EFFECT OF CRACKING AND HEALING ON DURABILITY OFENGINEERED CEMENTITIOUS COMPOSITES UNDER MARINEENVIRONMENT

摘要

Engineered Cementitious Composites (ECC) offer significant potential for durable civilinfrastructures under marine environment, due to its high tensile strain capacity of more than3%, and controlled micro-crack width of less than 60 gm. An experimental study wasdesigned to investigate the durability of ECC material with regard to cracking and healingunder combined mechanical loading and environmental loading conditions. ECC couponspecimens were firstly preloaded under uniaxial tension to different strain levels, and thenexposed to a chloride environment for 1, 2 and 3 months and subsequently reloaded up tofailure. The reloaded specimens retained multiple micro-cracking behavior and tensile straincapacity of more than 3%, although the average crack width increases from 40 um to 100 Jimand the tensile strength was reduced by 10%. The test results indicated strong evidence ofself-healing of the micro-cracked ECC material, which can still carry considerable tensilestress and strain. The phenomenon of self-healing effectively closes the microcracks. Theseresults confirmed that ECC, both uncracked and micro-cracked, remain durable despiteexposure to a severe marine environment.