Advanced Materials Research Vol. 857

Abstract: In order to investigate the activity of different original slags and the coupled relation between the slag and the clinker, the simplified slag cement system was designed in the experiment, in which clinker was replaced by lime.The reactional degree of slag in cement was determined through using chemical combined water content method, and the hydration processs were determined through using DSC-TGA. The results showed that for the different original slags, the destruction and rebuilding process of their microstructure were important to distinguish the activity of slags. And the process of slag hydration mainly experienced two stages, including microstructure destruction at early ages and microstucture rebuilding at later ages. And the variation of Calcium hydroxide content in cement indicated the interaction between the slag and clinker, and slag may improve the clinker hydration velocity.

Abstract: To study the effect of different dosage of recycled asphalt mixture particles on the performance of concrete, the mechanical characteristics, shrinkage performance and durability testing were performed, the results show that the compressive strength and flexural strength of concrete are decreased with the increase of dosage recycled asphalt mixture particles, while still meet the regulatory requirements; the capability of plastic shrinkage resistance can be improved by incorporated recycled asphalt mixture fine particles, yet slight effective on the temperature shrinkage; the durability of concrete changes as a result of incorporation of recycled asphalt mixture fine particles, the durability of concrete with a dosage of 20% is considered in the optimal state, so the recommended dosage is 20%.

Abstract: This paper presents some research results on the durability of magnesium phosphate cement-based material, such as strength, coefficient of thermal expansion, drying shrinkage, corrosion protection, deicer-frost resistance, abrasive resistance and strength loss while soaking in water or 3%NaCl solution. Experimental results indicate that MPB materials possess high deicer-frost resistance, high abrasion resistance and high corrosion protection for reinforcing steel. In addition, the MPB materials have good compatibility and bond with old concrete, and very low drying shrinkage. However, for the MPB materials soaked in water or 3% NaCl solution for a long time, the strength loss occurs. Laboratory and field studies show that the MPB materials are suitable for rapid repair of concrete structures, especially pavements, airport runways, bridge decks and key municipal roads, etc.

Abstract: Graded crushed aggregate mixture form internal friction resistance rely on the interlocking and friction effects between the particles ,with high shear strength and resistance to deformation, which is difficult to compacted. Through the analysis of factors affecting the compaction properties of materials,self-vibration phenomenon and resonance phenomenon,theoretical study on the effect of shear strength of the material vibration, the comparative experiments were conducted by heavy compaction instrument and vibration compaction instrument,accommodate compaction property of graded crushed aggregate,the test methods were obtained,also the test parameters were determined, and verified by experiment.

Abstract: The optimum overlay structure and the better regeneration of the old cement concrete pavement were analyzed by empirical method, which compared the merits and faults of crack-seat and rubblization with the better regeneration to the old cement concrete pavement, then the concept of hair-crack-rubblization (HCR) was put forward, specific parameter standard of HCR was calculated by mechanical method. According to the desired requirement of HCR the hair-crack-rubblization machine was produced by Xi’an Changda Highway Maintenance Technology Co., Ltd. After that concrete realizable control standards of HCR and the optimum overlay scheme were gotten by the construction condition, then the merits of high strength, stable plate, good water-resistant and so on after HCR of the old cement concrete pavement, which combines the merits of crack-seat and rubblization, were showed by the engineering application.

Abstract: This paper presents an experimental study on the permeability and the pore structure of lightweight concrete with fly ash, zeolite powder, or silica fume, in comparison to that of normal weight aggregate concrete. The results showed that the mineral admixtures can improve the anti-permeability performance of lightweight aggregate concrete, and mixed with compound mineral admixtures further more. The resistance to chloride-ion permeability of light weight concrete was higher than that of At the same strength grade, the anti-permeability performance of lightweight aggregate concrete is better than that of normal weight aggregate concrete. The anti-permeability performance of LC40 was similar to that of C60. Mineral admixtures can obviously improve the pore structure of lightweight aggregate concrete, the total porosity reduced while the pore size decreased.

Abstract: Air-entraining agent turely is one of the necessary compositions of the high durability concrete. The influence of air content and vibration time on the frost resistance of concrete was researched, and air void characteristics of hardened concrete was analysed. The results showed that the air contents could reduce the compressive strengthof hardened concrete excessively, but it made the spacing factor reduce obviously and significantly improve the frost resistance of concrete.The air voids with different structure in concrete were realized by vibration time. It was found that the air void structure and the frost resistance properties were influenced by the vibration time largely. The optimized vibration time is 30s, the appropriate vibration time is 20s~30s, no more than 35s.

Abstract: The purpose of this paper is to examine the effect of various polypropylene fibre additions (length and content) to concrete on compressive strength and explosive spalling when subjected to high temperatures, which simulate the building or tunnel fires. The experimental results show that the compressive strength of polypropylene fiber concrete (PFC) and plain concrete decreases with increasing temperature. Fibre content in a certain range has a small effect on the compressive strength of the concrete, therefore the polypropylene (PP) fibers has a great influence on the anti-spalling behavior of concrete under fire loading to ensure the integrity of the structure. Keywords: concrete, polypropylene fibre, high temperature, compressive strength, spalling

Abstract: Wax emulsion was modified by adding high polymer latex,in order to improve the film-forming ability and sealing ability of wax emulsion,and improve the brittleness of parafilm to prevent it from cracking. By orthogonal design experiment to analysis the dosage of various materials for curing compound,and based on effective water retention and concrete compressive strength ratio the two indicators to determine the optimal mixture ratio of curing compound.

Abstract: Calculate and analysis influence of the temperature field for Continuously Reinforced Concrete Pavement design. The temperature and crack of pavement are tested, so that the temperature changing and early cracks development inside the tunnel have been got. Studies have shown that: the tunnel temperature changes slowly, the temperature difference is small. In the first two days after concrete paving, the internal temperature of the slab was significantly higher than the ambient temperature, 79% of early cracking appears in this stages; Panel temperature rise because of the cement hydration. Strain increases in process of the growth of the concrete strength and shrinkage, the cracks appears. The number of cracks in the first two days accounted for 50% of the total number in 7 days, only the number of the second day accounted for 37.59%. Crack width accounted for 60.5% of the total, which is mainly concentrated in 0.1 mm and 0.2 mm. The crack spacing is mainly concentrated in 2m to 8m, accounted for 76.8% of all. The maximum crack spacing is 84 m, the minimum is only 0.5m.