Applied Mechanics and Materials Vols. 584-586

Abstract: Applying modified waste rubber particle to surface mortar can give full play of the unique characteristics to utilize the waste and decrease environmental pollution. In order to study the application performance of crumb rubber mortar, five different mortar proportions are selected to determine the compressive strength, flexural strength, impact strength and thermal aging strength. The results show that rubber particles mortar possess excellent toughness, impact resistance and heat aging properties.

Abstract: Al-Mg alloy plates with 10mm thick were welded by multi-pass MIG welding with the self-made wire as filler material, and microstructure of the welded joint were examined by metallographic and electron backscatter diffraction (EBSD). The results indicate, because of the grain refining effect of Zr, the grains in welding joints fusion zone formed grain-refining layer tissue by competitive growth. In the juncture zone of two welding passes, because of the grain epitaxial growth mechanism, it formed obvious coarse grain zone, which became a weak link of welding joints. And the coarse grain zone exist faint <110> texture, but to the whole, the welding zone did not exist obvious preferred orientation.

Abstract: This paper presents the development of a detailed 3D nonlinear finite element (FE) numerical model that can accurately predict the load-carrying capacity and response of RC beams strengthened with NSM CFRP-PCPs composite bars subjected to four-point bending loading. The predicted FE mid-span deflection responses agreed very well with the corresponding measured experimental tested data at all stages of flexural loading.

Abstract: The mechanism and conditions of superficial modifying of wood by phosphoric and siliceous organic compounds are studied. Essentially new fire- and bioprotective preparations are developed and introduced. Wood can absorb moisture from air; the moisture considerably affects physical and mechanical characteristics of wood. While moisture of wood increases by 30%, its mechanical strength decreases by 70%. Increase in wood moisture leads to its rotting. Nowadays, due to ecological pollution, atmospheric moisture often contains acid agents. Wooden external constructions due to their contact with acid atmospheric moisture are subject to considerable hydrological destruction. Hydrophobization of wood happens with the help of polymers and siliceous organic compounds, the effect of the decrease of hydroscopability occurring because of the block system of hydro groups, filling of capillary porous structure of density of suture of lignocarbohydrate mould[5]. But if there is a considerable amount of polymers in wood, density of polymeric net gets broken which leads to worse characteristics of the material, and sometimes to its spontaneous destruction. Siliceous organic compounds (SOC) are considered to be traditional hydrophobizators of wood and cellulose materials. To create stable effect of hydrophobization it is necessary to carry out. Treatment of wood by silicium compounds. Saturation of wood by SOC has certain difficulties as SOC are hydrophobic agents. Saturation is carried out by means of autoclave, by method of hot-cold baths with overfall of temperatures from 65°C to 20°C. The time of saturation must be no less than 7 hours. These methods of saturation mean the usage of great number of materials and they are energy consuming. The present research is aimed at the development of technology of ‘’soft’’ treatment by silicium compounds under which a level of chemical modifying is not high and content of chemically related Si is 1%. As silicium agents alkilhydrosiloksans and alkoksilans were used. To make it easier for SOC to enter into wood , various hydrofilous additions were used, which had to decrease the energy of activation of silicium reaction simultaneously in order to turn treatment by silicium compounds into a “soft” regime. Out of alkilhydrosiloksans polythilhydrosiloksans (PEHS) and polymethilhydrosiloksans with various levels of polymerization were used. The role of activating hydrophilian additions performed ammonia phtorids, potassium, hydrochloric titanium acid.

Abstract: In order to improve the performance of concrete, reasonably use industrial waste and realize the sustainable development target of economy and environment, mineral admixtures have been widely used in concrete. But, widely using mineral admixtures reduces the overall performance of concrete, the reason is that the mineral admixtures dilutes the SO₃ content in cementitious material, restricts generating the hydrates in the later concrete. If also add industrial by-products desulphurization gypsum in concrete, the added desulphurization gypsum as admixture not only improves the SO₃ content in concrete, but also prime and crystal sulfate active, promote other admixtures pozzolanic effect, configuration effect and micro-aggregated effect. Experiments show that, when the desulphurization gypsum that added into cementitious material content is following 10%, in other words the desulphurization gypsum content is 3.1%, it can improve the mechanical performance of the concrete. Considering the early strength and work performance of cement, the desulphurization gypsum content that added into cementitious material should be controlled in the range of 8%, early strength increases by 16.9% and late strength also increases.

Abstract: Reinforced concrete composite beam plays a very important role in the precast concrete structure, composite beam research is critical. Based on the research results about it in China, on the one hand, from the traditional composite beams to the improved ones, the various kinds of composite beams were concluded; on the other hand, the applications of new building materials in the composite beams had been included, which included fiber reinforced cement-based composites, steel fiber reinforced concrete, reactive powder concrete and crumb rubber concrete. Through to the both related tests and theoretical studies, the progress of the composite beams was summarized. Finally, the further research was prospected.

Abstract: The domestic and overseas research progresses of microstructure of the concrete and fatigue damage after treated by high temperature are reviewed. The main research direction and current shortage on the high temperature process, fatigue damage and the microstructure evolution mechanism of concrete are discussed. A view of the application prospects of concrete research on the high temperature process, fatigue damage and the microstructure evolution mechanism of concrete is forecast.

Abstract: The rammed cement-soil pile compounded foundation is widely used in collapsible loess of northwest China. There are many factors influencing the bearing capacity of compounded foundation. The calculation result with empirical formula are usually not accurate. The influence factors on bearing capacity of compounded foundation are analyzed with finite element method based on the static load results. The result show that pile body elastic modulus has little effect on the bearing capacity of compounded foundation. This is quite different from bearing behavior of single pile. However, the soil parameters, such as soil elastic modulus, soil internal friction angle and soil cohesion have significant impact on compounded foundation bearing capacity.

Abstract: Inorganic polymer material is a new green energy-saving building material which has a broad development prospect. It has been a hot engineering research issue. In this paper, inorganic polymer concrete is made by using fly ash, mineral powder and alkaline activator. Its basic mechanical properties are studied by the cube compressive strength test, the drying-wetting cycle test and flexural strength test and compared with the ordinary concrete in the same sand ratio. The compressive strength of inorganic polymer concrete specimen with mineral powder in early days is much greater than the same level of ordinary concrete. Without mineral powder, its compressive strength has developed rapidly in the early days, but it become very slower in the later days. Furthermore, its ultimate compressive strength is less than the same level of ordinary concrete. After the drying-wetting cycles, the compressive strength of the inorganic polymer concrete specimen is lower than that of the standard conservation. The reduction rate with mineral powder is smaller. The flexural failure characteristics of inorganic polymer concrete specimen are the same with ordinary concrete. However, its bending strength is lower than the same level of ordinary concrete specimen. Research results provide valuable experimental data for the engineering application of inorganic polymer concrete.

Abstract: Internal curing was especially beneficial to improve concrete performance. The super absorbent polymer and fly ash were used in the concrete and the frost resistance of concrete was studied. The result indicated that the super absorbent polymer changed the pore structure, increased the quantity of the pore, decreased the strength loss 5-10% after 250 freeze-thaw cycles and improved the frost resistance of concrete.