Applied Mechanics and Materials Vols. 253-255

Abstract: The new type of gypsum compound waterproof agent was composed of organic emulsion that emulsified by polyvinyl alcohol and stearic acid and saline waterproof agent made of carboxylic acid sodium, aluminium sulfate etc. The influences on the hydration exothermic effect and crystal growth of gypsum were studied when different amount of the organic emulsion, the saline waterproof agent were added. According to the hydration exothermic effect and microstructure of crystal growth of gypsum after mixing the different amount of waterproof agent, the relationship between gypsum hydration exothermic effect and gypsum crystal growth were discussed theoretically.

Abstract: Modified asphalt emulsion，which worked as a new type of freeway maintenance material, have attracted much attention since it be exploited. The emulsion’s properties were easily effected by external factors, such as production technique, the pH value of soap solution, stability additive, emulsifier, modifier and so on. On the basis of indoor tests, this paper researched the pH value’s influence on the performance of modified asphalt emulsion emphatically.

Abstract: Waste tiers increasing with geometric series, in view of that seeking a new treatment process has already become an urgent affair. Over the years, there has been mounting interest in the use of recycled tire rubbers in highway construction. Which have an important benefit to the recycling utilization of scrap tires and environmental protection, and can consume a large number of scrap tires. This paper presents an overview of some of the research published regarding the use of crumb rubber in highway engineering, but the study about the using of crumb rubber in cement-stabilized macadam base is seldom reported. This paper used ANSYS to build the pavement structure model, analyzed the effect to pavement by changing the thickness and modulus of cement stabilized macadam base with crumb rubber. It may serve as a useful reference for the future application of crumb rubber to the projects of cement-stabilized macadam base roads and other fields.

Abstract: Influence of fly ash on alkalinity of pore solution and microstructure characteristics of hardened cement pastes were investigated by means of ex-situ leaching (ESL), MIP and SEM. The results reveal that the decline of alkalinity of pore solution is not endless, even though the contents of fly ash in fly ash-cement(FC) pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Abstract: The effect on stripped the wood fiber with organic molecules inserting pretreatment to recycled HDPE plastic was researched. Organic molecules inserting wood fiber has layered hollow structure by screw extruder and silane coupling agent molecules can insert into hollow fibers. The results show that composites with stripped wood fibers have better mechanical properties than unstripped composites. SEBS elastomer treatment can further enhance the toughness of the wood-plastic composites.

Abstract: Concrete filled steel tubular is a steel-concrete composite material. Its stiffness is reasonable or not will affect the accuracy of the internal force and deformation. Based on the two mixed material stiffness calculation theory that superposition theory and unified theory, a conversion stiffness formula list recommended by domestic and international codes and researchers was derived. By matlab program, the ratio between combination stiffness and conversion stiffness was calculated, and the relation curves between the stiffness ratio and parameters including steel grade, concrete grade and steel ratio were obtained. A conclusion is drawn: for the concrete filled steel tubular structure, we can calculate the conversion stiffness first, then by the combination stiffness and conversion stiffness ratio, so as to obtain the combination stiffness. In practical engineering applications, the combination stiffness is more in line with the mechanical characteristic of the composite structure, and the calculation results are more closer to the actual situation.

Abstract: Doped fly ash with lime as a binder, can be used to stabilize the crushed stone, sand and gravel, as well as other types of aggregate formation of two gray gravel, two gray gravel and lime soil or other structure used as a road pavement base or sub-base, in order to to verify the effect of the high activity of fly ash in the actual project, taking into account two gray macadam base and cement fly ash macadam base for semi-rigid base type commonly used in the early construction of the highway in Guangxi, the ash proportion indoor test range, and ultimately determine the best ratio.

Abstract: In this paper, the test of compact tensile fatigue fracture of 16MnR steel was done after high temperature, and the relation between the proof values Ji at crack initiation of fatigue fracture and fatigue fracture fractal dimension was studied. The experimental results show that the relation between the proof values Ji at crack initiation and the heating temperature. The compact tensile fatigue fracture fractal dimension was changed when 16MnR steel sample was heated to different temperature.

Abstract: After 51 C40 HPC specimens with a size of 100mm×100mm×400mm were heated to 400°C, 600°C, 700°C, 800°C for 2 hours, and 300°C and 500°C for 1h, 2h, 3h, 4h, 5h separately, cooled naturally and placed for 24 hours, the flexural strength were experimented respectively. Subsequently, the effect of high temperature and its acting time on the flexural strength of HPC and the variation discipline were analyzed; meanwhile, the degradation mechanism of HPC after elevated high temperature was discussed.

Abstract: In order to explore the effect of vibrating mixing technology in industrial production of concrete, the influence of vibrating mixing and common forced mixing on the mixing quality and efficiency were comparatively investigated by field tests of concrete mixing plant. The vibrating mixing scheme was achieved by adopting mixing shaft and blades as vibrating source based on conventional twin-shaft mixer. The field tests included mixing time test and reducing cement test. The experimental results show that under different mixing time, the freshly mixed concrete by both mixing methods have similar uniformity but the hardened concrete have distinctive compression strength; comparing with common forced mixing, vibrating mixing makes the materials in vibrating status to destroy their sticky connection and distribute cement particles, so both 7d and 28d compression strength are significantly improved and the mixing time is reduced; with the cement reduction, the compression strength of concrete by both mixing methods decrease, but comparing with common forced mixing, vibrating mixing can save cement under the condition of ensuring necessary concrete strength due to its improved cement utilization.