Mechanical properties and flexural behaviour of green light weight concrete beams exposure to salty soils

Abstract

This paper presents an experimental investigation on the mechanical properties, durability and flexural behaviour of green concrete beam when subjected to harsh environments by using recycled building materials. Concrete resistance to external aggressive environmental condition is one of the most significant characteristics to maintain the concrete durability. The fundamental goal of this study is to understanding the performance of green lightweight concrete beam of (10×10×40 cm) under two different severe saline conditions; Ground Water Condition (GWC) and Severe Saline Clay Soil Condition (SSC) that contain chlorides and sulfates at concentrations like to those existing in groundwater and soil of the southern and middle parts of Iraq. In this research, in addition to normal concrete; three basic categories of green lightweight concrete are used: structural, non-structural and moderate strength using recycled of clay bricks and themestone blocks as coarse Light Weight Concrete (LWA) by a replacement ratio of (0, 50 and 100) % volume of natural coarse aggregate. All green Light Weight Aggregate Concrete (LWAC) beams and related specimens for mechanical properties were subjected to GWC, SSC and Laboratory Air Condition (LAC) for till (3, 6 and 9 months) after twenty-eight days of curing by tap water. Compressive strength, splitting tensile strength and density were also studied. The results obtained offered that the GWC and SSC have impacted the performance of all concrete beam types negatively with exposure age. The decadence was more for non-structural green LWAC beam. It is found that the resistance of beams contains bricks aggregate to GWC and SSC was a better than the other types of the green LWAC, the percentage decreases in failure load were 15.47% and 13.31% at 9 months of exposure to GWC and SSC measured relative to concrete beam exposed to LAC, respectively. Under the effect of aggressive conditions till 3 months, the results clarified that the improvement rate in the mechanical properties of the green LWAC were increased with age in comparison with ordinary concrete. The percentage reduction in compressive, splitting tensile strength and density at 9 months were ranged between (8.70-17.05) %, (14.71-36.50) % and (0.11-3.98) %, respectively measured relative to the same specimens in LAC.