While almost every batch of aggregate will come with some contaminant level, the key to improving its workability and effectiveness is understanding the type, quantity, and variability of the contamination.
Whether its mineralogical speciation or physical properties such as fineness, surface area, surface charge or ability to swell, each of these will have an impact on the structural integrity of the concrete mix.
Usually, contaminated aggregates are tackled by adding more cement, but this only increases the cost and, more importantly, CO2 emissions.
Sika Stabilizer-500 VCC is an innovative concrete admixture specially formulated to improve the plastic and hardened properties of concrete containing fine aggregates with variable contaminant content.
Negating the effect of contamination, it can control the variability of the properties of concrete and improve the materials’ environmental credentials.
Dr Martin Liska, R&D manager at Sika Limited, said: “There’s a finite resource of aggregate which needs to be managed effectively.
“From the customer being flexible on the spec, to the supplier adequately processing the aggregate at source and then enablers, like Sika, working with their partners to help the industry effectively work with lower-grade materials; each party in the supply chain has a responsibility to facilitate the longevity of aggregate stores.
“By working with and not against contamination, we can collectively elongate the availability of raw materials and start making long-term spec decisions based on sustainability rather than short-term choices based on cost rather than value.”
