The compressive strength of concrete using reconstituted stone aggregates

Abstract

The immense quantity of construction projects undertaken in Malta since the 1960's building boom (MEPA, 2012) have exhausted the islands' limited natural resources. Furthermore, considering the relatively short building life expectancy and Malta's ever-changing built fabric, an unsustainable quantity of construction and demolition (C&D) waste is being generated, and going to landfill (Ministry for Sustainable Development, the Environment, and Climate Change, 2014). This has led to the need for recycling of C&D waste, now more than ever. One such proposal for recycling is presented by Buhagiar and Montesin (2010), whereby limestone powder is reconstituted using a cementitious binder and compressional pressure. Locally, taking to account current construction practices, concrete is the most widely used building material, mainly due to its versatility in numerous forms such as in-situ, blockwork and prestressed slabs. One can argue that this has resulted in the deprivation of good quality aggregate and that in the future, concrete suppliers will have to resort to importation in order to be able to produce consistent mixes. Taking the aforementioned aspects into account, this study will investigate the possibility of using reconstituted stone in the production of coarse aggregate. This will be presented by comparatively assessing concrete mixes using reconstituted stone, Globigerina Limestone and Lower Coralline Limestone aggregates, in terms of compressive strength. The research study will also investigate on the possible optimisation of the reconstituted stone aggregates, by using different production methods to yield more desirable aggregate forms. By doing so, a better understanding of how reconstituted stone aggregate can be used in concrete mixes will be deduced. Furthermore, the results obtained will lead to a better understanding of the role that aggregate shape can have in the compressive strength of hardened concrete mixes. This research study will therefore provide initial procedure and testing as a basis on which further research can be carried out with the ultimate focus being to produce an efficient aggregate using reconstituted stone.