Advanced Materials Research Vols. 194-196

Abstract: In order to investigate the effect of particle size on expansive behavior of MgO-based expansive agent (MEA), linear expansion of paste containing MEA and hydration process of MEA in paste were measured. The results indicated the expansion of paste increased with the drop of particle size at early age, however, MEA with lager particle size expanded faster at late age. Finally, the expansion of paste increased with the rise of particle size. MEA with larger particle size was detrimental to the soundness of cementitious matarials. These two rules were more obvious to MEA burned at higher temperature. In addition, the hydration degree of MEA increased with the drop of particle size.

Abstract: This paper presents the experimental research on the bending resistance performance of 3 GFRP tube filled with steel-reinforced high-strength concrete flexural members. It studies that the GFRP tube fiber tangle angle, and GFRP tube thickness of GFRP tube filled with steel-reinforced high-strength concrete flexural members have an effect on mechanical performance of this investigation. The experimental results show that the flexural bearing capacity of members obviously increases with the decrease of the fiber tangle angle. The bearing capacity of flexural members increases with the thickness increase of GFRP tube. Based on the test study and theory analysis, a calculation method is proposed, and good agreement with the test results is achieved.

Abstract: A design idea has been brought forward about SRC beams strengthened with CFRP, in order to solve flexural capacity shortage and need strengthening engineering problems. By analyzing loading process, failure mode and loading mechanism, flexural capacity was calculated by superposition method. According to different failure modes and neutral axis’ location in the steel, the computed formula of flexural capacity about SRC beams strengthened with CFRP was proposed, and it provided references for design of SRC beams strengthened with CFRP.

Abstract: Reactive powder concrete (RPC) is one of new composite material, which is applied in the pilot project of the railways construction. According to the literature survey and test data report, the major factors which influence the reliability of 32m prestressed RPC girder in railway bridges are given in this paper. Furthermore, combining numerical simulation with finite-element method, the reliability of the prestressed RPC girder is calculated. The results show that the failure probability and reliability parameter can be obtained through direct sampling method and the latin hypercubic sampling method. The reliability parameter of fracture is 3.9 with two methods, while the reliability parameter of deflection control is 4.1 and 4.2 respectively with the two methods, and the reliability parameters meet the demands of norm of railway bridges. Consequently, the RPC is safety to be used in the railway bridges.

Abstract: In this paper, a equivalent-section method of analyzing shear lag effects in box girders is presented. The effect of two major parameters on shear lag is investigated for cantilever and continuous box girders with variable section under two kinds of loads. It is shown that the span-width ratio, in addition to the flange stiffness to total stiffness ratio, has a significant influence on the shear lag. Finally, conclusions are drawn with regard to further study and research.

Abstract: This research aims to find a new way of “turning trash into treasure” for the waste concrete. In the research, waste concrete was first ground, then, after analyzing its mineral composition, combined with some other ingredients according to the modulus of the cement clinker to become raw materials of cement. Mixed raw materials were made to be a thin cake, and then sent into high temperature furnace (HTF) to sinter for a certain period of time. Properties of cement, such as the compressive strength, required water of standard consistence and setting time were tested. The composition and microstructure of clinker were analyzed with X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis. The experimental results showed that the main mineral components of clinker are C₃S, β-C₂S, CA₂, CA, C₃A, C₄AF, the compressive strength of the recycled-cement is approximately equal to P.O32.5, there exists an optimum sintering temperature for the recycled-cement clinker with a given mix ratio of raw materials and content of seed crystal added,, and this temperature is usually much lower than the temperature adopted wildly in the cement plants.

Abstract: Through double punch test, the tensile strength of compacted loess is determined under different water contents and different dry densities, the relationship between tensile strength, water content and the dry weight density is discussed, and their relationship is established. Comparing with Brazilian test, it proved the feasibility of determining tensile strength of compacted loess with double punch tests.

Abstract: The experiment results show that the microstructure control plays a key role for enhancing toughness of heavy thick X80 plates at low temperature, especially DWTT property. The toughness of heavy thick X80 plate at low temperature is not only related to the bainite grains and M/A islands, but also impacted by the original austenite grain size. Finer original austenite grain size benefits to increase the BF/AF ratio in volume of a base material enlarge the crystal orientation difference of microstructure transformation inside austenite. Cracks on a broken section of DWTT samples can (a) penetrate the coarse grains directly, (b) propagate in Zig-Zaga way in the fine grains, and (c) be around the boundary of original austenite grains. The stable and high toughness of heavy thick X80 steel plates from the mass production can be achieved at low temperature made with the reasonable chemistry, clean steel, non-defect slab technologies and OHTP rolling practice.

Abstract: Molten, commercially pure aluminum has been treated ultrasonically with differing input power. The results show that the ultrasonic power can significantly refine the microstructure of the aluminium and increase the hardness of the samples. A mathematical model developed in this paper can predict the effect of the ultrasonic power on the grain size of the pure aluminium well.

Abstract: Analytical model for isochronal phase transformation kinetics attracts much attention for its advantages and importance. Adopting an effective treatment for the so-called temperature integral, an analytical model for isochronal transformation kinetics has been developed by considering various nucleation and growth modes. After applying to the analysis of the austenite-ferrite phase transformation recorded by the high-resolution dilatometric measurements, it is recognized that the developed analytical phase transformation model could be adopted effectively to determine the nucleation and/or growth mechanism prevailing during the isochronal phase transformation processes.