Effect of using substitution urea on fresh and hardened state properties of cementitious systems

Abstract

It is well known that to ensure the durability of concrete throughout its service life, the search for alternative materials continues. The durability of concrete is enhanced by industrial urea. This study investigated the effect of urea on various fresh and hardened cementitious systems, focusing on durability performance. The durability of concrete is enhanced by industrial urea. This study investigated the effect of urea on various fresh and hardened cementitious systems, focusing on durability performance. Two series of paste and mortar mixtures were prepared for the research, and the replacement of water and cement was determined as 10%, 20% and 30% of the binder volume. The study investigated several properties of the produced cement paste and mortar mixes, including drying shrinkage, time-dependent flow, compressive strength, microstructural analysis, freeze-thaw resistance, carbonation depth, ultrasonic pulse velocity and water absorption. The results of the study showed that urea substitution increased the freeze-thaw resistance by up to 20% and reduced the drying shrinkage behaviour by up to 49%. The use of urea reduced the carbonation depth of mortar mixtures by 35%. It was also observed that the use of urea improved flowability.