VANCOUVER (miningweekly.com) – Aim-listed Sunrise Resources has reported strong initial strength-test results for natural pozzolan sourced from its Pozz project, in Nevada.
The test results indicate that the CS Deposit sample is a high quality natural pozzolan competitive with natural pozzolans available on the market today.
Independent cementitious materials laboratory Magmatics has recommended that further tests be undertaken to optimise performance in terms of particle size and water demand, and thereafter its effectiveness against alkali-silica reaction and sulphate attack to qualify the material in both the cement and concrete industries as a certified natural pozzolan.
The Pozz project comprises two separate mineral deposits (the CS and Pozz Ash deposits) located in different parts of Nevada and each is being evaluated as a potential standalone project.
Magmatics analysed a composite field sample taken from the CS deposit, which the company staked in November, using bench-scale physical (reactivity) testing.
The sample was finely ground and mixed as a 20% replacement with Portland cement, sand and water and allowed to cure under standardised testing in laboratory conditions. The strength of the resultant cement/pozzolan mix was then compared with the strength of an ‘index’ 100% Portland cement sample after seven days and then again after 28 days.
The seven-day ‘strength against index’ (SAI) was 88% and the 28-day SAI was 97% (minimum requirement 75%). The SAI is a measure of pozzolanic reactivity and these are considered by Magmatics to be very good results, Sunrise stated.
Tests showed the sample’s water demand was within the normal range for a good natural pozzolan, near that of cement. This is important as wide acceptance in the concrete market is difficult if the water demand is too high, as this reduces the workability of the concrete mix and requires the use of expensive water-reducing admixtures.
Sunrise advised that given the encouraging results obtained from the CS deposit and given its more favourable location relative to the cement markets of Las Vegas and California, it will give priority to CS deposit for further work under the company’s Pozz project in 2017.
Natural pozzolan is used as a replacement for Portland cement with substitution rates typically around 15% to 25%.
Natural pozzolan has been used in concrete for millennia and many of the Roman structures built with pozzolan concrete are still standing. Today it is used as a ‘green’ alternative to ordinary Portland cement which is responsible for 5% of global man-made carbon dioxide (CO2) emissions with nearly one tonne of CO2 generated for each tonne of cement produced. Pozzolan can also provide benefits in terms of long-term strength and stability in cement and concrete and can replace the use of fly-ash in cement which is diminishing in quantity and quality of supply.