EFFECT OF MIXING CEMENT WITH RICE STRAW TO USING AS BUILDING BRICKS

Abstract

The purpose of this research was to investigate the effects of mixing cement with rice straw on brick making. Two particles size of rice straw were used namely small rice straw chops and large chops. Three formation pressures were used (by handle, 1.3 and 2.5 MPa). Four different ratios of cement were used (35, 45, 60, and 75%). The quality of the bricks was evaluated through the measurements of bulk density, thermal conductivity, water absorption percentage, expansion percentage and compressive strength. The obtained data showed that increasing of cement percentage lead to increase bulk density for both small and large rice straw chops, and increasing formation pressure lead to increase bulk density for both small and large rice straw chops, and the values of bulk density were higher at small chops than large chops. The minimum value of bulk density was 0.29 g/cm3 at pressing by handle and mixture percentage of 35% for large chops, the maximum value was 1.242 g/cm3 at 2.5 MPa and mixture percentage of 75% for large chops. The minimum value of thermal conductivity was 0.062 W/m.°c at pressing by handle and mixture percentage of 35% for small chops, the maximum value was 0.204 W/m.°c at 2.5 MPa and mixture percentage of 75% for small chops. Water absorption decreased with increasing of cement percentage for both small and large rice straw chops, and increasing formation pressure lead to decrease water absorption for both small and large rice straw chops, and water absorption percentage increases with the increase of absorption time T (h). The values of water absorption percentage were higher at large chops than small chops. The minimum value of water absorption percentage was 32.06 % after 1 h at 2.5 MPa and mixture percentage of 75% for small chops. The maximum value of water absorption percentage was 195.13 % after 3 h at pressing by handle and mixing ratio of 35% for small chops. Expansion percentage decreased with increasing of cement percentage for both small and large rice straw chops, and increasing formation pressure lead to increase expansion percentage for both small and large rice straw chops. The values of expansion percentage were higher at large chops than small chops. The minimum value of expansion percentage was 0.70 % at pressing by handle and mixture percentage of 75% for small chops; the maximum value was 44.20 % at 2.5 MPa and mixture percentage of 35% for large chops. Compressive strength increases with increasing of cement percentage for both small and large rice straw chops. The values of compressive strength were higher at small chops than large chops. The minimum value was 1.75 at pressing by handle and mixture percentage of 35% for small chops, the maximum value of compressive strength was 182.15 kg/cm2 at 2.5 MPa and mixture percentage of 75% for small chops.