Concrete is prone to cracking over its service life due to various factors, including early-age shrinkage and loading. These cracks become a conduit for water and waterborne chemicals, which could lead to degradation of the concrete. This will in turn compromise the durability of a structure, which leads to an inevitable decrease in the service life of a concrete structure. In response, concrete has been found to have an ability to seal cracks autogenously, or to “self-seal.” This property can play a vital role in sealing cracks to ensure durable concrete with a longer service life. Moreover, this ability to self-seal can be greatly increased with the addition of some permeability-reducing admixtures (PRAs). Increased self-sealing attributes are beneficial for any concrete but are essential for concrete structures with waterproofing systems based on permeability-reducing admixtures for hydrostatic conditions (PRAHs). Self-sealing has been widely observed anecdotally in the field. This evaluation of self-sealing performance using a standard test method in the laboratory has recently been developed by the authors.
This research paper presents an innovative test method to study and characterize the self-sealing performance of concrete by directly measuring water flow rates through leaking cracks. This flow rate measurement technique was designed to simulate a real, leaking structure. This test method is able to induce realistic, repeatable cracks in laboratory specimens with consistent crack patterns similar to those observed in the field. This research involved analyzing chemical admixtures and their effect on the self-sealing of concrete. Current research explained in this paper indicates that some PRAHs can improve the self-sealing properties of concrete. This patented test method is essential to evaluate the self-sealing ability of PRAs used for waterproofing applications. This test method can be further applied to the study of corrosion protection and extending a concrete structure’s service life.
Rishi Gupta, Assistant Professor, Civil Engineering Program, University of Victoria, Victoria, B.C., Canada.
Alireza Biparva, Development Manager, Kryton International Inc., Vancouver, B.C. Canada.