Characteristic of 'Tulakan' Soil as Natural Pozzolan to Substitute Portland Cement as Construction Material

An alternative material have been tested that will substitute the role of Portland cement. The new alternative material is soil from Tulakan-Pacitan-east java and will be take a role of Portland cement in certain quantity on concrete mix. Tulakan soil has some materials that are needed in forming of conventional cement, that are CaO, SiO2, Al2O3, and Fe2O3. Tulakan soil contains siliceous and aluminous materials which react with calcium hydroxide in the presence of water. This forms compounds possessing cementitious properties at room temperature which have an ability to set underwater. The ratio of Tulakan soil is vary at 10% 15% 20% 25% of Portland cement composition. Fifty concrete cylindric samples have been tested to study the concrete performance at two water cement ratio that are 0.4 and 0.5. As a result, the Tulakan soils effectively substitute the Portland cement, as it can increase the concrete compressive strength up to 3.24% on the percentage of Tulakan soil replacement of 10% - 20%. (C) 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of Department of Civil Engineering, Sebelas Maret University