I-Minerals has developed a natural pozzolan that could replace fly ash.
I-Minerals marketing personnel attended the Natural Pozzolan-New Pozzolan Symposium/Demonstration held in Corona, CA on October 4 and 5, to showcase natural pozzolans to the California Department of Transport (CalTrans).
Natural pozzolans are one of many supplementary cementitious materials (SCMs) which contribute to the properties of hardened concrete through hydraulic or pozzolanic activity.
In the past CalTrans has relied primarily on fly ash as an supplementary cementitious material for its infrastructure projects. However, good quality fly ash (the ash which remains when coal is burned to generate electricity) is becoming increasingly harder to source as less electricity is generated using coal as the heat source and only certain ashes are acceptable for use in concrete. The lack of availability of qualified supplementary cementitious materials has caused delays to some CalTrans projects with such delays having adverse budget impacts, says Thomas M Conway, president and chief executive, I-Minerals.
I-Minerals has developed a natural pozzolan known as Bovill Metakaolin that is produced by calcining (heating to about 900°C) kaolin, one of the four mineral products produced from the Helmer Bovill property. Metakaolin is one of the best performing supplementary cementitious materials and consequently can be used in smaller quantities than fly ash and still generate as good or better results. Testing has also shown metakaolin to be a more consistent pozzolan than other natural pozzolans such as pumice. I-Minerals is uniquely positioned as it is the only potential new producer of metakaolin outside of the Georgia Clay Belt.
Cement manufacturing produces CO2 as it requires very high temperatures to burn raw materials and give the clinker (used in cement production) its unique properties. Supplementary cementitious materials are partial substitutes for cement and therefore reduce greenhouse gas emissions — and California has committed to reduce greenhouse gas emissions to 1990 levels by 2020.
“As coal fired power plants get converted to natural gas or otherwise shut down, the shortage of SCMS is only going to increase,” Conway says.
“The situation in California is not unique as we are aware of similar shortages of quality SCMs in Colorado, Oregon and elsewhere. When our metakaolin production volumes as detailed in our Feasibility Study are contrasted with SCM demand in states close to our Bovill, Idaho operations, we could easily sell out our entire metakaolin production to one concrete company in one state. Metakaolin is one of four co-products targeted for production at our Helmer-Bovill property and with minimal other metakaolin production in the Western US, the opportunities are exciting.”
It was noted at the Symposium/Demonstration that as fly ash has been the prime supplementary cementitious material for concrete in California since the 1960s, few people within the California concrete industry including government officials have experience using natural pozzolans within concrete; yet, natural pozzolans will most likely fill the supplementary cementitious materials gap created by the shrinking and erratic supply of Class F fly ash which is imported into the state.
CalTrans only accepts supplementary cementitious materials that are on the authorized cementitious materials list — if an supplementary cementitious material is required in the concrete mix. I-Minerals is now taking the initial steps towards getting Bovill Metakolin on CalTrans authorized cementitious materials list.
About I-Minerals Inc.?I-Minerals is developing multiple deposits of high purity, high value halloysite, quartz, potassium feldspar and kaolin at its strategically located Helmer-Bovill property in north central Idaho.