Field of the Invention

[0001] The present invention relates to a concrete mixture. More particularly, the present invention relates to a method for preparing a concrete mixture for less curing.

Background of the Invention

[0002] Concrete is the most essential construction materials, having been used for constructions like bridges, dams, tunnels, buildings, sewerage systems, pavements, runways, roads, and fertiliser plants around the world.

Curing of the concrete plays an important role in strength development and durability of the concrete. In construction industry, curing takes place immediately after concrete placing and finishing, and involves maintenance of desired moisture and temperature conditions, both at depth and near the surface, for extended periods of time. When the surface of the concrete is not kept moist within the first 24 hours after the casting, the evaporation from the exposed horizontal surface results in plastic shrinkage cracks and a weak and dusty surface. Due to inadequate curing, concrete develops plastic shrinkage cracks, thermal cracks, along with a considerable loss in the strength of the surface layer. Therefore, proper curing of the cement is a mandatory step to get a better result. The curing requires large amount of water and labour.

[0003] Also, the concrete is one of the most powerful drivers of global warming as the process of making the concrete mixture emits the large amount Co2. Currently, many attempts are being made to prepare a substitute for this concrete mixture which can reduce the damage to our environment. [0004] An excessive temperature difference between the outer and the inner layers of the concrete results in thermal cracking due to restraint to contraction of the cooling outer layers from the warmer inner concrete.

[0005] When concrete is allowed to freeze before minimum degree of hardening is achieved after casting, the concrete gets permanently damaged due to expansion of water within the concrete as it freezes. This results in irretrievable strength loss and makes concrete porous. Inadequate curing of concrete results in the loss of properties of the surface layer of concrete up to 30-50 mm, not meeting the requirements of the design in terms of durability, strength and abrasion resistance.

[0006] Therefore, there is a need for a method for preparing a concrete mixture for less curing which can overcome one or all existing problem of the concrete mixture.

Objects of the Present Invention

[0007] One objective of the present invention is to provide a method for preparing a concrete mixture for less curing.

[0008] Another object of the present invention is to a method for preparing a concrete mixture for less curing that is economically viable.

[0009] Yet another object of the present invention is to provide a method for preparing a concrete mixture for less curing, which is using material to make the cement mixture that is readily available and easy to use. [0010] Yet another object of the present invention is to provide a method for preparing a concrete mixture for less curing that is environment friendly.

[0011] Yet another object of the present invention is to provide a method for preparing a concrete mixture for less curing that has better results as compared to existing traditional concrete mixture.

[0012] Yet another object of the present invention is to a method for preparing a concrete mixture for less curing that reduces labour cost and water consumption in construction.

Summary of the Invention

[0013] The present invention relates to a method for preparing a concrete mixture for less curing. The method may include preparing a primary mixture by adding Cement, Mineral Admixtures, Coarse aggregate, Fine Aggregate, Crushed sand in a fixed proportion.

[0014] The Cement is used in the range 185.5 kg/m3 and the water is used in the range 156 kgm3.

[0015] The mineral admixture is Ground Granulated Blast Furnace Slag (GGBS). The Ground Granulated Blast Furnace Slag (GGBS) is used in the range 185.5 [0016] The coarse aggregates are a coarse aggregate of two categories viz 12.5 mm down and 20 mm down (any other aggregates size can also be used) used in quantity of 550-600 kg/m3 and 550-600 kg/m3 respectively. In one embodiment the coarse aggregate of 12.5 mm and 20 mm used in quantity of 597 kg/m3 and 593 kg/m3 respectively. Further, the Coarse sand is used in the range 188 kg/m3.

[0017] Further, the method may include adding water to the primary mixture to form a secondary mixture. The water is used in the range 156 kg/m3.

[0018] Further, the method may include adding a chemical admixture to the secondary mixture to increase the retention time of a secondary mixture. By adding the chemical admixture to the secondary mixture forms the concrete mixture. In the present embodiment, the chemical admixture used is the PCE. The PCE is a water reducing agents used here for maintaining a high fluidity via the polymer adsorption to the cement particles. The PCE is used as superplasticizers in concrete mixture. The admixture is polycarboxylate ethers (PCE) used is 4.45 kg/m3 which is in the ratio of 0.5 to 1.2%. The quantity may vary depending upon the concrete mix design requirements. The optimum dosage of Admixture to meet specific requirements is determined by trials using the materials and conditions that will be experienced in use.

[0019] Further, the method may include keeping the concrete mixture to a predefined time to gain maximum compressive strength without curing of the concrete mixture by casting the cement mixture in a required form. [0020] The concrete gains compressive strength of 26-35 n/mn2 in 7 days and 45- 51 n/mn2 in 28 days. The calculations and formulas in the design sheet are used while preparing a mix design. The calculations are carried out by referring the IS Code 10262: 2009.

[0021] Further, a slump test is performed to check the consistency.

Brief description of the drawings

[0022] The advantages and features of the present invention will be understood better with reference to the following detailed description and claims taken in conjunction with the accompanying drawings, wherein like elements are identified with like symbols, and in which:

[0023] FIG. 1 illustrates a flow chart of a method for preparing a concrete mixture for less curing in accordance with the present invention.

A detailed description of the invention

[0024] An embodiment of this invention, illustrating its features, will now be described in detail. The words "comprising, "having, "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items.

[0025] The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “an” and “a” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.

[0026] The present invention relates to a method for the preparation of a concrete mixture for less curing. The method is economically viable and easy to use. The method is environmental friendly. The method has better results as compared to existing traditional concrete. The method reduces water consumption in construction and helps in water saving. The method uses Quarry sand (QS), Rice husk ash (RHA), and Ground granulated blast furnace slag (GGBS) are solid wastes generated by industry, and the concrete sector is always looking for additional cementitious material to reduce the solid waste disposal problem. Partially replacing cement with GGBS and RHA, as well as partially replacing natural sand (NS) with Quarry sand, can be a cost-effective solution to this problem.

[0027] The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms.

[0028] Referring now to figure 1, a flow chart of a method (100) for preparing a concrete mixture for less curing in accordance with the present invention is illustrated. The concrete mixture is used in the construction industry, civil engineering and the like for constructing various entities. The concrete mixture prepared by the method 100 does not require huge amount of water and labour for curing. Specifically, the curing is the process of maintaining an adequate water cement ratio and temperature in concrete from the time the concrete is poured, and until the concrete has met the specified properties of the concrete mix design. The process of curing is carried out after casting of the concrete mixture.

[0029] The method (100) includes the use of dry materials such as Cement, crushed sand, coarse and fine aggregate, and mineral admixtures. An exemplary embodiment of the method for preparing the concrete mixture is explained here with the steps of the method 100. The quantities mentioned are for one cubic meter of concrete and quantity /proportion of these ingredients may vary depending upon the performance and concrete mix design requirements.

[0030] The method (100) starts at step (110).

[0031] At step (120), a primary mixture of cement, coarse aggregates such as crushed rock, coarse aggregates either manufactured or processed or recycled, fine aggregates such as natural sand, crushed sand, manufactured sand, silica sand, recycled sand etc., construction chemicals and/or admixtures as per requirement of the mixture design, fibres such as steel, glass polypropylene etc. as per requirement of the mixture design, mineral admixtures, and/or cementitious materials/mineral admixture such as Ground Granulated Blast-furnace Slag (GGBS), fly ash, rice husk ash, micro silica, silica fume or any secondary cementitious material etc. is prepared. The GGBS is a granulated powder obtained from the slag obtained in the blast furnaces. The fly ash is obtained from coal. All the dry ingredients are mixed to form the primary mixture in a fixed proportion.

[0032] The coarse aggregate of 12.5 mm downsize and 20 mm downsize used in a range between 597 kg/m3 and 593 kg/m3 respectively. The Cement and GGBS is used in the range of 180 to 185.5 kg/m3. The Coarse sand is used in the range of 180 tol88 kg/m3. The water is used in the range of 150 to 156 kg/m3. The chemical admixture used is Poly carboxy late Ether Admixture (PCE), the PCE used is 4.45 kg/m3 which is in the ratio of 0.5 to 1.2%.

[0033] In the present embodiment, the GGBS and the coarse sand used are 185.5 kg/m3 and 188 kg/m3 respectively. Further, the cement added is 185.5 kg/m3. The coarse aggregates are of two types namely a coarse aggregate of 12.5 mm downsize and a coarse aggregate of 20 mm used in quantity of 597 kg/m3 and 593 kg/m3 respectively. Further, the Coarse sand used is 188 kg/m3.

[0034] In another embodiment, the quantity of the coarse aggregate may vary depending upon the concrete mix design requirement. The mixer is made slightly wet before adding the dry ingredients in the mixer.

[0035] At step 130, a fixed quantity of water is added into the secondary mixture to form a final concrete mixture for less curing. The fixed quantity of the water is 156 kg/m3.

[0036] At step 140, the admixture is Polycarboxylate Ether Admixture (PCE) is added, the added amount is 4.45 kg/m3 which is in the ratio of 0.5 to 1.2%. [0037] In the present embodiment, the chemical composition of Polycarboxylate

Ether Admixture (PCE) is:

[0038] In another embodiment, any other chemical admixture such as SNF based, SMF based, any other chemical admixture to improve the concrete performance in any way may be used depending upon the mix design requirements. If required any fibres such as Polypropylene, Glass, steel, synthetic, etc, or any kind of fibres maybe used depending upon the mix design requirements where the quantity may vary depending upon the concrete mix design requirements.

[0039] At step 150, the concrete mixture is kept for a predefined time by casting in a required form to gain maximum compressive strength without curing of the concrete mixture.

[0040] Further, a slump test is performed. The slump test is the most well- known and widely used test method to characterize the workability of fresh concrete. The test, which measures consistency, is used on job sites to determine rapidly whether a concrete batch should be accepted or rejected. The initial slump should collapse. If the required retention time is 2 hours, the mix is left untouched for the next two hours before conducting another slump test.

[0041] After 2 hours, the slump is tested again and the value should roughly be 140- 150mm, which shows the calculated mix design is correct as per the requirement. The method (100) ends at step.

[0042] The method ends at step 160.

[0043] Further, a regular mix design of concrete is replaced with the composition for concrete mixture for less curing in desired proportions depending on the type of structure to be built.

[0044] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.