Effect of latex concentrate on the strengths and drying shrinkage of concrete

Abstract

The inclusion of polymeric substances into hydraulic cement mixes aimed at improving strength and durability characteristics is rapidly gaining a world wide acceptance. In this paper, the findings of a study conducted to assess the effect of natural rubber latex (NRL) on the compressive, tensile and flexural strengths as well as drying shrinkage of the conventional concrete were reported. Latex concentrate consisting of several centrifuged clonal latices and dry rubber content (DRC) of about 60.1% is used. While a range of 0 – 6% latex/water ratio was applied in the preparations of strengths specimens, 0 - 15% was however considered for drying shrinkage assessments. Curing systems in accordance with Japan Industrial Standard (JIS) which involves; moist, water and air (M/W/A) exposures were considered. Results have shown that the optimum amount of latex concentrate for both compressive and tensile strengths is about 1% of the mixing water. However, 4 and 10% are required in order to achieve highest flexural strength and lowest drying shrinkage respectively. In fact, there was a continuous decrease in the drying shrinkage with a corresponding increase in the latex/water ratio up to 10%, beyond which the shrinkage increases with increasing latex content. The outcome of the work indicates the level of efficiency and importance of using appropriate quantity of latex concentrate in the modification process of normal concrete and mortar mixes.