repetability of self healing in fiber reinforced concretes with and without crystalline admixtures: preliminary results

This paper analyzes the repeatability of autogenous and engineered self-healing in fiber reinforced concrete (FRC) with and without crystalline admixtures. To this purpose, the tensile behavior of two different mixes, differing by the presence of the crystalline admixture, has been investigated after a series of pre-cracking and conditioning cycles. An indirect testing methodology has been employed to the aforementioned purpose, i.e. Double Edge Wedge Splitting (DEWS) test. Three different exposure conditions were considered: open air exposure, water immersion and wet/dry cycles. Specimens were pre-cracked up to a crack width of 0.25mm (0.01 in.) (precrack cycle). Then, specimens were healed for one month and tested again up to a crack width of 0.25mm (0.01 in.) (cycle after 1st healing). After that, specimens were healed for two months further (2nd healing) and finally, they were cracked once again up to 0.25mm (0.01 in.). The highest healing rate was reached for specimens immersed in water; moreover, as expectable, the larger the initial crack width, the lower is the percentage of crack closure. Regarding the repeatability, a general better trend was found for the mix with crystalline admixtures, in which, in addition, the maximum load regain was measured after the 2nd healing cycle rather than after the 1st healing.