Workability, strength, and microstructure of high strength sustainable concrete incorporating recycled clay brick aggregate and calcined clay

This study examines the workability, strength, and microstructure of high strength eco-concrete incorporating recycled clay brick aggregate and calcined clay. The study adopted a design mixes proportioning of 1:1:2 by weight at a constant water/binder ratio of 0.25. The waste bricks were crushed, then used to partially substitute sand at levels of 0, 10, 20, 30, 40, and 50%, while calcined clay was used as a pozzolanic supplement was blended with cement at a constant replacement dosage of 10%. The workability was determined using the slump apparatus. The compressive, split tensile and flexural strengths of the hardened samples were evaluated using cubes, cylinders and beams of dimension 100 mm(3), 100 x 200 mm and 100 x 100 x 550 mm, respectively. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX) was conducted on selected samples. Results from the tests indicated a decreasing trend in the workability as the recycled clay brick content increases. Results on the mechanical properties show some levels of improvement in the strength performance and microstructure of the hardened samples containing recycled clay brick aggregate, not beyond 30% at constant calcined clay content. Concrete mix with 10% recycled clay brick aggregate and 10% calcined clay achieved a higher strength compared to the control. This implies that recycled clay brick aggregate can be utilize in the production of structural concrete.

Automated summary

This study investigated the feasibility, strength, and microstructure of high strength eco-concrete with recycled clay brick aggregate and calcined clay. Results showed that the mechanical properties and microstructure of hardened samples containing up to 30% recycled clay brick aggregate improved, but no significant improvement was observed beyond that level when maintaining a constant calcined clay content.