Process of andesite stone as material of cement substitution in making paving block

Abstract

This study was conducted to determine the effect of andesite stone substitution on compressive strength paving block. The percentage of andesite substitution of cement by 10, 20, 30, 40, and 50% by weight of cement. Andesite rock after calcination was characterized using XRD (X-Ray Diffraction). The results of XRD analysis after calcination at the calcination temperature of 900°C have formed muscovite, hedenbergite, and microcline phases. The highest compressive strength of the paving block is found in the substitution of andesite stone of 10% of age 28 days and the lowest compressive strength is in the substitution of andesite 50% of 7 days. This decrease is due to the excessive SiO2 content will bind to the free CaO contained in the cement and form Ca(OH)2. Ca(OH)2 causes reduced paving block density due to the formation of air cavities. Besides the high FAS factor and the gradation of sand size also affect the decrease of compressive strength of paving block.