Advanced Materials Research Vols. 255-260

Abstract: Compound crumb rubber modified asphalt (CCRMA) is a kind of compound modified asphalt. It is made from putting granulated crumb rubber (GCR) crashed from scrap tires and SBS modifier into matrix asphalt, though shearing by high speed shearing machine and growthing. It has good low temperature crack-resistant attributes, and better preventing high temperature distortion as well. The application of abandoned rubber tire is significant to cutting down on pollution,developing circular economy and protecting the environment. The microstructure of matrix asphalt and CCRMA is observed by SEM. Based on the results of temperature sweep test for CCRMA and uniaxial compression creep test for CCRMA mixture, the high-temperature characteristic of compound modified asphalt and mixture is studied. It is observed that, CCRMA has preferable anti-permanent deformation performance. CCRMA mixture has perferable anti-high temperature deformation performation. In the meantime, the viscous-elastic parameters of CCRMA mixture is obtained by fitting experimental data, it provides a referance for viscoelastic mechanics analyze of bituminous pavement.

Abstract: In order to analyze the changes of joint opening displacement(JOD) for cement concrete pavement under different road structures and material parameters, the joint model is derived and presented. The model takes into account conservation of various factors, the results have shown that JOD is significantly effected by temperature gradient, base modulus, slab length and slab thickness, and then the formula of joint changes have been set up with the consideration of four main factors. According to theoretical results, three different base types about lean concrete, cement stabilized macadam and graded broken stone have on-site observation of JOD for one year in Guangxi, and the above formula is verified, which provides the potential for the joint design and selecting the joint filler.

Abstract: The evaluation of airport pavement service performance plays an important role in pavement maintenance, rehabilitation and overlay. A systematic pavement performance evaluation model was established using the Fuzzy Complex Matter Element and combination weights. Firstly, the indices for evaluation such as Pavement Condition Index, Friction Coefficient, roughness performance and Bearing Capability were chose to evaluat the airport pavement service performance. Secondly, the synthesis weight of each evaluation index was determined using Entropy Method and Analytic Hierarchy Process Method. Finally, the relevancy degree fuzzy complex matter element was determined, and the degree of the airport pavement service performance can be determined according to the largest relevancy degree principle. This evaluation method has a broader applicable scope, because it is not only capable in considering subjective factors based on experts and experience, but also capable in considering the precision of objective information from the actual measuring reasonably. Finally, three regions of an airport pavement are evaluated by this method, and the evaluation results agree well with the actual pavement condition.

Abstract: According to preparation of noise-reducing concrete with the technology of exposed-aggregate, this paper exploits high performance roller compacted concrete used in tunnels. Based on optimizing proportion, exploiting special exposed-aggregate agent and corollary technology, it is necessary that the high strengthening and the stability in the Course of Using of the exposed-aggregate roller compacted concrete should be further studied. During the study on the properties of strength change of common strength grade exposed-aggregate roller compacted concrete pavement, it found that its strength varied from 38.6MPa to 19.2MPa when the depth of exposed-aggregate reached 3mm.This is the main reason that serious damage occurred in one tunnel pavement which is used less than one year. Consequently, this paper carried out experimental study of high strengthening. Furthermore, this paper have been optimized the parameters of exposed-aggregate roller compacted concrete. And the effect is relatively remarkable.

Abstract: Usually resistant to salt water corrosion of concrete prepared with fly ash and slag grinding fine admixture, however, such mixed concrete frost resistance is bad, resistant to seawater freeze-thaw performance is worse, usually with higher air-entraining, can overcome the defects. In the project, even if the liquidity of concrete is very good, the difference in bubble size and its distribution is very complicated. In order to prepare the concrete with high resistant to seawater freezing-thawing and corrosion, this paper studied on the relationship of the high air content of concrete with high resistance to sea water freezing-thawing and chloride ion diffusion coefficient. It was found that concrete air content, bubble fractal dimension and electric flux has good correlation, concrete anti-chloride ion diffusion ability can introduce bubbles cluster fractal dimension and bubbles distribution fractal dimension to characterization. With the increase of fractal dimension, the concrete resistance to chloride ion diffusion capacity enhanced. the complexity of the bubble was reflected from the bubble distribution fractal dimension, which objectively describes the gradation of bubbles, bubbles gradation improved greatly improve the concrete anti-chloride ion diffusion capacity.

Abstract: How to prevent and delay the emergence of reflective cracks effectively is a most important task for road researchers to the asphalt mixture overlaid on the old cement concrete pavement. Several methods preventing reflective cracks prevention have been used before, but few are satisfied. In this paper Sampave is put forward as a new method or structure which is better than the others. Base on principle of reflective cracks, a new layer named Sampave was put forward. And this paper discusses its aspaht, gradation and performance. According to the requirement reasonable gradation is suggested for practice. By means of researching on materials performance in the lab, it is obviously that Sampave has good performance at low temperature. Results of bending and creep test indicate that Sampave has good ability in resisting deformation. Meanwhile the result of fatigue test indicates that the fatigue life of Sampave is more than 210 thousand, therefore it has good performance in anti-cracking, and also the results of application in the project show its advantages in resisting reflective cracks.

Abstract: Making reference to the process of cement concrete pavement evaluation about current design, construction quality examination，highway maintenance management code, this paper builds up a hierarchy process and fuzzy evaluation model about the cement concrete pavement on the basis of the fuzzy mathematics theory, and confirms the weight of every process by the analytic hierarchy process, trying to elicit the import of each index, and sets up an evaluation system of the cement concrete pavement.

Abstract: The seepage field of tailings pond is analyzed. Based on the result distribution of hydraulic head and velocity in the dam body, seismic analysis is carried out for the tailings pond in steady flow state. Three seismic waves are input and the safety factors of dam under seismic action are also achieved. The results show that the safety factor will decrease 9%~16% with the seismic intensity increase one degree.

Abstract: Fatigue performance of asphalt layer was studied by ALF full scale accelerated loading test. Fatigue performance characteristic of ALF test road was analyzed during accelerated loading. The relationship of road performance index of test period and accelerated loading times was established. Asphalt mixture laboratory four-point flexure beam fatigue test was processed by controlled strain mode. The relationship of field ALF test sections and laboratory fatigue test were built; the fatigue life of asphalt layer predicted methods were proposed.

Abstract: 3-D permeability model is set up through image analysis of porous asphalt mixture sample slice by cosmos image technique on the basis of 2-D permeability model of porous asphalt mixture. The result shows that the numerical simulation permeability outcome is consistent with the indoor permeability test outcome. The model can simulate any maximum congregate diameter in different water surface level and the permeability coefficient of any open-graded porous asphalt mixture. The model offers an effective method for the designing of the porous asphalt mixture.