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DURABILITY OF ASPHALT CONCRETE MIXTURES USING DOLOMITE AGGREGATES

DURABILITY OF ASPHALT CONCRETE MIXTURES USING DOLOMITE AGGREGATES

1- It was found that the bulk unit weight, Mar- shall stability and stiffness values of asphalt concrete mixtures increase with increase of compaction temperatures, while percent air voids, percent voids in the mineral aggregate (% V.M.A) decrease with increase of compaction temperatures at optimum bitumen contents. 2- Results show that the standard Marshall Stability values of mixtures at optimum binder contents are not useful for the prediction the du- rability performance of these mixes when com- pared with immersion Marshall Stabilities. 3- The immersion time has a marked effect on the durability of asphalt concrete mixtures, when this is assessed by the Marshall Stability tests. In general, the values of Marshall Stability de- crease with increase in immersion time. The sta- bility falls gradually in the first day and rapidly after that.
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Repositório Institucional UFC: Relationship between multiple stress creep recovery (MSCR) binder test results and asphalt concrete rutting resistance in brazilian roadways

Repositório Institucional UFC: Relationship between multiple stress creep recovery (MSCR) binder test results and asphalt concrete rutting resistance in brazilian roadways

recovery (MSCR) binder test results and asphalt concrete rutting resistance in Braz...2. Article in Construction and Building Materials · April 2017.[r]

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Calculation of the temperature of asphalt concrete at making the joints of multilane road pavement of non-rigid type

Calculation of the temperature of asphalt concrete at making the joints of multilane road pavement of non-rigid type

The construction quality of road surface of non-rigid type essentially depend on providing the temperature regimes in the process of laying and packing of hot asphalt concrete mixtures. In order to provide the required characteristics of asphalt concrete due to the surface width it is necessary to provide the temperature regimes of hot as- phalt concrete mixture in the zones of lane connection. The hot mixture is promptly cool- ing right after laying within several minutes, which results, according to the construction technology and the speciic conditions of work production, in temperature abuse of the mixture at joints of the lanes at packing.
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EFFECTS OF STYRENE-BUTADIENE-STYRENE ON STIFFNESS OF ASPHALT CONCRETE AT DIFFERENT TRAFFIC CONDITIONS

EFFECTS OF STYRENE-BUTADIENE-STYRENE ON STIFFNESS OF ASPHALT CONCRETE AT DIFFERENT TRAFFIC CONDITIONS

Awanti et al. [12] showed that the static indirect strength values for SBS modified asphalt concrete were higher in order of 49 -101% when compared to conventional asphalt mixtu res in the temperature range of 15-40°C. The viability of using SBS as an additive in stone mastic asphalt (SMA) was investigated in another study. The mixture mod ified with 5% SBS showed higher stability and tensile strength, lower moisture susceptibility and about 40% increase in resilient modulus values at 25°C [13]. Singh et al. [14] reco mmended the 5% SBS content for better strength and moisture susceptibility. The use of SBS modified bitu men is recommended to be more benefic ial with siliceous or aggregates exhibiting acidic character compared to calcareous aggregates.
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Choosing mineral carrier of nanoscale additives for asphalt concrete

Choosing mineral carrier of nanoscale additives for asphalt concrete

12. Korolev I.V. Model' stroyeniya bitumnoy plenki na mineral'nykh zernakh v asfal'tobetone [Structural Model of Bituminous Film on Mineral Grains in Bitumen Concrete]. Izvestiya vuzov. Stroitel'stvo i arkhitektura [News of Higher Educational Institutions. Construction and Architecture]. 1981, no. 8, pp. 63—67.

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Evaluation of permanent deformation of asphalt rubber using multiple stress creep recovery tests and flow number tests

Evaluation of permanent deformation of asphalt rubber using multiple stress creep recovery tests and flow number tests

Three specimens were compacted using the Superpave gyratory compactor at 150mm of di- ameter and 175mm of height and then cored to obtain 100mm of diameter and 150mm of height, for the *low number test, according to AASHTO T 342-11. Originally is recommended to use specimens compacted to 7,0% in the *low number tests, because this is the upper critical value usually permitted to compact dense gradations of asphalt concrete pavement layers. How- ever, in this study the target air voids was 5.5%, since this is the upper limit observed in appli- cations of these mixes in a speci*ic highway in Brazil. The specimens were conditioned at 54°C and then tested applying an uncon*ined cyclic load of 600kPa. The *low number value obtained in this test corresponds to the number of cycles at which the tertiary *low starts or the number of cycles at which the rate of change of compliance is minimum (NCHRP, 2016).
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Study of the porous asphalt performance with cellulosic fibres

Study of the porous asphalt performance with cellulosic fibres

The problems related to environmental issues have motivated the research about eco-friendly materials. This fact combined with the relatively high binder percentage and with the need to improve the mixtures durability has led to the additives incorporation like the fibres, not only in asphalt mixtures but also in stone matrix asphalt and asphalt concrete. A wide variety of fibre types has been used in asphalt mixtures, including cellulose, mineral, synthetic polymer, glass fibres, newsprint, carpet fibres and recycled tire fibres [28–36]. Cellulosic fibres are the most commonly used addi- tives [37–42]. The current study uses cellulosic fibres to improve porous asphalt performance. These fibres present a set of impor- tant advantages, such as wide availability at relatively low cost, recycling ability, biodegradability, non-hazardous nature, zero car- bon footprint, and interesting physical and mechanical properties (low density and well-balanced stiffness, toughness and strength) [43,44]. One of the main objectives of cellulosic fibres is to stop binder drainage preventing its loss during storage and transport [45].
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Adhesion at asphalt-aggregate interface through surface energy

Adhesion at asphalt-aggregate interface through surface energy

velopment of the research 11 types of aggregates were taken analyzing their physical and chem- ical properties. Eight types of asphalt concrete were made according to the Strategic Highway Research Program (SHRP). Tests carried out included freezing and thawing processes to deter- mine the moisture sensitivity of mixtures when this physical phenomenon occurs. The most relevant indicator was insolubility in acid with calcium content, silicon content, loss by ignition, and zeta potential. Porosity was the second most important variable. One of the most signi icant predictors was acid insolubility. Some of the results indicated that aggregates containing a high percentage of iron, calcium and magnesium and a low percentage of silicon, aluminum and po- tassium are less susceptible to moisture damage. [7] (Mansour Solaimanian, David Fedor, Ra- mon Bonaquist, Ali Soltani, Vivek Tandon, Ilan Ishai, Gordon Airey, Art Johnston, Richard Davis, Gerald Reinke, Michael Heitzman, Frank Fee, Michael Dunning, n.d.) conducted a research to develop and improve the Environmental Conditioning System-ECS for analyzing the moisture sensitivity test in Hot Mixture Asphalt-HMA. This study was made in two phases. The irst phase with a focus on low time, low number, and dynamic modulus concluded that the dy- namic modulus test was the most appropriate of the three simple performance tests. The sec- ond phase worked on eight samples that were well known from its moisture damage behavior in ield. They were tested in the Hamburg Wheel Tracking Device, the main result of this phase was that through the ECS test it is possible to identify the good and poor performance mixtures according to the stripping failure. The aggregates that were tested are: Granite, Siliceous Gravel (poor), Siliceous Gravel (good), Chert Gravel, Limestone, Sandstone, Dolomite and Siliceous Gravel, and the asphalt used was: PG 67-22 , PG 64-22, PG 58-28, PG 67-22, PG 64-22, PG 76-22, PG 64-22 and PG 64-22 respectively.
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Avaliação de um trecho experimental de pavimentação urbana em concreto asfáltico à quente com resíduos de construção e demolição de obras (RCD) como camada de revestimento

Avaliação de um trecho experimental de pavimentação urbana em concreto asfáltico à quente com resíduos de construção e demolição de obras (RCD) como camada de revestimento

In order to investigate the incorporation of residual materials to asphalt concrete as a substitute for gravel 1 and natural sand, volumetric parameters, Marshall stability and an experimental stretch were analyzed, according to the standards established by the Brazilian Technical Standards Association (ABNT) and the National Department of Infrastructure and Land Transport (DNIT). The compositions of the traces used in this research are exhibited in Table 3. We chose to maintain at least 53%, 49.3% and 53% of the materials represented by the coarse aggregates as follows: laboratory trace with residue incorporation, experimental stretch trace with residue incorporation, and experimental stretch trace without residue incorporation -conventional, respectively, since in a bituminous mixture such as Hot- machined Bituminous Concrete (HBC) type, support capacity is provided more effectively by the coarse aggregate. Furthermore, we decided to set the amount of cement at 2% in the laboratory mix containing the residue to avoid problems due to excessive void filling, which could, in turn, result in the non-release of tension, increasing mixture rigidity. The fine aggregate percentages varied in regard to total mineral constituents, due to better granulometric framing within the C curve limits of the DNIT standard 031/2006 (2006) and greater proximity to ideal curves.
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Introduction to concrete curing effect on the early performance of modern concrete

Introduction to concrete curing effect on the early performance of modern concrete

In order to meet the requirements of the modern structure of concrete performance, the composition of modern concrete produced bigger change, this inevitably made an impact on the other properties of concrete. Especially the change of cement fineness and composition, a large number of add mineral admixtures, and the widespread use of high efficiency water reducing agent, has a great influence on the early performance of concrete, especially on the early shrinkage performance, which affect the early cracking of concrete. By collecting and analysising relevant test result, The article summarizes the characteristics of the early performance of modern concrete and their requirements of early curing environment.
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Evaluation of binder blending on warm mix asphalt recycling

Evaluation of binder blending on warm mix asphalt recycling

Aiming to investigate other factors that could have affected the results of rheological tests, all the binders obtained on the staged extraction procedure for both mixtures were tested follow- ing the procedure ASTM D8078-16 for determination of ash content. This test is useful to de- termine if iner residues of the aggregates remained in the recovered binders after extraction, what might affect the accuracy of measured properties. Results are presented in Figure 10 and indicate that only the binder obtained in Step 3 for the 0% RAP mixture showed high ash con- tent, of 1.75%. According to the standard ASTM D1856-09, ash contents of recovered asphalts greater than 1% may affect the accuracy of other test results, and that might be the case for the binder obtained in Step 3 of the WMA 0% RAP mixture, what would explain the higher values of |G*| and lower values of δ observed, in relation to Steps 1 and 2 of the same mixture. That could explain also the elevated result for the Glover-Rowe parameter in Step 3 of the 0% RAP mixture, since it is calculated using both |G*| and δ. All the other binders had ash content values below the 1% limit, so their rheological behavior should not be affected by the ash content. It is important to emphasize that other factors might be involved in this result as well, such as a possible burning of the asphalt binder when it got in contact with the aggregates, and further investigations should be conducted before con irming this hypothesis.
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Experimental Studies on Glass Fiber Concrete

Experimental Studies on Glass Fiber Concrete

C. Selin Ravikumar and T.S. Thandavamoorthy, The study there has been a significant increase in the use of fibers in concrete for improving its properties such as tensile strength and ductility. The fiber concrete is also used in retrofitting existing concrete structures. Among many different types of fibers available today, glass fiber is a recent introduction in the field of concrete technology.

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Thermal Insulating Concrete Tiles

Thermal Insulating Concrete Tiles

Taking care of the reduction of insulation due to the concrete ribs; By multiplying by  415 / 500  2  0 . 69 , where the 415 mm is average internal dimension of the tile specimen, and reduction of the fact that walls and openings of the room are not 100% multiplied by 0.7. Also, taking care of the bad workmanship, by multiplying by 0.5, the ratio becomes:

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Use of Cellulosic Fibres in Double Layer Porous Asphalt

Use of Cellulosic Fibres in Double Layer Porous Asphalt

Abstract— Climate change, namely precipitation patterns alteration, has led to extreme conditions such as floods and droughts. In turn, excessive construction has led to the waterproofing of the soil, increasing the surface runoff and decreasing the groundwater recharge capacity. The permeable pavements used in areas with low traffic lead to a decrease in the probability of floods peaks occurrence and the sediments reduction and pollutants transport, ensuring rainwater quality improvement. This study aims to evaluate the porous asphalt performance, developed in the laboratory, with addition of cellulosic fibres. One of the main objectives of cellulosic fibres use is to stop binder drainage, preventing its loss during storage and transport. Comparing to the conventional porous asphalt the cellulosic fibres addition improved the porous asphalt performance. The cellulosic fibres allowed the bitumen content increase, enabling retention and better aggregates coating and, consequently, a greater mixture durability. With this solution, it is intended to develop better practices of resilience and adaptation to the extreme climate changes and respond to the sustainability current demands, through the eco- friendly materials use. The mix design was performed for different size aggregates (with fine aggregates – PA1 and with coarse aggregates – PA2). The percentage influence of the fibres to be used was studied. It was observed that overall, the binder drainage decreases as the cellulose fibres percentage increases. It was found that the PA2 mixture obtained most binder drainage relative to PA1 mixture, irrespective of the fibres percentage used. Subsequently, the performance was evaluated through laboratory tests of indirect tensile stiffness modulus, water sensitivity, permeability and permanent deformation. The stiffness modulus
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Evaluation of Carnauba Waxes in Warm Mix Asphalt Technology

Evaluation of Carnauba Waxes in Warm Mix Asphalt Technology

The concept of warm asphalt technology comprises several different approaches. A variety of additives are used in order to reduce mixing temperature. The most widely used additives for this purpose include natural and synthetic waxes– organic additives, also called flow improvers. An example is the commercial Sasobit®, a synthetic wax with longer chain lengths and melting point above 70°C. It is obtained from coal gasification using the Fisher Tropsch synthesis. The long- chains hydrocarbons (40-115 carbon atoms) maintain the wax in solution and reduce binder viscosity, improving its workability during asphalt mixing and compaction. The additive further improves durability and resistance to fuel leaks. Fuels such as kerosene, diesel and gasoline from vehicles damage the asphalt coating, softening the asphalt binder in the surface, then making the aggregates lose their adhesiveness (Cowley & Fisher, 2002; Richter, 2002; Barman et al., 2011). Besides Sasobit, materials such as Cecabase, Evotherm, Rediset and other waxes have been tested as additives for warm mix asphalt (Banerjee et al., 2012; Polacco et al., 2012). Some previous studies have evaluated the use of carnauba waxes in asphalt technology (Leite et al., 2010; Feitosa et al., 2012). A patent was published in 2011 by Petrobras applying carnauba wax to modify asphalt binders (Martins et al., 2011).
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Verificação do “self-healing asphalt” através do aquecimento das misturas betuminosas

Verificação do “self-healing asphalt” através do aquecimento das misturas betuminosas

O conceito de “self-healing asphalt” está relacionado à capacidade inerente da parte betuminosa do pavimento para reverter parcialmente danos, tais como a formação de pequenas fendas que possam ter ocorrido durante a sua vida útil. Sabe-se que as misturas betuminosas são um material “self-healing” por si só, mas só funciona se não houver circulação do tráfego. Também tem algumas limitações: é um processo lento à temperatura ambiente e não é eficaz se as fendas forem significativas (Qiu J., 2012; Garcia A., 2012).

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Low temperature specifications for asphalt binders: tests and simulation

Low temperature specifications for asphalt binders: tests and simulation

BBR tests allow the estimation of low temperature speci- fications, but they are only based on materials’ linear vis- coelastic properties. Higher stiffness induces higher stresses in the material under loading, but this is not the only factor determining crack growth. This phenomenon is associated to material toughness. Concerning cracking re- sistance ranking, three points bending tests and bending beam rheometer give different results. Results with asphalt modified by crosslinked SBS and crosslinker-free SBS seem to show that limit cracking temperature is a reliable

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Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

In general, the interpretation and validation of NDT results should involve three distinct phases [10]: processing of collected data, analysis of within-test variability, and quantitative evaluation of the property under analysis. Relevant information can be obtained by the analysis of within-test variability, by comparing the obtained results in a location with the typical one for the NDT method in use, either to provide a measure of the quality control or to detect abnormal circumstances in NDT application [10]. A good planning of a research when inspecting a concrete structure should also include the procedures for data treatment and interpretation of in-situ test results prior to the inspection. When monitoring concrete compressive strength during construction, it is usually sufficient to compare test results with the limits established by trials made at the start of the contract, but in other complex situations, like in old structures, the prediction of the actual concrete compressive strength could be required for calculation design. Depending on the purpose of the research, either for estimation of the in-situ concrete compressive strength for conformity checking, either for design calculations, many questions concerning the conversion between the mean value of compressive strength and the characteristic value or the minimum in-situ design value, or either about the safety factor coefficient to apply, may lead to complex discussions, because of the basic differences between in-situ concrete and the standard test specimens upon which most specifications are based [1,4].
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Punching shear in concrete reinforced flat slabs with steel fibers and shear reinforcement Punção em lajes lisas de concreto armado com fibras de aço e armadura de cisalhamento

Punching shear in concrete reinforced flat slabs with steel fibers and shear reinforcement Punção em lajes lisas de concreto armado com fibras de aço e armadura de cisalhamento

The slabs were loaded in steps of 50 kN until failure. Ultimate load was the maximum load obtained from the load cell recorder. The slab´s self-weight and the steel beams are not considered in the ultimate load. Table 3 presents the most important slab char- acteristics and compares their ultimate loads. Concrete compres- sive strength in slabs without fibers was 42 MPa and compressive strength for slabs with fibers was 36 MPa on testing day. Concrete tensile strength ranged from 3.7 MPa to 4.0 MPa. To evaluate fiber influence on punching shear, ultimate loads from slabs with fibers (loads V uLFi ) were compared to ultimate loads from similar slabs without fibers (loads V uLi ), as for example, slabs LF1 and L1 (ratio
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