Evaluating the Effects of Two Modifiers on the Mechanical Properties of Sulfur Concrete Using a Novel, High-Capacity Lab-Scale Mixer for Sustainable Construction

Sulfur concrete represents a promising sustainable alternative to traditional Portland cement due to its rapid setting time, superior chemical resistance, and recyclability. Nonetheless, inherent brittleness and susceptibility to long-term deterioration limit broader applications, necessitating effective modifiers to improve mechanical and durability performance. This study investigates the influence of incorporating high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) at dosages of 5, 10, 15, and 20 wt.% into sulfur concrete containing 30 wt.% sulfur. Comprehensive evaluations included mechanical testing (compressive, flexural, and tensile strength), non-destructive testing methods (ultrasonic pulse velocity and rebound hammer), accelerated corrosion assessments via impressed voltage technique, and microstructural analyses (SEM, FTIR, and XRD). Results revealed optimum mechanical performance at 5 wt.% polymer content, with LLDPE modification achieving maximum compressive, flexural, and tensile strengths of 25.24 MPa, 3.31 MPa, and 1.75 MPa, respectively, compared to the control’s 20.6 MPa, 2.75 MPa, and 1.21 MPa. Corrosion resistance significantly improved with polymer additions, notably at 20 wt.% LLDPE exhibiting the lowest current intensity (~0.03 A). SEM analysis confirmed enhanced matrix density with HDPE modification, whereas FTIR and XRD analyses indicated no chemical interactions, affirming physical blending. These findings highlight that carefully selected polymer modifications significantly enhance the mechanical integrity and durability of sulfur concrete for sustainable infrastructure applications.