Investigating Effects of Clay and Carbonaceous Nanoparticles on Asphalt Degradation Aerobic Microorganisms

Background: Hot mix asphalt (HMA) is one of the most important structures to implement the road and street surfaces, which always exposed to destruction. Provide new solutions to reduce the destructive process of effective factors on asphalt destruction and increasing prolong of its lifetime is important for society of road engineers. Traffic loading and weather conditions are the major factors that have role on different asphalt destruction.Materials and Methods: In this study, three types of HMAs, which contain nanoclay, and carbon nanotubes were produced by Marshall method in Iran University of Science and Technology, and one type of aged HMA were also collected for further investigations. The HMA samples were transferred to microbiology laboratory of Shahid Beheshti University of Medical Sciences, and then suspensions were prepared from specimens and cultured on nutrient agar medium. After 24 hours’ incubation at 37 ̊C the bacteria that were grown on the plate were identified. At least the effect of clay and carbon nanoparticles on minimum inhibitory concentration (MIC) of bacteria, were determined by microdilution broth method.Results: A lot of bacterial colonies (Bacillus and Pseudomonas) were collected from the aged specimens. The asphalt, which contain nanoclay had more bacteria than the nanocarbon asphalt. The carbon and clay nanoparticles in 2% and 4% concentration prevented the growth of bacteria, respectively.Conclusion: The old asphalt had more bacteria than other samples, which shows bacteria are one of the main factors in decomposition of asphalt by applying corrosion to bituminous hydrocarbons. Presence of clay and carbon nanoparticles in asphalt structures could increase the durability of the HMAs and reduce the relevant economics costs

Interface condition influence on prediction of flexible pavement life

The effects of interface condition on the life of flexible pavements have been determined. The methodology consists of implementing a previously derived interface constitutive model into the Kenlayer programme to compute the stresses and strains in typical flexible road structures. The shell transfer functions for fatigue cracking and terminal serviceability were used to estimate the pavement life. The behaviour of in‐service pavements indicates that the condition of the bonding between pavement layers plays an important role in the road structures performance. Premature failure of road sections due to layer separation, leading to redistribution of stresses and strains in the pavement structure, is often encountered, especially in areas where the vehicles are more likely to apply horizontal forces. In computing the critical stresses and strains, most of the mechanistic design procedures of flexible pavement structures consider that pavement layers are completely bonded or completely unbounded. Susieties būklės įtaka nestandžiųjų dangų tarnavimo trukmei numatyti Santrauka Straipsnyje nustatyta susieties būklės įtaka nestandžiųjų kelio dangų tarnavimo trukmei numatyti. Pagal taikytą metodiką anksčiau sukurtas sudėtinis susieties modelis buvo įdiegtas į Kenlayer programą tam, kad būtų galima apskaičiuoti įtempius ir deformacijas tipinėse nestandžiųjų kelio dangų konstrukcijose. Dangos naudojimo trukmė apskaičiuota pasitelkiant sluoksnių perkėlimo funkcijas nuovargio plyšiams ir ribinio tinkamumo eksploatacijai. Esamų dangų elgsena rodo, kad dangos sluoksnių tarpusavio surišimo būklė yra labai svarbi kelio dangos konstrukcijos kokybei. Ankstyvas dangos ruožų irimas dėl sluoksnių atsiskyrimo, dėl kurio dangos konstrukcijos įtempiai ir deformacijos persiskirsto, yra gana dažnas, ypač tose vietose, kur transporto priemonės sukelia horizontaliąsias jėgas. Apskaičiuojant kritinius įtempius ir deformacijas, daugumai mechaninio nestandžiųjų dangų konstrukcijų projektavimo metodikų imama, kad dangos sluoksniai yra visiškai surišti arba visiškai nesurišti. Reikšminiai žodžiai: būklė, tiesinis tamprumo modelis, pagruntavimas, nestandžioji danga, Kenlayer programa, sluoksnių perkėlimo funkcijos, nuovargis, vėžių susidarymas. First Published Online: 14 Oct 201

Preventive maintenance of flexible pavement and mechanical properties of steel slag asphalt

Preventive maintenance is beneficial if pavement life is increased while maintaining its service ability, and it is an environmental problem. Steel slag material is inorganic, it can neither be incinerated nor decomposed, so it may be difficult to reclaim. This work aims to study the performance of asphalt concrete where some of the fractional fine aggregate is replaced with crushed steel slag material. Steel slag materials are brittle and rich in carbon and silicon, so the key technical indexes of steel slag‐asphalt concrete are strength. Materials used in the tests included AC 60–70 bitumen, limestone aggregate and crushed recycled steel slag. The Marshall test was used to examine the influence of optimal asphalt content, volume properties and strength of asphalt concrete when different percentages of crushed steel slag were added. The high‐temperature stability and creep stiffness performance of steel slag asphalt concrete was also tested, and the results are satisfactory. The investigation has demonstrated that the recycling and use of waste steel slag in asphalt concrete is feasible. Santrauka Profilaktinis remontas yra naudingas, jei kelio dangos patvarumas didinamas išlaikant teikiamas paslaugas, kartu tai svarbi aplinkos problema. Plieno šlakas yra neorganinės kilmės ir negali būti nei deginamas, nei skaidomas, todėl sunkiai utilizuojamas. Šiame darbe stengtasi įvertinti asfalto betono charakteristiką, kai dalis smulkios frakcijos yra pakeista susmulkintu plieno šlaku. Ši medžiaga trapi, joje daug anglies ir silikono, todėl vienas pagrindinių techninių plieno šlako rodiklių yra stiprumas. Tyrimams buvo naudotas AC 60–70 bitumas, klinčių užpildas ir susmulkintas perdirbtas plieno šlakas. Maršalo tyrimas taikytas siekiant įvertinti optimalų asfalto kiekį, asfalto betono tūrines savybes ir stiprumą esant skirtingai susmulkinto plieno šlako procentinei daliai. Tyrimo rezultatai parodė pakankamą plieno šlako asfalto betono stabilumą esant aukštai temperatūrai ir šlyties standumą. Tyrimo rezultatai parodė, kad plieno šlakas gali būti perdirbamas ir panaudojamas asfalto betone kaip sudėtinė dalis. Reikšminiai žodžiai: plieno šlakas, asfalto betonas, standumas šlyčiai, atliekos, profilaktinis remontas, perdirbimas. Профилактический ремонт дорожного покрытия и механические свойства асфальта со стальным шлаком Резюме Профилактический ремонт полезен, если долговечность дорожного покрытия увеличивается при сохранении оказываемых услуг, а также в отношении охраны окружающей среды. Стальной шлак не является органическим веществом, поэтому его нельзя сжечь либо как-то утилизировать. Нами была предпринята попытка оценить характеристику асфальтобетона, мелкая фракция которого частично заменена дробленым стальным шлаком. Этот материал хрупок, в нем много угля и силикона, поэтому одним из основных технических показателей стального шлака является прочность. Исследованиям подвергался битум АС 60–70, известковый заполнитель и дробленый переработанный стальной шлак. Для определения оптимального количества асфальта, свойств и прочности асфальтобетона при разном процентном составе дробленого стального шлака применялся метод Маршалла. Исследования подтвердили достаточную стабильность асфальтобетона со стальным шлаком при высокой температуре, сдвиговую жесткость, а также возможность переработки стального шлака и применения его в качестве составной части асфальтобетона. Ключевые слова: стальной шлак, асфальтобетон, сдвиговая жесткость, отходы, профилактический ремонт, переработка. First Published Online: 14 Oct 201

Resilient behaviour of hot mixed and crack sealed asphalt concrete under repeated loading

Bituminous mixes are becoming increasingly important in the road industry. The road engineers identify rutting as a major source of distress in Hot Mix Asphalt (HMA) pavements. The Asphalt Mix Design Marshal method adequately addresses the aggregate and asphalt binder properties that contribute to permanent deformation. However, there is no laboratory test currently at hand to quickly predict permanent deformation susceptibility of HMA. The main purpose of this paper is to provide practical information of laboratory samples for practitioners and mix designers. Thus, relevant test procedures and results of tests conducted are reported in this paper. Two resilient behaviours of cracked sealed asphalt concrete were studied by varying temperature and time of loading to understand the crack sealed pavement behaviour under Iran conditions. Karšto ir supleišėjusio asfaltbetonio tamprumas veikiant kartotinei apkrovai Santrauka Bitumo mišiniai tampa vis svarbesni kelių statyboje. Kelių tiesėjai nustatė, jog didžiausia problema yra provėžos karštoje kelio dangoje. Asfalto mišinio užpildų ir rišamosios medžiagos savybių įtaką ilgalaikėms deformacijoms tiksliai vertina Maršalo metodas, tačiau šiuo metu nėra jokio laboratorinio testo, kuris operatyviai nustatytų ilgalaikes karšto betono mišinio deformacines savybes. Pagrindinis šio straipsnio tikslas – suteikti informaciją apie laboratorinius bandinius mišinių gamintojams ir kelininkams. Taigi čia aprašyti atlikti testai ir gauti rezultatai. Bitumo kiekio mišinyje ir temperatūros įtakos ilgalaikėms asfalto dangos deformacijoms tirti panaudota laboratorinė įranga. Bandant suvokti supleišėjusios dangos elgseną Irano sąlygomis, nagrinėtos dvi supleišėjusio asfaltbetonio tamprumo charakteristikos, keičiant temperatūrą ir apkrovimo trukmę. First Published Online: 21 Oct 2010 Reikšminiai žodžiai: ilgalaikė deformacija, Maršalo metodas, karšto asfalto mišinys, provėžos, įtempis, pleišėjimas

A Framework for Economic Evaluation of Highway Development Projects Based on Network-Level Life Cycle Cost Analysis

For economic evaluation of a highway development project, multiple criteria must be considered on a timeframe longer than the project implementation interval and a geographical area larger than the project zone. In this study, a framework is proposed based on the Network-Level Life Cycle Cost Analysis (NL-LCCA) to assess the effect of highway development projects on mobility, safety, economy, environment and other monetizable criteria. In this approach, project impacts are estimated within physical boundaries of highway network over the network life cycle. This framework can be used as a decision-making support for evaluation and ranking of pre-defined development projects, proposing new cost-effective development projects, assessment of cost efficiency of existing highway network and budget allocation optimization.</p

Laboratory Investigation of Fatigue Characteristics of Asphalt Mixtures with Steel Slag Aggregates

There are many steel-manufacturing factories in Iran. All of their byproducts, steel slag, are dumped randomly in open areas, causing many environmentally hazardous problems. This research is intended to study the effectiveness of using steel slag aggregate (SSA) in improving the engineering properties, especially fatigue life of Asphalt Concrete (AC) produced with steel slag. The research started by evaluating the physical properties of the steel slag aggregate. Then the 13 types of mixes which contain steel slag in portion of fine aggregates or in portion of coarse aggregates or in all portions of aggregates were tested. The effectiveness of the SSA was judged by the improvement in Marshall stability, indirect tensile strength, resilient modulus, and fatigue life of the AC samples. It was found that replacing the 50% of the limestone coarse or fine aggregate by SSA improved the mechanical properties of the AC mixes

Investigation of Rutting Performance of WMA Mixtures Containing Copper Slag

Abstract: Copper slag (CS) is an abrasive blasting grit made of granulated slag from metal smelting processes. As copper slags are known to be waste material and cause a lot of environmental problems, it would be a good idea to use them in different sections of industry such as pavement construction. On the other hand, in order to save energy and reduce the amount of pollutants released during the construction of asphalt pavements, the technology of Warm Mix Asphalt (WMA) is developing considerably. A very high amount of copper slag is produced in south of Iran where the weather is considered to be hot and rutting is the most important distress of asphalt concretes. This paper presents the influence of utilization of copper slag as fine material on the rutting performance of warm mixed asphalt. A laboratory study has been conducted on five asphalt mixtures with various CS contents, namely; 0%, 10%, 20%, 30% and 40% by weight of total aggregates. The amount of optimum bitumen and the value of Marshall Stability (MS) were determined with MS test for the samples. Then creep test and wheel track tests were conducted on the produced samples. The results indicated that the use of 20% CS in WMA enhances the marshal stability and rutting performance of WMA mixtures. However, the resistance of mixtures against rutting falls substantially by adding more than 20% CS

Locating stations of public transportation vehicles for improving transit accessibility

Since transportation is one of the most complicated and the basic problem of urban life in developing countries at the present time and in various dimensions, so it is necessary to view it more scientifically‐ practically. Reducing travelling time is one way to reduce its cost .In public transportation system, it is important to determine proper travelling costs. There are various methods to determine the distances between stations. One of these methods used in England is based on logical and calculative relations in mathematics. In this paper, in addition to studying this method some changes have been made in order to reduce and modify required variables for calculation of those relations. A numerical example is designed to demonstrate the effectiveness of the method and thus developed to optimize the public transportation stop location problem. The sensitivity of the total travel time, access, speed and the effect of the parameters on the optimum stop location are analyzed and discussed. First Published Online: 27 Oct 201

Influence of Recycling Agents Addition Methods on Asphalt Mixtures Properties Containing Reclaimed Asphalt Pavement (RAP)

Recycling agents (RAs) are used to restore the physicochemical properties of the aged asphalt binder existing in the reclaimed asphalt pavement (RAP) material. The best location for adding the RAs in the manufacturing process of the asphalt mixtures containing RAP has always been of concern to asphalt mixture researchers. In this study, vegetable, paraffinic and aromatic extract oils were used as RAs. The effect of RA location on the performance properties of the asphalt mixtures containing different percentages of the RAP material was investigated by adding the RAs in three different locations, including in the virgin binder, in the hot RAP material, and in the final mixture. For this aim, the rutting, cracking, and moisture sensitivity of the mixtures containing different RAs at different locations was investigated. The results showed that the best location for adding the RAs is different for various RAs. The best place for adding the paraffinic, aromatic extract, and vegetable oils in terms are in the virgin binder, in the RAP, and the final mixture, respectively. Therefore, using RAs in their appropriate location can improve the mechanical properties of asphalt mixtures containing RAP

Influence of Recycling Agents Addition Methods on Asphalt Mixtures Properties Containing Reclaimed Asphalt Pavement (RAP)

Recycling agents (RAs) are used to restore the physicochemical properties of the aged asphalt binder existing in the reclaimed asphalt pavement (RAP) material. The best location for adding the RAs in the manufacturing process of the asphalt mixtures containing RAP has always been of concern to asphalt mixture researchers. In this study, vegetable, paraffinic and aromatic extract oils were used as RAs. The effect of RA location on the performance properties of the asphalt mixtures containing different percentages of the RAP material was investigated by adding the RAs in three different locations, including in the virgin binder, in the hot RAP material, and in the final mixture. For this aim, the rutting, cracking, and moisture sensitivity of the mixtures containing different RAs at different locations was investigated. The results showed that the best location for adding the RAs is different for various RAs. The best place for adding the paraffinic, aromatic extract, and vegetable oils in terms are in the virgin binder, in the RAP, and the final mixture, respectively. Therefore, using RAs in their appropriate location can improve the mechanical properties of asphalt mixtures containing RAP