Advanced Materials Research Vols. 250-253

Abstract: The roles of B₂O₃ and P₂O₅ in the formation of clinker which stand on the each side of the IV main group are discussed. The results show that the role of B₂O₃ and P₂O₅ in the formation of clinker are different: B₂O₃ has evident effect, which is lost at higher temperature, on the consumption of CaO at 1300°C while the effect of P₂O₅ is mainly reflected at higher temperature, especially at 1400°C; Suitable B₂O₃ makes C₃S transform form R to M₃, but P₂O₅ induces C₃S change into M₁. What they have in common is that more B₂O₃ and P₂O₅ will decrease the content of C₃S.

Abstract: Doing experiment about weathering of two kinds of stone cultural relics, through measuring some technology index, comparing weathering resistance and surface deterioration of these stone cultural relics, discussing the reason of arising weathering and surface deterioration from internal and external factors, so these may offer some contribution to protect this kind of stone cultural relics.

Abstract: Through the laboratory dynamic triaxial test of sandy pebble soil, evolution law of influence of confining pressure and vibration frequency on dynamic strength is analyzed. Analysis indicates that dynamic stress of sandy pebble soil improves in a large degree with accretion of vibration frequency, dynamic strength of which increases significantly with confining pressure rising, and relation of dynamic stress and dynamic strain can also be symbolized with the R.L.Kondner hyperbola curve. Meanwhile, dynamic elastic modulus of sandy pebble soil decreases with growth of dynamic strain, while increases with growth of consolidation pressure.

Abstract: The continuous cooling transformation (CCT) behaviors of two vanadium (V) micro-alloyed steels with different Nitrogen (N) levels were investigated under the undeformed and deformed conditions, respectively. It is found that the austenite-bainite transformation is suppressed during dynamic CCT process due to hot deformation. For V-N steel, the transformation of austenite-proeutectoid ferrite and austenite-acicular ferrite (AF) occur under a wider range of cooling rates.

Abstract: It is inevitable for steel reinforcement to be corroded when mixed with seawater-and-seasand concrete. In order to improve steel corrosion protection properties of seawater-and-seasand concrete, reduce the chloride ion’s attack on steel reinforcement in structural concrete and lengthen the steel reinforcement’s service time, this paper presents an experimental study on whether admixtures like fly ash, slag and metakaolin in the seawater-and-seasand could retard the corrosion to steel reinforcement and provide protection to steel reinforcement in seawater-and-seasand concrete. The results indicated that metakaolin had a significant anti-corrosion effect and greatly enhanced the steel corrosion protection properties of seawater-and-seasand concrete whereas both fly ash and slag did not appear to have any obvious influence on curbing the corrosion of steel reinforcement.

Abstract: Based on fundamental ideas in tribology and basic concept of stress state in solid mechanics, the existence of frictional force on shear plane is discussed under uniaxial compression of brittle materials. On account of macroscopic fracture forms and mesoscopic fracture mechanisms, the key factors influencing shear fracture angle are analyzed. The results show that, when brittle materials are compressed and shear fracture occurs, shear fracture surface at the crack initiation point is consistent with the maximum shear stress. But the reason of shear fracture angle examined in experiment greater than 45º lies in that, the existence of frictional force between endface of specimen and pressure head of testing machine, and additional tensile stress produced in the materials when harder crystalline grain wedge in softer medium have changed original uniaxial compression stress state and the direction of maximum shear stress on next fracture path.

Abstract: Through the consolidation drained triaxial shear test of sandy pebble soil, the stress-strain curve of sandy pebble soil is obtained, analysis manifest that in the shearing process, shear dilatancy deformation and shear contraction deformation of sandy pebble soil are intercoupling, making asymptote of the curve after peak stress nearly a horizontal line. Meanwhile, based on the Duncan-Chang model, elastic modulus and Poisson ratio features of sandy pebble soil are analyzed, and Duncan-Chang model parameters are obtained.

Abstract: The RC frame structure in epicentral area was severely damaged in the 8.0 magnitude Wenchuan earthquake. After the earthquake have using three strengthening methods, such as enlarging the cross-section, exterior steel clad reinforcement and Paste CFRP was used in reinforcement the short RC columns damaged. To analysis the three-dimensional mechanical properties of short RC columns reinforced under nonlinear load in the condition of different strengthening methods and axial compression ratio by using finite element software ANSYS, the results show that: ( 1) The ultimate bearing capacity of short RC columns reinforced by using the paste CFRP and steel method has improved greatly as well as the ductility, can effectively avoid the brittle failure of short columns. (2) Axial compression ratio has a greater impact on the ultimate load and ductility of RC columns strength by enlarging the cross-section but the impact on that reinforced by using the paste CFRP and steel methods is relatively weak.

Abstract: This paper presents the effects of mineral admixtures and the water to binder ratio (W/B) on the tensile and compressive strength and micro pore structure of hardened cement pastes. The test results show that: with the water to binder ratio increasing, the tensile and compressive strength of cement paste with different mineral admixtures will decrease, air content and mean pore diameter will decrease and the cement paste with the ground blast furnace slag is the lowest. The artificial neural network based on its nonlinear mapping function can fit the relationship between strength and pore structure more accurate than an empirical formula.

Abstract: In the present work, the effect of heat treatment parameters on microstructure and strength of the 30MnSi PC steel bars was investigated and analyzed systematically. The results show that the fine tempered martensite, thinning tempered troostite and tiny tempered sorbite can be obtained when quenching temperature reach 920°C and the temper temperature is 240°C, 430°C, 600°C, respectively. The relationship between heat treatment parameters and tensile strength was also obtained. Optimum strength can be obtained by quenching at 920-950 °C and tempering at 430 °C with constant heating time.