The Effect of Fineness Modulus of Fine Aggregate (sand) on Concrete Compressive Strength
Concrete is a buildings material made from a mixture of cement, sand, broken stone or gravel, and water. The fineness modulus is one of the physical properties of fine aggregates (sand). The Fineness Modulus (FM) of fine aggregates (sand) is an empirical figure obtained by adding the total percentage of the sample of a sand retained on each of a specified series of sieves and dividing the sum by 100. The fineness modulus of sand differs for each sand quarry. The purpose of this research is to analyze the effect of fineness modulus of fine aggregate (sand) on concrete compressive strength. The sand quarry taken in this study are from three sand quarry in Aceh Tamiang District. They are Johar quarry, Tanjung Karang quarry, and Alur Bamban quarry. The specimens of concrete used in the form of the cube measuring 150x150x150 mm amounted to 36 specimens. The compressive strength of concrete (fc') required is 21 MPa or K-250 with w/c ration 0.5. Concrete mix design using American Concrete Institute (ACI) method. The results showed that the fineness modulus of sand strongly influence the compressive strength of concrete. The classification of sand type is differentiated based on the results of fineness modulus test on each sand quarry. Sand fineness modulus (FM) of Johar quarry is 3.66 called medium sand (zone 2). Sand fineness modulus of
Tanjung Karang quarry is 3.15 called mild sand (zone 3). And, Sand fineness modulus of Alur Bamban quarry is 2.52 called fine sand (zone 4). concrete compressive strength test results on johar quarry specimen is 21.1 MPa, tanjung karang quarry specimen is 22.1 MPa, and Alur Bamban quarry specimen is 21.5 MPa. Sand fineness modulus does not affect the concrete compressive strenght. The best classification of fine aggregate to increse concrete compressive strenght is mild sand (Tanjung Karang quarry).