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In southern Ontario, the premium coarse aggregate sources for concrete construction are quarried from the Niagara Escarpment Amabel and Lockport dolostone formations. As access to this resource becomes more and more restricted, alternative limestone formations are being utilized by the construction industry, but they exhibit inconsistent performanc...
Contexts in source publication
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... alumina and silica coatings, as well as calcined limestone, pozzolanic, and portland cement based coatings have all been tried with varying degrees of success ( Muñoz et al. 2010, Sanfilippo et al. 2010, Yang et al. 1992, Popovics 1987, Li et al. 2009, Zhihui et al. 2013). The premise that coarse aggregate surface texture is related to compressive strength was explored in this research for two different carbonate aggregate sources available in southern Ontario: the Amabel dolostone, a durable rock that caps the weather-resistant Niagara Escarpment for over 400 km between Hamilton and Manitoulin Island, and the Gull River limestone, a stratigraphically older rock that outcrops east of the escarpment (Figure 1). Certainly, many other aggregate parameters can influence concrete strength, but this research was limited to an investigation into alterations of the aggregate surface texture by abrasion or by the application of special coatings. ...
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... source of Amabel limestone used in this research originated from a quarry near Milton, Ontario (Figure 1). The Milton source consists of a light grey, porous, medium to coarsely crystalline dolomite with abundant fossils (Vos 1969). ...
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... Milton source consists of a light grey, porous, medium to coarsely crystalline dolomite with abundant fossils (Vos 1969). Two sources of Gull River limestone were used, one from a quarry near Orillia, Ontario, and another from a quarry near Buckhorn, Ontario (Figure 1). The Orillia source consists of a light grey to grey-brown, micritic to very fine-grained limestone (Armstrong and Anastas 1993). ...
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... coarse aggregate particles are present in the Amabel dolostone concrete, but absent from the Gull River limestone concrete. Figure 10 compares typical micro-fracture patterns within the coarse aggregate particles split by the primary tensile crack. ...
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... increases of ~ 15% with nano- coated aggregate, and avg. strength increases of ~ 12% with SiC-abraded aggregate as compared to the untreated aggregate ( Figure 11). The nano-coating and SiC-abrasion treatments also brought the strength of the Gull River limestone mortars to similar levels as the untreated control Amabel dolostone mortar at both 7 and 28 d. ...
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... Gull River limestone surface treatments did not provide any improvement in compressive strength for the concrete mixtures ( Figure 12). In most cases, with the exception of the powder-coating, the compressive strengths were even lower than that of the original untreated Gull River limestone concrete. ...
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Citations
The need for finding sustainable alternative sources of coarse aggregates as an ingredient for concrete has been increasing globally. Recycled and brick aggregates are two viable options in this regard. Many properties of recycled and brick aggregate concrete remain to be investigated to predict their behaviour accurately and to set proper code guidelines. In this study, a few properties of recycled and brick aggregate concrete and their behaviour in flexural members have been investigated. In particular, the stress–strain relationship, modulus of elasticity and splitting tensile strength of concrete made of brick, recycled and natural aggregate have been analysed. Using these properties, some of the flexural properties of reinforced concrete members made with these three types of aggregates have been determined and compared. To the best of our knowledge, for the first time, a comparative analysis of these properties of brick, recycled and natural aggregate concrete has been conducted in this study. Results from the study show that while the code equations for predicting some of the important mechanical properties of concrete are suitable for natural aggregate concrete, they are not appropriate for recycled or brick aggregate concrete. The moment–curvature response and deflection properties in flexural members made of recycled and brick aggregate concrete are affected by the difference in the properties of the aggregate. Finally, it is suggested that the utilization of recycled and brick aggregate in concrete is likely a feasible option without any significant degradation in the mechanical and flexural properties of the structural members.
Due to the fact that aggregates are the largest component in concrete (typically 60–70% by volume), the characteristics of the aggregates significantly affect the performance properties of fresh and hardened concrete. This article reviews the literature on the effects of coarse aggregate type on the mix design of concrete. Key parameters are identified, and a chart is plotted to help organize them. The relevant characteristics of aggregates are categorized into physical characteristics and geological characteristics. It is found that shape, texture and gradation have the most important role on the properties of fresh concrete, particularly workability. The porosity of the aggregate is reported to affect the workability during the first 15 min of mixing, as well as the creep and shrinkage. Depending on the mineralogy of the aggregate source, aggregates may react negatively with the matrix or beneficial interactions may occur between the matrix and the aggregates. Consequently, mechanical and strength properties of concrete can be affected by the aggregate mineralogy. Another important characteristic of aggregate is the presence and type of surface coatings which can affect workability and plastic shrinkage of concrete. Generally, an increase in dust content, increases the water demand of the mixture, which decreases workability and reduces air content. Aggregate type does not affect the setting time of concrete directly; however, the presence of soluble salts or organic contamination on the surface of aggregate may influence the setting time. Due to these impacts on the properties of concrete, adjustments to the mix designs are necessary when concrete suppliers are switching from one source of aggregate to another source.
