Sustainable Construction Materials: Mechanical and Durability Performance of Rubberized Concrete Paving Blocks Modified with Silica Fume

The accumulation of waste tires around the world led to a serious environmental problem. In order to solve this issue, an alternative way by using the tires waste in production of sustainable concrete was adopted. However, adding waste rubber has proven less efficient to increase the strength of concrete, hence silica fume is added to enhance rubberized concrete mixtures. This research aims to study the potential of rubberized concrete modified with silica fume as green paving blocks for construction applications. The experimental work included producing rubberized concrete paving blocks made of 10%, 20%, 30%, 40% and 50% rubber aggregate by replacement of sand (volume), in addition, mixes were modified with 10% of silica fume by cement weight. The physical properties included visual inspection and determination of density. The mechanical properties examined are compressive strength, flexural loading, abrasion resistance and ultra-sonic pulse velocity, while for durability water absorption was evaluated. Besides, microstructural inspection was also conducted. The results obtained showed that an inclusion of silica fume significantly improved the properties of rubberized concrete paving blocks up to 20% rubber content. This is supported by UPV results which exhibited a good quality of the produced composite. The modified rubberized paving blocks exhibited a slight increase in flexural strength of 12% and 3% for paving block of 10% and 20% rubber content compared to plain specimens. In addition, the microstructure image showing a good bonding between rubber aggregate particles and cement matrix proofing an efficiency of silica fume to enhance this sustainable composite.