Today, WRAP (the Waste & Resources Action Programme) launches new guidance for the use of hydraulically bound materials (HBM) in working platforms for construction sites. Use of HBM can lead to cost savings and a reduced need for quarrying and landfill.
A working platform provides a safe and durable working surface from which construction plant, such as piling rigs and cranes, can operate. They can be utilised many times through a construction life-cycle providing formwork for casting pad foundations, a surface for steelwork erection and acting as a structural element within a floor slab or pavement.
HBM, made using lime, cement and other binders, is an extremely cost-effective method of converting weak on-site soils and granular materials into stable working platforms. By using HBM, virtually any soils found on site can be improved to provide a stable and durable base from which construction plant can operate even in adverse weather conditions.
‘Guidance on the use of HBM in working platforms’ covers the key issues related to working platforms constructed using stabilised materials, providing detailed guidance for the platform’s design, specification, installation, operation, maintenance and repair.
Through the use of site-won materials, contractors can reduce the environmental impact caused by lorry movements for landfill and importation of primary aggregates. They also gain from the associated cost savings and reduced site delays caused by poor ground conditions.
Within the guidance document are case studies on three construction projects, which have made significant gains from using on-site soils and granular materials in the construction of a working platform.
A good example of the benefits HBM working platforms can offer can be seen in the construction of a BMW car showroom in Costessey, Norwich, where £200,000 was saved in lorry movements alone.
Due to the fact the BMW site’s surface was soft clay, which was slurry-like in places, access to large parts of the site was virtually impossible with tracked plant. Contractor, Adonis Construction did not want to remove the 15,000m3 of wet fill material and replace it with stone due to cost and time implications. Adonis employed the stabilisation specialist, O’Keefe Soil Remediation, to treat the site initially with quicklime and then with cement to create a stable working platform across the whole site.
The stabilised material was used to support piling rigs and was sawn through and used as permanent formwork for the foundation bases/pile caps. It was also engineered to replace the asphalt base layer to asphalt surfacing for all car parking areas.
Those who saw the site before and after were amazed by the transformation.
“The BMW project is just one illustration of how a relatively new technique can be so much better than traditional methods,” comments John Barritt, WRAP’s Aggregates Technical Advisor. “WRAP has produced this guidance document so contractors can see the benefits they can gain from utilising on-site materials. At the same time, the guidance on using HBM in working platforms provides advice and best practice for every stage of the process.”