Experimental research on dynamic tensile mechanics of limestone after chemical corrosion

To investigate the dynamic tensile mechanical properties of limestone corroded in the chemical environment, the mixed solution of NaCl and KHSO₄ with pH=3 was prepared to corrode limestone samples for different corrosion time, i.e. 30 days, 60 days, 90 days, 120 days and 150 days, respectively. The T₂ spectra and porosity of the corroded limestone samples were obtained by nuclear magnetic resonance (NMR) test, and the dynamic tensile test was carried out on corroded limestone samples by using the separated Hopkins compression bar (SHPB). Finally, the variation law of dynamic tensile strength and energy dissipation with corrosion damage degree of limestone was obtained. In addition, microscopic images and mineral contents of samples at different corrosion stages were analyzed by scanning electron microscopy (SEM) and X-ray fluorescence spectrometry (XRF). The result shows that, after being corroded for 150d, the porosity of limestone rises from 0.32% to 5.32% and the corrosion damage degree increases.The deterioration of dynamic tensile strength can be divided into two stages by the slope, with the total decrease extent of 32.52%. Dissipative energy and transmission energy exhibit two-stage decreasing trend and distinct correlation to damage degree. The failure mode evolution of limestone after chemical corrosion changes from the typical splitting failure to the tensile-shear, shear failure and ultimate powders failure. There is a distinct relationship between the macro-mechanical properties and the micro-structure damage of specimens. The research results can provide references for the design and construction of underground engineering.