Applied Mechanics and Materials Vols. 275-277

Abstract: Barite concrete with density grade of 3 and strength grade of C30 was prepared by mixing with different fineness of fly ash. The workability, mechanical properties and long-term high temperature performance of the prepared barite concrete were researched. Results show that the workability of barite concrete is improved by mixing with fly ash, and no segregation of mixture has been observed. The apparent density and 3d, 28d compressive strength of barite concrete are decreased obviously after mixing with fly ash. But with the increasing of the fineness of fly ash, the apparent density and 3d, 28d compressive strength of barite concrete have a slight increase. High temperature residual compressive strength is decreased with the increasing of temperature. The cycle times of heat treatment at 400°C only has a little effect on residual compressive strength of barite concrete.

Abstract: Drying creep of self-compacting concrete (SCC) has two different sources: microcracking and stress-induced shrinkage. Based on theory for pore water and microcracking theory of concrete, the model for drying creep caused by constant stress is derived from rheological equations. The proposed model is coupled with FEM analysis by recursive calculation, so that the creep caused by changing load can be calculated without considering stress history. Verification of the model is conducted through comparison with experimental result and Bazant’s empirical model. The comparing results validate the model for drying creep of SCC.

Abstract: With low content in CaO, blast furnace slag is a unique local engineering material with characteristic of multi-hole structure and high strength. According to present technical stardard, mix composition of cement stabilized slag is determined by indoor test in different proportion of cement content. Meanwhile, in pilot project, field tests are conducted to both cement stabilized slag and traditional aggregate and indicate cement stabilized slag has obvious superiority and could be adopted completely in application in road base project.

Abstract: In order to study the effect of manufactured-sand’s feature on the alkali activity of slate aggregate, refer to the accelerated mortar bar test in the “Standard for Constructional Quality Acceptance of Railway Concrete Engineering” TB 10424-2010. The text has studied the expansion of the specimens that are made from slate aggregate with different powder contents or different particle size distribution. The results show that: When the content of powder in slate aggregate is less than 10%, the powder dose not have adverse effects on the expansion of specimens, and when the powder content is 15% to 20%, the expansion has downward trend. Slate powder is an active powder. It can not suppress the alkali-aggregate reaction of slate aggregate, but it can reduce the expansion of specimens. Particle size has influence on the expansion of specimens. The most unfavorable particle size of slate aggregate for the alkali activity is 0.16~0.315(mm).

Abstract: The phosphogypsum (PG) sample produced as the waste of the phosphoric acid fertilizer plant from Guizhou, China was studied for its properties and as a material for anhydrite cement. The impurity content, type and distribution, as well as thermal behavior and solubility of the PG were carefully studied by XRD, DTA techniques and gravimetric determination. The China Standard GB175-2007. The mineralogical studies were physical properties of the sample were studied as per the determined by XRD. The results showed that the impurities of PG are mainly water-soluble P2O5, F, organics and P2O5 and F in the gypsum lattice which has entered in to solid solution with gypsum as well as the insoluble Ca3(PO4)2 and CaF2. Experimental datum showed that a suitable anhydrite can be produced by heating PG at 1000 °C and PG up to 60% used can be as a main raw material in production of anhydrite cement.

Abstract: The effects of initial high humid air-curing, standard water-curing and sealed-curing on thaumasite form of sulfate attack (TSA) of cement based materials were studied. The erosion products after three years attack in 5% MgSO4 solution were analyzed by means of X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Initial high humid air-curing can delay the TSA of specimens for CaCO3 generated by carbonation and filled in the pores of the specimens, forming a compacted surface and restricting the intrusion of SO42-. In comparison, specimens cured in sealed condition occurred TSA most serious resulting from that large amount of inter-defects in specimens for the lower hydration degree, and SO42- ions could intrude into specimens more easily.

Abstract: The present study is related to a process development for producing high purity fused magnesia. A newly designed 3000 kVA electric arc furnace is used in the field experiment. The electric resistance characteristic of fused magnesia is analyzed and the effect of electrode diameters and electrode depth buried in molten magnesia on melting electric resistance and electric arc heat conversion are discussed in detail. It shows that, for the new 3000 kVA electric arc furnace, 350~450 mm diameter electrode and ~300mm depth in molten magnesia are suitable.

Abstract: An comparative study was made of microstructure and mechanical properties of steel constaining Ni of 9% in different heat treatments. Shielded metal arc welding (SMAW) was employed as jointing technique. Double normalizing and tempering (NNT) and quenching, intercritical quenching and tempering (QLT) were applied as the heat treatments. Instrumented impact and tensile tests were performed between 20°C and 196°C. The results show that both the microstructure and mechanical properties of base and weld metals in QLT solution turn out to be the optimal.

Abstract: Present work describes a piercing process using the finite element method in order to investigate the wear of mold punch. In present investigation, the piercing clearance and punch fillet radius was studied by simulating the piercing operation of an AISI 1035 sheet. Simulation used the FEM program ANSYS/LS-DYNA. The results show that the best resistance of the mold punch is reached when the punch round radius reached 0.03mm and piercing clearance reached 0.15mm.

Abstract: Power Law Model and Cross Model are widely used in Metal Powder Injection Molding computer simulation analysis. The feedstock viscosity data of Ti-6Al-4V is got through field tests, regression analysis is used to calculate the model parameters, which provides the theoretical basis for the application of computer simulation analysis in metal powder injection molding.