# Mechanical Properties of Cement Concrete with Waste Rubber Powder
## 1 Introduction  
The construction industry is one of the largest consumers of resources and energy [1], and concrete is the second most widely used construction material after water [2]. Due to its cost efficiency and ease of manufacturing, concrete can be molded into various forms to meet a wide range of specifications [3]. The incorporation of waste rubber powder into concrete can decrease landfill and incineration volumes, while also minimizing the extraction of raw materials [4, 5]. Since the early 1990s, scholars have investigated waste tire rubber powder in cement concrete. Most studies suggest that the mechanical strength of concrete typically decreases with the addition of rubber, and this trend exacerbates as rubber content increases [6, 7, 8, 9]. Adding rubber powder tends to reduce the strength and other mechanical properties of cement concrete, but this effect can be mitigated by the inclusion of silica fume [10, 11]. Additionally, [PERSON] et al. [12] noted that the interface between rubber and cement, along with the distribution of rubber particles, play pivotal roles in shaping the mechanical properties of rubber aggregate concrete. Crum rubber concrete demonstrates notable resistance to chloride ion erosion [13]. According to most studies, rubberized concrete treated with NaOH shows enhanced mechanical properties [13, 14]. Experimental results conducted by [PERSON] et al. [15] showed that the durability of rubberized concrete or mortar samples with 15% or 25% NaOH-treated rubber replacement is enhanced. [PERSON] et al. [16] discovered that incorporating rubber into concrete enhances both its compressive strength and compactness in chloridesalt-corroded environments. [PERSON] et al. [17] concluded that employing a low W/C ratio in crumb rubber concrete significantly enhances resistance to chloride penetration. The study by [PERSON] and [PERSON] [18] revealed that the inclusion of waste rubber powder reduces the elastic modulus of cement concrete, with a lesser impact on compressive strength observed with larger mesh sizes of waste rubber powder. Following this, [PERSON] and [PERSON] [19] noted the influence of crumb rubber size on concrete's elastic modulus, observing a decrease in concrete with fine crumb rubber while enhancing its ductility. [PERSON] et al. [20] demonstrated that incorporating rubber flakes or granules to partially replace the aggregate effectively lowers the static elastic modulus of concrete. [PERSON] et al. [21] proposed that utilizing rubber as aggregate could notably improve concrete durability. [PERSON] et al. [22] observed that the increase in abrasion resistance of crumb rubber concrete is primarily due to the absorption of wear energy by the rubber particles. [PERSON] et al. [23] determined that rubberized concrete mixes were functional up to a certain sand replacement level, yielding lighter concrete. Consequently, rubberized concrete presents advantages for lightweight building construction [6]. It has been observed that concrete incorporating elastic materials like crumb rubber exhibits a high fracture toughness. [PERSON] et al. [24] demonstrated that pretreating rubber particles enhances the strength, ductility, and crack resistance of rubberized concrete. [PERSON] et al. [25] discovered that rubber-treated concrete samples display increased ductility under pressure testing compared to ordinary concrete, and they exhibit slower fracture rates. Research indicates that the addition of waste rubber powder substantially reduces the thermal conductivity of concrete and significantly improves its sound absorption [26]. In summary, although numerous studies have delved into rubber concrete, the bulk of them center on mechanical properties. However, research on the durability of rubber concrete remains inadequately thorough, yielding divergent and inconclusive outcomes. The introduction of rubber powder may reduce the strength of concrete. The shape and surface characteristics of rubber powder may affect the workability of concrete.