Impacts of non-sieved waste construction sand under various moisture states on engineering properties of cement-based mortar

The construction industry generates a significant amount of waste, with leftover sand from masonry construction being a notable concern. This paper investigated the utilization of non-sieved waste construction sand (CS) under various moisture states to assess its impact on engineering properties of cement-based mortar. Along with the primary objective was to compare the effects of non-sieved and sieved waste CS on engineering properties of mortar. Various engineering properties of mortar were tested, including consistency of fresh mortar, bulk density, and the compressive and flexural strengths of hardened mortar specimens. Three moisture states for the waste CS were proposed, including oven-dry (OD), natural (NA), and saturated surface-dry (SSD) states. Compared to sieved waste CS, the consistency of fresh mortar with non-sieved CS increased by 14.3–66.7%. In addition, using CS in the SSD state improved the consistency by 60.0–133.3% and 23.3–27.2% compared to that in OD and NA states, respectively. Moreover, the difference in the bulk density of mortar specimens was insignificant, regardless of the moisture states of the waste CS. In terms of mechanical properties of mortar at 28 days, the results showed a reduction in compressive strength (27.0–32.3%) and flexural strength (32.2–36.4%) of mortar specimens using non-sieved waste CS compared to those using sieved waste CS, regardless of the moisture states of the CS. Furthermore, using waste CS in the SSD state improved the mortar strengths when compared to that in other moisture states (OD or NA state). Additionally, a linear correlation was observed between compressive and flexural strengths of the mortar, regardless of types and moisture states of the waste CS. In conclusion, the use of non-sieved waste CS led to a reduction in mechanical strengths of hardened mortar while increasing the consistency of fresh mortar, regardless of the moisture states of the waste CS. Utilizing the waste CS in the SSD state proved to be an effective method for enhancing the consistency of fresh mortar, and mechanical strengths of cement-based mortar compared to that in other moisture states.