Starch as a modifier for asphalt paving materials

This paper investigates the viability of using starch (ST) as a new modifier for asphalt paving materials. Different ratios of ST (2.5, 5.0, and 7.5% by weight of asphalt) were blended with 70/100 paving grade asphalt. Unmodified and modified asphalt binders were subjected to physicochemical, alkali, acid and fuel resistance tests. The performance tests including, Marshall stability, Marshall Quotient (MQ), tensile strength, tensile strength ratio, flexural strength, rutting resistance and resilient modulus (MR) were carried out on unmodified and modified stone matrix asphalt (SMA) mixtures. The analyses of test results show that the performance of ST-modified asphalt mixtures are better than conventional and styrene–butadiene–styrene (SBS)-modified mixtures. The rutting potential, moisture susceptibility and temperature susceptibility can be reduced by the inclusion of ST in the asphalt mixture. The laboratory MR values are lower than the calculated ones using the empirical equations. The results also revealed that this modifier can be used as anti-stripping agent. It also shows resistance to fuels and most common chemicals. A ST content of 5% by weight of asphalt is recommended for the improvement of the performance of asphalt concrete mixtures similar to that investigated in this study.     

复合式SMA桥面铺装混合料配比设计及高温抗车辙性能研究

为了提升桥面铺装的高温抗车辙性能,采用马歇尔配合比设计方法对3种SMA沥青混合料分别进行级配设计及体积指标验证,选用轮辙试验和车辙试验对所设计的5种复合式SMA桥面铺装结构组合的高温性能评价指标进行测试.结果表明,SMA混合料沥青析漏损失及飞散损失均满足技术要求,SMA具有合理的最大沥青用量,且粘附性良好;提出的5种复...     

粗骨架沥青混合料路用性能

通过试验研究,系统分析了Superpave和SMA沥青混合料的路用性能,包括原材料性能,级配分析,混合料马歇尔稳定度,水稳定性,低温抗裂性,高温稳定度,疲劳耐久性和抗滑性能,并与密级配沥青混凝土进行了对比分析。     

Laboratory evaluation of flexible pavement materials containing waste polyethylene (WPE) film

This paper presents a research to recycle the waste vinyl (waste polyethylene film: WPE film) in asphalt mixtures for improving the performance properties of the mixtures. Conventional Marshall mix designs were carried out with varying WPE contents, and the best performing content of WPE film was determined from the previous study. Also, asphalt mixtures with two commercial polymer modifiers, low-density polyethylene (LDPE) and a styrene–butadiene–styrene (SBS), were used to compare the effectiveness of WPE-modified mixture. The strength characteristics such as Marshall stability and indirect tensile strength (ITS) were evaluated, and the wheel tracking test, result of which is generally considered to reflect the field performance, was conducted to measure the rutting resistance of the asphalt mixtures. From the results of this study, asphalt mixture with waste vinyl showed much better rutting resistance than normal asphalt mixture without WPE. It is hypothesized if an optimum content of waste vinyl is used, it is expected that the waste vinyl will be effective as much as commercial modifier in improving the performance of asphalt pavements.     

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.     

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.     

多碎石沥青混凝土路用性能的研究

研究了掺与未掺木质素纤维的多碎石沥青混凝土的路用性能，其中包括马歇尔稳定度，水稳定性，低温抗裂性，高温稳定度，疲劳耐久性和抗 滑性能，并与密级配沥青混凝土进行了对比，结果表明，多碎石沥青混凝土是一种性能优良的沥青混和料。     

密级配沥青混合料沥青膜厚度优选

通过Bailey,Superpave和马歇尔三种方法设计级配,选用六种沥青含量进行了车辙试验,研究了沥青膜厚与车辙动稳定度之间的关系,提出了基于高温性能的密级配沥青混合料沥青膜厚的建议.     

沥青混合料纤维加强作用的研究

通过对沥青混合料掺加纤维的研究,系统分析了纤维加强沥青混合料的马歇尔稳定度、水稳定性、高温稳定性、低温抗裂性及耐疲劳性能,探讨了纤维增强沥青混合料的强度形成机理,并与普通密集配沥青混凝土进行了对比、分析,结果表明：纤维沥青混合料是一种具有优良品质的沥青路面材料。     

Laboratory evaluation of HMA with high density polyethylene as a modifier

This paper investigates the viability of using high density polyethylene (HDPE) as a modifier for asphalt paving materials. Different ratios of HDPE by weight of asphalt were blended with 80/100 paving grade asphalt. Unmodified and modified asphalt binders were subjected to physicochemical and homogeneity tests. The performance tests including, Marshall Stability, Marshall Quotient (MQ), tensile strength, tensile strength ratio, flexural strength and resilient modulus were carried out on unmodified and modified hot asphalt mixtures. The analyses of test results show that the performance of HDPE-modified asphalt mixtures are better than conventional mixtures. The moisture susceptibility and temperature susceptibility can be reduced by the inclusion of HDPE in the asphalt mixture. A HDPE content of 5% by weight of asphalt is recommended for the improvement of the performance of asphalt concrete mixtures similar to that investigated in this study.     

Performance of the SMA mixes made with the various binders

This paper compares the performance of the stone mastic asphalt (SMA) mixes made with the various binders. Three types of binders namely: 20–30, 40–50 and 70–100 penetration grade were considered. The performance tests including, Marshall stability, tensile strength, tensile strength ratio, resistance to permanent deformation, flexural strength and resilient modulus were carried out on the SMA mixes. The safe pavement design criteria of the SMA mixes based on the anisotropic elasticity analysis through finite-element simulation were obtained and reported herein. In addition, an optimization table was prepared to select the type of SMA mixture for any field applications.     

Evaluating permanent deformation in asphalt rubber mixtures

Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures, mainly in countries with high temperatures such as Brazil. Throughout the years, researchers have used different test methods to estimate the rutting performance of asphalt mixtures. One of the alternatives to reduce permanent deformation in asphalt pavement layers is through the use of mixtures produced with asphalt rubber. Crumb rubber from waste tires introduced into the asphalt is one of suitable application to dispose the tires and used as an additive to enhance the properties of the conventional asphalts. This work aims at comparing the rutting performance of asphalt rubber mixtures (with dense and gap-graded aggregate gradation) with the conventional dense graded mixture most used in Brazil. The asphalt rubber mixtures were produced by the wet process using continuous blend and terminal blend asphalt rubber. To study their performance, two laboratory tests, the Repeated Simple Shear Test at Constant Height (RSST-CH) and the Accelerated Pavement Testing Simulator Test (wheel tracking) were carried out. The testing results confirmed that the use of asphalt rubber binder improves significantly the resistance to rutting. The highest resistance is presented by the mixtures produced with continuous blend binders and gap-graded aggregate gradation. The results of both testing apparatus can be correlated by a linear relationship. The testing results allowed concluding that the characteristics of the asphalt rubber binders cannot be used to predict the permanent deformation resistance of the asphalt rubber mixtures.     

Investigation of rutting performance of asphalt mixtures containing polymer modifiers

The purpose of this study is to evaluate mechanical properties of control and modified asphalt mixtures. Conventional and five modified asphalt mixtures were studied on hot mix asphalt permanent deformation resistance. Amorphous polyalphaolefin, cellulose fiber, polyolefin, bituminous cellulose fiber and styrene butadiene styrene were used as modifiers. Indirect tensile strength, indirect tensile, static and repeated creep and LCPC wheel tracking tests were used for different loading conditions and temperatures. Research was focused on comparing the interaction between LCPC wheel tracking and other mechanical tests. According to the LCPC wheel tracking and repeated creep test results SBS mixtures were found as the most resistance mixtures in view of the rutting. Additives performed different performance levels but showed more resistance to permanent deformation according to the conventional mixtures. As far as the static creep test results are concerned there are controversial results because conventional mixtures are better. It is thought that this result may stem from the static behavior of the load and rheological change of bitumen with modifiers.     

浅谈纤维在桥面铺装中的应用

桥面铺装沥青混凝土层直接承受行车荷载、梁体变形和环境因素的作用,受力情况复杂,因此对桥面铺装沥青混凝土的性能提出更高的要求。该文通过水稳定性、高温车辙、低温弯曲和单轴静态蠕变试验系统研究了纤维改性沥青混凝土的性能。研究结果表明,掺加纤维后能够有效提高沥青混合料的残留稳定度和冻融劈裂强度比,同时能够改善低温抗拉性能和抗高温变形能力,纤维增强沥青混合料适宜用作桥面铺装层。     

纤维和车辙剂对沥青混合料路用性能的影响研究

为了探究纤维和车辙剂共同作用对沥青混合料路用性能的影响,将聚酯纤维和抗车辙剂掺入沥青混合料中,通过宏观性能试验对沥青混合料的高低温和水稳性能进行研究。结果表明,聚酯纤维单掺、抗车辙剂单掺、两种材料复掺均可改善沥青混合料的高温和水稳性能,聚酯纤维可有效改善沥青混合料的抗弯拉性能,但抗车辙剂对沥青混合料的最大弯拉应变不利。车辙剂和聚酯纤维复掺对沥青混合料的改善效果更佳。     

Mechanistic analysis of ST and SBS-modified flexible pavements

This paper deals with the viability of using starch (ST) and styrene–butadiene–styrene (SBS) as an additive in stone matrix asphalt (SMA) mixtures. A 5% of ST and SBS by weight of bitumen were blended with (70/100)-paving grade asphalt. Unmodified and modified bitumen were subjected to physiochemical tests. The performance tests including, Marshall stability, tensile strength, tensile strength ratio and resilient modulus were carried out on unmodified and modified SMA mixtures. A mechanistic-empirical design approach was used for estimating the improvement in service life of the pavement or reduction in thickness of SMA and base layer for the same service life due to modification the SMA mixtures. The analyses of test results show that the moisture damage and temperature susceptibility can be reduced by the inclusion of ST and SBS in the asphalt mixture. The results also revealed that ST-modifier can be used as anti-stripping agent, and reduced plant emissions and energy consumption by 30%, as well as it shows resistant to fuels, most common chemicals and solvents. The results of multi-layer elastic analysis presented herein indicate that the pavement consisting of ST and SBS-modified SMA as a surface layer is beneficial in reducing the construction materials. In addition, the safe pavement design criteria of unmodified and modified SMA mixtures based on the anisotropic elasticity analysis through finite-element simulation were obtained and reported herein.     

Field and laboratory performance comparison for asphalt mixtures with different moisture conditioning systems

The purpose of this study is to compare laboratory and field performances for dense graded asphalt mixtures. Control road pavement section was constructed in Black Sea Coast Highway. Marshall identical control samples produced in laboratory and core samples taken from wearing courses before the traffic opened were used. Three different moisture conditioning methods were applied to control laboratory and core samples. Mechanical properties of samples were evaluated with indirect tension, indirect tension strength and repeated creep tests. Indirect tensile strength test results for laboratory mixtures were found 1.22 and 1.30 times more in accordance with field samples at 10 °C and 20 °C respectively. Marshall samples gave higher resilient modulus for all control and conditioned mixtures. Repeated creep test results also proved the difference between laboratory and field sample performance. Laboratory samples protected their structural integrity along with the test duration and did not showed tertiary creep. It is concluded from this study that laboratory samples state expressly higher performance according to the core field samples.     

橡胶粉掺量对环氧沥青及其混合料性能的影响

通过黏度、拉伸、马歇尔、车辙和低温弯曲试验分析了掺2%~10%（质量分数）橡胶粉的改性环氧沥青及其混合料的性能.结果表明：掺橡胶粉后,改性环氧沥青的容留时间略有缩短,断裂延伸率有所提高,其中掺6%橡胶粉的改性环氧沥青断裂延伸率可达261%;与普通环氧沥青混合料相比,掺2%,4%,6%橡胶粉的改性环氧沥青混合料其高温稳定性能良好,低温脆性均有所改善,且掺4%,6%橡胶粉的改性环氧沥青混合料低温强度较高、变形能力较好.     

纤维稳定剂对排水沥青混合料水稳定性的影响

聚酯纤维和木质素纤维这2种稳定剂常用于排水沥青混合料以提高其高温稳定性能。该文对比分析了掺加聚酯纤维和木质素纤维的OGFC-13沥青混合料的水稳定性能,通过浸水时间不同的马歇尔稳定度和循环次数不同的劈裂强度试验,得出排水沥青混合料OGFC-13的残留稳定度和冻融循环劈裂强度比的变化趋势。同时比较了2种纤维的标准飞散损失和浸水飞散损失。结果表明,在马歇尔残留稳定度、冻融循环劈裂强度和飞散损失的水稳定性试验中,掺聚酯纤维和木质素纤维的OGFC-13沥青混合料表现出不同的性能,不能笼统地说明哪种纤维改性排水沥青混合料性能的优劣。     

环氧沥青混凝土桥面薄层铺装性能研究

为了研究环氧沥青混凝土在薄层铺装中的性能优势,通过马歇尔试验、浸水马歇尔试验、车辙实验、弯曲试验、劈裂试验,分析比较了环氧沥青混凝土与SBS改性沥青混凝土、沥青玛脂碎石SMA的路用性能。研究结果表明:环氧沥青混凝土桥面薄层铺装路用性能优于当前普遍采用的SBS改性沥青混凝土和沥青玛脂碎石SMA,是一种良好的桥面铺装材料。