The utilization of walnut shells as a partial replacement of sand in mortar mixes

The effect of walnut shells on different properties of mortar was investigated through several experimental tests. The investigated properties include dry density, thermal conductivity, compressive and flexural strengths. Percentage replacements of the walnut shells to sand ratio were 5, 10, and 15%. The walnut shells used in this study were treated by soaking in boiling water for two periods: 1/2 hr and 1 hr. All mortar mixes have same proportion of 1:3:0.7 by weight for cement, sand, and water, respectively. The test results showed that the use of 15% walnut shells treated for 1/2 hr lead to decrease of the density and thermal conductivity of mortar by 15 and 31%, respectively. On the contrary, the compressive and flexural strengths of mortar were decreased by 17 and 25%, respectively, in comparison to the control mortar after 28 days of moist curing. This study leads to a conclusion that by soaking the walnut shells in boiling water for 1/2 hr enhanced the behavior of mortar compared to the un‐soaked ones. This results in achieving an acceptable strength, good thermal insulator, and environmentally friendly mortar.