Performance of recycled waste aggregate mixed with crushed glass over a weak subgrade

Aggregate layers, 200–400 mm thick and formed of Construction and Demolition Waste (CDW) alone or mixed with 5%, 10% or 15% of Crushed Waste Glass (CWG), were used to improve the bearing pressure-settlement response of a weak sand bed. The results show bearing pressure of foundation beds with CDW layers is ∼ 1.6–2 times that of beds with the same thickness of sandy soil layers. Employing a 200 mm thick CDW layer (0.67 times of the footing diameter) can deliver a higher bearing pressure than sandy soil twice as thick. Bearing pressure increased with an increase in the CWG content of the CDW-CWG, although the trend flattened when the CWG content exceeded 10%. At a settlement level of 2% and a CDW-CWG layer 400 mm thick (1.33 times of the footing diameter), the improvement in bearing pressure was ∼ 21%, 44% and 52%, respectively with the use of 5%, 10% and 15% CWG as compared with no CWG. Adding CWG to CDW enables the thickness of the waste aggregate layer to be reduced by at least 25% while still increasing the system’s bearing pressure. It is concluded that CDW and CWG could beneficially aid foundation construction at the same time as reducing the environmental consequences of waste disposal and natural resource acquisition.