Determination of Poisson’s ratio of coal gangue-based shotcrete materials using a non-contact test method

Preparing shotcrete materials using coal gangue is an effective method of disposal and use of gangue solid waste, while testing the Poisson's ratio of coal gangue-based shotcrete materials (CGSM) is an important step in evaluating the mechanical properties of such materials. Therefore, to study the evolution of the Poisson's ratio of CGSM under different influencing factors, detailed test schemes and procedures were designed based on the non-contact test method of Poisson's ratio. The accuracy of the non-contact test method is verified. In addition, changes in the Poisson's ratio of CGSM under different factors were studied. Results show that the Poisson's ratio of CGSM tends to reduce with prolonged curing. When the particle sizes of coal gangue are 0 ~ 2.5 and 2.5 ~ 5 mm, fine particles can fill interstitial voids in shotcrete materials. As the mass concentration and cement content increase, the Poisson's ratio of CGSM gradually decreases; as the sand content rises, the Poisson's ratio gradually increases.