Ultra-fast Hard-repair Material And Its Action Mechanism

The super early-strength & quick-hardening repairing matetial, as is so called, refers to a kind of compound material which can change the hardening time of normal cement concrete, enable its strength to reach 70% strength of 28 days within several hours, and in the meantime maintain its durability. The HW series of super early-strength & quick-hardening repairing materials, as we name them, are new materials which are rich in resources, low in cost and convenient to be produced.After working on the basic properties of HW series, the study results show that HW series can obviously increase the early period strength (at best in 4h its flexural strength can reach 4.38MPa) and its later period strength of cement mortar. They have longer initial setting time which makes the repairing work easy to be done, shorten the time between the initial and final setting which provides enough time for the development of the early period strength. Numerous test results and theoretical analysis indicate that using concrete mixed with early-strength & quick-hardening repairing materials can apparently increase higher hour-strength of the early period and do not decrease its later period strength.Based on the test observations and analysis of the DSC, X-ray and electric-microscopy, the cement stone with repairing materials have dense structure, more AFt and AFm formed in its early stages and more gel, but small number of Ca(OH)2 crystals which do harm to microstructure. All these show that using repairing materials can change the mechanism of cement coagulation and hardening.