Title of Invention | AN ADDITIVE FOR USE IN ORDINARY PORTLAND CEMENT CAPABLE OF REPLACING ORDINARY PORTLAND CEMENT |
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Abstract | This invention relates to an additive for use in ordinary portland cement capable of replacing upto 30% of ordinary portland cement comprising flyash and at least a plasticizer and further this invention relates to a process for the preparation of an additive for use in ordinary portland cement and capable of replacing upto 30% of ordinary portland cement comprising in the steps of introducing flyash into a blender, adding at least a plasticizer thereto and ensuring a proper blending said polymer being added in a amount of 0.25 to 0.5% by weight of fly ash. |
Full Text | -2- FIELD OF INVENTION This invention relates to an additive for use in ordinary portland cement. The additive of the present invention constitutes a part replacement of ordinary portland cement. BACKGROUND OF INVENTION It is generally known that ash can be generated from coal, and the ash normally comprises a hard coal ash. Hard coal ash also consists of two portions, namely a first portion of lighter particles and taken out in a dry form through electrostate precipitators. Such a portion is normally the major portion and may comprise in as much as 80% of the flyash. The other portion comes from the bottom of the furnace and is referred to as slag or bottom ash and consists of bigger particles. Yet another ash known in the art is generated from wood and has different chemical constituents to that of fly ash generated from furnaces or boilers. The ash used in the present invention is flyash from furnaces or boilers. -3- Fly ash, a by-product of the combustion of pulverized coal was hitherto considered as a waste material but having excellent pozzolanic properties. This pozzolanic property of fly ash has been utilized for quite some time in construction activities such as ready mix concrete. OBJECTS OF THE INVENTION An object of this invention is to propose an additive for use in ordinary Portland cement. Another object of this invention is to propose an additive for use in ordinary portland cement which provides an increase in strength by 25 to 30% beyond 28 days of curing at low cost. Still another object of this invention is to propose an additive for use in ordinary portland cement which lowers the initial curing time and hence reduces the de-shuttering time Yet another object of this invention is to propose an additive for use in ordinary portland cement which utilizes the waste fly ash of power plant for a more useful purpose. A further object of this invention is to propose an additive for use in ordinary portland cement which is efficient. Further objects and advantages of this invention be more apparent from the ensuing description. -4- DETAILED DESCRIPTION OF INVENTION According to this invention there is provided an additive for use in ordinary portland cement capable of replacing upto 30% of ordinary Portland cement comprising flyash and at least a plasticizer. Further, according to this invention there is provided a process for the preparation of an additive for use in ordinary portland cement and capable of replacing upto 30% of ordinary portland cement which comprises in the steps of: 1.) introducing flyash into a blender 2) adding at least a plasticizer thereto and ensuring a proper blending 3) said polymer being added in an amount of 0.25 to 0.5% by weight of fly ash. In accordance with this invention, a dry powder form of flyash is added as an admixture to ordinary portland cement in conjunction with a super plasticizer. If flyash and super platicizer is added separately to ordinary portland cement, the required results are not achieved. Thus, flyash and super plasticizer is added in the form of an admixture, which has synergism. -5- The flyash is introduced into a blender, such as a ribbon blender, and the plasticizer is added thereto in incremental doses. The quantity of each dose is not of importance, as such as introduction in dose form is only to ensure a proper blending of the plasticizer with flyash. The admixture contains 0.25 to 0.5% by weight of plasticizer to that of flyash. The plasticizer comprises a sulphonic based polymer, such as napthaline sulphonatic based polymer. The admixture may by way of another embodiment also contains 0 to 0.75 of red oxide by weight of flyash. The function of red oxide is limited only to impart a colour. The blending is carried out for a period 30 to 60 minutes. During the process of blending the temperature rises which is responsible for the synergism effect of the admixture. The fly ash used in the additive conforms to IS: 3812-2003 which underlines the limiting value for some specific parameters such as: Loss on ignition: 5.0% (Max); Fineness: 3200 cm2/gm (Min.) Lime reactivity: 45Kg/cm2 (Min.) etc.) of fly ash to be used for mixing with Ordinary Portland Cement (OPC). Laboratory test indicates that when fly ash alone is mixed with OPC early strength of 3 and 7 days is lower than the strength of OPC alone. To improve upon the strength of 3 and -6- 7 days chemical admixtures arc to be added in fly ash. For this purpose, admixtures (super plasticizers) in powder form is developed for making homogenous mixture with fly ash. Fly ash used is of ASTM class F type. The studies were conducted on M-25 and M-30 grade concrete cubes of 1) plain OPC 2) plain OPC replaced with 40% fly ash 3) OPC replaced with varying percentages of developed product. All these cubes were tested for compressive strength as per India standard. Optimization study of product mix with OPC were carried out and found that strength in 3,7,28 and 90 days is increased when 20-30% of OPC is replaced with product and conforms to be cement standard. The advantages of the present invention will be apparent from the various examples as representated in Table 1. -8- It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:- _9- We Claim: 1. An additive for use in ordinary portland cement capable of replacing upto 30% of ordinary portland cement comprising flyash and at least a plasticizer. 2. An additive as claimed in claim 1 wherein said plasticizer is a sulphuric based polymer and preferably naphthalene sulphonatc based polymer. 3. An additive as claimed in claim 1 wherein said admixture is present in an amount of 0.25 to 0.5% by not. 4. An additive as claimed in claim 1 substantially as herein described. 5. A process for the preparation of an additive for use in ordinary portland cement and capable of replacing upto 30% of ordinary portland cement comprising in the steps of: 1) introducing flyash into a blender 2) adding at least a plasticizer thereto and ensuring a proper blending 3) said polymer being added in an amount of 0.25 to 0.5% by weight of fly ash. -10- 6) A process as claimed in claim 5 wherein said plasticizer is a sulphuric based polymer and preferably naphthalene sulphonate based polymer. 7) A process as claimed in claim 5 wherein said admixture is added in dose form to said fly ash. This invention relates to an additive for use in ordinary portland cement capable of replacing upto 30% of ordinary portland cement comprising flyash and at least a plasticizer and further this invention relates to a process for the preparation of an additive for use in ordinary portland cement and capable of replacing upto 30% of ordinary portland cement comprising in the steps of introducing flyash into a blender, adding at least a plasticizer thereto and ensuring a proper blending said polymer being added in a amount of 0.25 to 0.5% by weight of fly ash. |
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Patent Number | 270378 | ||||||||||||||||||
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Indian Patent Application Number | 1163/KOL/2007 | ||||||||||||||||||
PG Journal Number | 51/2015 | ||||||||||||||||||
Publication Date | 18-Dec-2015 | ||||||||||||||||||
Grant Date | 16-Dec-2015 | ||||||||||||||||||
Date of Filing | 23-Aug-2007 | ||||||||||||||||||
Name of Patentee | NTPC LIMITED | ||||||||||||||||||
Applicant Address | 7B PRETORIA STREET, 3RD & 4TH FLOOR, KOLKATA. | ||||||||||||||||||
Inventors:
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PCT International Classification Number | C04B7/42 | ||||||||||||||||||
PCT International Application Number | N/A | ||||||||||||||||||
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