PEMANFAAT POZOLAN ALAM SEBAGAI BAHAN BAKU DALAM REKAYASA TEKNOLOGI BETON DI KABUPATEN PACITAN

Abstract

Numbers of Active Mountain in Indonesia make it have an abundant deposit of Pozzolan soil. Pozzolans are already known in Indonesia as a material combined with calcium hydroxide, but the exploitation on this material is not optimal yet and need special treatment to make a new technology. An alternative material have been tested which is that material will be applicate to the place of Portland cement role. The new alternative material is soil from Tulakan-Pacitan-East Java and will be role as Portland cement in certain quantity on concrete mix. Tulakan soil containing compounds that are needed in forming of conventional cement, there are CaO, SiO2, Al2O3, and Fe2O3. The Tulakan soil containing siliceous and aluminous materials will reacts with calcium hydroxide in the presence of water. This forms compounds possessing cementitious properties at room temperature which have the ability to set underwater. Lack of CaO can be satisfied by the addition of lime. Composition of Tulakan soil with the addition of lime to the mixture is (10% of lime + 0%, 5%, 10%, 15%, 20% of Tulakan soil) of the amount of cement used, with five test specimens for each variation of the mixture. Mix concrete design using the design method according to SNI. Water cement ratio used is 0.5. The objects are test on the 28th day. The replacement with 5% Tulakan soil + 10% lime, the compressive strength increased from 9.092% to 31.689 MPa. On the replacement of 10% Tulakan soil + 10% lime, becomes 32.632 MPa of compressive strength, up 12.338% of normal concrete. For the replacement of 15% Tulakan soil + 10% lime, compressive strength up to 31.877 MPa or 9.739% of normal concrete. Then the replacement of 20% tulakan soil + 10% lime, an increase in compressive strength of 9.415% to 31.783 MPa. So, the optimum of compressive strength is 32.632 MPa, occurred on the replacement of concrete with 10% of Tulakan soil + 10% of lime.