Research on Use of Local Aggregates: Alkali Reactive Carbonate Rocks

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The objective of this research is to study the root cause of one common cited distress mechanism in concrete caused by reaction of certain carbonate rocks has been conventionally referred to as alkali carbonate reaction (ACR). Carbonate concrete aggregates are important, particularly in certain regions of the world where carbonate rocks are the predominant aggregate sources available (for example, mid-west region of the US). It is necessary to fully understand the mechanism of ACR to select appropriate measures for preventing deleterious expansion in new concrete structures by designing concrete mixtures that minimize the risk of ACR potential. Understanding the mechanism of ACR is also important to choose suitable technologies to mitigate or suppress the effects of deleterious ACR in existing structures. The goal of the reach has been: (1) to study the ACR reference carbonate aggregate using a holistic approach to quantify reactive forms of silica and expansive types of clays which may have a role in the controversial ACR mechanism in concrete, (2) to mix concrete prisms using potentially reactive carbonate aggregates from different sources and measure long-term concrete prism expansions, and (3) Investigate the root cause of the concrete prisms expansions, (4) Also investigate concrete distress mechanism(s) of concrete pavements made using potentially reactive carbonate aggregate.