Applied Mechanics and Materials Vols. 174-177

Abstract: “Strong column and weak beam” failure rarely occurred in the Wenchuan earthquake, and the reasons were analyzed in this paper. A new type of frame column is presented, i.e. green high-performance fiber-reinforced cementitious composites (GHPFRCC) column, and the seismic behaviors are discussed. And this new type of structural member is vital to improve the seismic capacity of the frame structure.

Abstract: The effect of non-thermal microwave on purifying natural graphite was studied. It was found that with existence of microwave field, the carbon content of the product was improved from 95.840% to 99.125% and the result of the purifying was affected by the power of the microwave，the reaction pressure and the reaction time. Add 5% (volume fraction) of hydrofluoric acid in the mixed acid system can improve the carbon content of greater than 99.9% of the natural flake graphite. The use of mixed acid of microwave-assisted purification of natural flake graphite is a better way of producing high-purity graphite.

Abstract: An increasing trend towards the demand for resisting to Freeze/thaw exposure has led to fibers being incorporated into concrete. This paper addresses the freeze/thaw durability of carbon fiber reinforced concrete by using a paired comparison test based upon relative dynamic elastic modulus and the rate of loss mass. The carbon fiber reinforced concrete was found to be more durable than plain concrete probably due to the high elastic modulus of carbon fiber. Durability is an important material property and carbon fiber reinforced concrete needs to be widely tested to gain confidence for use within the industry and this work shows future possibilities.

Abstract: Titanate coupling agent can modify the surface of inorganic filler and promote adhesion property of asphalt mortar. Moreover, it can also improve asphalt performance and pavement performance of asphalt mixture effectively, and reduce optimum asphalt content of mixture.

Abstract: The fast-growing poplar wood, Populus ussuriensis Kom, was prepared into wood-polymer composite by the in-situ polymerization of methyl methacrylate (MMA) and styrene (St) under vacuum/pressure and subsequent catalyst-thermal conditions. SEM observation, FTIR, XRD and DMA analysis indicated that the resulted polymer well filled up wood cell lumen in an amorphous form and physically reinforce wood matrix, which resulted in the improvement of glass transition temperature and storage modulus of wood. Such method could endow low-quality wood with potential value-added applications.

Abstract: The testing rule of mechanical properties of material can be established and the mechanical performance can be found by studying the basic mechanical properties of BFRP bars. Using the opressive sleeve anchor developed by the researchers,tensile tests of BFRP bars are carried out according to the national standards of “GFRP bar tensile test methods”.The BFRP bar’s force-deformation curve is linear before the force-deformation relationship is destroyed,therefore,referring to steel wire or steel cable,the BFRP bar’s reliable strength is suggested to be approximately 80% of its ultimate tensile strength. The BFRP bar’s tensile elastic modulus is related to the content of basalt fiber.The tensile elastic modulus increases with the increase of the basalt fiber’s content and the content increases when the BFRP bar’s diameter becomes longer, so the tensile elastic modulus increases with the increase of its diameter. Compared with steel, the BFRP bar is obviously superior in the aspects of tensile strength, corrosion resistance ,etc,therefore to use the BFRP bar in reinforced concrete structures insead of steel is feasible.

Abstract: Epoxy resin adhesives are widely used in various sectors, particularly in the aerospace and automotive industries. However, the solidification of the three-dimensional network structure of pure epoxy resin, which causes greater density and brittleness, results in poor system resilience. With the ultimate goal of improving the resilience of epoxy resin, nano-sized SiO₂ particles were introduced to improve the adhesion strength of both modified and unmodified epoxy adhesive. The results indicated increases of shearing strength from 16.66-Mpa to 18.01 -Mpa, impact strength from 15.4-kJ/m2 to 33.68-kJ/m2, and flexural strength from 70.5-Mpa to 80.94 Mpa.

Abstract: A simulation experiment on PVC waterproofing under sustained load and evaluated the results ,to find out the waterproofing tensile property change at 70 °C. 1) The tensile property of PVC waterproofing increased with ratio of initial elongation at 70 °C. when the ratio of initial elongation is 57.4%, the ratio of rupture elongation decreased more than 70%,and the Average of tensile strength increased 71.8%。2) Between one and seven days, the time duration had little influence on tensile property of PVC waterproofing. at 70 °C

Abstract: This study investigated the influence of calcination temperature on the pozzolanic activity of shale. Calcination temperatures of 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C were used. The calcined shale powder was then passed through a No.200 sieve before being used to replace 20% of the cement in standard mortar samples. X-ray fluorescence spectrometery (XRF) was used to analyze the chemical composition of the calcined shale. In addition, the effects of replacing mortar with calcined shale were also examined with regard to setting time, pozzolanic activity, compressive strength, ultrasonic wave velocity, and the water absorption of the mortar. The test results demonstrate that the chemical composition of SiO2+Al2O3+Fe2O3 exceeded the 70% required by ASTM C618 specifications. The strength activity index (SAI) of calcined shale at 7, 28, 56 days exceeded 75%. At 28 days, the SAI values of samples produced with shale calcined at 700 °C and 800 °C exceeded 99%. After 28 days, the SAI, water absorption, and ultrasonic wave velocity values were nearly identical to those of control samples produced using only cement. Among all shale samples, those calcined at temperatures between 700 and 800 °C demonstrated the highest pozzolanic activity.

Abstract: It was investigated that the technology of hot prepressing temperature and hot pressing duration had influence on the mechanical and physical properties of soybean adhesive bonded laminated veneer lumber(LVL) from poplar wood. The results show that lower mat prepressing temperature may be beneficial to the mechanical properties of LVL. The effects of hot pressing duration on the properties of LVL are less than those of prepressing temperature. When the prepressing temperature is 70°C and hot pressing time is 100s/mm with glue spread amount of 450g/m², hot pressing temperature of 160°C and mat pressure of 1.6 MPa, the mean modulus of rupture value is 78 MPa, mean modulus of elasticity value is 14.4 GPa, mean horizontal shear strength value is 7.8 MPa and immersion peel rate is 0.4%, respectively.