Calcium hydroxide curing for accelerated carbonation testing of high volume fly ash cementitious blends

During wet curing, the alkali concrete compounds, such as calcium hydroxide, can be leached out to the curing solution, due to the pH gradient between concrete and curing solution. In the presence of high volume fly ash cementitious blends, there is a decrease in concrete pH that may further magnify the problem. In this context it was carried out a research in mortars with an original composition of high volume fly ash and calcium hydroxide. These were exposed to water curing and water saturated with calcium hydroxide curing. The results show that the introduction of calcium hydroxide in the curing solution, provides a slightly enhancement of carbonation resistance. Based on the obtained results, the incorporation of calcium hydroxide in the initial composition seems to be useful to develop extra strength to carbonation of high volume of fly ash concrete.The authors wish to acknowledge the team of the Laboratory of Building Materials of University of Minho and the Unit for Research and Development Materials of ESTG from Polytechnic Institute of Viana do Castelo in this research collaboration. Also thank Secil SA, BASF SA and Mota Engil by its kindly supply of cement, superplasticizer and fly ash, respectively. SEM and XRD facilities were funded by FEDER Funds through QREN - Aviso SAIECT- IEC/2/2010, Operacao NORTE-07-0162-FEDER-000050