Applied Mechanics and Materials Vols. 744-746

Abstract: Designing recycled concrete mixture proportion of different recycled coarse and fine aggregate replacement content by pulp content ,then testing compressive strength and splitting tensile strength. The text results show that: With the increasing of recycled aggregate content , the compressive strength and splitting tensile strength of recycled aggregate concrete trended to decrease. Compared to recycled coarse aggregate, recycled fine aggregate impact on the properties of recycled concrete is greater. Establishing the compressive strength and splitting tensile strength formula of recycled concrete based on a lot of experimental results.

Abstract: The effect of different layers of silane impregnation on chloride resistance of concrete materials at various curing ages is systematically discussed. The chloride resistance of two types of concrete specimens with surface silane impregnation has been investigated through the Rapid Chloride Migration (RCM) method. The testing results indicate that the chloride penetration can be effectively restrained by silane impregnation, and the chloride diffusion coefficients of samples are significantly decreased. After curing for 28 days, when compared to the untreated samples, the chloride diffusion coefficients of two types of concrete specimens both with two layers of silane impregnation decreased by 37.4%, 37.6% respectively.

Abstract: In order to study the flexural toughness of PVA fiber reinforced concrete, employ the volume mixing ratio is 0.2%, 0.1%, 0.08%, polyvinyl alcohol (PVA) will be mixed with ordinary C40 concrete to form PVA fibers reinforced concrete. Its flexural toughness properties were tested and the load-deflection curve of all beams is obtained. Based on the ASTM method, the flexural toughness of PVA fiber reinforced concrete is analyzed. The experimental results indicate that the PVA fiber can improve the flexural toughness and the deformation ability of concrete beams remarkably. When the fiber volume ratio is 0.1%, the flexural toughness index I₅ and I₁₀ of concrete with PVA fiber are 3.73 and 6.23 times higher than that of the plain concrete respectively. The failure mode of PVA fiber concrete is changed from brittle to ductile fracture.

Abstract: Starting from the development of building materials, expounds the definition and connotation of green building materials, this article analyzes the development of domestic green building materials from the building materials and recycled materials and technology two aspects, and then points out that the development of green building materials in China still has a long way to go.

Abstract: The effect of sodium hydroxide (NaOH) and polycarboxylate superplasticizer amount on over-sulfur phosphogypsum–ground granulate blast-furnace slag cement was investigated. The mechanical performances and hydration mechanism of the cement with different proportions of NaOH and polycarboxylate superplasticizer (BASF) were analyzed based on setting time, the additive quantity of water, strength test, XRD and SEM analyses. The results showed that the polycarboxylate superplasticizer, can increase the densification and the strength of the cement ,to improve the performance of the cement anti-carbonation properties. NaOH as an alkali activator significantly reduces the cement setting time and improves the cement early strength. But the acceleration of hydration process produces coarse crystalline hydration products and the osteoporosis structure of hardened paste, which has a negative effect on long term strength.

Abstract: The effects on the waterproofness, the flexural and compression strength of cement mortar were investigated under single mixing and complexes mixing conditions of 4 kinds of modifiers, Polycarboxylic water-reducing agent, composite waterproofing agent, Sulphoaluminate expansion agent and fly ash. The results show that it is better in improving the water-resisting property and impermeability of mortar when complexes mixing any two of the 4 kinds of modifiers than single mixing. The mortar has the best water-resisting property and impermeability with the contents of 0.75% Polycarboxylic water-reducing agent and 6% composite waterproofing agent.

Abstract: Concrete is a typical heterogeneous porous media material, but the influence of the heterogeneity of concrete on coupled temperature and moisture transfer is rarely involved in the present numerical methods. Thus, the research direction on the coupled temperature and moisture transfer with damage evolution of the heterogeneous material will be greatly helpful to understand the coupling mechanism. This paper firstly presented the purpose of the study on the coupled temperature and moisture transfer in concrete, and then offered a literature review of the development of this theory. To launch the elaboration of this topic, three relative important parts were presented separately in this paper. (1)The comprehensive theory of porous media heat and mass transfer. (2)The development of the coupled temperature and moisture transfer on mesoscopic scale. (3) The numerical simulation methods of the coupled temperature and moisture transfer. And then the influence of damage on the parameters of temperature field and humidity field was pointed out, which would be a valuable research field.

Abstract: Through a number of literature analysis and research, this paper investigates the reviews and comparison under the meso model for numerical simulation of crack in a finite element model (FEM), including discrete fracture model, smeared crack model, fracture mechanics crack model,bond crack model. Studies show that: compared to other fracture models , smeared crack model by eliminating the need to change the unit type and re-division unit grid computing simple and widely used for treatment of concrete cracks in finite element method, the author cites a using smeared crack model example that are discussed in the paper.

Abstract: Powder-cement ratio plays a key role in asphalt mixture. Only after asphalt adsorbs the surface of mineral powder to form a thin film, asphalt produces the adsorption on aggregate, so slag asphalt is real asphalt binder. Powder-cement ratio is different, road performance is different too. Through laboratory test, analysis powder-cement ratio reflects on heat, cold, water stability and anti-reflective cracks of ATB, make a range of radio of filler to bitumen, in order to provide a reference for the design of ATB composition.

Abstract: We selected a typical filter material for high voltage electrostatic filter composite horizontal collector. Air filter can achieve high speed. It cost very low and can endure high temperature resistance. Removal of fine particles of dust effect is good. Solving the complex problems of higher smoke temperature conditions of traditional bag house can not handle, while reducing the dust collector investment cost, promote the development of China's dust remover industry.