高速公路路面组成材料的研究

介绍了高速公路路面组成材料的研究情况，对沥青结合料、粗集料、细集料、填料、纤维稳定剂等各种材料逐一进行了论述，提出了各种材料对高速公路的影响。     

Experimental study of recycled asphalt mixtures with high percentages of reclaimed asphalt pavement (RAP)

This paper presents an experimental study to characterize the mechanical behaviour of bituminous mixtures containing high rates of reclaimed asphalt pavement (RAP). Two semi-dense mixtures of 12 and 20 mm maximum aggregate size and containing 40% and 60% RAP, respectively (S-12 and S-20, in accordance with Spanish specifications), which were used for rehabilitation of a highway section, were evaluated. First, the effect of RAP variability on the recycled mixtures was analyzed. Their mechanical properties were then studied by determining the stiffness modulus and indirect tensile strength and cracking and fatigue behaviour. Results show that high rates of recycled material can generally be incorporated into bituminous mixes by proper characterization and handling of RAP stockpiles.     

Statistical methods of aggregate durability evaluation

The advent of microcumputers and access to sophisticated statistical software packages allows the researcher unprecendented opportunities to evaluate his data. In aggregate research, it allows the comparison of basic aggregate properties with empirical tests often used in specifications of aggregate quality. Recent research by the author resulted in some thirty five test results (variables) for one hundred samples of aggregates used for concrete and bituminous mix applications in Ontario. The large amount of data invited statistical treatment. In addition to the usual univariate statistics such as mean, standard deviation, variance, linear regression and correlation, multivariate statistical techniques were used to study the inter-dependence of aggregate properties and tests. These included stepwise regression and factor analysis. The results indicate that some of the simpler properties of rock, such as specific gravity, absorption, adsorption abrasion, impact resistance, and freezing-thawing tests are interrelated, and can be used in empirical mathematical relationships to predict the behaviour of the aggregate in service. Other simulation tests, such as the sulphate soundness and Los Angeles abrasion tests routinely employed in North America bear no relationship to aggregate properties and should therefore be discontinued. The paper describes how the statistical techniques can improve the quality evaluation methods and criteria applied to aggregates anywhere in the world.     

浅谈改善沥青混合料高温性能的措施

从影响沥青混合料高温性能的因素，即材料，设计，施工入手，详细阐述了改善沥青混合料高温性能的有效措施，提出改善沥青混合料的高温性能提高路面的质量具有积极意义。     

Image analysis for detecting aggregate gradation in asphalt mixture from planar images

The mechanical properties of bituminous mixture strongly depend on the gradation of the aggregate that represents the mineral skeleton of the mixture, since for open and gap-graded mixtures, stresses due to vehicles in movement on the pavement are mainly transmitted through their contacts. Internal structure of bituminous mixture is, therefore, of great interest for road and infrastructure engineering and it is appropriate to study it with recently developed image analysis method. The purpose of this study was to finalize an effective analysis of asphalt section image for automatically extracting aggregate gradation without the need of separation of the bitumen from the aggregate. This paper proves that, thanks to the synergic use of different segmentation methods of the digital images taken on slices of cores from the pavement, it is possible to obtain a reliable gradation of the mineral skeleton of the mixture. The proposed methodology allows one to estimate the aggregate gradation that, otherwise, it would be necessary to establish via specially equipped laboratory, undertaking time-consuming tests that also imply health risks for the operators, due to the use of solvents and other hazardous materials.     

Reuse of sludge from the decorative quartz industry in hot bituminous mixes

The concept of sustainability has become crucial in today’s world. In fact, one of the major environmental priorities in scientific research is to discover innovative ways to recycle waste matter for its use in activities that benefit society. In the construction engineering sector, this trend has led to new techniques for recovering waste from industrial processes, and using it as a replacement for raw materials.The Construction Engineering Laboratory at the University of Granada carried out a research project to study the viability of using waste from the decorative quartz industry (sludge and chips from stone sheets) in the manufacture of bituminous mixes for road surfacing. This research study was performed in two phases. The first phase analyzed scraps and chips from stone sheets to see if they could be used to replace natural aggregate. The second phase focused on evaluating Silestone® sludge to see if it could be used as a substitute for the filler fraction in hot bituminous mixes. This paper presents the results obtained in this second phase in which different job-mix formulas were evaluated by varying their sludge content (0%, 60% and 100%). The properties of the various mixes were analyzed by subjecting them to a battery of mechanical tests that determined their susceptibility to moisture and resistance to rutting.The results obtained are eloquent proof of the viability of reusing Silestone® sludge as a replacement for conventional filler. This study showed that when performance of such mixes was tested, they amply fulfilled the standard technical requirements for roads in Spain. Furthermore, it was found that the job mixes with sludge had a significantly better performance than the standard F10 mix that did not contain it.     

粉胶比对沥青混合料高温稳定性的试验研究

通过试验对比分析了不同粉胶比的沥青胶浆软化点和针入度,以及沥青混合料的马歇尔试验指标和动稳定度。试验结果表明：粉胶比越大,沥青混合料高温稳定性越好。从提高沥青混合料高温稳定性角度出发,建议在进行沥青混合料配合比设计时,粉胶比宜控制在1.0～1.4之间。     

Mix design and performance analysis of asphalt concretes with electric arc furnace slag

The paper presents the results of a laboratory study, aimed at verifying the possibility to use two particular typologies of electric arc furnace (EAF) steel slags, in substitution of the natural aggregates, in the composition of wearing course asphalt concrete for flexible pavements. The experimental research has been articulated in a preliminary study of the chemical, leaching, physical, and mechanical properties of the EAF steel slag, and in the following mix design and performance characterisation of the bituminous conglomerates, through gyratory compaction tests, permanent deformations tests, Stiffness Modulus tests at various temperatures, fatigue tests and indirect tensile strength tests. All the mixtures with EAF slag have satisfied the requisites for acceptance in the road sector technical standards, thus resulting as suitable for use in the construction of road infrastructures, moreover presenting higher mechanical characteristics than those of the corresponding asphalts with full natural aggregate.     

Utilization of municipal solid waste incineration ash in stone mastic asphalt mixture: Pavement performance and environmental impact

The objective of this study is to the use of municipal solid waste incinerator (MSWI) fly ash as a partial replacement of fine aggregate or mineral filler in stone matrix asphalt (SMA) mixture. For saving natural rock and reusing solid waste, basic oxygen furnace slag (BOF slag) was used as part of coarse aggregate. And this makes SMA mixtures contain more than 90% solid waste materials by mass. A comparative study of the performance of two mixes designed using superior performance asphalt pavements (SUPERPAVE) and Marshall mix design procedures was carried out in this research. Samples from both mixes were prepared at the design asphalt contents and aggregate gradations and were subjected to a comprehensive mechanical evaluation testing. These tests included Marshall stability, water sensibility, resilient modulus, fatigue life and rutting. In all the performed tests SUPERPAVE mixtures proved their superiority over Marshall mixtures. TCLP test for environmental impact indicated that asphalt is an effective stabilization and solidification agent for heavy metal in MSWI ash. The heavy metal leachates in TCLP tests have great positive correlation with their initial concentration in waste. But Ni is an exception that lower initial concentration leaded to higher cumulative leaching rate.     

Linear viscoelastic behaviours of bituminous mixtures and fiberglass geogrids interfaces

One major research topic is to characterize the mechanical behaviour of actual reinforced pavement structures from laboratory experimentation and take it into account for the design. This investigation aims to verify the effect of fiberglass geogrid presence on interface linear viscoelastic (LVE) behaviour separately and as a system along with the bituminous mixture layers. To conduct the research, two different fiberglass geogrids, with ultimate tensile strength (UTS) of 100 and 50 kN/m, and tack coat made of straight-run bitumen and modified by polymer were combined for the fabrication of three reinforced configurations. In addition, two unreinforced configurations were also fabricated. The first was a single layer slab and the second was a double-layered slab composed of two bituminous mixtures (same type) bonded layers by a tack coat. Complex modulus tests were carried out in specimens cored in two different directions, vertically (V) and horizontally (H) cored. The experimental data were fitted using the 2 Springs, 2 Parabolic Elements and 1 Dashpot (2S2P1D) model. The test results showed that all interfaces’ complex modulus obtained for V specimens were LVE. Moreover, complex viscous properties of the interfaces were obtained from the used binder. The interface containing polymer modification presented the highest stiffness.     

The effects of using lime and styrene–butadiene–styrene on moisture sensitivity resistance of hot mix asphalt

This study focuses on determining the effects of styrene–butadiene–styrene (SBS) and using mineral filler with lime on various properties of hot mix asphalt especially moisture damage resistance. The asphalt cement was modified with 2%, 4% and 6% SBS. The lime treated mixtures containing 2% lime by weight of the total aggregate as filler. The physical and mechanical properties of polymer modified binder and binder–aggregate mixes were evaluated through their fundamental engineering properties such as dynamic shear rheometer (DSR), rotational viscosimeter (RV) for binders, Marshall stability, stiffness modulus, indirect tensile strength and moisture susceptibility for mixes. The retained Marshall stability (RMS) and tensile strength ratio (TSR) values were calculated to determine the resistance of mixtures to moisture damage. To investigate clearly the effective of SBS and lime seven freeze–thaw cycle was applied to specimens at TSR test. The results indicate that application of SBS modified binders and lime as mineral filler one by one improves the stability, stiffness and strength characteristic of hot mix asphalt. According to retained Marshall stability it is concluded that addition of only 2% lime have approximately same effect with addition of 6% SBS. Using lime together within the SBS modified mixes exhibit high accordance and exacerbates the improvement of properties. Specimens containing both 2% lime and 6% SBS, have the highest stiffness modulus which is 2.3 times higher than those of the control mixture and showed the least reduction in tensile strength ratio while maintaining 0.70 tensile strength ratio after seven freeze–thaw cycle.     

不同添加剂对沥青混合料性能影响的研究

主要介绍了一些已经研发出来的新的添加剂Zeolite,Sasobit和Evotherm,并对其性能进行了试验研究,研究表明,采用这些新的添加剂加入到沥青混合料中,能够在不损失路面性能的前提下,降低热拌沥青混合料的拌合温度和压实温度.     

浅谈如何提高Superpave沥青混合料矿料间隙率

针对Superpave沥青混合料设计中经常会遇到VMA较低以及VMA对级配变化不敏感情况,从级配、表面结构、颗粒形状三方面入手,探讨了如何提高Superpave沥青混合料矿料间隙率,以期指导实践。     

Effect of glass cullet on the improvement of the dynamic behaviour of asphalt concrete

The stiffness modulus is one of the most important parameters for the prediction of pavement strength against dynamic loads. Previous research indicated that glass can reduce the construction costs of asphalt concrete pavements while providing better dynamic behaviour because of its unique properties. In this research, the behaviour of Hot Mix Asphalt (HMA) in different temperature conditions depending on the variation of the admixture contents and the gradation of the aggregates will be evaluated. Afterwards, for the first time, models for the prediction of the stiffness modulus of waste glass–asphalt in terms of three different parameters including temperature, percentage of additives and the aggregate gradation will be presented. The results of this research are indicative of an improvement in the dynamic behaviour of glass–asphalt mixture in comparison with conventional HMA mixtures.     

Evaluation of high modulus mixture behaviour with high reclaimed asphalt pavement (RAP) percentages for sustainable road construction

The aim of this work is to characterize the behaviour of high modulus bituminous mixes with low penetration grade bitumen and high reclaimed asphalt pavement (RAP) percentages. Four mixtures with RAP percentages of 0%, 15%, 30% and 50%, respectively, were analyzed. Their volumetric and mechanical characteristics were evaluated for several binder contents to define a job mix formula for real scale testing. Mechanical properties included stiffness modulus, toughness, moisture sensitivity, resistance to rutting and fatigue resistance. The most important conclusion is that it is possible to prepare high modulus mixtures (HMM) with high RAP contents and good mechanical properties similar to those of conventional high modulus mixes. However, preparation in non-adapted plants, where RAP is not previously heated, allows a maximum RAP percentage of approximately 30% only.     

浅析SBS改性剂对沥青混合料性能的作用

介绍了沥青混合料的强度形成过程 ,通过对SBS型改性剂试验结果的分析 ,提出了SBS型改性剂是一种综合改善沥青混合料性能的改性剂     

细集料对沥青混合料水稳定性影响分析

通过对不同细集料组成的沥青混合料进行水稳定性评价,分析了细集料砂当量与沥青混合料水稳定性的关系,发现细集料砂当量偏低会明显降低沥青混合料的水稳定性能,因此在沥青混合料的生产过程中要加大除尘力度,保证拌合站生产的沥青混合料优良的水稳定性。     

沥青混合料离析成因及评价方法探讨

对沥青混合料离析的原因进行了分析,从沥青混合料的拌和、运输、摊铺等方面提出了防止离析的预防措施,介绍了离析的检测评定方法及其新发展,以有效地防止沥青混合料的离析现象,从而提高了沥青混合料路面质量。     

Utilization of recycled brick powder as alternative filler in asphalt mixture

The objective of this study is to investigate the use of recycled brick powder as replacement of mineral filler in asphalt mixture. A comparative study was carried out on the performance of two mixtures using recycled brick powder and limestone filler. The experimental performed were indirect tensile tests, static and dynamic creep tests, water sensitivity tests and fatigue tests. The results show that the mixtures prepared with recycled brick powder have better mechanical properties than the mixtures with limestone filler. Thus, it is promising to use recycled brick powder as mineral filler in asphalt mixture.