Concrete made with Geofortis SCMs replacing 20 - 35% of the Portland cement provide superior performance compared to typical mixes which use fly ash in terms of:
Geofortis' Product Development Laboratory is staffed with engineers and technicians who, over the past 5 years, have conducted thousands of test mixes with natural pozzolans. We have optimized our SCM blends and perfected our procedures to evaluate how our products perform with customers' local raw materials and cements.
Compressive Strength, Water Demand, Set Time
Concrete using Geofortis products instead of, or in addition to, fly ash consistently exceeds compressive strength of mixes using fly ash alone.
Set times are typically equal to or faster than fly ash mixes.
Water demand, an important factor in concrete strength and economics is very close to that of Portland cement.
Alkali Silica Reaction (ASR) Mitigation
ASR is a swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive non-crystalline (amorphous) silica found in many common aggregates. This reaction causes expansion by the formation of a soluble and viscous gel. This hygroscopic gel swells and exerts an expansive pressure inside the siliceous aggregate over time, causing spalling and loss of strength of the concrete, finally leading to its failure.
ASR can cause serious cracking in concrete, resulting in critical structural problems that can even force the demolition of a particular structure.
Geofortis SCMs quickly and preferentially react with the cement alkalis without formation of an expansive pressure, because siliceous minerals in fine particles convert to beneficial compounds that add strength and reduce permeability.
A successful ASR test indicates expansion less than 0.10% after 14 days.
Cement Efficiency - (How much can I use?)
Cement Efficiency refers to the strength gained or lost per pound of replacement SCM. Mixes using fly ash to replace Portland cement, for example, are not as strong as Portland cement alone. Therefore, the amount of SCM replacement is limited. Fly ash mixes are typically 20 - 25% maximum and average 15 - 20%.
Geofortis' natural pozzolans are chemically more reactive than fly ash and have higher pozzolanic activity. Customers are able to use higher replacement percentages, up to 30 - 35%, without sacrificing strength or other performance characteristics. Higher replacement means greater cost savings, better ASR mitigation, reduced reliance on scarce cement supply, and greater GHG reduction.