Hydration characteristics of cement-bonded composites made from rattan cane and coconut husk

Abstract

This work examines the effect of CaCl 2 on the hydration of rattan ( Laccosperma secundiflorum ) and coconut ( Cocos nucifera ) husk particles mixed with Portland cement. Hydration tests were conducted in sealed thermally insulated containers using an aggregate/cement/water ratio of 15 g : 200 g : 90.5 ml. CaCl 2 was added at four concentrations (by weight of cement): 0 (control) 1, 2 and 3% for the rattan and coconut husk particles, and at 0 (control) and 3% for a 50:50 mixture (by weight) of rattan and coconut husk. Hydration temperature was monitored on-line over a period of 23 h. The compatibility of both aggregates and their 50:50 mixture with Portland cement was assessed using the parameters of time to maximum hydration temperature, maximum hydration temperature, inhibitory index, and rate of heat generation. Findings showed that without CaCl 2 both aggregates exhibited relatively low level of compatibility with Portland cement, with the rattan particles exhibiting relatively higher degree of inhibition. The addition resulted in reduced setting time (about 60%), increased hydration temperature (50–80%), lower inhibitory index and higher rate of heat generation in all the aggregate/cement mixtures. Recommendations for further research include the identification of the cement-inhibitory chemicals present in coconut husk and rattan and investigations on the mechanism of CaCl 2 interaction with rattan/cement and coconut husk/cement systems.