Study on Crack Bridging Ability of Polymer-modified Cement based compounds for Waterproofing Material

摘要

China's existing polymer-modified cement based compounds for waterproofing material standards are used for the tensile strength test and elongation at break test as the test method to evaluate the performance of the product extension. The elongation only reflects the extension ability of product, but cannot indicate the crack bridging ability of the product. In engineering applications, there is a requirement for higher bridging cracks ability of the products. In this paper, 9 samples of polymer-modified cement based compounds for waterproofing material were tested. Crack bridging ability was tested under the standards and methods in DIN EN 14891:2013-07. Tensile strength and elongation at break were tested according to the standards and methods in GB23445:2009. The crack bridging ability test results are between 0 to 2.08mm, in which 5 of them meet the requirements of greater than 0.75mm according to DIN EN14891:2013-07. The tensile strength test results are between 1.13MPa to 3.19MPa, the elongation at break test results are between 4% to 350%. The results show that higher tensile strength and higher elongation at break will have good ability of crack bridging. Samples with better crack bridging ability are close to type III product according to GB23445-2009 which requires tensile strength ≥ 1.8MPa and elongation at break ≥30%. Crack bridging ability directly reflects the product's ability of crack bridging, and is more in line with the actual requirements in engineering applications. It is recommended that the crack bridging ability test method should be adopted in the formulation of China polymer-modified cement compounds for waterproofing material standards.