Applied Mechanics and Materials Vols. 193-194

Abstract: Waste concrete as the main object of the study, was proved to be capable of producing recycled-cement. The chemical composition of recycled-cement was analyzed by X-ray diffraction and compared with industrial clinker from Onoda Company. The result of comparison showed that the minerals in recycled-cement were almost the same as the industrial clinker, except a little MgO and CA. The amount of four main minerals in cement clinker was reasonable. The mechanical property of mortar produced with recycled-cement was measured. The results showed that the compressive strength of recycled-cement mortar can reach the standard of mortar with P.O 32.5. The excess MgO and the strength grade of waste concrete we used in the research were identified as the restriction of the strength development of recycled-cement.

Abstract: Cement-based material samples having 0%, 5%, 10% and 20% B₄C concentrations have been prepared for this reserach. Neutron attenuation measurement has been done by using 14.8MeV neutrons from the 5SDH-2 accelerator, and some mechanics properties of the same proportion also have been tested. It has been shown that when the B₄C precentage and thickness of the samples increase, neutron attenuation values of the samples increase. Both the flexural and compressive strength firstly increased with B₄C addition up to 10% approximately, and then decreased sharply with an addition up to 20%. It is thus possible to enhance the neutron shielding property of cement-based materials by adding B₄C.

Abstract: Currently, energy saving and consumption reduction has been a crucial task the domestic people are facing with. It has been considered as essential question in the field of building materials to research and develop a new energy saving building material. In this paper, we classified new wall material and thermal insulation material, analyzed the performance, feature and application of such materials, selected typical foam concrete and slurry insulation material and analyzed their thermal properties and technology parameters and so on, to present the development trend and direction of energy saving building material, to provide valid scientific data to relevant building energy saving management units, design units and construction units, to play a positive guiding role in improving the application level of new energy saving building material and promoting new energy saving building material of high quality.

Abstract: The properties and precipitation rules of secondary phases generated during isothermal aging of duplex stainless steels and factors affecting the precipitates were reviewed in this article. These secondary phases include carbides(M23C6,M7C3), nitrides(Cr2N,CrN) and intermetallic phases(σ-phase, χ-phase, Fe3Cr3Mo2Si2, R-phase, π-phase, α′-phase). With the right understanding about the phases, the aim is the suitable heat-treating processes would be chose to avoid the unfavorable influences of secondary phases.

Abstract: Alkali-activated slag cementitious material (AASCM), a high-temperature resistant inorganic adhesive, is presented in this paper. The components of AASCM were optimized for favorable mechanical properties. A FRP-to-concrete bond test to account for the influence of FRP and adhesive types was performed on thirty-three specimens. The results show that after the double shear tests, the interfacial shear strengths and reinforcing effects of AASCM are comparable to that of epoxy adhesive, and this strengthening method of strengthening concrete structures with CFRP sheets bonded with AASCM is feasible.

Abstract: This technical note discusses an innovative use of rice hull ash (RHS) as filler in concrete. RHS in the range of 0–30% was used as a partial replacement for ordinary cement in a concrete of mix ratio 1:2:4:0.6 (cement: sand: coarse aggregate: water cement ratio). Fresh concrete properties, compressive, split tensile strengths, and modulus of rupture were measured for concrete mixtures with RHS within the investigated replacement levels. The results showed that the setting times of RSH concrete increased with higher ash content, while the compressive, split tensile strengths and modulus of rupture showed a reverse trend.

Abstract: In order to characterize how the temperature influence Low Temperature anti-cracking performance and the ability of asphalt mixture resist low temperature, on the basis of bending test at low temperature, this paper from the angle of energy, introduce the concept of failure energy per unit volume as the evaluation index for the low temperature performance of asphalt mixture. Meanwhile, this paper used this evaluation index to perform bending test at low temperature for two kinds of different type of asphalt mixture which under three temperature as follows:0°C，-10°C，-20°C, And separately calculated failure energy per unit volume, then analyzes the characteristics and regularity of the index.

Abstract: This study presents an investigation into high-temperature resistance of alkali-activated slag concrete (AASC). Sodium oxide (Na2O) concentrations of 4%, 5% and 6% of slag weight and liquid sodium silicate (SiO2) with modulus ratio of 0.8 ( mass ratio of SiO2 to Na2O ) were used as activators to activate granulated blast furnace slag (GBFS). All cylindrical specimens with the same binder content and liquid/binder ratio of 0.5 were cast and cured in the air, under the saturated limewater and in a curing room at relative humidity of 80% RH and temperature of 60 °C, respectively. Test results demonstrate that the high-temperature resistance of AASC decreased with an increase of temperature. The compressive strength and high-temperature resistance of AASC improved with an increase dosage of Na2O and AASC cured at relative humidity of 80% RH and temperature of 60 °C has the superior performance, followed the AASC by air curing and saturated limewater curing. The higher compressive strength and superior high-temperature resistance have been obtained in AASC than comparable OPC.

Abstract: By using the High-performance water-reducing agent to do a series of technical demonstration test, and using the local raw materials, mixing with large numbers of mineral admixture, this paper makes up the cost lower C80 high strength and high performance concrete successfully. The test results show that the High-performance water-reducing agent can improve construction of concrete and physical and mechanical performance and durability after hardening

Abstract: To understand the water transport properties and generally the mass and heat transfer performance, the sorptivity of different building gypsum plasters are investigated by experiments. The sorptivity of five kinds of gypsum materials are measured and compared with that of fired clay brick. The effects of water/plaster ratio, wet/dry cycles and lightweight additives on the absorbing properties are investigated. The “square root of t” law and the validity of sharp water front (SWF) model are also analysed. It is concluded that the absorption properties of gypsum plasters are sensitive to premixed lightweight aggregates, water/plaster ration and wet-dry cycles