## 1 Introduction  
From the establishment of environmental protection as a basic national policy to the implementation of the sustainable development strategy and the construction of a resource-saving and environmentally friendly society, the strategic position of ecological environmental protection has been continuously upgraded. However, with China's economic and social development, solid waste is increasing, which has become a challenge for sustainable development [1]. According to relevant statistics, the rate of recycling waste rubber in China is less than 50% [2]. Although part of the rubber is recycled, most of the waste rubber is buried or incinerated, which causes fire hazards and public health and safety and environmental problems [3; 4; 5; 6]. For the disposal of waste rubber, experts and scholars at home and abroad have put forward a series of recommendations [7; 8; 9], in which rubber is used as an aggregate to replace original concrete aggregate, which can effectively solve the problem of rubber recycling and pollution and at the same time achieve waste recycling. In addition, relevant studies have shown that rubber incorporation can have a positive effect on the antifreeze, impermeability, and deformation capacity, and the chloride ion penetration, of concrete [10; 11; 12; 13], which shows that rubber particles incorporated into concrete can effectively improve the relevant characteristics of concrete and at the same time achieve the effect of recycling resources. When rubber particles replace the aggregate and are incorporated into concrete, they can effectively meet the needs of concrete and protect sand and gravel resources. Rubber added to concrete can effectively improve its anti-cracking properties. According to the analysis of three-point test results, rubber can effectively absorb part of the energy to improve the toughness of concrete [14; 15]. Further, adding rubber to concrete can make the slump of concrete smaller, resulting in poor working performance [16]. In order to solve this problem, 1-3 mm, 3-6 mm, and 60-mesh rubber were mixed into concrete. It was found that for the particle size of 1-3 mm and 60-mesh rubber, at a 15% admixture, the slump first increased and then decreased. The particle size of 1-3 mm rubber admixture reached the maximum slump at 10-15%, and the 60-mesh rubber admixture reached the maximum slump at 5-10%. The rubber particle size and the admixture had different effects on the slump [17]. Also, for concrete mixed with coarse and fine rubber, its related work performance was also quite different. Relative to the mixing of fine rubber, the work performance of coarse rubber concrete was better. For an equal volume replacement of fine aggregate with rubber mixed into concrete, its work performance increased with the increase in coarse rubber mixing, while for fine rubber, it was the opposite. For rubber directly mixed into concrete outside, whether it was coarse rubber or fine rubber, its work performance showed the same effect on the slump with the increase in the amount of rubber mixed in [18], and the slump showed a pattern of increasing and then decreasing [19]. The work performance of rubber admixture undergoes a series of changes and also has a series of effects on its static mechanical properties. Percentages of 15%, 30%, and 45% of rubber were added to concrete with an equal volume replacement of coarse aggregate. It was found that with the increase in the amount of mixing, the compressive strength decreased more obviously. The mixing particle size also had an effect on the strength, but it was not the case that the larger the particle size, the more the strength decreased [20]. When rubber powder and rubber blocks were added to concrete in different contents, it was found that the rubber powder had less of an effect on the compressive, flexural, and splitting strength of concrete with the same content [20; 21]. After carrying out tests on concrete with different rubber contents, it was found that the compressive strength decreased with the increase in admixture.