Papers by Keyword: Aggregate Gradation

Abstract: With the implementation of the "One Belt, one Road" national strategy, the western region traffic can develop rapidly. This paper aims to improve the service performance in Inner Mongolia cold and heavy-load asphalt pavement through research. The mix design and performance verification of Zhuozi mountain mixture is the main line, in order to get a good fit to the local situation, and draw the key technical indicators of the design.

Abstract: In the rolling process, reasonable way of grading and rolling can improve the compactness and anti-permeability of roller compacted concrete (RCC), as well can make its strength meet the design requirements. Vibration liquefaction is the key step for RCC in the rolling process. Therefore, this paper first puts forward the more suitable method, Modified Vebe Vibration Liquefaction Test, to account for the characteristics of vibration liquefaction in RCC, and then, studies the coarse aggregate gradation scope using aggregate gradually filling theory. Though Modified Vebe Vibration Liquefaction Test, the research show that the aggregate VCA and the characteristics of vibration liquefaction of RCC have a good correlation. Finally, by studying the sand ratio and fineness modulus of sand how to affect the performance of liquefied RCC, the optimum value range of sand ratio and fineness modulus of sand was determined.

Abstract: California bearing ratio (CBR) test was carried out, CBR changing laws of different graded crushed rocks were analyzed, an aggregate gradation on the base of port was put forward, and its performances were verified through laboratory test. Test result shows that the main skeleton structure composed of the aggregate with diameter 19mm-4.75 mm has interlocked force, and the optimal mass fraction is 90%~65%. The aggregates with diameter 4.75mm-0.075mm have the effects of filling the void of main skeleton structure, whose optimal mass fraction is 10%-35%.And the optimal mass fraction of the aggregate with diameter 19mm-9.5 mm is 25%.When the optimum proportion of coarse aggregate to middle aggregate is 25:40, the CBR value of coarse-middle-fine combined aggregate reaches the highest point, and is more than 158.97%, and the ratio reached 377%. On this basis, the optimal aggregate gradation of graded broken stone is reference on design and construction of graded crushed rock on the base of port.

Abstract: The recycled asphalt mixture was analyzed by the microstructure, grading variability and agglomerate degree evaluation from the Guaxing road. The results showed that some aggregate was more in quantity and smaller in the variation for the 9.5mm to 0.6mm material of recycled aggregate; the fineness modulus ratio (FMR) was 0.89, so the agglomerate degree of recycled asphalt mixture is relatively small, which had a little effect on the strength of the cold recycled mixtures; the gradation and unconfined compressive strength test of cement stabilized wasted asphalt mixture were made at different blending ratios; the reasonable range of the cold recycled utilization was 20% to 40% for the recycled old materials in Guaxing road.

Abstract: The skeleton of concrete is determined by aggregate gradation. This paper studies the permeability and mechanical properties of pervious concrete affected by the aggregate gradation. Eight levels of aggregate gradation were selected, which included the single grain grading, double size grain grading and continuous grading. It is found that by series of tests, compared to the pervious concrete with the single grain grading and double size grain grading, the pervious concrete with continuous grading has low porosity, small permeability coefficient, high cubic compressive strength and similar splitting tensile strength and the flexural strength.

Abstract: The determination of appropriate pavement thickness using laboratory determined parameters is one of the key issues facing the road manager. Five different types of asphalt mixes were produced in laboratory to modify pavement performance mixture. The main objective of this study is to evaluate the characterization methods for fatigue performance of asphalt mixes to Western Australia road. In this study, laboratory test for indirect tensile modulus, dynamic creep, wheel tracking and aggregate gradation tests were taken to analyze each asphalt mixtures for a design traffic road. The results and analysis showed that AC20-75 asphalt mix blow is the most effective and efficient in pavement performance than the other asphalt mixes. AC14-75 was the second in rank to strengthen and durability of asphalt pavement. All asphalt mixes in this study can be used to strength and stable the overall stiffness of pavement, and modification rank can be described as AC20-75 Blow > AC14-75 Blow > AC14-50 Blow > AC7-50 Blow > SMA7-50 Blow in this research.

Abstract: In order to find out the influence of geometric characteristics, distribution and combination condition of mineral aggregates on mixture properties, the single and multi aggregates were built using finite element method and the mechanical properties of aggregates was discussed. Then comparison analysis was carried out for three representative asphalt mixture structures with different gradations. Finally the optimal gradation curve was obtained. Simulation results are as follows: extreme values or damage of stress was likely to emergence on the interface between mortar and aggregate; the impact on the equivalent stress of aggregate space in vertical direction is greater than in horizontal direction; in comparison with "framework-pore" structure, the "suspend-dense" structure and "framework-dense" structure had better shear resistance behavior and load-carrying capacity. The results shows that the macroscopical carrying capacity of asphalt mixtures was determined by the microcosmical mechanical properties of aggregates, and it was a new mehtod for researching mechanical behavior owing to internal nonuniformity of asphalt mixture in future.

Abstract: With good vibration alleviating properties, resin mineral composite (RMC) has been used to produce precision machine tool beds to satisfy the requirements of machining accuracy. Aggregate is one of the key components in RMC to bear loads, its gradation design determines the overall mechanical properties of the composite directly. In this article, an optimal method to determine critical dimension of screen holes is proposed based on Euclidean geometry and Particle interference theory, and the corresponding proportion of each component is adjusted on the basis of fractal theory. Variation tendency of porosity corresponding to different fractal dimension is obtained by using simulation method. On this basis, image processing technology is used to validate the aforementioned assumptions. Experimental results show that the optimal design has smaller porosity performance, which is consistent with the simulation results.

Abstract: Concrete permeability is one of the key properties of concrete which largely effects concrete durability. Conventionally concrete permeability is considered as a function of water to cementitious materials ratio. But aggregate being the major constituent of concrete, was found to have considerable effects on various properties of concrete. In this research the effects of aggregate gradation on concrete permeability have been examined for two different types of cement. Total twenty concrete mixes were prepared using two different types of aggregate gradations, CEM I and CEM II/B-M cements. Concrete permeability measured in terms of depth of water penetration under pressure as per the standard EN12390-8. It has been found that concrete mixtures having same w/c ratio and keeping all other properties same, may have different permeability only because of different aggregate gradation. This article also features the use of concrete compressive strength as an alternative parameter for controlling concrete permeability based on the test results.

Abstract: The influence of the accumulated structure formed by the aggregate particles on permeability and strength of permeable concrete was investigated by three-dimensional geometry method, which was proved by theoretical analysis and experimental study. In theoretical analysis, the accumulation structure of the aggregate was in a steady or quasi-steady state, particle size distribution was optimized to obtain the desired permeability coefficient and sufficient strength. The results showed that it is more appropriate that the ratio of the secondary particle size is 0.2d - 0.4d when the large particle size is d. To obtain good permeability in experimental study, the large voids have a large proportion in all kinds of voids statistics distribution of aggregate accumulation of structure in pervious concrete. The percentage of fine particles needs to be controlled to achieve the desired permeability and concrete strength.