Almost every batch of aggregate will come with some level of contaminant, the key to improving their performance in concrete is understanding the type, quantity and variability of the contamination.
To combat the issue of problem sands, Sika scientists have developed Sika® Stabilizer-500 VCC – an environmentally-friendly concrete admixture to help improve the performance of contaminated material.
Why use Sika® Stabilizer-500 VCC?
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.
Sika® Stabilizer-500 VCC is a unique concrete admixture specially formulated to improve the plastic and hardened properties of concrete containing fine aggregates with variable contaminant content. It can reduce the impact of deleterious substances found in both natural and manufactured sands and can help control water demands and lower cement contents whilst reducing variation in plastic properties.
Why Sika® Stabilizer-500 VCC is a more sustainable option
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 not only a robust solution, but also one which is cost-effective and more sustainable.
Negating the effect of contamination, it can control the variability of the properties of concrete and improve the materials’ environmental credentials.
As Dr Martin Liska, R&D manager at Sika Limited explains: “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 prolong 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.”
Characteristics/advantages of Sika® Stabilizer-500 VCC?
Reduces variation in consistence control
Improved cohesion properties
Improved rheology
Reduces the effect of clay contamination
Reduces the effect of ultra-fine particles in sand (<63μm)
Potential to reduce cement contents in problem packages
Potential to utilise secondary aggregate sources
Improved durability
Reduced segregation and bleeding
Reduced drying shrinkage
Reduced mix costs.