Developing a Bushfire Resistant, Lightweight and Loadbearing Masonry Block Using Pumice Fine Aggregate

Abstract This paper presents results of an experimental study about developing a lightweight and loadbearing masonry block with enhanced bushfire-resistant characteristics by using pumice fine aggregate. First, the chemical, physical and thermal properties of the pumice aggregate were examined. Then, cement mixes for masonry blocks consisting of one cement—sand mix, taken as the control mix and three different cement—pumice mixes that replace sand in the control mix with pumice fine aggregate at varying percentages of 100%, 80% and 60%, were developed by using absolute volume method. Slump and fresh density of these cement mixes and hardened properties such as density, compressive strength and water absorption were measured while bushfire resistance and building fire resistance were examined using the developed masonry blocks against standard fire exposure for 30 and 180 min, respectively. The results from this study showed that the highest density and compressive strength were obtained by the control mix, but masonry blocks made of the control mix showed the lowest bushfire and building fire resistances. In contrast, the bushfire and building fire resistances of masonry blocks made of the cement—pumice mixes were relatively higher, and they satisfied required density and compressive strength for lightweight loadbearing masonry units. Further, the obtained results were compared with a previously developed lightweight masonry block using expanded perlite fine aggregate and the new masonry blocks made with 80% of pumice fine aggregate have shown to be the most suitable for use in the walls of bushfire shelters and other buildings in bushfire prone areas.