Study on stability of polyurethane reinforcement materials for mining

The chemical grouting reinforcement materials that are widely used in mining engineering mainly include polyurethane and silicate modified polyurethane.Generally, the volume ratio of two components is required to be 1∶1, but the accuracy of volume ratio cannot be strictly controlled in the actual construction, and certain weighing errors are inevitable in the production process.In order to ensure the stable and reliable performance of grouting reinforcement materials in underground construction, the imbalance of two-component ratio and the weighing error of main components were simulated under laboratory conditions. The effects of the reaction temperature and the compressive strength, shear strength and tensile strength of the consolidated body were investigated. The results show that the main components are within ±5% of the weighing error, the mechanical strength of the consolidation of the two types of reinforcement materials fluctuates little.When the proportion of the two-component slurry of type 2 materials is less than 10%, the mechanical strength of the two kinds of materials decreases, but it does not affect the normal reinforcement effect. When the distribution ratio of the two-component was out of adjustment by 20%, the shear strength and tensile strength of polyurethane decreased by 56.9% and 72.7% respectively, and the maximum reaction temperature increased by 6 ℃.After the AB component of the silicate modified polyurethane reinforcement material was mixed, there would be problems such as foaming, effluent, efflorescence and difficult molding. Therefore, when changing the formula of Type 2 reinforcement materials, in addition to the relevant performance specified in the standard, the maximum ratio fault tolerance should be explored,the normal proportion shall be kept as far as possible during the construction to avoid safety problems caused by the imbalance of proportion.Among them, in the use of polyurethane reinforcement materials, we should be careful to prevent the mechanical strength from greatly reducing due to excessive white materials and the reaction temperature from increasing due to excessive black materials.For the silicate-modified polyurethane reinforcement materials, serious abnormalities will occur if the proportion is greatly misaligned, and it is difficult to achieve the normal reinforcement effect.In addition, the weighing error of the main components has little effect on the mechanical strength of the two types of materials.