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Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used 'washing with water' and 'neutralization with quicklime' methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the 'washing with water' method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge. [ABSTRACT FROM AUTHOR]

Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used 'washing with water' and 'neutralization with quicklime' methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the 'washing with water' method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge. [ABSTRACT FROM AUTHOR]

• High-strength fiber-reinforced concrete (HSFRC) was fabricated using polypropylene fibers. • The performance of the SCB setup in determining the fracture characteristics was evaluated. • Finite element simulation was carried out using concrete damaged plasticity (CDP) model in ABAQUS. Semi-Circular Bending (SCB) Setup is commonly used to investigate the fracture parameters of the road materials like asphalt mixtures. This paper examines the performance of the SCB setup in extracting the fracture characteristics of high-strength fiber-reinforced concrete (HSFRC). Monofilament and fibrillated polypropylene fibers with polyolefin coatings of 19, 30, and 50 mm length were added to a high-strength concrete mixture at three volume percentages of 0.5, 1, and 1.5 %. Standard cube and cylinder specimens were initially fabricated for conventional material properties tests. Subsequently, the three-point bending test specimens, i.e., intact rectangular beam, notched beam, and SCB, were made using the same concrete mix of different fibers lengths and percentages. A total of 36 beam and SCB tests with three replications was conducted to find the fracture energy and pick load of each specimen. Results showed that selecting the shortest fibers (19 mm) of 0.5 % and 1.5 % by volume increased the elastic modulus and the splitting tensile strength by 70.5 % and 43 %, respectively. Also, increasing the fiber length and volume enhanced the fracture energy of the notched beam and SCB specimens up to 90 times and 40 times, respectively. However, increasing the volume of the fibers was more effective than using longer fibers in fracture energy increase. For these three test setups, finite element models were generated and analyzed to develop a numerical framework capable of predicting the fracture characteristics of HSFRCs with acceptable accuracy (maximum error of 4 %). The concrete damaged plasticity (CDP) model in ABAQUS software package were adopted to simulate the damage initiation and progression in concrete using the material properties from the conventional tests. Comparing the results of beam setups with SCB tests, it was found that SCB can be a reliable and economical setup to find the fracture characteristics of the HSFRCs. [ABSTRACT FROM AUTHOR]