The shortage of natural sand, a non-renewable resource, is a growing environmental issue for concrete production
Once again, CHRYSO is the first out of the starting blocks, having introduced its CHRYSO® Quad range of concrete admixtures to the market in 2022 – helping customers to promote sustainable practice in their use of challenging sands.
According to Patrick Flannigan, Technical Manager in the Concrete Business Unit at CHRYSO Southern Africa, the use of crusher or manufactured sand in construction has been prevalent for many years as it is a cost effective and more readily available alternative to natural sand.
“There have, however, been issues with grading which often prompts contractors to supplement with natural sand from sources such as rivers and dunes,” he explains. “This is where the challenges lies with less availability of natural sands which increases costs as well as the presence of clays which means that less of this material can be used or it has to be excluded completely.”
“Our CHRYSO® Quad range allows customers to reduce their use of natural sand while making better use of crusher sand, without compromising the quality of their concrete mixes, and successful laboratory trials have already been concluded with customers in various market segments are already realising the benefits,” Flannigan continues.
“Working with customers such as contractors, readymix suppliers and precast manufacturers, CHRYSO is making significant contributions to industry sustainability and reduced carbon footprint,” he says.
He highlights that using less natural sand gives the industry a lower environmental impact on sources like rivers. Where natural sand is still being used, CHRYSO® Quad CLEAR® (Clay Enabling Admixture Response) allows a wider choice of sources – even challenging sand that contains swelling clay. This can allow contractors to source from locations closer to site, reducing the carbon footprint and cost of transporting sand over a long distance.
“The challenge is that swelling clays absorb newer generation plasticisers, thereby preventing them from delivering benefits such as water reduction or slump retention,” he says.
CHRYSO Southern Africa also offers the quick and innovative CHRYSO® CLEAR Test to identify where these swelling clays could present a problem for concrete users. Where they are identified in the source material, CHRYSO® Quad CLEAR® can be added as a liquid to the relevant plasticiser.
Another important contribution to sustainability in the construction and concrete manufacturing sectors is CHRYSO® Quad GRAFT® (Gap Gradation Fixing Technology), he notes. This can solve the challenge of an excess or lack of fines in source material – which often occurs in crusher sand.
“The industry is seeing the environmental benefit of moving away from natural sand and more toward crusher sand, but this product often has varying levels of fines,” he says. “In the past, this could have compromised the performance of concrete, but CHRYSO® Quad GRAFT® now solves this challenge.”