This project was for the second building at the Harwell Campus in Didcot. The building, Quad 2, will provide four stories of Grade A office accommodation within a quadrangle of commercial and leisure facilities seeking to enhance employee health and wellbeing. As the existing substrate for the building footprint would not achieve engineering requirements soil stabilisation, the strengthening of material, was considered. This process can offer a very cost effective alternative to other options such as piling and proved to be viable in this case.
Working with Principal Contractor SDC our works involved the excavation of 5,000cu.m. to a depth of 3m over a four week period. This also including breaking out a large concrete obstruction. The material was then replaced in 300mm layers, treated, compacted and tested prior to the next layer being placed. This strengthening of the existing material achieved the specification requirement of a bearing capacity of 300kN/sq.m.
As the soil was naturally chalky cement only treatment was required which consistently achieved well above the contract requirements. The result of the stabilisation works was that shallow foundations could be used for the superstructure and any potential settlement issues removed. This has also provided a cost saving on the project. The final surface was treated to 30%CBR before topping with stone to act as a working platform.