With ever-increasing urbanisation and the resultant sprawl of rooftops and hard-surfaced landscapes, the effective management of storm water drainage has become increasingly difficult. The risk of flash floods escalates and the impact of rapid runoff on natural watercourses can cause serious environmental damage.
Lafarge Readymix has launched Hydromedia™, a new, fast-draining concrete pavement solution to address this problem in South Africa. Hydromedia provides for rapid storm water removal from streets, parking areas, driveways, walkways and other hard surfaced areas. It offers a drainage medium that enables rainwater to return to and replenish groundwater reserves locally and it can reduce the costs and long-term maintenance requirements of storm water management systems – for public authorities and private property owners.
The advanced technology used in Hydromedia has been developed by the international Lafarge group, a world leader in building materials and related solutions-driven research and development. The innovative concrete mix is the key to the product’s performance, which surpasses the benchmarks set by standard permeable paving.
Neville Wearne, national marketing manager for Lafarge Readymix in South Africa, highlights some of Hydromedia’s attributes. “As a porous pavement concrete, it can be used cost-effectively as part of a sustainable urban drainage system (SUDS). It also allows for more efficient land use by eliminating the need for drainage swales, retention ponds, catchment basins and other storm water management devices. And it filters out surface pollutants, limiting contamination of groundwater.”
Manfred Braune, technical executive of the Green Building Council of South Africa (GBCSA), notes, “Water is a scarce resource in South Africa and requires careful management, planning and protection: this includes our precious groundwater which is often forgotten. In urban areas, permeable paving is an important sustainable urban drainage system. GBCSA welcomes and values innovative SUDS solutions that can contribute to protecting and conserving our environment.”
It is Lafarge’s breakthrough in paste technology that enabled the company to create a no-fines concrete that uses sufficient paste to coat and bind the aggregate particles together and form a system of highly permeable, interconnected voids that drain freely and quickly. The aggregate matrix is designed to minimise compaction and provide a predictable and homogeneous permeability in the final hardened product.
The mix is particularly fluid in application but robust and resilient after placement and curing. It provides for simple application and is workable for up to 90 minutes but dries rapidly and cures to become fully trafficable within seven days. The concrete should be cast to a minimum thickness of 150mm, onto a prepared subgrade and sub-base as for standard paving placements. Hydromedia has a compressive strength of 10 to 20MPa and flexural strength of 1.5 to 3.0MPa and will carry a maximum load of up to 7.0 tonnes. Depending on the mix design, it can provide a permeability rate of between 150 and 1 000 litres/min/m².
“We have adapted this world-class technology for the South African construction industry and we are ready to work with the industry to put it to good use,” says Wearne. He highlights that Lafarge is offering training for applicators wanting to work with Hydromedia, and the company itself offers a placing and finishing service.