Effects of Cement and Polycarboxylate Ether on the Performance Concrete with High Sludge Content

Abstract

The use of precast concrete structural systems in civil engineering industry in Indonesia will still increase due to the needs of buildings and infrastructure for social and economic development continuously increase from the year to year. In spite of the use of sand accompanied with its suitable sludge content has been widely used as one of the important raw materials for fabricating a precast concrete, the availability of low cost method to obtain a good quality of sand with its sludge content of less than 5% is difficult to find in many regions in the country. The aim of this study was to assess the performance of four cylindrical concrete specimen (CCS) samples by conducting the experiments of testing the natural sand with its high sludge content of 12.7% with using the different ordinary Portland cement (OPC) compositions of 2.5, 5.0, 7.5 and 10.0% and the super-plasticizer of polycarboxylate ether. Two CCS samples of the same composition (1) using the washed sand with its sludge content of 3.7% and (2) without addition of OPC were used as control. The results of compressive strength and slump test verified that the addition of OPC at least by 2.5% into concrete slurry to ensure optimal performance of the CCS samples can be recommended using the natural sand accompanied with its sludge content of 12.7%. This study concluded that the use of local natural sand with its high sludge content as long as the other material compositions used properly could be safe in the fabrication of precast concrete structure for the future civil engineering applications.