欧洲沥青混凝土路面的施工方法

本文介绍了德国粗细骨料的控制，填加的矿物填料和各种填加物，以及这些材料在分批投配设备中的配混，还介绍了这些混合料的摊铺和碾压。

Recycling of industrial waste and performance of steel slag green concrete

Workability and mechanical properties of steel slag green concrete with different types of steel slag and different dosages of admixtures were investigated. The effectiveness of steel slag powder on suppressing alkali aggregate reaction(AAR) expansion was assessed using the method of ASTM C441 and accelerated test method. Experimental results show that mechanical properties can be improved further due to the synergistic effect and mutual activation when compound mineral admixtures with steel slag powder and blast-furnace slag powder are mixed into concrete. In addition,about 50% decrease in expansion rate of mortar bars with mineral admixtures can be achieved in AAR tests. Mineral admixtures with steel slag powder as partial replacement for Portland cement in concrete is an effective means for controlling expansion due to AAR.

Influence of Recycled Construction Materials Aggregate on Mechanical and Physical Properties of Concrete

The main purpose of this research is to study the properties of re-use different types of construction materials such as PVC （polyvinylchloride） scraps, clay brick and recycled concrete as a partial replacement of coarse aggregate. Different proportions （1%, 3%, 5% and 7%） by weight were used for PVC. scrap, （10%, 20%, 30%, and 40%） by weight were used for recycled concrete and （5%, 10%, 15%, and 20%） by weight were used for clay brick. Mechanical tests such as compressive and tensile strength tests and physical tests such as ultrasonic pulse velocity, bulk density, porosity, specific gravity and water absorption tests were done to the samples after curing in normal water for 28 days. Test results showed slightly degradation in mechanical and physical engineering properties of concrete specimens that used partial replacement of recycled concrete coarse aggregate, degradation increased with increasing of replacement but test results still closely to reference samples. Use of polyvinyl chloride in proportions not more than 5% as a partial replacement of coarse aggregates given acceptable results in comparison with reference samples but all test results degraded at 7% replacements. Test results of partial replacement of crushed brick coarse aggregates unacceptable and the range of degradation are wide because of increased （water： cement） ratio to improve the concrete workability.

Alternative Method for Concrete Structures Compressive Strength Estimation with Small-Scale Destruction

To estimate a compressive strength from existing concrete structures by core drilling are usually gathered with a diameter specimen of 100 mm or three times of maximum coarse aggregate size and examined by uniaxial compressive strength （UCS）. It is relatively difficult to gather a large sized core, and a pit place will be limited by main members. To get an alternative solution with smaller specimen, point load test （PLT） has been sele,：ted which is a simple test and widely accepted in rock materials research, but relatively new in concrete. The reliability of PLT is evaluated by extracting a lot of core drilled specimen from ready mixed concrete blocks with maximum coarse aggregate size, G of 20 mm in representative of architectural structures and 40 mm in representative of civil structures on the range of concrete grade from 16 to 50. Compressive strengths were classified into general categories, conversion factors were determined, and scattering characteristics were also investigated. The relationship between point load index （Is） and compressive strength of concrete core specimen （fcc） can be written as linear approximation as fcc = k.Is- C.

Bond Strength of Bamboo Reinforcement in Light Weight Concrete

Bamboo reinforced concrete as a building material is expected to be an alternative to steel reinforced concrete. Due to the fact that steel is not renewable and polluting steel mills are fairly high. The bond strength is a major concern for the natural fiber used as reinforcement in structural composites. This paper reports study on the bond strength of bamboo reinforcement in concrete, to determine the adhesion reinforcement in concrete often do by the pull-out test. The research objective was bond strength of lightweight concrete and bamboo reinforcement. The test used light weight concrete with foam additives klerak. Bamboo slats were coated with paint and sprinkled with sand. The results obtained showed that the bond strength bamboo 60% of the bond strength steel.

Test and prediction of chloride diffusion in recycled aggregate concrete

Recycled aggregate concrete （RAC） specimens with different recycled zoarse aggregate replacement ratios by mass （R） are fully immersed in a 10% chloride solution for 235 days. Both free chloride concentration （CI） and total chloride concentration （Ct） are then measured employing a rapid chloride test （RCT） system. The Fick＇s second diffusion law is verified by the test data and used to predict chloride concentration distribution at different immersion periods. Addilionally, pore structures of the new and old mortar in RAC are tested by mercury intrusion porosimetrV （MIP）. It is found that bind- ing chloride concentration （Cb） linearly increases with Cf. In natural aggregate concrete （NAC）, Cf is obviously smaller than that in the RAC in the same testing environment and this is different from the test results of Ct and Cb. Furthermore, the effects of R on the chloride concentration of RAC become severe for specimens subjected to long immersion periods, which can be explained in terms of the pore structures of the new mortar and old adhesive mortar in RAC.

Biomechanical researches on tissue engineering bone constructed by deproteinated bone

Objective： To study biomechanical changes of newly formed bones 24 weeks after repairing large defects of long bones of goats using heterogeneous deproteinated bone （DPB） prepared by modified methods as an engineering scaffold. Methods： According to a fully randomized design, 18 goats were evenly divided into three groups： normal bone control group （Group A）, autologous bone group （Group B） and experimental group （Group C）. Each goat in Groups B and C were subjected to the periosteum and bone defect at middle-lower part of the right tibia （20% of the whole tibia in length）, followed by autologous bone or DPB plus autolognus MSCs ＋ rhBMP2 implantation, respectively and semi- ring slot fixation; while goats in Group A did not perform osteotomy. At 24 weeks after surgery, biomechanical tests were carried out on the tibias. Results： At 24 weeks after surgery, the results of anticompression test on tibias in three groups were recorded by a functional recorder presented as linear pressure-deformation curve. The shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values were 10.74 MPa±1.23 MPa, 10. 11 MPa±1.35 MPa and 10.22 MPa±1.32 MPa and fracture compression rates were 26.82%±0.87%, 27.17%±0.75% and 28.22%±1.12% in Groups A, B and C, respectively. Comparisons of anti-compression ultimate pressures and fracture compression rates among three groups demonstrated no significant difference （PAB=0.415, PBC=0.494）. Three-point antibend test on tibias was recorded as load-deformation curves, and the shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values of the anti-bend test were 481.52 N±12.45 N, 478.34 N±14.68 N and 475.62 N±13.41 N and the fracture bend rates were 2.62 mm±0.12 mm, 2.61 mm±0.15 mm and 2.81 mm±0.13 mm in Groups A, B and C, respectively. There was no significant difference between groups （PAB=0.7, PBc=0.448）. The ultimate anti-torsion torque values were 6.55 N.mi-0.25 N.m, 6.34 N＇m^0.18 N＇m and 6.42 N＇m^0.21 N＇m and fracture torsion rates were 29.51°±1.64°, 28.88±1.46° and 28.81°±1.33° in Groups A, B and C, respectively. There was no significant difference between groups （PAB=0.123, PBc=0.346）. Conclusions： The biomechanical characteristics of newly formed bones from heterogeneous DPB for repairing large segmental long bone defect are comparable to those of normal bones and autologous bones. DPB has the potential for clinical usage as bone graft material.