| Research and preparation on high performance concrete have been made great progress both home and abroad near twenty years. The compressive strength has been regarded as a major index when we design traditional concrete, but its durability has been neglected. The examples of engineering have shown that much concrete is prematurely destroyed for their weak durability, and yet, the first reason for weak durability is cracking and leakage of concrete. The methods to solve the problem of concrete cracking is comprehensive. We research the causes of concrete cracking,develop the high performance anti-cracking additive, optimize the concrete mix and construction techniques , increase the stability of concrete volume by shrinkage compensation, enhance splitting tensile strength, and can meet demand of high workability of fresh concrete..In the study, a thorough investigation of this problem is made from all points of view, with the aid of various modern measurement & testing technology and different theories & methods in surface physical chemistry, structural chemistry, solid-state chemistry, composite materials, fracture mechanics, etc.Our research results have shown that the various shrinkage of concrete cause concrete cracking in building engineering, such as autogenous shrinkage,dry shrinkage,temperature shrinkage,plastic shrinkage,carbonized shrinkage,etc. When the confined shrinkage value which resulted from the confined action of all above shrinkage exceed the ultimate tensile strain, cracks occur. At the primeval moulded time, cracks are mainly caused by temperature shrinkage and autogenous shrinkage, after that, it is mostly caused by dry shrinkage.The effects of mineral additive such as fly ash,slag, and Dura fiber on concrete expansive property are studied, the results show that these mineral admixture reduce shrinkage in common concrete and also reduce expansive value in shrinkage -compensating concrete. It is very important for reducing and compensating concrete shrinkage and preventing cracks forming to construction and curing. The expansive property of concrete curing in water is better than that curing in air.The curing time of multiple anti-cracking and impermeability concrete can not less than 14 days.IllTo take all account of the factors such as raw materials, construction, curing, and tensile strength, limit tensile strain, etc.,which have effect on anti-cracking property of concrete,the overall crack probability is brought forward to access anti-cracking property of concrete ,with aid of mathematics.A new kind of multiple anti-cracking additive composed of multiple organic and inorganic ingredient is developed.lt improves anti-cracking and impermeability property of concrete.and can meet the demands of compressive strength and workability of fresh concrete.At the same time, we offer the integrity manufacture method of anti-cracking HPC.We discussed the relationship among compositions, construction and properties, studied the chemical reactions of phases, made the mechanism of reinforced and crack-resistance of concrete clear, and made concrete designed according to properties and engineering demand.Inorganic anti-cracking reinforced chemical additive ,called WJ, generates some tittle expansive crystals in hydration process in concrete to reduce the porosity and improve the distribution of pore size.The expansive power is process in common to tumefaction that petty crystalloid AFt suck water and pressure to concrete pores that AFt crystal gather volume.Its adding weight was 8%--12% in cement, its restrained expansive ratio was about 0.02%--0.06% ,and relevantil brought self-stress 0.2Mpa?.6Mpa.The concrete added organic water-reduce and plastic agent,called YJ,would improve concrete workability, and reduce slump loss, decrease the exothermic rate at the early stage and postpone the arrival time of the highest temperature.lt is compatible to cement well,and had good retarding property, and some air-entrained effect.HPC which added multiple anti-cracking additive ,called...
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