IMPROVING MECHANICAL PROPERTIES OF LIGHTWEIGHT FOAMED CONCRETE USING SILICA FUME ANDFIBERS

الملخص

Lightweight foamed concrete (LWFC) is characterized as a light in self-weight, selfcompacting (no need vibration), self-leveling, and thermal and sound isolation. The application of (LWFC) in the building construction is limited because of its the low strength and the low ductility. In this study the workability of the fresh mix of (LWFC), the hardened properties include, compressive strength, tensile splitting strength, flexural strength, and modulus of elasticity were evaluated. This study focuses mainly on the effect of the adding of silica fume and fibers on the mechanical properties of (LWFC). Silica fume was added as 5% and 10% by the weight of cement. Steel fiber and polypropylene fiber volume fraction were of (0.2%, 0.4%), While the hybrid fibers (steel+ polypropylene) volume fraction was (0.2% steel+0.2%PP), and (0.4%steel+0.2%PP) of the total mix volume. The results of the program test show that the increase of silica fume improves the mechanical properties of (LWFC) significantly. The adding of fibers to the (LWFC) reduces the flowability and improves the mechanical properties. The hybrid fibers mix (0.4% steel+0.2% PP) presented the best test result of the mechanical properties as (10%,21%,53%, 24.4%) for the compressive strength, flexural strength, tensile splitting strength, and modulus of elasticity, respectively.