Title of Invention	"A PROCESS FOR THE PREPARATION OF CELLULAR OR AERATED CONCRETE"
Abstract	This invention relates to a process for the preparation of cellular light weight concrete which comprises in the steps of preparing a mortar in a slurry form containing cement, flyash, aggregates and introducing a foaming agent such as Neopar in the form of a slurry into said mortar, containing 25 to 35% by dry weight of flyash.

Full Text

This invention relates to a process for the preparation of cellular or aerated concrete. A process is known in the art for the preparation of cellular or aerated lightweight concrete. Such a process consists in preparing a mortar in a mixer by the addition of cement, aggregates and water. Compressed air and a chemical agent is injected into the mixer containing the mortar. Several disadvantages are associated with the aforesaid known process of preparation of cellular or aerated lightweight concrete. One such disadvantage is of the high costs due to the presence of a considerable quantity of cement therein. Yet another disadvantage is that such a concrete does not have the required strength properties comparable to ordinary portland cement. Yet another disadvantage is that such a process required the step of autoclaving. Yet another process is known in the art employing the use of fly ash of upto 6 to 8%. A disadvantage is that such a process still envisages a high content of cement, which contributes to the end cost of concrete. An object of this invention is to propose an improved process for the preparation of cellular lightweight concrete. Another object of this invention is to propose a process for the preparation of cellular light weight concrete which obviates the disadvantages associated with those of the prior art. Yet another object of this invention is to propose a process for the preparation of cellular light weight concrete having the required strength properties. Still another object of this invention is to propose a process for the preparation of cellular light weight concrete which can be made into precast elements. According to this invention there is provided a process for the preparation of cellular light weight concrete which comprises in the steps of preparing a mortar in a slurry form containing cement, flyash, aggregates and introducing a foaming agent such as Neopar in the form of a slurry into said mortar, containing 25 to 35% by dry weight of flyash. One of the aspects of the present invention resides in the use of flyash in the preparation of the mortar. As described hereinabove, it is known to use flyash in the preparation of the mortar. However, hitherto only 6 to 8% by weight of flyash was used. As the mortar contained only 6 to 8% of flyash, it was necessary to use substantial quantity of cement and with the result that the presence of flyash did not substantially reduce the end cost of the mortar. In distinction , the present invention envisages the use of flyash to the extent of 25 to 25% based on dry weight. Due to the presence of a substantial amount of flyash, the concrete has a reduced quantity of cement, and whereby the costs are substantially reduced. Simultaneously, the strength of concrete does not substantially reduce. If more than 357. by dry weight of flyash is present in the concrete, the strength property is not suitable. Further, the setting properties are adversely effected. The concrete produced by the process of the present invention has suitable strength properties by employing flyash having a carbon content of 1 to 5X, and preferably 1 to 1.5%. It has been found that the use of flyash having a higher content of carbon, such as 1OX, does adversely affect the strength properties. A foaming agent in the form of a slurry is introduced into concrete. Any suitable stable foaming agent may be employed, and which does not get destroyed during a pumping operation. In the known step of preparation of concrete, it is necessary to vibrate the mortar mixture so as to expel air the re from. In distinction, the mortar is not subjected to any vibration as the presence of air is desirable. However, a foaming agent in the form of a slurry is introduced into the mortar. By way of example, one such foaming agent is Neopor. A concrete prepared by the process of the present invention reflected the following properties. Tests Carried Out Result Obtained Lime reactivity, kg/cm2 42 Fineness (Blaine), cm2 /g 37 28 Compressive strength, as percent of strength of 88.6 corresponding plain cement mortar cubes Drying shrinkage, percent O.O66 Soundness by Autoclave 0.11 expansion, percent A sample of the concrete of the present invention exhibited the following chemical analysis. Test* Carried Out Result Obtained CHEMICAL ANALYSIS Constituents Determined i) Loss on ignition ii) Silica iii) Iron Oxide (Fe 0 ) iv) R2 O3Fe2 O3 /Alumina (Al O v) Calcium Oxide vi) Magnesium Oxide vii) Total Sulphur (SO ) viii) Insoluble residue ix) Alkalies Percent by weight 0.90 60.76 5.49 26.92 1.95 O.7O Traces a) Sodium Oxide (Na2 O) 0.16 b) Potassium OxideCK20) 1.O3 Another sample of the concrete of the present invention exhibited the following chemical analysis. Test Carried Out Result Obtained CHEMICAL ANALYSIS Constituents Determined Percent by weight i) Loss on ignition 1.4O ii) Silica 57.O7 iii) Iron Oxide (F2e3) 9.O2 iv) R 0 Fe O /Alumina (A12 03 ) 27.3O 2323 v) Calcium Oxide 1.17 vi) Magnesium Oxide 1.14 vii) Sulphate (SO3) nil viii) Insoluble residue - ix) Alkalies a) Sodium Oxide (Na2O) O.32 b) Potassium OxideCK20) 1.21 Drying Shrinkage O.O68 percent Tables 1 to 4 show mix designs under column A shows a known mix details and coulmn B shows a mix details of the present invention and when Table 1 is for a mix design to provide a density of 800 kg/m3, Table 2 is for a mix design to provide a density of 1000 kg/m3, Table 3 is for a density of 1200 kg/m3 and Table 4 is for a density of 166 kg/m3. (Table Removed) WE CLAIM: 1. A process for the preparation of cellular light weight concrete which comprises in the steps of preparing a mortar in a slurry form containing cement, flyash which has carbon content of 1 to 1.5% aggregates, characterized in that a foaming agent which is Neopar in the form of a slurry into said mortar, containing 25 to 35% by dry weight of flyash. 2. A process as claimed in claim 1 wherein the foaming agent such a Neopar is pumped into the mortar. 3. A process for the preparation of cellular light weight concrete substantially as herein described and illustrated in the examples.

Documents:

3642-del-1997-abstract.pdf

3642-del-1997-claims.pdf

3642-del-1997-correspondence-others.pdf

3642-del-1997-correspondence-po.pdf

3642-del-1997-description (complete).pdf

3642-del-1997-form-1.pdf

3642-del-1997-form-19.pdf

3642-del-1997-form-2.pdf

3642-del-1997-gpa.pdf