Applied Mechanics and Materials Vols. 253-255

Abstract: In this investigation, the combined confinement effect of spacing of lateral ties, volume fraction of polyolefin fibres and fibre reinforced polymer(FRP) wraps was studied both experimentally and analytically from the point of deformability characteristics of concrete for seismic resistance. Low modulus synthetic fibers such as polyolefin based fibers, it is shown that polyolefin fibers with sufficient tensile strength can successfully enhance the mechanical properties of concrete. The mechanism of delaying and arresting the progressive internal cracking by the fibres can be made use in passive confinement of concrete. In this study the confinement effectiveness of GFRP wraps of single and double layer and polyolefin fibres of volume fractions 0.7% and 0.9% in addition to lateral ties of spacing 145mm and 75mm on concrete prisms of size 150 ×150 ×300 mm were investigated. Such concrete is termed as FRP confined fiber reinforced concrete(FRPCFRC).This paper presents an analytical model(profile) for predicting the constitutive behaviour of FRPCFRC based on the experimental and analytical results. A total of thirty nine prisms of size 150 ×150 ×300 mm were cast and tested under strain control rate of loading. The results of the testing demonstrate the behavioral differences between FRP confined concrete and FRP confined FRC and the ability of the synthetic macro fiber to be used as secondary reinforcement in performance based seismic resistance applications.

Abstract: The hydrated products, unhydrated cement and water (capillary pores) in the cement paste are seen as matrix, inclusion, Equivalent medium respectively, We used the micromechanics theories and Power’s Volume model to develop a multi-phase micromechanics model capable of simulating the elastic properties of cement-based materials, and the evolution of elastic properties in the hydration process was calculated at different water-cement ratio. The final experimental results show that this model can be used to predict the elastic properties of cement-based materials.

Abstract: Abstract. In order to analyze the polymer mortar performance with different cement volume polymer mortar specimens by the compression tests,the bending tests, scanning electron microscopy method, test results shows that: 115% of the cement dosage and cement dosage compared to 0%，flexural strength of polymer mortar increased 95%, compressive strength increased 74%, the ratio of flexural and compressive strength increased accordingly. However, when the dosage is higher than 115%, resulting in large specific surface area of cement, bending strength and compressive strength has declined.

Abstract: This paper examined the mechanical property of rubber mortars with different amount of rubber granules addition and the influence of fly ash, slag and silica fume. The increase of rubber granules results in the decrease in compressive and flexural strength of rubber mortar, but increases the ratio of flexural to compressive strength. The fly ash, slag and silica fume are useful for improving the mechanical property of mortar. The examined contact angle of water against rubber is 99.5°, which suggests the rubber surface is hydrophobic, and the hydrophobic surface interprets the weak interface between rubber and cement matrix.

Abstract: Geosynthetics is developing rapidly in civil engineering, water project, transportation engineering and other fields in recent years due to their advantages of lightweight, good continuity, easy construction, excellent tensile, anti-ripping strength and good resistance to chemicals and microorganism. The development, specific classification and application of Geosynthetics are depicted in this paper.

Abstract: Industrial residues--fly ash, carbide slag, desulfurization gypsum--of different proportions were used as raw materials to discuss the sintering characteristics and thermal effect of each proportion and their effects on porous cementitious materials. The properties of those materials were analyzed and the formula were calculated according to sulphoaluminate cement formulations . The sample were burned at different temperatures according to ceramsite-making method so that some hard water minerals and a microporous structure could be formed. By analyzing the content of and β-C2S in the burned sample using XRD, SEM and EDS and discussing the effects of different burning processes on porosity and water absorption rate of materials to know the sintering system. The results show that the material burned at 1250°C for 20 min has good thermal insulation properties and cementing properties.

Abstract: Resin mineral composite (RMC) reinforced by fibers belongs to a multiphase material, whose mechanical strength depends on its material properties of components and microstructure characteristics of fibers including surface state, shape, and so on. The interface mechanism between fiber and matrix was analyzed. Finite element simulation was employed to discuss the reinforced effect of fiber on resin matrix, and the influence of fiber shape, surface state on interface bonding property respectively. Research results showed that linear fibers with surface dents or fibers shaped like S, U, V, N, W English letters performed well, and had much better reinforced effects on matrix than ordinary linear fibers.

Abstract: The manufacturing process is a significant influencing factor on the mechanical properties of fiber-reinforced cement-based composites. This paper presents the investigation of the effects of the manufacturing processes on the properties of fiber-reinforced cement-based panels (FRCBPs). Two types of FRCBPs were manufactured using a casting process (FRCBP-C) and an extrusion process (FRCBP-E), and then their bending properties were evaluated using flexural tests. The test results demonstrated that the strength and stiffness of the FRCBP-C specimens were lower than that of the FRCBP-E specimens. However, the FRCBP-C specimens exhibited more ductile behavior than the FRCBP-E specimens.

Abstract: In this study, jute fibers were added into cement based materials to improve their compressive strength, flexural strength and early-age crack resistance. Results showed that the compressive and flexural strength of the fiber reinforced concrete were significantly enhanced with 30mm length jute fiber at the mixing amount of 0.5-0.6 kg•m-3. For early-age crack resistance test, the effective mixing amount would be 0.9 kg•m-3 and the fiber should be shorter than 20mm.

Abstract: In order to study the concrete compound crack and fracture extension problem such as brittle material, based on the analysis of the fracture criterion theory ,on the analysis of some measured data, and the near crack tip portion of the shape change energy, the strain energy criterion of Iso- line for Ⅰ-Ⅱ mixed mode crack was proposed, a crack initiation angle formula and the fracture criterion were established, and the variation law among ， with Poisson ratio was discussed . Using the criterion, the concrete compound crack was analyzed. Results show that the theoretical values are consistent with the measured values. So the criterion can be applied to analyze the mixed mode crack fracture of brittle material such as concrete.