Pumping stations utilize lightweight infill material within their raft foundation voids to minimize dead load and mitigate settlement. Filling these voids with concrete is undesirable due to the risk of thermal cracking and the substantial increase in load on the structure. General fill is also unsuitable as its weight is comparable to concrete.
Leaving the voids empty poses risks as well. Water infiltration during operation can significantly increase the dead load of the pumping station, leading to potential structural issues.
Therefore, a carefully selected lightweight infill material, possessing non-water-absorbing and non-biodegradable properties, is employed. This solution effectively prevents water ingress and reduces the overall dead load of the pumping station, ensuring its stability and long-term performance.