## 1 Introduction  
The speed of global infrastructure has been increasing in recent years, and the infrastructure construction material that is mainly used is concrete [1], which produces more and more construction waste. A big problem that follows is the disposal of construction waste, but the global recycling rate of construction waste is very low [2]. A small amount of construction waste is recycled and utilized mainly for backfilling foundations, while the rest is piled up at empty sites. Since it is difficult for construction waste to decompose on its own, dumping it randomly will damage and pollute the ecological environment. The use of recycled coarse aggregates enables the reuse of resources and reduces the extraction of natural stone; it also reduces the ecological damage caused by construction waste. However, when recycled coarse aggregates are crushed and processed again, the microcracks inside the aggregates increase a lot, and part of the old mortar is attached to the surface, resulting in high water absorption of the recycled concrete [3; 4; 5]. Thus, it is necessary to strengthen recycled coarse aggregates. Currently, the more frequently used and effective strengthening method is the chemical modification method; the chemical modification method is involves the recycled coarse aggregate being soaked in a chemical solution to improve the performance of the recycled coarse aggregate through the product of a chemical reaction [6]. [PERSON] et al. [7] measured the capillary water absorption of bridges treated with silane for 20 years and found that the bridges were still well waterproofed and protected. [PERSON] and [PERSON] et al. [8] found that the water absorption of concrete surfaces treated with silane hydrophobizing agents was reduced by 2.12 times. [PERSON] et al. [9] experimented by either applying silane on the surface of concrete or by adding it to the concrete as a whole, and it was found that both treatments improved the resistance of recycled concrete to capillary water absorption, carbonation, and chloride ion penetration. [PERSON] et al. [10] showed a 7% decrease in the water absorption of concrete after treating glass powder with silane. [PERSON] et al. [11] found that both the surface silane modification of recycled aggregate and cementitious monolithic silane modification can improve the freeze-thaw durability of recycled aggregate pervious concrete. [PERSON] et al. [12] found that the addition of an appropriate amount of water glass to recycled aggregate concrete can improve its strength. [PERSON] et al. [13] impregnated concrete with water glass and found that the strength of the concrete was slightly increased, but the porosity of the concrete was improved more significantly, and its resistance to chloride ions was significantly increased. [PERSON] et al. [14] showed that the microcracking of concrete with the addition of sodium silicate material was less than that of conventional materials. [PERSON] et al. [15] used 4% and 6% water glass as activators to be added to the concrete, and the durability of the concrete was better in both cases. [PERSON] et al. [16] found that soaking the recycled coarse aggregate in the prepared water glass solution reduced the water absorption of the recycled coarse aggregate. [PERSON] et al. [17] treated the surface of recycled coarse aggregate with a 3% solution of water glass, which resulted in decreases in the water absorption and crushing value of 23.36% and 16.59%, respectively. [PERSON] et al. [18] found a more pronounced decrease in the water absorption of concrete by immersing the concrete in a diluted water glass solution and then in a diluted alkyl quaternary ammonium salt solution. The silane and water glass production process has become more mature, with less pollution to the environment, good adhesion with concrete, corrosion resistance, high-temperature resistance to weathering, and low production costs.