The study on the mechanical properties of sustainable concrete made with recycled and by-products wastes fine aggregates

Extensive research efforts have been undertaken in the past to utilize several kinds of recycled fine aggregates to produce environmentally friendly and more sustainable concrete. In Thailand, various types of bricks, are manufactured for constructing low-rise buildings. There is an urgent requirement to employ recycled fine aggregates made from these bricks to mitigate the disposal and demolition waste generated by the brick industry. Waste by products and ashes are produced and released unintentionally into the environment by combustion or some chemicalprocesses. Eco-friendly and sustainable concrete is a combination of eco-friendly alternatives. In pursuit of this objective, extensive research has been conducted on the use of 4 different types of construction waste (solid clay brick, hollow clay brick, cement clay interlocking brick and demolished recycled concrete), by-products (fly ash) and ash (sugarcane bagasse ash). The recycled fine brick aggregates were substituted for natural fine aggregates at proportions of 0%, 10%, and 20% to formulate the concrete mixes. Furthermore, three distinct types of tests- ompression, splitting, and flexural tests were conducted to evaluate the mechanical properties of the concrete and the water absorption test is also carried out to determine the durability performance of concrete. The compressive and splitting tensile strengths increased with the replacement ratio of recycled aggregates. Moreover, higher compressive and splitting tensile strengths than natural aggregate concrete wasachieved with recycled aggregate concrete attributed to the pozzolanic reaction and the absorption of water by the fine brick aggregate powder, which contribute to the cement's hydration process. However, flexural strengths exhibited an opposite trend, and a higher replacement ratio resulted in lower flexural strength and the water absorption tendency was reduced by incorporating recycled fine aggregates in concrete. In particular, the strength reduction caused by the recycled fine aggregate was due to the exceed amount of fine powder which exerts a diluting effect on the paste resulting in a reduction in strength.