Visualization and quantitative fracture analysis of rubber mortar under in-situ loading

In order to improve the ductilityof cement-based materials, rubber is often added to cement-based materials. But the rubber-cement interface will introduce more initial defects, and make the three dimensional images obtained by the X-ray micro-computed tomography (X-ray μCT) technology more complex, and finally,which leads to the full threshold method no longer applicable to analysis of the internal three-dimensional cracks.This paper presents an improved image processing method, which can accurately identify mesoscopic cracks and achieve the separation of pores and cracks. In order to verify this method, X-ray computed tomography (XCT) in-situ observation technology is used to obtain the crack formation of rubber mortar with different replacement ratios. Pores and cracks are well identified and separated by this method. Quantitative analysis shows that the new method has higher accuracy and better identification of mesoscopic cracks than traditional methods. Due to the incorporation of rubber, there are more initial cracks in the rubber mortar, but the rubber will improve the overall absorption of the input energy of the sample, resulting in a decrease in the number of large cracks and the total crack volume when the specimen is failure.Compared with the sample without rubber content, the total crack volume of the sample with 5% and 10% mass fraction of rubber decreases by 30% and 45%, respectively.