Abstract
In this study, we examined the effects of different temperatures and accelerators on the gelation (gel) time and compressive strength of a Polyethylene Terephthalate (PET)-type unsaturated polyester resin anchorage agent. First, the formation temperature of 20–70°C was simulated using self-made test equipment. N,N-Dimethylaniline (DMA), N,N-dimethylp-toluidine (DMT), and hydroquinone were selected as accelerators to determine gel time and heat release peak. The gel time of an anchorage agent is strongly influenced by accelerant and temperature. When DMT, DMA, and hydroquinone were added at the same temperature, the gelation time increased; with increasing ambient temperature, the gelation time of the anchorage agent decreased. The peak exothermic value of the curing reaction was less affected by the accelerator, and the peak exothermic value of the anchoring agent increased with the increase in ambient temperature. Then, the compressive strength of the anchorage agent, maintained at 20, 50, and 80°C for 1.5, 6, 12, and 24 h, was measured. We found that the compressive strength of resin anchorage agent decreased significantly with the increase in temperature, and the addition of DMT can improve the compressive strength of resin anchorage agent slightly at the same temperature conditions. Finally, through Fourier transform infrared scanning analysis, we determined the intrinsic causes of the influence of temperature and accelerator on the gelation time and compressive strength of the anchorage agent. Through SPSS fitting analysis, an empirical formula for predicting gelation time based on ambient temperature is proposed. Our findings provide a basis for reasonable mixing time and support design optimization of anchorage support in deep stratum in high-temperature geothermal environments.
Highlights
In mine roadways, bolt support is used for timely and active load bearing, which can signi cantly improve the self-supporting ability, and stability of the surrounding rock [1,2,3].e resin anchorage agent is an important part of the bolt support system. ese agents have the advantages of cure quickly at room temperature, high bonding strength, durability, and stability [4]
E resin anchorage agent is an important part of the bolt support system. ese agents have the advantages of cure quickly at room temperature, high bonding strength, durability, and stability [4]
Some mines are deeper than 1000 m, and the formation temperatures can be as high as 40–50°C. e spontaneous combustion of coal during coal mining results in high-temperature geothermal environment [5,6,7]. e anchorage force on the bolt support system is o en lower than the designed value due to the high-temperature geothermal environment in deep stratum, thereby reducing the anchorage safety [8,9,10]
Summary
Bolt support is used for timely and active load bearing, which can signi cantly improve the self-supporting ability, and stability of the surrounding rock [1,2,3]. E resin anchorage agent is an important part of the bolt support system. E anchorage force on the bolt support system is o en lower than the designed value due to the high-temperature geothermal environment in deep stratum, thereby reducing the anchorage safety [8,9,10]. E anchorage agent commonly used for bolt support in coal mine roadways is composed of unsaturated polyester resin, curing agent, accelerator, and ller. Typical formulations are as follows: 100 copies of unsaturated polyester resin, 5 copies of curing agent, 1 part of accelerator, and 500–550 copies of stone powder. The gel time of resin anchorage agent is adjusted using accelerants and curing agents
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