FRESH AND HARDENED PROPERTIES OF LIGHTWEIGHT CONCRETE MADE WITH PUMICE AS COARSE AGGREGATE.

The purpose of this research is to utilize pumice waste as one of the constituent materials of lightweight concrete. Indonesia, as an archipelagic country, has produced coral pumice waste scattered throughout the country. It is expected that by utilizing pumice waste, lightweight and environmentally friendly concrete may be produced. The tests carried out consisted of three series to examine the effect on the composition of light aggregate (series 1), the effect of light aggregate size (series 2), and the effect of the water to binder ratio (series 3). The composition of light aggregate as a substitute for coarse aggregate by 25%, 50%, 75%, and 100%, with a maximum aggregate size of 20 mm and water to binder ratio of 0.50. In the second series, the maximum size of lightweight aggregate is 9.5 mm, 16 mm, 20 mm, and 25 mm, using 100% lightweight aggregate with water to binder ratio of 0.50. In the third series, the water to binder ratio is varied 0.46, 0.48, and 0.50. A slump test was conducted to check the workability of fresh concrete, while the hardened properties test consisted of compressive strength and mass density. The results of the tests show that using a larger amount of lightweight aggregate reduces compressive strength. The variation of the maximum size of lightweight aggregate shows a pattern that the larger the aggregate size produces lower the compressive strength. The decrease in compressive strength also occurs in concrete with high water to binder ratio. [ABSTRACT FROM AUTHOR]