Effects Of Concrete Synergist CTF Mixing With Different Type Water-Reducers On The Performance Of Cement-Base Materials

This paper discusses influences of a new concrete admixture CTF mixing with three kinds of commonly used water-reducers, including polycarboxylate, naphthalene and aliphatic, on the comprehensive performance of cement-base materials. At the same time, mechanism of its action was discussed. On the basis of mixing chemical admixtures, the multivariate effects of limestone powder-fly ash-slag powder on the performance of concrete are studied. The main research contents and results are as follows:The compatibility of CTF mixing with different type water-reducers with cement was comprehensively evaluation by testing the fluidity, loss of fluidity, bleeding of cement paste as well as the workability and compressive strength of mortar.Under the conditions that reducing10%cement of benchmark concrete or nor, the influence law of CTF mixing with different type water-reducers on the concrete strength was studied by preparing concrete at two water-binder ratios of0.35and0.50. The results indicated:the addition of CTF not only can effectively reduce the cement consumption, but also improve the strength of concrete. The promoting effect of CTF to concrete strength was mainly concentrated in the later-age.Through testing hydration heat of cement inthe very early age, conductivity of cement suspension and chemical bonding water of cement paste, to explore the effects of chemical admixtures on cement hydration process, and analyze the interaction mechanism between cement and chemical admixtures. The results showed:The first peak of hydration heat was promoted with the addition of CTF or polycarboxylate, but it was reduced with the addition of naphthalene or aliphatic water-reducer. There were CTF and three kinds of commonly used water-reducers using in this experiment, any one of them can accelerate the accumulation heat of hydration in45minutes. The ionic release was promoted in the cement suspension within CTF, as a result, the conductivity of cement suspension was increased. Besides, the ions dissolution by hydration of cement complex with the water-reducers using in this experiment, as a result, the conductivity of cement suspension was decreased with the ions decreasing. CTF mixing with the water-reducers using in this experiment had promoted the later age hydration extent of cement in varying degrees.Explore the multivariate effects of limestone powder-fly ash-slag powder and CTF on the working performance, strength, durability and microscopic pore structure of concrete. Form a correlation analysis between microscopic pore structure and anti-chloride-permeability, anti-carbonization of concrete. The results show that:under the appropriate mixing content, limestone powder equally replacing fly ash or slag, can effectively improve the working performance. And the effect on compressive strength is little. But it could lead to the deterioration of pore structure when limestone powder equally replacing fly ash or slag, as a result, there are negative impacts on the durability of concrete.With adding of CTF, the workability, anti-chloride-permeability, strength, anti-carbonization and microscopic pore structure of concrete was improved. There are some correlations between the porosity, average pore diameter and anti-chloride permeability, anti-carbonization of concrete, but not a single pore structural parameter can play a determined role in affecting the performance of concrete. Besides, data analysis found that as long as under the same water to binder ratio, there were high correlations between porosity and anti-carbonization, the quadratic polynomial correlation coefficient is0.9533, and no matter what compositions of concrete are.