Advanced Materials Research Vols. 194-196

Abstract: The interfacial properties of reactive powder concretes (RPCs), other known as ultra-high performance concrete (UHPC), containing steel slag powder and ultra fine fly ash are studied in this paper. The microstrctural characterization of interfacial transition zones (ITZs), including the aggregate-cement paste interfacial zone and the steel fiber-paste interfacial zone, is investigated by SEM. The microhardness of the aggregate-paste ITZ and the steel slag-paste ITZ is studied and the bond strength of steel fiber in matrix is tested through fiber pullout tests. The results indicate that the microhardness of the steel slag-paste ITZ is slightly higher than that of the aggregate-paste ITZ, which implies the advantage of the substitution of quartz powder with steel slag powder in preparation of RPCs to some degrees. Moreover, the hardness of these two ITZs is higher than that of the hardened paste. A certain amount of hydration products has been observed exsiting on the surface of steel fiber by SEM and the bond strength of steel fiber-martix is up to 9.3MPa. These interfical properties are definitely critical to obtain high performance of UHPCs containing steel slag powder and fly ash.

Abstract: A compatilizer PP-g-Vi-PDMS for PP/RTV blends was prepared through a melt extrusion-grafting method. The tentative mechanism of the enhanced compatibility effect was discussed. The interfacial tension of PP/RTV blends was calculated based on contact angle method. The results indicated the grafting reaction between PP and Vi-PDMS, which was demonstrated by both the decreasing melt flow rates with increasing Vi-PDMS contents and the appearing of IR peaks at 1260cm^-1、1100~1000cm^-1、800cm^-1 ascribed to Vi-PDMS′s characteristic IR absorption. The compatilizer significantly decreased the interfacial tension of PP/RTV blends. The compatibility of PP/RTV blends was improved successfully using the compatilizer PP-g-Vi-PDMS.

Abstract: Carbon in wood accounted for 50% of oven dry weight, and wood construction architecture consumes less energy than any other material architecture. Through using drying of wood, fire-retardant, wood preservative and other protective treatment for the materials of wood construction architecture can extend service life of wood construction architecture and increase carbon storage. This article based on the processing characteristics of wood, estimated carbon storage and carbon emissions of the wood construction architecture, conclude that wood construction architecture has significant influence on the greenhouse effect and the recycling of carbon sequestration.

Abstract: This paper presents a numerical strategy for realistic modelling of the internal material configuration and cracking of concrete on mesoscale. Polyhedron shapes resembling crushed rocks are adopted to represent the aggregate. A packing approach in which the particles are heaped up layer by layer is proposed for 3-D condition. A cubic representative volume element (RVE) is generated using the method. The cohesive approach, in which zero thickness cohesive elements are inserted into the ordinary finite element mesh along the potential cracking path, is adopted to model the cracking developing process. The cracking behaviours of created RVE under uniaxial tension are well simulated using the current approach.

Abstract: The transient temperature field and thermal creep surrounding concrete are analyzed with a three-dimensional FEM model that simulates the construction process of spiral case, based on program development of ABAQUS. The effect of hydration and cooling pipes on temperature is studied. The comparison of temperature difference in schemes is performed, and then the reasonable construction scheme has been defined. The distribution of thermal creep stress with construction is given. It is concluded that the control measures is effective to temperature crack prevention.

Abstract: With the unilateral extending test on 4 teams*12 aluminum alloy round pipes, compressing test on 4 teams*4 pipes and repeating extending/compressing test on 4 teams*4 pipes, get the stress-strain relationship of the aluminum alloy round pipe, and get the elastic modulus f_0.1 and f_0.2. At the same time, get the conclusion that the damaging type is brittleness. The test result is the foundation for follow-up studies on the loading capacity of the aluminum alloys.

Abstract: The liquid soil stabilizer technology is a chemically modified method that can stabilize or reinforce those soils with weak engineering properties. In this paper, two typical high liquid limit soils ，which can not be directly used as subgrade materials，were treated with a new soil stabilizer and it were processed that serials of comparison test on the main engineer properties of soil that pre-and post-treated with soil stabilizer. Then the results show that the soil liquid stabilizer is effective to improve strength and moisture susceptibility for two selected soils. The liquid soil stabilizer technology opened up a new approach for soil improvement and ground treatment.

Abstract: Fiber reinforced polymer (FRP) bars are being used as an alternative to steel bars to overcome the corrosion problem. Design criteria and methods have to be reinterpreted for its different properties, and several countries have already established corresponding design codes. The method for predicting crack widths of concrete beams with FRP bars provided in ACI440 is based on the method for that with steel bars. Similarly, a modified method based on GB50010 is proposed in this paper to estimate crack widths of concrete beams with FRP bars. Furthermore, the new method together with ACI440 and GB50010 ones are verified by nine test beams in three existing experiments and most of them show a good agreement with the experimental data. Simultaneously, the new method also proves precise and accurate with the same level as the ACI440 one and indicates its potential to estimate crack width in Chinese concrete code system.

Abstract: In order to study on the influence of chloride ion on pavement performance of base material with fly-ash-flushed-by-seawater and the feasibility of fly-ash-flushed-by-seawater material used to road construction, the analysis and evaluation on the influence of chloride salt content on pavement performance of material base course are obtained through the laboratory test on pavement performance of base course with adding different content of chloride salt. The study shows that the chloride salt content in fly-ash-flushed-by-seawater influences slightly on the early strength of base course and even plays a function of early strength agent; the chloride salt content in fly-ash-flushed-by-seawater has an inhibiting effect on the growth of strength when it is more than 1.3%; the dry shrinkage coefficient increases with the aggrandizement of chloride salt content and the anti-erosion performance of material is sensitive to the chloride salt content, but temperature shrinkage coefficient and anti-freeze performance are slightly influenced by it. Fly-ash-flushed-by-seawater used to base course construction is feasible because the pavement performance of fly-ash-flushed-by-seawater base material satisfies the request of Specifications for Design of Highway Asphalt Pavement JTG D50-2006.

Abstract: 24 100mm × 100mm × 300mm recycled concrete prisms and 96 150mm × 150mm × 150mm cubes are completed in this paper.The relationships of the carbonation depth in each carbonation age with replacement rate of recycled coarse aggregate and fly ash is studied; The SEM is used to observe the interface structure of recycled coarse aggregate concrete and compared with ordinary concrete, and finally,a recycled concrete carbonation model is proposed. The results showed that: the substitution of recycled coarse aggregate and fly ash cut down the recycled concrete carbonation resistance significantly, which are related with the replacement rate; the content of Ca(OH)2 in the recycled aggregate concrete decreased ,also there are obvious interface transition zone between the recycled coarse aggregate and the new cement;obvious cracks and large voids are exist before the recycled aggregate concrete is loaded, which lead directly to lower carbonation resistance of the recycled concrete.