Applied Mechanics and Materials Vols. 268-270

Abstract: Three different volume ratio steel fiber and polypropylene fiber were mixed into concrete matrix to study the hybrid effect of fibers. Cube HFRC specimens were tested under uniaxial and triaxial load. Hybrid effects on compressive strength of the results were analyzed and compared. It was founded that there were positive and negative effects in HFRC under compression. Positive hybrid effects of HFRC could be found when volume ratios of fiber (no less than 1.0% for steel fiber and 0.1% for polypropylene fiber) were added into HFRC.

Abstract: Abstract: The scheme and implement of dynamic compaction on red sand soil embankment, Ying(tan)-Rui(jin) expressway, is introduced in this study. The settlement of the subgrade in the field was observed. The density and the water content of it were tested. Then bearing capacity of the subgrade was detected by PFWD. All the work done is to analyze the effect of dynamic compaction on the red sand soil roadbed. It shows that the water content decreases while the strength increases with compaction. That is, the embankment is compacted effectively by dynamic compaction.

Abstract: The workability is an important property for roller compacted concrete (RCC). Because of different construction process, the requirement of its workability is differ from the normal concrete. So, the factors which will affect the workability of RCC should be considered in mixture gradation design. The effects of cement content, water cement ratio, maximum size of aggregate and mixing time on the workability of RCC were tested.

Abstract: A prediction model of blasting vibration peak is put forward and analyzed combined with the tunnel blasting in Changxiang highway projection. The attenuation law of blasting seismic wave in tunnel and the evolution law of cumulative damage in concrete layer are discussed in the paper. Furthermore, a detailed analysis of the damage caused by blasting vibration for different bench is presented based on the increment formula of concrete cumulative damage coming from indoor experiment with the vibration monitoring data of Shizilong tunnel, which will play a guiding role for those large-span tunnel constructions in future.

Abstract: In this analysis, 3-D nonlinear FEM model is built in consideration of the cooperation and interaction among backfill soil, panel and reinforcement strip; the backfill soil is simulated by nonlinear static and dynamic elastic-plastic model; the reinforcement is simulated by the dual-phase enhanced linear elastic-plastic model which can describe the intensified features of the reinforcement; the interaction of soil and retaining structures is simulated by the friction-element. By comparison of before and after earthquake, result is get of the axial force difference reinforcement layer. The increased maximum location is close to toe of the wall.

Abstract: The effects of Al₂O₃ and Al(OH)₃ on expansion due to alkali-silica reaction (ASR) were tested by using Accelerated Mortar Bar Test and through prolonging the curing age, and the ffect was compared with silicon fume and fly ash. The results show that ASR can be inhibited effectively by proper content of silicious admixtures within 14 days, but can not in long term, while it can be inhibited by proper content of Al₂O₃ and Al(OH)₃ not only within 14 days but also in long term. The composite of silicious admixtures and aluminous admixtures has synergetic effect on inhibiting ASR, and there exists a value of Al₂O₃/SiO₂ with which ASR is suppressed best. For the composite, ASR is suppressed mainly by silicious admixtures in early age and mainly by aluminous admixtures in long term.

Abstract: The effects of aminosulphonic acid-based Superplasticizer(ASP)on the fluidity of cement paste and harden perfomance and mechanical performance of fresh concrete are studied.The water reducing rate, adaptation to cements and compatibility with naphthalene-based water reducer of ASP are tested. Teating results indicated that in comparison with naphthalene-based water reducer, ASP has the characteristics of low cost, highly effective water reducing ability and the ability restraining slump loss, and also has excellent adaptation to cements and good compatibility with naphthalene-based water reducer.

Abstract: Phosphoric acid, pentaerythritol and aniline were used to synthesize a novel intumescent flame retardant agent(IFR), then IFR was added into high density polyethylene based wood plastic composites(WPC) by three different ways. Thermal degradation behavior, combustion properties and mechanical properties of WPC were evaluated by means of limiting oxygen index(LOI), thermogravimetric analysis(TGA), universal testing and scanning electron microscope(SEM) images of char formed after LOI tests. The results show that when IFR was added directly into WPC, the composite has the best flame resistant property, but the worst mechanical properties; when IFR is dissolved into solution, and the immersion method is adopted, the WPC has the best mechanical properties and better fire retardant property.

Abstract: In this paper, utilizing the purified flue gas desulfurization (FGD) gypsum as raw materials to prepare calcium sulfate whisker (CSW) by hydrothermal method, the effects of the dosage of crystal modifier, reaction temperature, pH, etc. on the crystal morphology of CSW were discussed. The results show that the purified FGD gypsum can replace high-quality natural gypsum for the preparation of the CSW with excellent quality. The dosage of crystal modifier (K2SO4) and reaction temperature have a significant effect on the morphology and aspect ratio of CSW, while pH and reaction time have a minor effect. When the dosage of K2SO4 is 3 wt%, pH is adjusted to 2 and the solution is reacted at 130 °C for 60 min, CSW with excellent quality can be obtained.

Abstract: Because of long-term chloride erosion and alternate drying-wetting effect, anchorage support structure of underground engineering is liable to reinforced corrosion and its strength is decreased. According to previous research theory and test results, reinforced corrosion to deteriorate load-bearing role of anchorage support structure system is studied by means of numerical analysis FLAC3D and idea of finite element strength reduction. The results are as follows: (1) losses in the anchor structural performance in underground engineering with corroded reinforcements are caused by three factors: losses in the effective cross-sectional area of anchoring body, losses in the mechanical performance of reinforcing bars and losses in the bond performance of anchoring body. (2) Based on reinforcement mechanical model in FLAC3D, deterioration of mechanical performance of anchor structures caused in underground engineering was analyzed due to reinforcement corrosion. And according to idea of finite element strength reduction and results of laboratory test, deterioration analysis parameter caused by corrosion can be reduced accordingly. The research results can provide the theory support to analyze corrosion deterioration of anchor structure in underground engineering using numerical simulation.