Research On Preparation And Performance Of Ultra-high-strength Concrete(C100) With Low Viscosity

With the development of society and progress of science and technology, humanbeings broaden their own living space continuously. People are developing highaltitude, ground and marine constantly in forming a high-level, lightweight, andlong-span of modern buildings. All these are realized by improvement of concretetechnology and the level production processes. Ultra high strength concrete hasadvantages in improving the durability of concrete effectively and reducing energyconsumption and construction cost compared with ordinary concrete. However, therealso have disadvantage of high viscosity, which is due to achieve the purpose of highstrength on basis of low water consumption (<150kg/m3), But low water consumptionresults in high viscosity of fresh concrete, thus leading to difficulty pumping and thepumping accidents occurred frequently. Therefore, the problem of high viscosity ultrahigh strength concrete(UHSC) pumping construction in our country is very serious.Therefore, the problem of high viscosity of ultra high strength concrete is especiallyserious in pumping construction in our country. Research and development of ultrahigh strength concrete with low viscosity has great significance. Paper focuses onsystematic study of the preparation of ultra high strength concrete with low viscosity,work performance, rheological properties (viscosity) and interfacial transitionzone(ITZ), the main work and the important achievements are:(1) Microbead have continuous and uniform particle size distribution and densesphere morphology and the particle size between cement and silica fume particles, itcan be optimized the particle size distribution at the micro level, improve the density,thereby increasing the strength and reducing the viscosity. And spherical particleswill bring water reduction function and excellent ball lubricating effect, the furtherreduce the viscosity. The mixing (GGBS:IFA: M:SF=4:1:1:1.3) dosage of36.5%isreached balance of reducing viscosity and increasing compressive strength.(2) Research on the particle size distribution and consumption of cementitiousmaterial, sand ratio, water-binder ratio(W/B), the type and amount of fly ash andmicrobead, the results indicate that C100UHSC with low viscosity withslump/spread of260/725mm, T50of6.5s, V-funnel of35s, inverted slump time of7sand the compressive strength of135.3MPa at90d have been successfully prepared with W/B of0.21, binder content of630kg/m3(63.5%C,20%GGBS,5%IFA,5%M and6.5%SF) and sand ratio of40%.(3) Viscosity of fresh C100UHSC and mortar can be calculated bymicromechanics process, and research on the relationship between workability andviscosity of fresh concrete. T50, V-funnel and inverted slump improve with theincrease of viscosity of fresh C100UHSC. It has a good linear consistence betweenviscosity and T50of C100UHSC with low-viscosity.(4) Research on the microhardness of ITZ and cement matrix by microhardnesstester, the results indicate that the microhardness of ITZ and cement matrix did notchange significantly. According to EDS analysis, phase composition is basically thesame with uniform distribution of ITZ and cement matrix, The changing of theelements Ca and Si content is small, while it was not observed a large number ofCa(OH)2in SEM images. Therefore, ultra high strength concrete ITZ is not obvious.