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Utilizing a Different Technique for Improving Micro and Macro Characteristics of Coarse Recycled Concrete Aggregate


Sustainable development has significance for obvious and relevant reasons in all areas of civil transportation infrastructure. In the asphalt highway industry, a large number of innovative materials and technologies are explored in order to evaluate their suitability in the design, construction and maintenance of pavements. The utilization of Recycled Concrete Aggregate (RCA) is becoming a highly interesting issue in Canada, and worldwide, due to many reasons including lowering consumption of virgin materials, decreasing waste materials in landfills and reducing environmental problems. The main objective of this research is to investigate the utilization of different technique which includes the combination of various treatment methods for enhancing micro and macro characteristics of coarse recycled concrete aggregate (CRCA). Macro properties of CRCA included specific gravity, water absorption, abrasion loss and adhered mortar loss, whereas micro characteristics involved porosity and atomic Ca/Si ratio. In addition, the influence of each treatment type on the micro and macro properties of CRCA was examined separately. Furthermore, the relations among different micro and macro characteristics impacted by various treatment methods are explored. In order to achieve the objective, pre-soaking and heat treatment followed by different types of short mechanical treatment are conducted to evaluate macro and micro properties of CRCA before and after a combination of various treatment types. Heat treatments included various temperatures (250ºC, 350ºC and 500ºC). Presoaking method involved the use of strong acid, HCl, and weak acid C2H4O2, whereas short mechanical treatment included the utilization of a Micro-Deval device with two different testing techniques with/without steel balls. The obtained results revealed that the utilization of a combination of methods between different treatment types is a highly successful technique for improving macro and micro characteristics of CRCA compared with separate treatments. The combination between acetic acid treatment and short mechanical method with steel ball exhibits the best performance by reducing the water absorption by 36.9%. The use of weak acid is more effective than strong acid in enhancing macro and micro properties in terms of abrasion loss, adhered mortar loss and atomic Ca/Si ratio, whereas acid treatment with strong acid appears to be more efficient in improving water absorption and porosity. Heat treatment type at temperatures between 350°C-500°C has a noticeable negative impacts on different macro and micro CRCA characteristics. Different macro characteristics of CRCA including water absorption and abrasion loss and adhered mortar loss are strongly correlated with various micro properties in terms of porosity and atomic Ca/Si ratio.

Conference Paper Details

Session title:
Green Technology in Geotechnical and Materials Engineering
Al-Bayati, H.K.A.
Tighe, S.L.