The Use of Palm Oil Mill Effluent as Mixing and Curing Water in Cement-Based Composite

Abstract

The scarcity of water, especially during the dry season, is the main factor influencing water consideration with unknown characteristics for mixing cement mortar and concrete. This study investigates Palm Oil Mill Effluent (POME) effects as mixing and curing water on the hardened cement matrix properties. The cement pastes were prepared with ordinary Portland cement, which was used as a binder. In contrast, Potable Water (PW) and POME were used separately for mixing cement and a mixture of cement and sand to produce cement paste and cement mortar, respectively. Two different mix ratios of cement: sand of 1:3 and 1:5 with the constant water-to-cement ratio of 0.5 were used to prepare the cement mortar. The PW and POME were also utilized as the liquid curing media for hardened cement mortar until the testing ages of 7, 14, and 28 days. Soundness, normal consistency, and setting times tests were performed to evaluate cement paste’s fresh properties, while unit weight and compressive strength tests to determine the hardened properties of cement mortar at different ages. The results showed that soundness, normal consistency, and setting times of cement paste with POME as mixing water were higher than that of PW. This indicates that POME exhibits the potential of serving as retarding admixture. The unit weights of mortar (1:3 or 1:5 mix proportion) with POME as mixing water were lower than those produced with PW as mixing water after curing in PW or POME for 28 days; but for the mortar with POME as mixing water, the unit weight was slightly higher when cured in POME than water at the same curing age. The mortar specimens with 1:3 mix proportions with PW as mixing and curing water had the maximum 28-day compressive strength values of 26.01 N/mm2, while a decrease of 20% was recorded when cured in POME. Further decrease in 28-day compressive strength values was recorded cement mortar with 1:3 mix proportions and POME as mixing water after being cured in PW and POME. A similar trend was observed for cement mortar with 1:5 mix proportion with POME as mixing water when cured in PW and POME, and PW as mixing water when cured in POME, compared with the cement mortar with PW when cured in PW for 28 days. The maximum strength reduction of 20% specified by the standard for cement composite or concrete at 28 days of curing for water from the questionable source was exceeded with the use of POME as mixing water. It can be concluded that POME is not suitable for mixing cement mortar.