Investigation of coarse aggregate surface treatments to enhance concrete strength

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The Amabel dolostone is the weathering-resistant rock type that caps the Niagara Escarpment for over 400 km between Hamilton and Manitoulin Island. Resistance to the opening of new Amabel dolostone quarries in Ontario has been strong. As the existing supplies approach exhaustion, and the opening of new quarries seems unlikely, the construction industry will need to find alternative aggregate sources. Existing quarries within the Gull River Formation represent a potential replacement source, but preliminary work indicates that concrete produced with Gull River limestone does not achieve the same properties as concrete produced with Amabel dolostone. Consequently, the aim of this study is to modify the surface properties of the aggregate to help improve the bond with the hardened cement paste. The advantage of this approach is that the concrete producer can potentially switch to a surface-treated aggregate while maintaining their same basic mix designs. Several surface bond enhancement methodologies will be explored and assessed for feasibility in terms of production-scale for aggregate beneficiation of Gull River limestone, including mechanical abrasion to improve surface texture, as well as aggregate coatings based on nano-silica and sodium silicate.