The grading and maximum size of aggregates is important parameters in any concrete mix. They affect relative proportions in mix, workability, economy, porosity and shrinkage of concrete etc. Experience has shown that very fine sands or very coarse sands are objectionable – the former is uneconomical, the latter gives harsh unworkable mixes. Thus the object in this paper is to find the best fineness modulus of sand to get the optimum grading of combined aggregate (all-in-aggregate), which is most suitable, and for economy. In general, the grading of aggregates, which do not have a deficiency or excess of any size of aggregate and give a smooth grading curve, produce the most suitable concrete mix. Further a cohesive mix is also desired for the pumped concrete produced by RMC Plant. In the present investigations, effect of the grading of river sand particles has been investigated for a good Concrete mix. Sand has been sorted in three categories i.e. Fine, Medium, and Coarse. These were mixed with coarse aggregate in different proportions so as to keep the combined Fineness Modulus (all-in aggregate) more or less the same. Various proportions of such aggregate are mixed in preparing M 30 grade of Concrete mix. Effect is studied on concrete workability, cube strength, flexural strength and permeability. The results indicate that with the change in fineness of sand, workability gets affected. The details of findings and its effect on compressive and flexural strength and permeability, influencing durability are reported in this paper.
The grading and maximum size of aggregates is important parameters in any concrete mix. They affect relative proportions in mix, workability, economy, porosity and shrinkage of concrete etc. Experience has shown that very fine sands or very coarse sands are objectionable – the former is uneconomical, the latter gives harsh unworkable mixes. Thus the object in this paper is to find the best fineness modulus of sand to get the optimum grading of combined aggregate (all-in-aggregate), which is most suitable, and for economy. In general, the grading of aggregates, which do not have a deficiency or excess of any size of aggregate and give a smooth grading curve, produce the most suitable concrete mix. Further a cohesive mix is also desired for the pumped concrete produced by RMC Plant. In the present investigations, effect of the grading of river sand particles has been investigated for a good Concrete mix. Sand has been sorted in three categories i.e. Fine, Medium, and Coarse. These were mixed with coarse aggregate in different proportions so as to keep the combined Fineness Modulus (all-in aggregate) more or less the same. Various proportions of such aggregate are mixed in preparing M 30 grade of Concrete mix. Effect is studied on concrete workability, cube strength, flexural strength and permeability. The results indicate that with the change in fineness of sand, workability gets affected. The details of findings and its effect on compressive and flexural strength and permeability, influencing durability are reported in this paper.
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