Mechanical performance of cement mortar with olive pomace aggregates and olive mill wastewater: an experimental investigation

Abstract

This study investigates the potential use of olive aggregates (OA) in the production of cementitious materials as a substitute for natural sand to reduce excessive use of this resource. Two types of OA were used: OPA (olive pomace aggregates) and OPMW (OPA mixed with olive mill wastewater). The aim was to determine experimentally whether improvements in the mechanical properties of the produced lightened cement mortar could be obtained compared to the reference mortar. Laboratory tests were conducted on two series of mortar samples made by replacing 0%, 5%, 10%, and 15% of natural sand with both dry and saturated OA. The best results were observed in a mixture containing 5% of OPMW at the dry state, which had a marginal effect on the compressive strength of the produced mortar, reaching 33.50 MPa after 28 days of curing. However, microstructural analysis revealed low adhesion between the OA and the cement matrix at the interface transition zone (ITZ) after 28 days. Increasing the OA content was found to decrease the workability of the mixture while also increasing the porosity of the resulting lightened cement mortar. Additionally, the use of OA reduces ultrasonic pulse velocity and dynamic modulus of elasticity. Overall, the best results were obtained with the mixture containing 5% of OPMW at the dry state, which meets the standards for general use of building materials.

Keywords:

• Olive pomace aggregates
• olive mill wastewater
• sustainable building materials
• agricultural waste minimization
• lightweight aggregates
• lightened cement mortar
• mechanical properties

Highlights

• Two types of olive aggregates were used in cement mortar as a partial replacement for natural sand.

• Mixture workability is mainly affected by the saturation state and the percentage of substitution.

• The compressive and flexural strengths decreased with increasing the amount of olive aggregates in the mixture.

• Interesting mechanical properties are obtained for the mortar specimen containing 5% of olive pomace aggregates mixed with olive mill wastewater at dry state.

Acknowledgments

The authors appreciate the excellent technical support provided by LM2G laboratory, Casablanca.

Disclosure statement

The authors declare that they have no known conflicts of interest associated with this publication.