Advanced Materials Research Vols. 639-640

Abstract: In the highway tunnel construction, monitoring parameters are so various, and along with the construction uncertainties, it is very difficult to adopt one fixed model to generalize the complicated law of the monitoring information. Therefore, we choose data in different periods and assign the data with corresponding credibility respectively, and then the monitoring result is described using blind information. In this paper, the theory of blind information is introduced first, and then the blind information is applied in the engineering case of comprehensive assessment of tunnel safety monitoring. The research result has demonstrated that processing the monitored values by applying blind number can largely weaken uncertainty of the monitored information, and makes the evaluation of the construction safety issue more detailed and comprehensive, which overcomes the traditional methods’ defect that describes information too absolutely. The result indicates that blind data is valuable for comprehensive assessment of tunnel safety monitoring.

Abstract: The major loss of the hurricane was damage and collapse of structures, In particular, wind power tower wich requires both the use of wind, wind on the structure plays a leading role in the tall slender flexible structure.In this paper, tests of remote sensing dynamic monitoring of tower structure with wind power are carried out, using measurement techniques of high-frequency and high-speed electromagnetic interference.

Abstract: Laboratory experiments were conducted in this study to investigate the suitability and applicability of incorporating fly ash, bottom ash and paper sludge with various contents into CLSM mixtures. Fly ash was used as a substitute for Portland cement, bottom ash was added by partially replacing fine aggregate, while paper sludge was treated as a fibrous admixture. Physical and mechanically properties of the CLSM mixtures were examined through flowability, compressive strength, and splitting tensile strength tests. The test results indicated that both fly ash and bottom ash can be potentially used as basic materials for CLSM mixtures with desirable performances, and by limiting the amount of cement used in the mixture, the ultimate strength of CLSM could be easily controlled available for excavation. The strength of the CLSM mixtures were reduced to some extent by incorporating high content of fly ash, while they were significantly increased with high content of natural sand replaced by bottom ash. Due to the high water absorption of the paper sludge, the mixture with paper sludge added exhibited relatively low flowability, and it showed no benefits on enhancing compressive and splitting tensile strengths as common fibrous materials.

Abstract: Cement-asphalt mortar interlayer plays an important role in ballast-less track in high speed railway. Cement-asphalt mortar undergoes repetitive changes in temperature when it is exposed to its service environment. Change in temperature has a significant effect on the thermal deformation of cement-asphalt mortar, and even affects directly the durability of ballast-less track. In the paper, length and mass of the specimens of cement-asphalt mortar were continuously measured during the heating and cooling cycles within the range of temperatures of -10~60°C. The results indicate that there is an evidently irreversible shrinkage at the end of the first cycle of heating and cooling. The shrinkage taken place at the end of cycles of heating and cooling decreases with the increase in cycle numbers. Apart from the curve for the first heating, deformation curves of cement-asphalt mortar either for heating or for cooling are nearly lines. After being heated and cooled for 5 times, the temperature-deformation curve for heating nearly overlaps the curve for cooling. The percent of moisture loss at the end of every cycle decreases with the increase in cycle numbers. Thermal shrinkage occurs at about 0°C in the first heating.

Abstract: Concrete admixture has become one of essential components of the high performance concrete in recent years; however, the quality of high performance concrete fluctuates according to the compatibility between cement and admixture it used. Considering lower alkali cement is often provided by cement producers in order to get better durability of concrete, so low alkali cement and naphthalene-based superplasticizer were used as the main test materials in this paper. The causes of the compatibility between low alkali cement and superplasticizer were studied, and then several measures were proposed to improve the compatibility.

Abstract: Strength standard deviation determines the trial strength of recycled concrete, and it is vital to the mix proportion design and quality control of recycled concrete. But at present the data on the standard deviation for the compressive strength of recycled concrete is very little. On the basis of consulting extensive literatures, related data is summarized, and the values of strength standard deviation of recycled concrete are suggested, which can be for reference in the mix proportion design of recycled concrete.

Abstract: This study investigates the relationship between the amount of fiber reinforcement and flexural tensile capacity by evaluating the degree of dispersion and the fiber reinforcement effect in mortar mixes with low fiber contents (lower than 0.2%) in order to derive solutions enabling to improve the tensile performance of mortar with low contents in macro fibers. The results show that a certain degree of improvement of the toughness is achieved even in the case of fiber reinforced mixes with low fiber contents and that the variation of the toughness capacity is sensitive to the degree of dispersion of the fibers.

Abstract: Based on the compressive strength, the thermal conductivity, the elastic modulus and the steel bond strength of thermal insulation glazed hollow bead concrete, referring to the carbonation mechanism and the influence factors of the ordinary concrete, considering the impact of raw materials and the influence of construction technology, the study on thermal insulation glazed hollow bead concrete anti-carbonation was proposed. From the test results, it can conclude that for the same intensity level, the anti-carbonation capacity of the thermal insulation glazed hollow bead concrete is better than that of the ordinary concrete. For different strength grade of thermal insulation glazed hollow bead concrete, to some extend, the higher the intensity level is, the stronger the ability of thermal insulation glazed hollow bead concrete anti-carbonation is.

Abstract: The tensile and bending behaviour of steel-polypropylene hybrid fiber reinforced ferrocement were investigated in this paper through direct tensile test and four-point bending test. Different volume fractions of steel fiber, polypropylene fiber and steel wire mesh were considered. A total of 42 tensile and bending specimens were tested. Experimental results showed that, compared to plain ferrocement, the cracking tensile strength and the ultimate tensile strength of steel-polypropylene hybrid fiber reinforced ferrocement with 0.5% volume fractions of steel fiber and 1.0% volume fractions of polypropylene fiber increased by 9% and 15% , and the cracking moment and the ultimate moment also increased by 29% and 52%. It can be concluded that this mix ratio had best effect on the mechanical property of ferrocement.

Abstract: Textile reinforced concrete (TRC) allows the light weight structures and offers a high effectiveness of the reinforcement by using continuous yarns. The study on the bond behavior between textile and concrete matrix is significant for the development of computational methods that analyze the textile reinforced concrete. The paper analyzes the bonding constitutive model of TRC and the bonding mechanism that the stress is transferred from fine concrete to textile, pointing out quadruple linear model can accurately reflect the bond behavior between fiber and concrete, illustrates the main influences on bond between the fine grained matrix and fabrics based on the pull-out test, the result reveals that with initial bond length increasing, the maximum pull force increases, and increasing concrete strength and improving workability of concrete matrix, epoxy resin impregnating and sand covering of textile as well as prestressing textile can increase the bond strength between textile and concrete. Finally the paper proposes that epoxy resin impregnating and 0.15 ~ 0.30mm sand covering of textile can be used as a practical method of improving bond properties in the engineering.