Data quality and uncertainty assessment methodology for pavement LCA

In performing pavement life cycle assessment (LCA), users are facing various reports of energy intensity coefficient (EIC) of pavement materials which differ considerably among data sources and therefore alter the LCA results significantly. Instead of selecting a certain EIC without or of little explanation for the current pavement LCA practices, this study proposed a methodology to build probability density function (PDF) for EIC based on available data-set and their qualities. Each data was first evaluated about the data quality indicator (DQI) through data quality pedigree matrix and converted to PDF in modified Beta distribution form. Three weighting methods, the DQI one, coefficient of variation (COV) one and analytical hierarchy process (AHP) one, were developed to assign weightings for different data. Monte Carlo simulation was run with the weighted PDF of each data as input to obtain the ultimate PDF for EIC. A case study to estimate the bitumen’s EIC with eight data samples were performed using the proposed methodology. It is found (1): the estimates by the proposed methodology is of higher reliability (lower COV) compared to any single data due to utilisation of information of the overall data samples; (2) the AHP weighting method is most favoured despite the results of the three weighting methods are close; (3) the central estimates of bitumen’s EIC are between5.4~5.8 MJ/kg. The proposed methodology is helpful in aiding calculating EICs for pavement materials and capturing uncertainties in LCA results in a statistical sense.     

The effects of porosity,asphalt content and fiberglass incorporation on the tensile strength and resilient modulus of asphalt concrete blends

Asphalt concrete is the prevailing material used for road surface construction. Its adequate characteristics in providing stability, durability and driving safety are controlled by complex interactions between its components. Thus, it is important to estimate the sensitivity of asphalt concrete mechanical properties as a function of its volumetrics. For this study, different combinations between asphalt content (3.5, 5 and 7.5%) and porosity values (above 4%) were used in order to disassociate these properties. The influence of mixing in fiberglass (0.5%) was also analyzed. It was found that porosity is significantly more relevant than the asphalt content in the prediction of tensile strength and resilient modulus of fiber-free asphalt concretes. In fiber-reinforced mixtures, the mechanical properties are improved by increasing the asphalt content, which suggests a better bonding between fibers and aggregates. For both cases, decreasing porosity is beneficial. By grouping both sets of results, it was possible to create a unique theoretical curve for both the tensile strength (q_t) and the resilient modulus (RM). The RM/q_t ratio was 5800 for the fiber-free group, and 3900 for the fiber-reinforced group - suggesting a better fatigue life indicator for asphalt concretes when fibers are added.     

TRIZ创新方法剖析路面渗水仪底座和路面的密封性能

针对路面渗水仪底座和路面的密封性能不良问题，运用TRIZ创新方法的因果链、技术矛盾、物理矛盾、进化分析等工具找到原因，获得解决方案。通过调研及试用，不断优化及调整所选方案，达到最优解决效果。应用效果证明TRIZ理论有助于创新并快速解决工程实际问题。     

Verification of the new viscoelastic method of thermal stress calculation in asphalt layers of pavements

The new viscoelastic method of thermal stress calculations in asphalt layers has been developed and published recently by the author. This paper presents verification of this method. The verification is based on the comparison of the results of calculations with results of testing of thermal stresses in Thermal Stress Restrained Specimen Test. The calculations of thermal stresses according to the new method were based on rheological parameters of the Burgers model. The parameters were measured in laboratory at different low temperatures, at long time creep under constant loading. Five asphalt mixes were tested. Three of them were high modulus asphalt concretes and two conventional asphalt concretes. Specimens were prepared in exactly the same way both for rheological creep tests and for the Thermal Stress Restrained Specimen Test. The results of measured thermal stresses were compared with thermal stresses calculated from the new viscoelastic method developed by the author and in most cases a good agreement was found. For comparison, the measured stresses were compared with results of calculations according to the existing methods. The viscoelastic Monismith method failed in prediction of thermal stresses. The prediction from the quasi-elastic Hills and Brien method was underestimated, but better than from the Monismith method and worse than from the new viscoelastic method. The reasons of discrepancies were discussed.     

浅谈彩色沥青混凝土在路面工程中的使用

公路建设不断发展，对公路的要求越来越高。彩色沥青混凝土有多种特殊用途，被广泛应用和普及。本文就彩色沥青混凝土的应用进行了分析研究。     

贵州省干线公路沥青路面典型病害研究

"十二五"期间,随着贵州省交通建设的飞速发展,干线公路的里程及施工质量也迅速提高。但同时,干线公路沥青路面出现了许多早期病害,并且病害种类也更加多样化。本文对贵州省9个地市的干线公路沥青路面进行了系统调查,并就路面典型病害的成因进行了分析。     

抗凝冰乳化沥青涂层的性能研究

为了研究自制融雪剂对抗凝冰乳化沥青涂层性能的影响,将自制固态型融雪剂按5%、10%、15%的比例加入乳化沥青制备涂层乳液,采用水煮法、摆式摩擦仪、电导率试验分别对涂层材料的粘附性、抗滑性能和抗凝冰性能进行了测试。结果表明:自制型融雪剂对乳化沥青与集料的粘附性影响不大;随着融雪剂掺配比例的增大,抗凝冰乳化沥青涂层的摩擦系数有所降低,但均满足规范要求;相比于普通沥青涂层,抗凝冰乳化沥青涂层的抗凝冰性能得到改善,且随着融雪剂掺配比例的增大,凝冰性能逐渐提高。     

脱硫胶粉在乳化改性沥青中的应用

考察了不同规格胶粉及不同脱硫程度的脱硫胶粉对橡胶改性乳化沥青性能的影响,结果表明,采用100目胶粉即可制备出橡胶改性乳化沥青,但乳化沥青的性能较差;采用活化度为50%左右的100目脱硫胶粉制备乳化沥青时,脱硫胶粉的用量相比于胶粉可大幅提高;在通过外掺100目50%左右活化度的脱硫胶粉(质量分数15%,以沥青计,下同)和质量分数2%的苯乙烯-丁二烯-苯乙烯嵌段共聚物改性的乳化沥青中添加质量分数1%的丁苯胶乳,所制备橡胶改性乳化沥青无筛上剩余物,5 d储存稳定性为2.9%,蒸发残留物的25℃针入度、软化点和5℃延度分别为55 (0.1 mm)、64.5℃和22.5 cm,能够满足乳化改性沥青的技术指标要求。     

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel-permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti-cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high-average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.     

Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked.