Abstract: Anti-permeability, durability even strength of cement-based composites are closely related with the material pore structure. Polyvinyl alcohol (PVA) fiber reinforced strain hardening cement-based composites (SHCC) are provided with high ductility and multi- micro-crack propagation mode. Due to fibers adding, much more interface and tiny fracture had been drawn into SHCC, although it has some advantages such as high tensile strength, ductility and energy consumption under seismic load or other cyclic force. Water repellent treatment can improve the anti-permeability of SHCC. Investigations have been made through Mercury injection experiment to reveal influence on microstructure of PVA-SHCC by silane water repellence. Results show that, the pore structure of SHCC can be fined by inside water repellent agent. That is, water repellent infiltrate through the relative big hole or defect of cement paste and react with the alkali substance. Then the resultant colloids reduce the big hole, pore or fracture and reform the pore structure of the cement paste. Because the fine pore structure can prevent air, water and ions defuse into interior of cement-based composites, water repellent treatment is benefit to increase anti-permeability of high ductile SHCC.
Abstract: NaxCo2O4 (x = 1.4~1.9) ceramics were synthesized by solution combustion synthesis (SCS) method and sintered by spark plasma sintering (SPS) method in this paper. The synthesized bulk samples showed a relatively high orientation degree analyzed by XRD. Thermoelectric properties of the as synthesized bulk samples were investigated in the direction parallel to the press direction of SPS from room temperature to 857 K. Among all the samples, the highest power factor 3.07 ´ 10-4 W×m-1×K-2 was obtained at 817 K when x = 1.6, and the highest ZT value of this sample was 0.064 at 817 K.
Abstract: The paper takes a realistic coke drum as an example. A finite element analysis model using ANSYS is made, acquired with indirect coupling method, and circumferential thermal stress field of coke drum is calculated. Especially, the boundary conditions are based on the measured data of the realistic coke drum. Then circumferential thermal stress field of coke drum is calculated. The calculation results indicate that the circumferential temperature difference with the same height has little impact to stress of the drum and the circumferential temperature difference has the most important effect on coke drum skirt, so the impact to circumferential cracking of the skirt weld cannot be neglected.
Abstract: The development and application of Inorganic Ceramic Materials is a hot topic nowadays, especially in pollution controlling area. In this paper, the applications of Inorganic Ceramic Materials in water pollution control technology and air pollution purification, and the problems under implementing Inorganic Ceramic Materials are pointed out; meanwhile a trend analysis of ceramic materials is proposed.
Abstract: The influence of Nano- CaCO3 on the mechanical property of PALC was studied in the paper. And the mechanism of Nano- CaCO3 modified cement-based materials was also discussed by means of X-ray diffraction and SEM. The results shows that the PALC with 2% of added Nano-CaCO3 by weight of cement has an optimum splitting strength, in which the increase of splitting strength are about 15.2%,20.4% and 19.7% at 3days,7days and 28 days. The reasons for causing the above results are because Nano-CaCO3’s filling effect of micro-particle, surface effect of nano-particles as well as micro-nucleus effect.
Abstract: A new theoretical equation that represents the thermal conductivity of two-phase composite has been proposed. The Cheng-Vachon equation has been modified by introducing a new parameter that is the corrected porosity. It was found that the new equation can describe the thermal conductivity of cellular concrete very accurately. Development of the equation is helpful to understanding heat transfer mechanism and improving thermal property of cellular concrete.
Abstract: The split tensile strength and compressive strength of concrete mixed with SiO2 and CaCO3 nanoparticles have been experimentally studied. SiO2 nanoparticles as a partial cement replaced by 0.5, 1.0, 2.0 and 3.0 wt.% and CaCO3 nanoparticles by 1.0 and 3.0 wt.% were added partially to concrete. Curing of the specimens has been carried out for 7, 28, 78 and 128 days after casting. SiO2 nanoparticle as a partial replacement of cement up to 3.0 wt.% could accelerate formation of CSH gel at the early ages and hence increase the split tensile strength and compressive strength. The optimal replacement level of cement by SiO2 nanoparticles for producing concrete with improved strength was set at 2.0 wt.%. CaCO3 nanoparticles as a partial replacement of cement up to 3.0 wt.% could consume crystalline Ca(OH)2 and accelerate formation of calcium carboaluminate hydrate at the early ages and increase the split tensile strength and compressive strength. The optimal replacement level of cement by CaCO3 nanoparticles for producing concrete with improved strength was set at 3.0 wt.%.
Abstract: The organic-inorganic complex nano-particles with core-shell structure were synthesized by in situ emulsion polymerization based on fresh slush pulp of calcium carbonate (CaCO3) nanoparticles and acrylate polymer in this paper. The dispersion and encapsulation of nanoparticles were investigated by transmission electron microscopy (TEM). Unplasticized poly(vinyl chloride)(UPVC) was modified by organic-inorganic complex nanoparticles and the effects of toughening and reinforcing were systematically studied. The results showed that the effects of the reinforcement and toughening of organic-inorganic complex nanoparticles on UPVC were very significant. Especially, scanning electron microscopy(SEM) analysis results indicated that large-fiber drawing and network morphologies coexisted in the system of UPVC by joint modification of nanoparticles with CPE.
Abstract: In civil construction, β-hemihydrate pastes have been used as decorative ornaments, plasterboards, dry-wall and renderings. The application procedure of β-hemihydrate pastes for rendering generates large amounts of waste due to its hydration kinetics. Waste production also occurs due to the technique of preparation and application of this material. It is essential to minimize gypsum waste. The aim of this work was to quantify the amount of gypsum waste produced by the process of using it as renderings. It was observed the influence of workers applying pastes rendering on gypsum waste production. The application process of plaster renderings was followed measuring the waste generated and the time for finishing the process was also observed. Results pointed out waste production values in the range between 16% and 47%. The application technique influences the amount of waste production.
Abstract: To investigate the tensile parameters of carbon fiber composite laminated plate under bending, the three point bending tests of carbon fiber composite laminated plate with two kinds of layer's were carried out in this paper. The result indicated that tensile parameters obtained from the bending tests are usually higher than those from the standard tensile test, which should be considered on the design of composite laminated plate withstanding the bending stress. For composite laminated plate, the bending test results are relative to layer angle and order (e.g. according to the test results, for laminated plates, the difference between values of tensile parameters obtained from the bending tests and those from the standard tensile test is relative small, while for laminated plates the difference is relative bigger). Compared with the method of standard tensile test, the method of three point bending tests may be more appropriate for the composite laminated plate withstanding the bending stress.