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Since the interaction between the steel reinforcement and concrete directly controls the bond strength between them, poor bond performance results in a direct negative effect on the existing state of reinforced concrete structures. This bond is one of the most important factors affecting the strength of reinforced concrete. The bond strength is measured using the pull-out test. The present paper discusses the effect of the addition of brine and olive oil mill wastewaters to the reinforced concrete mixes. The main objective of this study is to determine the effect of brine wastewaters and olive oil mill wastewaters on the bond strength between steel and concrete when adding each of the admixtures to the concrete components. Pull-out tests were conducted on concrete mixes with additive contents of 2.5, 5, 7.5, 10, and 15 % by weight of water for each. It was found that the bonding strength of reinforced concrete specimens with an olive oil mill and brine wastewater improved and decreased by approximately 6–10% and 2–5%, respectively, if compared to the reference samples. These values were observed for mixes with additive contents of 7.5% for olive oil mill wastewaters and 10% for brine wastewaters. Doi: 10.28991/CEJ-2022-08-02-010 Full Text: PDF

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The authors conducted a comprehensive research study on adding olive oil mill and brine wastewater to the concrete mix to investigate torsion, bending stress, shear, and compressive strength. The total number of specimens were 33 beams 100 mm (depth) × 100 mm (width) × 500 mm (length). Three beams were used as control samples, and thirty beams were divided into two groups: fifteen samples were from an olive oil mill, and the other fifteen were brine wastewater with different percentages of additive material (olive oil mill and brine wastewater), with 2.5, 5.0, 7.5, 10.0, and 15.0 % of each. The beams were reinforced with 4 ϕ 8 mm as longitudinal steel bars and ϕ 4 mm stirrups spaced at 20 mm. All specimens were tested at 28 days. It was found that the torsional strength of the samples containing brine wastewater when added at the best percentage, which is 10%, was 5.46 MPa. As is the case when adding olive oil mill wastewater with the best percentage, which is 7.5%, it was 5.16 MPa. These data are greater than the torsional strength in the reference samples, which were 4.38 MPa, meaning that the torsional strength when adding brine wastewater and olive oil mill wastewater increases by 24% and 17%, respectively. Doi: 10.28991/CEJ-2023-09-03-012 Full Text: PDF