Evolution of Cracks in Nano-CaCO3 Modified Pre-Disintegrated Carbonaceous Mudstone Under Cyclic Wetting and Drying.

ABSTRACT

To explore the evolution of cracks in the pre-disintegrated carbonaceous mudstone, wetting-drying tests were carried out on nano-CaCO3 modified pre-disintegrated carbonaceous mudstone samples. The samples were prepared with aqueous solutions of different pH values. Scanning electron microscopy (SEM) was performed to clarify the mechanism of crack evolution of pre-disintegrated carbonaceous mudstone modified by nano-CaCO3. The results showed that development of shrinkage and cracks was basically divided into three stages, i.e., the gestation stage, the rapid development stage and the stable stage. For the samples without nano-CaCO3, the final crack rates and pore sizes of samples with pH = 3 and pH = 11 were larger than corresponding values of the sample with pH= 7. Moreover, final crack rate and pore size significantly decreased with the addition of nano-CaCO3 suggesting that nano-CaCO3 can effectively improve cracking resistance of pre-disintegrated carbonaceous mudstone.