The Effect of Utilizing Kuwait Fine Desert Sand as Partial Cement Replacement on Mortar Fresh and Hardened Properties

Abstract

This study assesses the potential of Kuwait's Fine Desert Sand (KFDS), a locally abundant material, as a partial replacement material for Ordinary Portland Cement (OPC). Mortars at substitution levels of 5%, 10%, 15%, and 20% by mass were produced. Fresh and hardened mortar properties were assessed through normal consistency and setting time of cement paste, as well as water absorption, flexural strength, and compressive strength after 28 days of water curing. Increasing KFDS content reduced the normal-consistency water requirement and generally extended the final setting time from 165 to 205 min. Water Absorption (WA) increased only slightly, from 10.94% to 11.1%. Flexural strength increased from 1.12 MPa for the control mortar to 2.30 MPa at 5% replacement, after which it remained nearly constant, reaching 2.39 MPa at 20%. In contrast, compressive strength decreased progressively from 29.9 MPa to 18.3 MPa, corresponding to a 38.8% reduction. The opposing trends indicate that physical filling and compaction effects may improve resistance to crack initiation under bending, whereas cement dilution governs compressive performance. Among the investigated mixtures, 5% of KFDS provided the most balanced performance, while higher replacement levels should be selected according to application-specific strength requirements.