Indirect tension test of epoxy asphalt mixtureusing microstructural finite-element model

A finite-element model of the thermosetting epoxy asphalt mixture（EAM） microstructure is developed to simulate the indirect tension test（IDT）.Image techniques are used to capture the EAM microstructure which is divided into two phases：aggregates and mastic.A viscoelastic constitutive relationship,which is obtained from the results of a creep test,is used to represent the mastic phase at intermittent temperatures.Model simulation results of the stiffness modulus in IDT compare favorably with experimental data.Different loading directions and velocities are employed in order to account for their influence on the modulus and the localized stress of the microstructure model.It is pointed out that the modulus is not consistent when the loading direction changes since the heterogeneous distribution of the mixture internal structure,and the loading velocity affects the localized stress as a result of the viscoelasticity of the mastic.The study results can provide a theoretical basis for the finite-element method,which can be extended to the numerical simulations of asphalt mixture micromechanical behavior.

公路大厚度水泥稳定碎石基层施工技术

结合某公路工程,对大厚度水泥稳定碎石基层施工技术加以分析。其中,大厚度水泥稳定碎石基层的主要施工工艺包括材料选择、配合比设计、测量放样、混合料拌和、混合料运输、混合料摊铺、混合料碾压、混合料养护等。为保证该公路大厚度水稳基层的施工质量,同时在施工结束后开展质量检测,旨在有效提升大厚度水泥稳定碎石基层的施工效果,供同类工程参考。

提高蒸压粉煤灰砖质量的工艺要素及操作

本文阐述了蒸压粉煤灰砖产品质量的重要性及生产优质墙材的必要性。对粉煤灰原料的选用、原料性能、原料配比、混合料处理、机械设备选用、坯体成型等生产工艺进行了分析。

New method to quantitatively evaluate the homogeneity of asphalt mixtures

To evaluate the homogeneity of asphalt mixtures,the images of sections obtained by cutting the asphalt mixtures specimen horizontally or vertically were analyzed with digital image processing techniques,and the particle area ratio was achieved by applying sector scan for horizontal specimen and vertical scan for vertical one.The research result indicates that the influence of random distribution of aggregates in cutting the specimen can be eliminated by using colored aggregates to distinguish coarse and fine aggregates and using color threshold to segment the images.Choosing three typical gradations,proving particle area ratio obeying normal distribution and using the variability of particle area ratio as an index,it is feasible to quantitatively evaluate the homogeneity of asphalt mixtures.

Optimization of Methane Production Based on Mixture Content of Sewage Sludge, Food Waste, and Glycerol

This paper presents bench scale experiments related to anaerobic co-digestion of aerobic sewage sludge from a pilot WWTP （waste water treatment plants）, raw glycerol from a biodiesel industry and food waste. Assays were conducted in 100 mL non-stirring penicillin vessels, at 30 ℃ and planned according to three optimization phases： （1） binary mixture of sewage sludge and FW （food waste）; （2） binary mixture of sewage sludge and glycerol; and （3） ternary mixture of sewage sludge, FW, and glycerol. In the first and second phases, the highest SMP （specific methane production） was achieved by 10% （v/v） FW and 0.5% （v/v） glycerol mixtures. The optimization of the ternary mixture during the third phase was reached by the combination of 10% （v/v） FW and 0.4% （v/v） glycerol. Despite the low SMP value, the addition of glycerol and FW contributed to doubling the SMP value of the sludge sample control.

Low temperature J-resistance curve determination of asphalt concrete using wavelet-Radon transform

A single specimen test using the three point single edge notched beam configuration at low temperatures for obtaining hot mix asphalt （HMA） resistance curves is developed.Resistance curves are obtained for mixtures at six temperature levels of＋5,0,-5,-10,-15,and-20 ℃ and three binder contents of 4％,4.5％,and 5％.Crack extension increments during the test are measured by means of an image processing technique using Radon transform and feature extraction.All the specimens exhibit a rising R-curve,indicating ductility and toughening mechanisms in the ductile-quasi brittle fracture of the mixture.It is observed that the reduction of temperature results in a further tendency of the mixture for unstable crack growth and less subcritical crack length.It is also shown that using the binarization process,an automatic index can be developed that can represent the extent of brittleness and extent of the low temperature in which the cracking has occurred.

Biological Protection against Fungal Diseases of Winter Wheat under Different Soil Tillage Technologies

The effect of biopreparations, homogenized with the seed （seed treatment before sowing as a dressing）, and used as a mixture with mineral fertilizer ANL （ammonium nitrate with limestone）, upon both grain production and the health state of the winter wheat were evaluated during 2006-2009. Besides conventional soil cultivation, reduced tillage with incorporated chopped straw, and direct drilling into untilled soil covered with mulch, were also used. The following biopreparations were applied： Supresivit （Trichoderma harzianum）, Polyversum （Pythium oligandrum）, and Trianum P （a different strain ofTrichoderma harzianum）. Attention was focused on the foliar fungi pathogens Drechslera tritici-repentis, Septoria tritici, and Alternaria triticina, as well as on the soil-borne pathogenic fungi of the genus Fusarium.

道路工程中沥青混凝土路面的摊铺施工技术与应用

为了探究出优化沥青混凝土路面摊铺施工效果的技术方法,现对道路工程中的沥青混凝土路面摊铺技术进行分析,总结摊铺施工技术应当关注的要点,并且以问题为导向探究优化路面摊铺效果的施工措施。最终得出的研究结论有:通过完善沥青混凝土路面摊铺的试验工作、混合料处理方法、混合料的摊铺与压实技术,能够使沥青混凝土路面的建设施工质量得到保障,优化沥青混凝土路面摊铺施工技术的应用效果。