The effects of using treated wastewater on the fracture toughness of the concrete

Abstract

ABSTRACTEvaluating the effects of using new water sources on the mechanical properties of concrete is an important issue that should be considered in practical projects such as dam construction and tunnelling. The fracture toughness as one of the mechanical properties describes the resistance of a material against the crack propagation and the effect of a new water source should be assessed on this property of concrete. This paper aims to investigate the use of domestic treated wastewater in making concrete. For this purpose, several single edges notched beam (SENB) are prepared using 5 different combinations of drinking water and domestic treated wastewater. The experimental results show that the values of fracture toughness obtained from concrete samples with wastewater have discrepancies between 2 to 6% in comparison with conventional concrete. Therefore, it is concluded that applying domestic treated wastewater as both curing and mixing water has no serious negative effect on fracture toughness. The slump of concrete samples using treated wastewater increased slightly related to using drinking water and setting time increased. Scanning electron microscope (SEM) images of the samples using treated wastewater indicated that existing ettringite, white and needle-like crystals, connected two sides of the cracks.