Abstract: It has important practical significance to research dynamic mechanical properties of silica fume concrete with silica fume concrete widely applying in civil engineering. Mechanical properties of silica fume concrete under impact loading were studied with the SHPB test device ofφ74mm to get its optimal design project and provided important bases and references for engineering applications.
Abstract: There are two groups of ceramics, traditional and modern ones. Brick, cement tile, and glass are traditional ceramics. They are inorganic non-metallic materials with high melting points, high strength, good strength, and excellent oxidation resistance. Construction industry mainly depends on them. However, traditional ceramics are brittle, low strength, low resistance. Compared with traditional ones, modern ceramics are magnitude finer, more homogeneous, and less porous. They include alumina, silicon nitride, silicon carbide, and boron carbide. They can be applied to building materials, components, and aerospace. Therefore, modern ceramics have stronger adaptability to modern society. Ceramic engineers need in-depth research on design and application modern ceramics.
Abstract: By plasma cladding technology, the Ni60B/TiC composite coating metallurgically bonded to Q235 steel were prepared using Ni-based alloy and TiC powders. The microstructure formation mechanism of the clad layers was investigated by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). The microhardness distribution and wear resistance of the specimens were tested. The results show that metallurgical combination is achieved between coating and substrate, the microstructure of composite coating is composed of dendrite γ-Ni, α-Fe, added TiC and FeNi. The hardness and wear resistance of composite coating have relationship with TiC particles content and TiC particles distribution. The hardness and wear resistance increase with the increase of TiC particles content.
Abstract: To investigate the effect of heat treatment on delayed fracture resistance of high strength steel, 30MnSi steel bars with different heat-treatments are produced. Tensile results showed that, the annealing and sub-temperature quenching steel bars have good delayed fracture resistance and satisfy the criteria that delayed fracture does not occur in 200 h, but there is a marked drop in delayed fracture resistance when the quenching temperature is higher than sub-temperature quenching
Abstract: The pile axial strains were measured according to the results of static loading test. The axial force and side friction of pile were calculated, and load transfer behaviors were researched. Analysis of the data shows that cement-soil mixing pile has the characteristics of friction piles. The rapid reducing of the upper pile axial force and friction show that load passed within a certain range. Horizontal crack occurred at the upper of the pile. Before and after the destructing of the pile load transfer mechanism is different.
Abstract: Abstract: The moisture flow and drying of porous media, such as concrete, is tackled through the Navier-Stokes equation, where the Navier-Stokes equation is considered as the link between the theory of fluid flow, Acoustic Emission (AE) experiments on cracking (sound propagation based on the wave equation) and Lattice Gas Automata, (LGA) being a numerical simulation of the Navier-Stokes equation. Early age cracking in the ITZ is induced by using the moisture flow as the only “load” that causes cracking due to drying shrinkage volume changes in Environmental Scanning Electron Microscopy (ESEM) tests. An attempt is made to link and compare experimental results conducted by means of AE and ESEM to the results of 2-D LGA numerical simulation. Lattice Gas Automata (FHP model) is used as a basis to generate a new model for drying of porous medium. Special emphasis in a model creation is given to the Interface Transition Zone (ITZ), between aggregate and cement paste, because of the early crack initiation in this highly porous and strength-weak zone.
Abstract: Experimental studies on the properties of cement paste and mortar with the use of limestone powder were carried out. The results show that the replacement with 10% to 30% limestone powder in cement paste can reduce the water requirement for certain flowability. As an inert material, the use of the limestone powder has significant negative effect on the mechanical properties of mortar. However, strength requirement of normal concrete (mortar) can be reached by reducing the water to cementious material ratio, which makes the use of limestone powder as a replacement of cement possible.
Abstract: Graphene film has been successfully grown on Cu foil by directly depositing carbon atoms with a solid source molecular beam epitaxy (SSMBE) system. The structural and electronic properties of the graphene sample are characterized by Raman spectroscopy, near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS). Results indicate that the graphene has the tubostratic stacking structure.
Abstract: Various reasons suggested to cause high performance concrete cracks were investigated, such as external and internal constraints, thermal deformation and creep. Firstly, the real temperature and stress fields simulated were suggested, and then the reasons for cracking and engineer measures for prevention from cracking in high performance concrete were analyzed. The main concept and characteristic of the measures are that the cracking prevention of concrete is a complicated comprehensive problem to be solved by application of combination with different measures in time under construction. The results show that the key economical measures for the prevention are the internal cooling water pipes and external superficial heat preservation. Moreover, the quasi real-time tracking observation, inversion, and feedback analysis under construction are also very necessarily, especially for projects using high performance concrete under severe conditions.
Abstract: This paper studys the effect of PAM on the strength of cement-soil by different PAM content cement soil unconfined strength test combined with a scanning electron microscope test to have a microscopic analysis of the impact mechanism of PAM on the strength of cement-soil, hoping to cement soil engineering applications to provide a reference. The study shows that: when cement content is 10%, the compressive strength trend of cement soil is first rose and then decreased with the increase of PAM content . Cement-soil that was mixed with an appropriate amount of PAM can effectively improve the compressive strength of cement-soil and there is an optimal content.