Date of Publication :12th April 2017

Abstract: In the modern techniques of the concrete formation there is a lot of interest in increasing amount of microfine particles (<75μm) in aggregates and it is important to understand their effect, including clay and nonclay mineralogy. The present study concentrates on extenuating the influence of fines and microfines on properties of concrete. Generally the sand used in construction industry in major metro cities is of manufactured type, which is obtained by mechanically crushing aggregates in washed or unwashed condition. After washing too some silt impurities remain in the sand and this study is carried out to understand their influence in high performance concrete (HPC). The study is carried out by preparing trial mixes, by adding 1% to 10% silt in washed manufactured sand by weight of sand for M-60 grade of concrete mix. For each trial mix workability, compressive strength, water permeability, rapid chloride penetration test, modulus of Elasticity tests are carried out as per given IS specifications to understand optimum percentage of silt should be present in the concrete, and its effect as the impurities are increased. The study confirmed that the extent of silt content decreases the workability and compressive strength of concrete

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