A STUDY OF ENGINEERING PROPERTIES OF CONCRETE BLOCKS MIXED WITH OYSTER SHELL WASTE

Abstract

      This research paper studied the engineering properties of concrete blocks mixed with oyster shell waste by substituting the crushed oyster shell waste for rock dust at a rate of 0, 20, 40, 60, 80, and 100 percent by weight, respectively. Concrete blocks were formed in the size of 7 x 19 x 39 centimeters with a 1:6 mixing ratio of cement to rock dust by weight. The blocks were taken into study after 7, 14, and 28 days of curing periods. The objectives of this study are 1) to investigate the physical properties and chemical composition of the crunched oyster shells; 2) to study the physical and mechanical properties of the concrete blocks using crunched oyster shells substituted with rock dust in alignment with the TIS 58-2017 regulation; and 3) to study and analyze the cost of producing non-load-bearing hollow concrete blocks substituted with the oyster shell waste as per the TIS 58-2017 regulation.

     The research results showed that the oyster shell waste consisted of 48.85 percent calcium oxide, a high percentage compared to only 1.8 percent of the rock dust. Since the oyster shell waste had not gone through the firing process, the moisture and free carbon content inside were still high, causing a higher water demand. The specific gravity of rock dust and oyster shell waste was 2.67 and 2.50, while the water absorption values were 3.2 and 9.3, respectively. As for compressive strength values, the concrete blocks with the 20 percent mixing rate, cured for 28 days at the maximum, had the highest compression resistance value of 84 kilograms per square centimeter. The research suggested that producing non-load-bearing hollow concrete blocks with oyster shell waste substitution at a rate of 20 percent, which is in alignment with the TIS 58-2017 regulation, can reduce the cost by 0.49 baht per block,  equivalent to a 9.58 percent reduction of each concrete block.