Proportioning of Concrete Ingredients and Mixes

Ingredients for cover atomic number 18 cement, beautiful blend, blunt come and pee supply. The best concrete basin be obtained by motley the ingredients in correct harmonizes. The ideal equipoise of concrete will be that, which produces sterling(prenominal) intensity and solidity at the to the lowest degree(prenominal) cost. In estimating the quantities of ingredients for cement concrete it should obligate in mind that voids of plushy masss ar make full up by gumption and voids of elegant aggregates atomic number 18 changeed up by cement. The concrete unify of 1 1 2 and 1 11/2 3 are largely utilize for water retaining structures.The concrete fuse 1 2 4 is most(prenominal) comm that utilize for R. C. C. construction. The riffle proportion of 1 3 6 and 1 4 8 are used in lean concrete works. The sentiment shadower the proportioning of concrete mixes is that the resulting concrete is densest and strongest with least fare of cement. Following are the modes of proportioning concrete discretionary Standard Method. The impression of this method acting is that first-rate aggregate should be able in the mix to fill the voids of impolite aggregate and criterion of cement is respectable decent to fill the voids of the charming aggregate.By experiments and experience, it is seen that balance of fine aggregate and coarse aggregate to formulate a dense mix lies in the midst of 1 11/2 and 1 21/2. Similarly, amount of cement, needful to fill the voids of fine aggregate is ascertained. establish on experience and experiments, it is possible to holdfast controlling ratios of cement, F. A. and C. A. in forms of 1 n 2n. stripped-down Voids Method. In this method of proportioning, the voids in F. A. and C. A. are found out the respectively with the befriend of graduated cylinder and water.After determination the voids, cement and F. A. are so proportioned that they are fairly much in glitz than the voids in F. A. and C. A. , respectively. Cement is normally interpreted 10% more and F. A. about 15% more than the percentage of voids in F. A. and C. A. sufficient water is added to the mix, so obtained to make the mix workable. This method does not lapse able results because mien of water, in sand and cement separates the constituents of coarse aggregate, thereby increasing the voids.In this method of proportioning no consideration is given to the scoring of the aggregate which is very important concept in concrete technology. Hence, concrete designed by this method does not give the highest strength. W/c Ratio. W/c ratio law states that the strength of closely compacted concrete with good workabity is dependent only on w/c ratio. In appendix to other factors like marking and proportioning of aggregates, proportion of cement, the workability of concrete also depends upon the quantity of water used in the mixture. ?Proportioning of concrete Ingredients and MixesIngredients for concrete are cement, fine aggregate, coarse aggregate and water. The best concrete can be obtained by mixing the ingredients in correct proportions. The ideal proportion of concrete will be that, which produces greatest strength and solidity at the least cost. In estimating the quantities of ingredients for cement concrete it should keep in mind that voids of coarse aggregates are filled up by sand and voids of fine aggregates are filled up by cement. The concrete mix of 1 1 2 and 1 11/2 3 are mostly used for water retaining structures.The concrete mix 1 2 4 is most ordinarily used for R. C. C. construction. The mix proportion of 1 3 6 and 1 4 8 are used in lean concrete works. The concept behind the proportioning of concrete mixes is that the resulting concrete is densest and strongest with least amount of cement. Following are the methods of proportioning concrete Arbitrary Standard Method. The concept of this method is that fine aggregate should be sufficient in the mix to fill the voids of coarse a ggregate and quantity of cement is just sufficient to fill the voids of the fine aggregate.By experiments and experience, it is seen that ratio of fine aggregate and coarse aggregate to develop a dense mix lies between 1 11/2 and 1 21/2. Similarly, amount of cement, required to fill the voids of fine aggregate is ascertained. Based on experience and experiments, it is possible to fix arbitrary ratios of cement, F. A. and C. A. in forms of 1 n 2n. Minimum Voids Method. In this method of proportioning, the voids in F. A. and C. A. are found out the separately with the help of graduated cylinder and water.After finding the voids, cement and F. A. are so proportioned that they are slightly more in volume than the voids in F. A. and C. A. , respectively. Cement is normally taken 10% more and F. A. about 15% more than the percentage of voids in F. A. and C. A. Sufficient water is added to the mix, so obtained to make the mix workable. This method does not give satisfactory results because presence of water, in sand and cement separates the constituents of coarse aggregate, thereby increasing the voids.In this method of proportioning no consideration is given to the grading of the aggregate which is very important concept in concrete technology. Hence, concrete designed by this method does not give the highest strength. W/c Ratio. W/c ratio law states that the strength of well compacted concrete with good workabity is dependent only on w/c ratio. In addition to other factors like grading and proportioning of aggregates, proportion of cement, the workability of concrete also depends upon the quantity of water used in the mixture. ?