Applied Mechanics and Materials Vols. 438-439

Abstract: nfluence of non-flowing model sulphate solution determined for cement mortar with pozzzolana admixture are presented in this paper. In the predetermined time intervals the influence of the aggressive liquid on chemical properties and mineralogical composition was tested. The changes caused by corrosive sulphate environment on the testing specimens were determined in dependence on the different type of cement and used ground clay brick as pozzolana admixture. From the results obtained follows that the additive of ground clay bricks has positively impact on the sulphate resistance.

Abstract: Mix design of high performance concrete was determined based on the pumping simulation test. It was indicated by test and field application that the trimixture technique and the double mixture technique can improve the pump of concrete, reduce the dosage of cement and the hydration heat; adding expansion agent can prevent harmful cracks in the concrete due to shrinkage stress, improve the compactness and impermeability. The reasonable construction technologies were used in mixing, transportation, pouring, vibrating and curing of the concrete in order to ensure quality of the construction.

Abstract: The mechanical behaviors and durability of concrete containing steel slag powder (SSP), silica fume (SF) and fly ash (FA) were presented in this study. The fresh concrete properties, compressive strength, split tensile strength, elastic modulus, stress-stain curve, chloride permeability as well as carbonation of concretes mixed with different SSP contents or concretes containing compound mineral admixture were tested. The experimental results reveal that the mechanical behaviors and durability of concrete with 10% SSP replacing cement are both improved than that of the reference concrete. Mechanical behaviors and durability of concrete with 20% SSP replacing cement are similar to the reference concrete. Concrete with compound mineral admixture of SSP and SF obtain the highest enhancement in both strength and chloride resistance.

Abstract: This paper uses dust, with particle size less than 0.08mm, produced by crushing limestone to replace the same amount of cement in different proportions and studies the performance of cement mortar. The result shows that limestone dust has water reducing effect and does not reduce strength of the mortar when its dosage is less than 12%, meanwhile, it can improve the shrinkage property and the durability resisting sulfate, which explains that limestone dust is not the inert material, but has a certain activity,.

Abstract: The effects of ground slag with different specific surface area on the rheology of mortar at water-binder ratio of 0.25, 0.28 and 0.30 were investigated, and the combined effects of packing density and solid surface area on the rheology of mortar were evaluated in terms of the water film thickness. The results show that with the increasing of specific surface area of slag (220 m²/kg-784 m²/kg), plastic viscosity and yield stress decrease. The correlations of yield stress and plastic viscosity to the water film thickness are basically linear with high correlation R² values. The action of the ground slag on the rheology of mortar can be characterized by water film thickness, and with the increasing of water film thickness the rheological parameters decrease.

Abstract: By using high-volume fly ash (FA), aluminum slag superfine powder (ASP) as raw materials to synthesize FA-ASP binder, this paper developed M10 masonry mortar. Comparing with the cement mortar and FA mortar, the FA-ASP mortar has not only good construction performance and mechanical performance, but also reduces the production cost obviously, which is a broad development prospect of green new building mortar.

Abstract: Cube crushing strength, resistivity and gas adsorption analysis of mineral admixture concrete are tested to analysis the effect of raw material on resistivity and its regression relationship with concrete microcosmic pore structure index. Test results show that concrete resistivity at different age increases with the increase of cementitious material and cement dosage, and both has a good nonlinear regression relationship. Concrete resistivity at different age decreases with the increase of 56d HK method cumulative pore volume, 7d and 14d resistivity has a good linear correlation relationship with 56d HK method cumulative pore volume. 28d and 56d resistivity has a good nonlinear regression relationship with 56d HK method cumulative pore volume. Concrete resistivity at different age decreases with the increase of 56d BJH method cumulative adsorption pore radius, and both has a good nonlinear regression relationship.

Abstract: Cube crushing strength, resistance to chloride penetration and gas adsorption analysis of mineral admixture concrete are tested to analyze the effect of raw material on chloride diffusion coefficient and its regression relationship with concrete microcosmic pore structure index. Test results show that chloride diffusion coefficient at different age increased with the increase of water-binding material ratio, decreased with the increase of cement dosage and both appeared a good nonlinear regression relationship. Chloride diffusion coefficient at different age increased with the increase of concrete microcosmic pore structure index. 56d chloride diffusion coefficient has a good linear correlation with microcosmic pore structure index, and 84d chloride diffusion coefficient has a good nonlinear regression relationship with microcosmic pore structure index.

Abstract: A new type of polycarboxylate superplasticizer with high dispersibility was synthesized by the method of free radical polymerization and the hydrothermal reaction. The synthetic process optimized the influencing factors of reaction had been discussed, including proportion of acid and ether, reaction temperature, initiator concentration, heat preservation time and additive. The dispersibility of new product was superior under the condition of low water/cement ratio, testing by gel permeation chromatography and C60 self-compacting concrete. The new product had already been used in Tianjin Goldin 117 Mega Tower project. The performance of C70 fresh mixed self-compacting concrete, which was added with new product, was very excellent in Tianjin Goldin 117 Mega Tower project, and was satisfied with the design code for high-strength self-compacting concrete in China. It is possible to realize industrial production.

Abstract: An experimental investigation was carried out to evaluate the effect of limestone filler (LF) with equivalent replacement of cement on its grain composition. The results indicated that LF optimized cement particle distribution, filled the empty place among cement particles and released more free water when mixing. With the decrease of the LF particle size and the increase of LF replacement ratio of cement, these effects were more remarkable. As a result, the finer and the more replacement ratio of the microfiller, the lower the flow resistance and plastic viscosity of the mixture from a rheological point of view.