrated lime, portland cement and
Na2SO4.10H2O activator dried at 42 + 2°C are ground to the fineness of 400
to 520 nr/kg, 400 to 530 nr/kg, 350 to 450 nr/kg, 300 to 330 m2/kg and 350
to 400 m2/kg (Elaine) respectively. After grinding, the fly ash, calcined clay,
gypsum anhydrite (fluorogypsum,by-product gypsum or natural gypsum)
hydrated lime, portland cement and Na2SO4.10H2O activator are blended in
two proportions (1) 60% fly ash, 5.0% calcined clay pozzolana, 10.0% each
of gypsum anhydrite (by-product gypsum or natural gypsum), and portland
cement, 15.0% calcined hydrated lime and 1.0% Na2SO4.10H2O activator
and (2) 50% fly ash, 20% clay pozzolana, 10.0% gypsum anhydrite
(fluorogypsum,by-product gypsum or natural gypsum), 20% hydrated lime
and 1.0% Na2SO4.10H2O activator (by wt.%) respectively followed by
grinding in a ball mill to form an uniform cementitious binder. The
cementitious binder is then ready for packing.
The chemistry of cementitious binder is predominently is based on the
reactivity of fly ash and clay pozzolana. Fly ash is a pozzolanic material
which shows reactivity when interacted with lime in presence of water and
produce insoluble stable cementitious products. The reactivity of fly ash is
due to amorphous SiO2, A12O3 and Fe2O3 constituents. Similarly, calcined
clay contains amorphous SiO2 and A12O3 including Fe2O3. The quantities of
these constituents vary with the type of the clay mineral used. The
metastable silicate present in fly ash and clay pozzolana reacts with Ca2+
ions contributed by the hydration of portland cement and lime and form
water insoluble calcium silicates (C-S-H), C4AH13 and aluminate hydrate
compounds. Besides fly ash and clay pozzolanas, the cementitious binders
contain gypsum anhydrite ( by-product gypsum or natural gypsum) which on
addition of water releases SO4
2" ions which further combiness with A12O3
and CaO available in the aqueous phase and form ettringite
(C3A.3CaSO4.32H2O). The development of C-S-H, C4AH13 and ettringite
compounds have been amply demonstrated by differential thermal analysis
(DTA) and scanning, electron microscopy of the hydrated cementitious
binder. The interaction of fly ash and clay pozzolana with the moist lime and
gypsum to form cementitious materials is shown below:
CaO + fly ash + clay pozzolana + H2O ->
CaaAlb.CH2O + CaxSiy.2H2O (1)
Calcium aluminate Calcium silicate hydrate
hydrate
Caa Alb.CH2O + CaSO4.2H2O -» C3A.3CaSO4.32H2O (2)
Calcium aluminate Gypsum Ettringite
hydrate
In the above equations a, b, c, x, y and z are the variables that are
dependent on the temperature, pressure and molar ratios of the reactants. It
may be noted here that transformation of gypsum anhydrite (by-product
gypsum or natural gypsum) which is an anhydrite (CaSCU) into gypsum
dihydrate is a slow process, the addition of Na2SO4.10H2O activator
facilitates rapid transformation of anhydrite into gypsum and also accelerate
the interaction of SiO2, A12C>3 and Fe2O3 of fly ash and clay pozzolana to
precipitrate cementitious compounds.
The following example is given by way of illustration of the present
invention and should not be construted to limit the scope of the present
invention.
Example 1
The sample of fly ash, gypsum anhydrite (fluorogypsum), lime sludge
and portland cement were procured from M/s Nasik Thermal Plant, Mumbai,
M/s Navin Fluorine Industries, Bhestan, M/s Rashtriya Chemicals &
Fertilizers Co. Ltd., Mumbai and Orissa Cement Ltd., Rajgangpur
respectively. The sample of clay was collected from Gujarat. These
materials were analysed for various chemical constituents (Table 1) as per
Indian Standard IS: 1727- 1967, Method of test for pozzolanic materials,
Indian Standard 18:1288-1983, Methods of test for mineral gypsum, Indian
Standard 18:6932-1973, Methods of test for building limes and Indian
Standard 18:4032-1989, Methods of test for chemical analysis of hydraulic
cements respectively.
The fly ash, calcined clay pozzolana, gypsum anhydrite
(fluorogypsum), hydrated lime sludge, portland cement and Na2SO4.10H2O
activator were ground to the fineness of 400-520 m /kg, 400-530 m /kg,
350-450 m2/kg, 350-430 m2/kg, 300-330 m2/kg and 350-400 m2/kg (Elaine)
respectively. These materials were then blended in different proportions
(Table 2)and ground in the ball mill to a fineness of 500-530 m2/kg (Elaine)
to produce uniformally mixed cementitious binder.
Table -1 Chemical Composition of Fly ash, Clay, gypsum anhydrite
(fluorogypsum), Lime Sludge and Portland Cement (Basis -
Oven dried)
(Table Removed)
Table - 2 Mix Composition of Cementitious Binders Based on Fly ash,
Calcined clay, gypsum anhydrite (fluorogypsum),
(Table Removed)

tested and evaluated for various physical properties. The test results are
depicted in Table 3.
Table - 3 Physical Properties of Cementitious Binder Prepared from
Ground Fly ash, Calcined Clay, gypsum anhydrite
(fluorogypsum), Hydrated Lime and Portland Cement
Physical Properties
(Table Removed)
The results show that mix composition ^B' i.e. fly ash : calcined clay :
gypsum anhydrite (fluorogypsum): hydrated lime : Na2SO4.10H2O :: 50 : 20
: 10 : 20 : 1.0 and mix composition 'D' i.e. fly ash : calcined clay : gypsum
anhydrite (fluorogypsum) : hydrated lime : portland cement :
Na2SO4.10H2O :: 60 : 5 : 10: 15 : 10 : 1 ( by wt. %) gave maximum
compressive strength complying with the strength requirements of BS:6610-
1991. The Cementitious binders were found sound as the cold expansion
was within the maximum specified value of 5.0 mm laid down in IS:6909-
1983, specification for super-sulphated cement. Hence, these two mix
compositions are recommended for commercialization.
The suitability of optimum mix composition of cementitious binders
i.e. 'B' and 'D' were tested and evaluated for making masonry mortars. The
results are listed in Tables 4 and 5.Data show that masonry mortars 1:3 and
1:4 binder-sand (P.M. 2.20 and P.M. 1.26) have much higher strength and
water-retentivity than the conventionally used 1:6, cement-sand mortars and
comply with the minimum specified strength of 2.5 and 5.0 N/mm2 at 7 and
28 days and water-retentivity of 60.0 percent laid down in Indian Standard
18:2250-1981, Code of practice for preparation and use of masonry mortars.
Table - 4 Properties of Masonry Mortars produced using Cementitious
Binder B'
Physical Properties
Mix Proportion Compressive strength (MPa) Water retentivity
(Table Removed)

Table - 5 Physical Properties of Cement Mortars produced using
Cementitious Binder 'D'
(Table Removed)
Suitability of cementitious binders 'B' and 'D' was examined as part
replacement of portland cement.In this context, concrete cubes(10 cm) were
cast according to IS : 516-1991, Methods of tests for strength of concrete
using 15% and 25% replacement of portland cement by the cementitious
binder, gravel(40% passing 3/8 inch and passing 3/16 inch IS sieves) and
Badarpur sand(fmeness modulus 2.2) in the proportions 1:2:4 and l:3:6.The
water cement ratio was fixed at 0.5.The concrete cubes were cured in water
and tested for compressive strength.The results are given in Table 6. It can
Table 6 - Compressive Strength of Concrete
SI. Cementitious Mix Proportion (Wt.%) Compressive Strength
No. Binder Cement: Binder : Sand : Coarse (MPa)
(Table Removed)

seen that by replacing the cement with 15.0% and 25.0% by the cementitious
binder, the compressive strength of the concrete reduced than the plain 1:2:4
and 1:3:6 concrete. However, 28 days strength of 15.0 and 10.0 MPa are for
the concrete 1:2:4 and 1:3:6 respectively given in IS : 456-1988, code of
practice for plain and reinforced concrete.
Example 2
The samples of fly ash and gypsum anhydrite (fluorogypsum) were
procured from M/s Indraprastha. Thermal Power Plant Delhi and M/s Sri
Ram Fibres Ltd., Bhewari. The samples of lime sludge, clay and portland
cement were collected from the same sources as cited in Example 1. The
chemical composition of fly ash and gypsum anhydrite (fluorogypsum) was
analysed and is reported in Table 7.
Table - 7 Chemical composition of Delhi Fly ash and Bhewari gypsum
anhydrite (fluorogypsum)
(Table Removed)

Data show that fly ash complied with the requirements of Indian
Standard 18:3812-1981, specification for fly ash for use as pozzolana and
admixture whereas gypsum anhydrite (fluorogypsum) possess main impurity
of F (fluoride) and show low pH. The low pH denotes acidic nature of
gypsum anhydrite (fluorogypsum) . The acidity of gypsum anhydrite
(fluorogypsum) is automatically adjusted when hydrated lime is mixed in
the binder. The chemical composition of other materials is same as reported
in Table 1 (Example 1).
The fly ash, clay pozzolana, gypsum anhydrite (fluorogypsum),
hydrated lime sludge, portland cement and Na2SO4.10H2O activator were
ground to the fineness of 512 m2/kg, 515 m2/kg, 415 m2/kg, 408 m2/kg, 315
m2/kg and 351 m2/kg (Elaine) respectively. These materials were then
blended in different proportions as cited in Table 2 (Example 1) for a period
of one hour followed by grinding in the ball mill to a fineness of 516 nT/kg
(Elaine) to formulate cementitious binder. The cementitious binders were
then tested and evaluated for various properties. The test results are shown in
Table 8.
Table - 8 Physical Properties of Cementitious binders
(Table Removed)

Data show that binders 'B' and 'D' conform to the requirements laid
down in BS: 6610 - 1991. The binders were sound as they complied with the
maximum specified value of 5.0 mm in 18:6909-1983. Hence, these binders
corroborate the results obtained in Example 1.
These cementitious binders ('B' and 'D') were tested for their
suitability for making masonry mortars. The results are shown in Tables 9
and 10. The results conclude that mortar mixes 1:3 and 1:4, binder-sand
Table - 9 Properties of Masonry Mortal's produced using Cementitious
Binder VB' Based on Delhi Fly ash.
(Table Removed)

Table -10 Properties of Masonry Mortars produced using Cementitious
Binder 'C' Based on Delhi Fly ash.
(Table Removed)

(P.M. 2.20 and 1.26) show higher strength and higher water retentivity than
the 1:6, cement-sand -mortar and complied with the strength requirement of
Indian Standard 18:3466-1981.
Suitability of cementitious binders 'B' and 'D' was examined as part
replacement of portland cement.In this context, concrete cubes(10 cm) were
cast according to IS : 516-1991, Methods of tests for strength of concrete
using 15% and 25% replacement of portland cement by the cementitious
binder, gravel(40% passing 3/8 inch and passing 3/16 inch IS sieves) and
Badarpur sand(fmeness modulus 2.2) in the proportions 1:2:4 and l:3:6.The
water cement ratio was fixed at 0.5.The concrete cubes were cured in water
and tested for compressive strength.The results are given in Table 11. It can
Table 11 - Compressive Strength of Concrete
SI. Cementitious Mix Proportion (Wt.%) Compressive Strength
(Table Removed)
seen that by replacing the cement with 15.0% and 25.0% by the cementitious
binder, the Compressive strength of the concrete reduced than the plain 1:2:4
and 1:3:6 concrete. However, 28 days strength of 15.0 and 10.0 MPa are for
the concrete 1:2:4 and 1:3:6 respectively given in IS : 456-1988, code of
practice for plain and reinforced concrete.
The main advantages of the present invention are :
1. The composition of cementitious binders consume 50 to 60% fly ash
plus 5 to 20% of calcined clay against the maximum specified value
of 53.0% fly ash specified in 88:6610-1991.
2. The fly ash, gypsum anhydrite (by-product fluorogypsum) and lime
sludge used as raw materials are industrial waste products.
3. The cementitious binders are cheaper than the conventional cements
such as portland pozzolana cement or portland slag cement.
4. The production of cementitious binders may be eco-friendly as it will
consume sizeable quantities of industrial wastes & may help in their
disposal.

We claim :
1. A composition for making cementitious binders based on high fly ash
content, clay pozzolana and other industrial wastes for use in cement mortar
and concrete which comprises:
Pulverised fly ash (400 to 520 m2/kg) in the range of 50 to 65 wt. %; gypsum anhydrite ( by-product gypsum or natural gypsum) (350 to 450 m2/kg) in the range of .5 to 15 wt. %; Calcined clay pozzolana (400 to 530 m2/kg) in the range of 5 to 20 wt. %; lime sludge (350 to 430 m2/kg) in the range of 10 to 25 wt. %; Portland cement (300 to 330 m2/kg) in the range of 10 to 15 wt. %; and Sodium Sulphate activator (350 to 400 m2/kg) in the range of 1 to 2 wt.%.
2. A novel composition as claimed in claim 1, wherein the waste by
products is selected from pulverized fly ash from thermal power plants,
gypsum anhydrite ( by-product gypsum or natural gypsum), lime sludge
from sugar, paper and acetylene plants used in formulating the
cementitious binders.
3. A novel composition as claimed in claims 1-2, wherein the pozzolanic
clay used is obtained by calcining the clay at a temperature in the range
700 to 1000°C for a period of 15 minutes to 200 minutes.
4. A novel composition as claimed in claims 1-3, wherein the lime used is
obtained by calcining the lime sludge at a temperature in the range 950 to
1100°C for a period of 15 minutes to 4.0 hours.
5. A novel composition as claimed in claims 1-4, wherein the fly ash used
may have SiO2 in the range of 50 to 60 wt.%, A12O3 + Fe2O3 in the range

of 20 to 33 wt.%, loss on ignition in the range of 0.5 to 5.0 wt.% and lime reactivity 3.0 to 5.0 N/mm2.
6. A novel composition as claimed in claims 1-5, wherein the gypsum anhydrite (by-product gypsum or natural gypsum), used is having SO3 in the range of 50.0 to 56.0 wt.%, loss on ignition in the range of 0.40 to 0.92 wt.% and fluoride in the range of 1.0 to 2.0 wt.%.
7. A novel composition as claimed in claims 1-6, wherein the clay used is having SiO2 in the range of 40.0 to 50.0 wt.% and A12O3 + Fe2O3 in the range of 35.0 to 40.0 wt.%.
8. A novel composition as claimed in claims 1-7, wherein the lime sludge is having P2O5 and F in the range of 1.0 to 3.5 wt.% and 1.0 to 2.0 wt.% respectively.
9. A novel composition as claimed in claims 1-8, wherein the fly ash used is ground to a fineness of 400 to 520 m2/g (Blaine) in a ball mill or pulverizer.
10. A novel composition as claimed in claims 1-9, wherein chemical activator - Na2SO4.10H2O used is in the range of 1.0 to 2.0 wt.%.
11. A process for the preparation of novel composition which comprises all the ingredients used are first blended in the blender followed by grinding in a ball mill or pulverizer to achieve a fineness of 500 to 530 m2 /kg (Blaine).
12. Cement mortars concrete made from the novel composition as claimed in claims 1-11, by known methods.

13. A novel cementatious binder composition substantially as herein described with reference to the examples.

Documents:

1086-del-2002-abstract.pdf

1086-DEL-2002-Claims-(24-09-2008).pdf

1086-del-2002-claims.pdf

1086-DEL-2002-Correspondence-Others-(24-09-2008).pdf

1086-del-2002-correspondence-others.pdf

1086-del-2002-correspondence-po.pdf

1086-del-2002-description (complete).pdf

1086-DEL-2002-Form-1-(24-09-2008).pdf

1086-del-2002-form-1.pdf

1086-del-2002-form-18.pdf

1086-DEL-2002-Form-2-(24-09-2008).pdf

1086-del-2002-form-2.pdf

1086-DEL-2002-Form-3-(24-09-2008).pdf

1086-del-2002-form-3.pdf

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Patent Number

226275

Indian Patent Application Number

1086/DEL/2002

PG Journal Number

01/2009

Publication Date

02-Jan-2009

Grant Date

16-Dec-2008

Date of Filing

30-Oct-2002

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	MANJIT SINGH	CENTRAL BUILDING RESEARCH INSTITUTE, ROORKEE.
2	MRIDUL GARG	CENTRAL BUILDING RESEARCH INSTITUTE, ROORKEE.
3	CHAMAN LAL VERMA	CENTRAL BUILDING RESEARCH INSTITUTE, ROORKEE.
4	KRISHNA KUMAR SOMANI	SOMA PAPERS AND INDUSTRIES LTD. MUMBAI.

PCT International Classification Number

C04B 28/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA