Investigation On The Self-healing Of Cementitious Materials

Cement based materials in a wide range of applications with the natural environment, disaster damage, the role of human factors caused by many diseases of cement based materials, and the cracking problem is the most serious of these disasters which are urgently needed to solve the problem.The traditional solution is to repair, but this passive method can not completely meet the needs of the people. This paper is the cement-based materials self-healing properties research, discussing the self-healing technology.(1) After adding admixtures, self-repairing effect of cementitious materials reduced, which the healing effects of the worst is fly ash, followed by slag, metakaolin and silica fume.Cementitious materials have self-healing characteristic when they are damaged, and along with the increasing of curing period, self-healing phenomenon is continued, but the early healing effect is remarkable, then later leveled off.When the cement based materials is in the heat curing condition, self-healing effect has the best results.As early maintenance time increaseing, pressure loss and standard curing strength value is restored gradually decreasing. With the pressure loss increases, injury degree is deepened, maintenance after repairing of compressive strength value decreases than the reference specimen.Hot water conservation has the largest flux recovery rate, standard curing secondly, water conservation is the worst, in which hot water conservation effect is the closest to no pressure loss stat.With the water cement ratio rising, flux recovery rate in general showes a declining trend.(2) Penetrating sealants and sodium silicate solution can improve the compressive performance, they can partly repair mortar specimen pores and cracks when mortar specimens are damsged under cyclic freezing and thawing and penetrating sealants and sodium silicate can reinforce mortar compactness.(3) Electrochemical deposition method for cement base material specimen fracture repairing is feasible and the current density is an important factor for the impact of crack healing effect. When the current density function is small, Mg (OH)2crystals deposition velocity are down and generating leaf-shaped crystals which have closely arranged structure and high strength.(4) Through the orthogonal experiment, this paper gets a new type of cement-based permeable crystallization repairing agent.The most prominent effect of these components is active agent, it has played a major role in repair. The optimal formula:4%auxiliaries,40%sulfur aluminate cement,1.5%active agents and35%cement.