Physiochemical characterization of coarse aggregates in Qatar for construction industry

Due to the sheer volume of construction activities in Qatar, the market of building materials including aggregates is stressed. The commercially available natural aggregates are either local limestone aggregate or imported limestone as well as gabbro aggregates from the United Arab Emirates. In addition, recycled concrete aggregates (RCA) are produced since 2009 as a result of the extensive construction and demolition activities. It is estimated that around 20,000 tons of construction and demolition (C&D) wastes are produced daily in Qatar; half of which are converted daily to RCA. Imported limestone and gabbro aggregates are widely employed for various construction activities in Qatar; however the use of local limestone aggregates are limited due to their substantial heterogeneity, uncontrolled water absorption and abrasion quality. Although, the specification of RCA for concrete applications has recently been introduced through the revised Qatar construction standards (QCS) in 2010, their commercial use is under experimental evaluation. However, the properties of the aforementioned virgin and recycled coarse aggregates were hardly ever systematically published. Hence, this study presents the initial physiochemical characterization and comparison of the virgin aggregate properties, with those of locally available RCA as a sustainable alternative. The physiochemical properties were bench marked against the stipulated thresholds of QCS (2010) and other characterization properties.It was observed that both local limestone and RCA have inferior water absorption and porosity characteristics in comparison to imported gabbro and limestone aggregates. Previous international standards and studies have demonstrated the successful partial RCA replacement of imported virgin aggregates in concrete applications; and if implemented, could potentially offer significant economic and environmental benefits to the State of Qatar.However, it was recommended to undertake further laboratory studies to assess the mechanical performance and durability of such replacements prior to practical implementations within the construction industry in Qatar.