Properties of environmental concrete that contains crushed walnut shell as partial replacement for aggregates

Abstract

Concrete production consumes a large amount of fine and coarse aggregates. Therefore, eliminating or reducing the consumption of aggregates in concrete can produce environment-friendly building materials. Considerable research has confirmed that the use of waste materials in concrete addresses the high utilisation of raw materials. Walnut is a common farming product in the north of Iraq. A substantial amount of walnut shells is disposed of in landfills. In the present work, crushed walnut shells (CWS) were selected as partial substitute for coarse and fine aggregates at ratios of 5 to 25% with an increment of 5%. The experimental work was divided into three parts. Firstly, fine aggregates were replaced with CWS at the preceding ratios. Secondly, coarse aggregates were substituted with CWS at the aforementioned ratios. Thirdly, fine and coarse aggregates were replaced by CWS at the same proportions. Absorption ratio, compressive strength, flexural strength, splitting strength and dry density were determined at 28 days for all the mixtures and the control sample. Results showed that all tested properties, except absorption ratio, decreased when CWS was used. Optimal results were achieved when fine and coarse aggregates were replaced together with CWS. Advantageous values were obtained with a 15% CWS replacement for both types of aggregates.