The use of concrete in various engineering fields has always been of interest due to its two key properties: strength and durability. In recent decades, there has been a world wide liking, including in Iran, toward greater use of concrete pavements because of these same characteristics. One of the main issues with concrete pavements is their poor surface skid resistance. Due to the rigidity and very low deformability of concrete, it absorbs less energy during braking compared to asphalt pavements, resulting in longer stopping distances. This issue becomes critical on high-speed roads and airport runways, where vehicles must decelerate over short distances. Moreover, concrete pavements are subjected to repeated impact loads, and the high stiffness and lack of deformability in concrete often lead to cracking and surface fragmentation. Thus, most of the problems with concrete pavements come from concrete’s rigidity and inadequate energy absorption. Therefore, finding solutions to improve the deformability and energy absorption of concrete can significantly enhance pavement performance. In this study, crumb rubber with particle sizes ranging from 0 to 5 mm was used as a partial replacement for sand in the concrete mix design, in proportions ranging from 0% to 30%. To compensate for the strength reduction due to the addition of crumb rubber, microsilica was used as a cement replacement at 0%, 2%, and 4% by the weight of cement. The mechanical and durability parameters of the concrete were then eva‎luated. Compressive strength, flexural strength, water absorption, freeze-thaw cycles, and impact resistance tests were conducted to assess mechanical properties and durability. Additionally, British Pendulum and Mean Texture Depth tests were performed to eva‎luate surface skid resistance and braking performance. Laboratory results showed that adding 30% crumb rubber could reduce strength parameters by up to 50%. However, using 20% crumb rubber along with 2% microsilica—identified as the optimal mix—reduced strength loss to less than 20%, which meets the required standards for pavement use. Durability tests also indicated that microsilica positively impacted the performance of the samples. Furthermore, in the impact resistance test, the number of impacts required for failure (an indicator of energy absorption and crack resistance) increased by about 40%, despite a 20% drop in compressive strength. The results of the British Pendulum and Mean Texture Depth tests were also consistent. The optimal mix showed a 15–20% increase in skid resistance compared to the control sample, which can significantly enhance braking performance.

مهدي ابطحي فروشاني , عليرضا سلجوقيان

محمدرضا افتخار , محسن ابوطالبي اصفهاني