Advanced Materials Research Vols. 168-170

Abstract: Based on nonlinear finite element method, the character of embankment reinforced with geotextile on sloping weak foundation has been studied. It is shown that the lateral displacement of embankment has been distinctly effected by the sloping of foundation, the value of lateral displacement on sloping foundation is greatly bigger than that of horizontal foundation. The peak value of lateral displacement can be effectively reduced by geotextile. With the same condition, geotextile in sloping foundation acts a more important effect than that of horizontal foundation. The development of plastic zone of embankment has been impeded and separated by geotextile, which enhanced the stability of embankment. The results also indicated that, if necessary, reinforcement such as anti-slide pile should be layout at lower toe of embankment on sloping weak foundation.

Abstract: To make appropriate rehabilitation decisions, determining structural layer moduli of the existing semi-rigid asphalt pavements is a crucial task for highway engineers. The objective of this study was to analyze the errors in layer moduli backcalculation due to modeling of layer interface condition. Firstly, according to the full bonding hypothesis, a dynamic finite element analysis model was established to generate a synthetic surface deflection database of the semi-rigid asphalt pavements. Then, the regression functions between deflections basin parameters and layer moduli were created and used to backcalculate layer moduli. Secondly, different friction coefficient values between asphalt layer and stabilized base layer were introduced into dynamic finite element model, accordingly, deflection basin parameters were calculated and layer moduli are determined based on the established regression functions. Finally, the backcalculated layer moduli and the original moduli values were compared. The analysis results demonstrate that assuming full bonding, instead of actual interface conditions of asphalt-stabilized base layer, moduli of stabilized base layers is underestimated, up to 2.5 times smaller than the original values. The improper interface condition of the binder-stabilized base layer has little influence on moduli of asphalt and subgrade layer.

Abstract: Rigid polyurethane foams were prepared from the liquefied wood polyols, which was obtained by the liquefaction of southern pine wood in the presence of polyhydric alcohols with sulfuric acid catalyst by using microwave-assistant as an energy source. The properties of liquefied biomass-based polyols and the rigid polyurethane foams were investigated. The results indicated that the foams exhibited excellent mechanical properties.

Abstract: Soil water characteristic curve is one of important topics of unsaturated soils. Pressure plate extractor and GDS unsaturated triaxial apparatus are used to study influencing factors including types of soils and net mean stress. Through method of least-squares, Fredlund five-parameter model were employed to fit soil-water characteristic curves. The results show that model provided a satisfactory fit to the experimental data. Through an analysis of influencing factors, we find that not only physical condition of samples but also external stress condition can affect the shape of soil water characteristic curve.

Abstract: This paper evaluates mainly the dry-mixed self-compacting concrete (DSCC) based on the experimental study. The study analyzes mechanical properties of DSCC at the hardened condition, which has been conducted as follows: compressive strength and split tensile strength with elapsed age as well as size effect of strength. Rate of gain in strength at different periods of curing such as 1day, 3days, 7days, 14days and 28days are studied for different DSCC mixes and suitable relations have been established for the gain in strength at the early ages. Relations have also been formulated for compressive strength and split tensile strength for DSCC mixes. Size effect of compressive strength and structural efficiency have been evaluated, all at cured after 28 days.

Abstract: The paper presents an inclination transducer with magnetic fluid, being dedicated to measure little inclination angles in comparison with a horizontal or a vertical plane. The functioning principle is submitted. The results of theory analysis show that output voltage of sensor and inclination angles are linear dependence. The factors affecting the sensor sensitivity are inspected, which include the exciting signal frequency, the peak voltage and the susceptibility of magnetic fluid.

Abstract: In order to write Hunan province engineering construction local standard named" Technical specification for autoclaved sand-lime brick masonry building ",the author has finished a series of fundamental mechanical properties experiments on autoclaved sand-lime brick masonry such as material character experiment, shear strength experiment , bending tensile strength experiment. By analysis on experimental data, the author found a startling regularity: there is a feature of optimal combination of strength for mortar and block of autoclaved sand-lime brick masonry.

Abstract: Ultra high toughness cementitious composite (UHTCC) is a newly developed, high performance, fiber-reinforced cementitious composite with substantial benefit in both high ductility and improved durability due to its tight crack width. The failure pattern of UHTCC exhibits saturated multiple fine cracks, so the durability of structures will be improved markedly by utilizing UHTCC partly or entirely instead of concrete. In this study, a total of 20 beams, including reinforced concrete beams that the cover zone was replaced by UHTCC (the thickness is 15mm, not containing reinforcement, and 50mm, containing reinforcement, respectively), reinforced concrete beams and reinforced UHTCC beams, had been manufactured. A power supply was used to accelerate the corrosion process of reinforcing bars, inducing different degrees of corrosion (the corrosion ratio was 1%, 2%, 4% and 5%) into reinforcing bars. The time of the cracks occurred and the crack width were recorded and the beams having different corrosion ratios of reinforcing bars were then tested under four-point bending for their load-deflection relations. The results showed that UHTCC could restrict the corrosion expansive crack of cover effectively, convert the crack pattern, and delay the appearance of first corrosion expansive crack, thereby to raise the service life of reinforcement concrete structures or components. Meanwhile, the bending test of beams after accelerated corrosion showed that the beams with a cover replaced by 50mm UHTCC and reinforced UHTCC having smaller amount of strength reduction and a reasonable ductile failure after corrosion. The experimental results showed that UHTCC could effectively delay the cover expansive cracking due to corrosion of reinforcing bars retain the ductile properties of reinforced concrete beams after reinforcing bar corroded.

Abstract: A new class of structural glue called permeant adhesive is introduced for repairing concrete cracks. The viscosity and strength of the permeant adhesive are tested, respectively. Then the durability of concrete such as sulphate attack, freeze-thaw resistance and impermeability of the repaired concrete are discussed. It is shown that temperature and reactive diluent are important factors in viscosity of the permeant adhesive. Curing agent and reactive diluent are important factors in strength. Hereby, the optimum proportion is A: B=1:0.5, and the amount of reactive diluent is 10% to 15%. The strength of the repaired concrete which is immersed in sulphate increases 3% to 26.2%, while the freeze-thaw resistance and impermeability of the repaired concrete are better. The above provide the theoretic and experiment foundation for simpling the pressure grouting technique of the concrete repaired and the application on the permeant adhesive.

Abstract: Numerous experimental studies have proven that the confinement with FRP-wrap or tube encasement could enhance the strength, ductility and durability of concrete columns. The variation of each distinct experimental test result to its actual mean value is the general cause of modeling inaccuracy, and this appears to be a lack of consensus among the research community. This paper critically reviewed the current experimental studies with the emphasis on the revelation of the mechanical behavior of FRP-confined concrete and analytical study of its behavior.