Morsy, M.S. & Aglan, H.A. J Mater Sci (2007) 42: 10188. doi:10.1007/s10853-007-1981-3
The effect of perlite loading on the thermal resistivity, solar reflectance and indirect tensile strength of Nanostructured Cementitious Binder is studied. The main objective of this research is to constitute structural lightweight surface compounds and to improve their thermal resistivity and reflectivity with suitable mechanical performances as a surface compound. Portland White Cement (PWC) was partially substituted by nano clay. An optimum blend of type I PWC, and nano clay was determined based on indirect tensile strength. The perlite dosage was added to the optimum cement-nano clay blend at different ratios (10, 20, 30, 40, 50, 60 and 70%) by weight. Superplasticizer with different ratios was used to study the performance of the 70% perlite mixture. The mixes were prepared using water of consistence. The wet compounds were molded in PVC molds and left for 24 h, then demolded and cured in humid air (20 ± 1 °C & 100% RH) for 28 days. The molds are 50 mm in diameter and 27 mm height. The thermal resistivity and indirect tensile strength of the different compounds were evaluated for the cured samples at 7 and 28 days. It was found that the 2% nano clay improved the indirect tensile strength of the neat PWC. As expected the addition of the perlite has reduced the indirect tensile strength but increased the thermal resistivity of the compound by 250%. The increase of perlite loading has not affected the solar reflectivity of the compound. Sokalan HP 80 polycarboxylate ether superplasticizer was successfully used to recover about 50% of the loss in the indirect tensile strength of the newly formulated Nanostructure Perlite Cementious Surface Compounds (NPCSC) containing 70% perlite loading.