Advanced Materials Research Vols. 652-654

Abstract: Absorption of water in concrete is often described by simple linear water uptake vs. square-root-of-time law. This model based on the classical capillary model derived from the Hagen-Poiseuille’ flow which travel on a single pipe dimension. However, in cement-like material concrete, the pore structure is complex, including for example, variable pore radius and complicated topological changes. In this work, an analytical velocity model of Hagen Poiseuille’s flow on a pipe with multiply sizes is constructed. This model takes the pipe geometry as described by two sets of parameters α_i and β_i;i=1,2…,N into account. In addition, a numerical study of other flow models using Navier Stokes and Stokes models has been conducted. The analytical model is in good agreement with the numerical models at a series of different pipe geometry sizes.

Abstract: Lightweight aggregate concrete with bleed air : the air-entraining agent added to the lightweight aggregate concrete , cement paste to form the porous structure of the porous structure of the right amount of artificial lightweight aggregate concrete . Reduce the density of the concrete to improve the insulation properties of the concrete . Applied to structural insulation concrete strength than 20Mpa, the thermal conductivity is less than 0.36W / ( m • K) . Of lightweight aggregate structure insulation concrete materials properties and microstructure of variation with air entraining agent .

Abstract: It was proceeded to the specimen without load in the former research of FRP constraint concrete. And this was not conformed to the reality of unload of the structure member when reinforcing. So that, this paper carried on the test research of BFRP constraint concrete square column. During the test, the deformation and the load random were recorded. Disposing the data, many stress-strain curves were plotted. Analyzing the curves, it was found that: BFRP can enhance the concrete obviously. At the same time, the effect of axial compression ratio preloaded to reinforcement was analyzed in the paper.

Abstract: Using self-designed indoor detecting methods, the performance test of shotcrete doped compound admixture and crude fiber were carried out. The results showed that compound admixture and crude fiber can improve the compressive strength, flexural toughness and crack resistance of shotcrete. Axial bond strengths of shotcrete with rock were more than 1.0MPa, and that can be increased by combined-doped compound admixture and crude fiber. Rebound rates of shotcrete were 23% and 20%, layer thickness in one shot cycle were 22cm and 25cm, and combined-doped compound admixture and fiber can increase the cohesiveness and reduce rebound rate. Self-designed methods can be used to compare construction performance of different shotcretes.

Abstract: According to Superpave mix design method, a thermosetting material (Epoxy Asphalt mixture) was designed for surfacing on orthotropic steel deck bridge. Firstly, based on the thermosetting feature, the viscosity increasing law of EA binder was studied by Brookfield test. Then, some characteristic indexes of EA mixture, such as the prior mixing time and the reserved time, were determined according to the viscosity increasing law and recommended viscosity range for mixing and compaction. Finally, using these characteristic indexes, an EA mixture with 3.0% air voids was designed by volumetric mixture design procedure of Superpave method. The results show: 1) different from other asphalt mixtures, the characteristic indexes of end mixing time and reserved time should be applied in EA mixture design because of the thermosetting character of EA binder; 2) the EA mixture designed by Superpave method in this paper has a higher EA binder content than that designed by conventional Marshall method.

Abstract: Influences of moisture content and loading rate on flexural toughness were experimentally studied for fiber reinforced shotcrete (FRSC) with steel fiber or macro synthetic polypropylene fiber. According to the four-point bending test method specified in ASTM C1609 and Chinese standard CECS 13, the flexural toughness of specimens after drying for 0h, 16h, 24h and 72h in condition of (20±2)°C and (60±5)% relative humidity was tested at a loading rate of 0.05 mm/min. For specimens after drying for 24h and 72h, flexural toughness was tested at loading rates of 0.05 mm/min, 0.10 mm/min, and 0.20 mm/min respectively. With the moisture content decreasing, the flexural toughness T100,2.0, first-peak flexural strength, and residual flexural strength at prescribed deflections of FRSC exhibited decreasing tendency. The specimens with 0.5 vol% of steel fiber showed higher T100,2.0 value than that with 0.9 vol% of macro synthetic fiber. The residual strength and flexural toughness of FRSC increased with the increase of loading rate.

Abstract: Through a large number of laboratory tests，authors study the preparation technology of exposed-aggregate cement concrete pavement, such as the spraying time, spraying dose of exposed-aggregate agent and the flush time. According to the tests results, the spraying time of exposed-aggregate cement concrete declines constantly with the increase of temperature and the appropriate spraying dose of exposed-aggregate agent is determined. The higher the temperature the earlier the flush time. There is a bigger time interval, more than 10h for normal temperature between the earliest and latest flush time.

Abstract: The cracking bending strength for steel-polypropylene hybrid fiber reinforced concrete (HFRC) had been studied based on experimental test. the inicial cracking strength achieve significant improvement compare to plain concrete, and the highest increase is 16.7%. There is a synergistic effect exist when steel fiber is 1.0% in volume or polypropylene fiber is 0.1% in volume, and the synergistic effect raise to vertex (1.043) when both of those two requirements are fulfilled.

Abstract: Sugarcane bagasse ash (ScBA) obtained as a byproduct of sugar processing may be used as a raw material for producing autoclaved lightweight concrete (ALC). We examined the chemical composition and physical properties of ScBA and determined that the material is not hazardous as defined by the Thai Ministry of Industry. The optimal production conditions for ScBA-containing ALC were a cement/sand ratio of 65/36, a water/total composition ratio of 0.24, and a curing time of 16 h. Maximum compressive strength was obtained in samples containing 20 wt% ScBA.

Abstract: Cement clinker was produced in laboratory using the same ingredient as actual production, comparing with the ones which incineration residue of glyphosate waste mother-liquor was added in. The products were characterized by XRD, and the results showed that the main constituents were not changed. And some of the main performances were tested according to GB standards. After the residue was added in, the water requirement of normal consistency remained no change as 26%; the setting time, both initial set and final set, was extended; the soundness was improved a little. And it could be inferred that within a certain range, the more the residue added in, the longer the setting time was, the better the soundness was. According to all the results, using rotary kiln to dispose the waste mother-liquor was feasible in the actual production.