Advanced Materials Research Vols. 639-640

Abstract: Cold-rolled deformed bar with wing is a new type of cold-rolled deformed bar, it has high tensile strength and better ductility than the general cold-rolled deformed bars, and has good bonding properties with concrete. Five types of totally 15 full-scale specimens were tested to investigate the mechanical behavior, failure mode and the suitable value of minimum reinforcement ratio of concrete slab with cold-rolled deformed bar with wing. Experimental parameters include the reinforcement ratio, concrete strength, and reinforcement diameter. The deflection of mid-span, the strain of cold-rolled deformed bar and the crack width measured under each load level were studied. The test shows that the specimens with the reinforcement ratio of 0.15% present ductile failure, while those with the reinforcement ratio of 0.12% present brittle failure. Based on the results of the experiment, this paper suggests that the value of minimum reinforcement ratio of concrete slabs with cold-rolled deformed bar with wing could be 0.15%.

Abstract: In order to verify the characterization degree of water stability, research selects some clay content aggregate retrieved from road engineering field to produce rubber asphalt mixture and carry out the water stability test. Test results show that clay content in aggregate has a significant influence on the water stability of rubber asphalt mixture. When the content of clay in aggregate less than 1%, the influence on water stability is smaller; when the clay content exceeds 2%, the decay rate on water stability performance and long term properties obviously speed up, resulted in serious water damage.

Abstract: The durability of thermal insulation glazed hollow bead concrete, which is a kind of structure self-thermal insulation material produced in the background of building energy efficiency, has been systematically researched in order to make it with a good workability. Theoretical analysis and experimental study have been made from the raw materials and construction mixing proportion in the basis of the analysis to the influencing factors of its durability so as to can improve its durability.

Abstract: The rheological mechanical properties of two kinds of self-designed epoxy adhesive curing systems were studied in this paper through the dynamic and static thermodynamics instrument named EPLEXOR 500N made by GABO® company in Germany. Short-term creep tests were carried out under three different temperature conditions of 20°C, 30°C and 40°C and the rheological model is developed to describe the materials creep law. In addition, the test results from the two different epoxy adhesive are also compared and analyzed.

Abstract: Based on the deficiency of high temperature stability among early damages for steel deck pavement, a new material of multi-modified asphalt had been developed, its performances and mixture have been tested. The tests such as the rutting tests, low temperature bend tests and fatigue tests had been done. The results sindicated this multi-modified asphalt had the lower temperature susceptibility and the better ability to resist the shear deformation. Every performance of its mixture had been improved especially its high temperature stability, and its economic benefits are considerable, it is suitable for the steel bridge pavement.

Abstract: Based on engineering practice, autogenous volume deformation and creep properties of C60 high performance concrete(C60 HPC) and C60 high strength concrete(C60 HSC) were evaluated in the study. The results showed that the cement partly-replaced with fly ash could significantly decrease the creep deformation, creep coefficient and creep degree. In comparison with C60 HSC, the creep coefficient and creep degree of C60 HPC were decreased 17.9％and15.8％ in 28 days, 22.9% and 21.0% in 270 days. For C60 HPC and C60 HSC at the same age, autogenous volume deformation of C60 HPC is greater than that of C60 HSC, but they were both less than 80×10-6 , and the autogenous volume deformation was basically completed in 7 days.

Abstract: The effects of mineral admixtures and superplasticizer on reducing the hydration heat of cementitious material were evaluated in this study, and the heat evolution rate and hydration heat were tested as the two parameters to evaluate the effect of improvement. The results showed that the cement partly-replaced with fly ash (FA) and slag (SG) could significantly decrease the release rate of hydration heat on the early stage of hydration, and lower the peak value of the heat evolution rate. The superplasticizer (TJ-Ⅲ) could reduce the hydration heat mainly on the early stage of hydration, and extended the induction period. In comparison with slag, the fly ash had more active effects on reducing the peak value and release rate of hydration heat.

Abstract: The wasted cement mortar and internal cracks induced by the secondary breaking process existing on/in recycled aggregates lead to significant reductions in the apparent density, strength and durability of recycled aggregate concrete compared to those of natural aggregate concrete. In this study, recycled aggregate intensification approaches was proposed by removing the old cement mortar from recycled aggregate surface through mechanical agitation, and immersing the recycled aggregate in chemical solutions. A series of laboratory experiments were carried out to validate that the proposed approach could improve various performances of the recycled aggregate, as well as the concrete made of it. The testing results showed that through the combination treatment or modification of mechanical and chemical intensification, both of the compressive and flexural strength of the recycled aggregate concrete could be increased to some extent.

Abstract: Crack is one of the major distresses in asphalt concrete pavements, which could significantly reduce the safety and amenity of driving, even the performance of the whole pavement structure. By means of diverse crack repairing manners, the durability and whole service life of the pavement can be improved and extended. After repairing, a composite structure of the repairing system is formed which consists of new crack filling materials and original asphalt concrete matrixes. In order to resist the external loads on the pavement, the composite structure mush work as an integrated structure and maintain sufficient adhesive strength. Therefore, the deformation compatibility of the composite structure is the vital performance for the stability and durability of the entire repairing system. In this study, a modeling analysis for the composite structure under various service conditions was carried out utilizing MIDAS software. The vertical and transverse deformation, transverse and longitudinal normal stress were analyzed by simulating the composite structure under several serving conditions. Based on the results，it was found that the strain, stress and related properties of the repair material and asphalt concrete matrixes could meet the requirements for an asphalt concrete pavement, and the compatibility of the composite structure was also satisfactory.

Abstract: Combining Shi Wu Passenger Dedicated Line and considering the effect of variety and content of mineral admixtures on concrete performance, the paper has investigated the microscopic structural’s variation of C40 high performance used in non-ballasted track base plate under the coupling conditions of acid rain and carbonization by using micro-testing methods such as SEM and XRD and optimizing mix design.The effect of variation on concrete performance has also been analyzed. Results show that when the concrete was eroded in coupling conditions of acid rain and carbon corrosion, C40 high performance concrete specimens produced a certain amount of acicular and columnar ettringite, the surface structure was loose, and pore increased, in addition, plate Ca(OH)2 crystal content gradually decreased with increasing of age, the concrete strength decreased, the maximum reducing value reached to 27%, what's more, the depth of neutralization increased with age. For different erosion pattern, its influence law was: S mode＜ST mode＜TS mode＜T mode.