The work presented here is a study on the measurement and prediction of the rutting resistance of previously rutted asphalt mixes rehabilitated with a layer of micro-surfacing manufactured with virgin and recycled agg...The work presented here is a study on the measurement and prediction of the rutting resistance of previously rutted asphalt mixes rehabilitated with a layer of micro-surfacing manufactured with virgin and recycled aggregates at different stages of aging. The experimental procedure consisted of rutting tests on hot mix asphalt slabs already degraded and repaired with virgin and recycled micro-surfacing. Then, the evolution of the behavior of micro-surfacing cast on the hot mix asphalt slabs is observed according to loading cycles of the pavement rutting tester MLPC. Before rutting tests, slabs are subjected to 24 hours at 50°C and aged for 2 days and 5 days at 85°C in the oven. The results showed rutting percentages of 6.3% for hot mix asphalt slabs aged for 2 days and 7.2% for 5 days. These hot mix slabs repaired with virgin micro-surfacing have rutting percentage of about 9.2 % for 2 days of aging and 6.5% for 5 days of aging. While, the HMA slabs repaired with recycled micro-surfacing have rutting percentage of about 8.1% for 2 days of aging and 5.9% for 5 days of aging. These results allowed the development of a prediction model based essentially on three predictor variables including cycle number, rutting state and percentage of water in the micro-surfacing material. The developed model shows a strong correlation between the predicted rutting values and the rutting values measured with the MLPC rut tester. Thermal aging in oven has a positive impact on the resistance to permanent deformation of new asphalt mixes and those rehabilitated with micro-surfacing. The parameters of rutting state and contribution water are significant in the rutting prediction model, while the cycle number remains a non-significant parameter in the model but determinant.展开更多
The main purpose of this article is to choose among advanced rheological models used in the French rational design, one that best represents the viscoelastic behavior of asphalt mixtures mixed with aggregates of Seneg...The main purpose of this article is to choose among advanced rheological models used in the French rational design, one that best represents the viscoelastic behavior of asphalt mixtures mixed with aggregates of Senegal. The model chosen will be the basis for the development of computational tools for stress and strain for Senegal. However, the calibration of these models needs complex modulus test results. In opposition to mechanical models the complex modulus can directly characterize the viscoelastic behavior of bituminous materials. Here determination is performed in the laboratory by using several types of tests divided into two groups: homogeneous tests and non-homogeneous tests. The choice of model will be carried out by statistical analysis through the least squares method. To this end, a study was carried out to “Laboratory of Pavement and Bituminous Materials” (LCMB) with asphalt concrete mixed with aggregate from Senegal named basalt of Diack and quartzite of Bakel. In this study, the test used to measure the complex modulus is the Canadian test method LC 26-700 (Determination of the complex modulus by tension-compression). There mainly exist two viewing complex modulus planes for laboratory test results: the Cole and Cole plane and the Black space. The uniqueness of the data points in these two areas means that studied asphalt concretes are thermorheologically simple and that the principle of time-temperature superposition can be applied. This means that the master curve may be drawn and that the same modulus value can be obtained for different pairs (frequency-temperature). These master curves are fitted during the calibration process by the advanced rheological models. One of the most used software in the French rational design for the visualization of complex modulus test results and calibration of rheological models developed tools is named Visco-analysis. In this study, its use in interpreting the complex modulus test results and calibration models shows that, the studied asphalt concretes are thermorheologically simple, because they present good uniqueness of their Black and Cole and Cole and Black diagrams. They allow a good application of the principle of time temperature superposition. The statistical analysis of calibration models by the least squares method has shown that the three studied models are suitable for modeling the linear viscoelastic behavior of asphalt mixtures formulated with the basalt of Diack and the quartzite of Bakel. Indeed their calibration has very similar precision values of “Sum of Squared Deviation” (SSD) about 0.185. However, the lower precision value (0.169) is obtained with the 2S2P1D model.展开更多
Pavement design tools are not universal. Indeed, in the sizing of pavements in the USA, the prediction models used in the calculation of the dynamic modulus of HMA are not adapted to the characterization of the minera...Pavement design tools are not universal. Indeed, in the sizing of pavements in the USA, the prediction models used in the calculation of the dynamic modulus of HMA are not adapted to the characterization of the mineral skeleton of the HMA mix designed with the French method.<span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">This article aims to assess the predictive models of the dynamic modulus used in the mechanistic-empirical design for their use in the design of bituminous pavements, and to develop new predictive models taking into account the sieve series LC and AFNOR standards. A total of six types of mixtures were subjected to the determination of complex modulus testing by direct tensile-compression on cylindrical specimens (26-700 LC) over a temperature range (5) and frequency (5) data. Dynamic modulus prediction models |</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">*| are studied Witczak model 1999 and model Witczak 2006. These models do not take into account the AFNOR or LC mesh sieve, an approach was made in relation to the US mesh sieve to replace </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">200</span></sub><span style="font-family:Verdana;"> (0.075 mm), </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> (4.76 mm), </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">38</span></sub><span style="font-family:Verdana;"> (9.5 mm) and </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">34</span></sub><span style="font-family:Verdana;"> (19 mm) respectively by the AFNOR mesh </span><i><span style="font-family:Verdana;">P</span></i><sub><span style="font-family:Verdana;">0.08</span></sub><span style="font-family:Verdana;"> (0.08 mm), </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">5</span></sub><span style="font-family:Verdana;"> (5 mm), </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">10</span></sub><span style="font-family:Verdana;"> (10 mm) and </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">14</span></sub><span style="font-family:Verdana;"> (14 mm). The result is the production of two models whose are evaluated by correlation with the values |</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">*|</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">of modulus measured in the laboratory is satisfactory (</span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.83 respectively </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.71 and </span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;">-value = 0.00). The optimization of these approximate models gave new models with the same frame as the original models and a better correlation with the data observed in the laboratory (respectively </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0. 95 and </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.91 </span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;">-value = 0.00).</span></span>展开更多
The most famous model known in prediction of dynamic modulus for asphalt concretes<span style="font-family:Verdana;"> is</span><span style="font-family:Verdana;"> the Witczak and ...The most famous model known in prediction of dynamic modulus for asphalt concretes<span style="font-family:Verdana;"> is</span><span style="font-family:Verdana;"> the Witczak and Hirsh models. These models didn’t use the mineralogical and chemical properties of aggregates. Witczak models used the passing or refusal percentage to sieve diameters and Hirsh model use</span><span style="font-family:Verdana;">d</span><span style="font-family:""><span style="font-family:Verdana;"> the volumetric analysis. All models developed until now considered that the aggregates were geotechnical conforming to standards. In this study the first mineralogical and chemical properties were considered through the percentage of silica in the rock source of aggregates and the electric aggregate particles charge zeta. Dynamic modulus values used for regression process are determined from complex modulus test on nine asphalt concretes mix designed with aggregate types (basalt of Diack, quartzite of Bakel and Limestone of Bandia).</span><span style="font-family:Verdana;"> Between Twelve initial inputs</span></span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> the statistical regression by exclusion process keeps only seven parameters as input for the model. The mineralogical model showed good accuracy with R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> equal to 0.09. The student test on the model parameters showed that all the parameters included in the model were meaningful with good p inferior to 0.05. The Fisher test on the model showed the same result. The analysis of the sensitivity of the mineralogical model to zet</span></span><span style="font-family:Verdana;">a potential showed that the dynamic modulus increase</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> <span style="font-family:Verdana;">with the positive zeta-potentials and decrease</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> with the negative zeta-potentials.</span><span style="font-family:Verdana;"> The analysis of the sensitivity of the mineralogical model to the silica showed that the dynamic modulus decreases with the increase of the silica.</span>展开更多
The mineralogical composition of an aggregate influences its adhesion with bitumen and therefore its dynamic modulus. However, few studies have been conducted on this aspect. One of the most used properties to describ...The mineralogical composition of an aggregate influences its adhesion with bitumen and therefore its dynamic modulus. However, few studies have been conducted on this aspect. One of the most used properties to describe the impact of aggregate on the adhesiveness phenomena is the zeta potential. In this study, the first mineralogical and chemical properties were considered through the percentage of silica in the rock source of aggregates and the electric aggregate particles charge zeta. Dynamic modulus values used for regression process are determined from complex modulus test on nine asphalt concretes mix designed with aggregate types (basalt of Diack, quartzite of Bakel and Limestone of Bandia). The results showed that aggregate with high percentage of silica have higher zeta potential than aggregate with low percentage of silica. The development of a zeta potential predictive model showed a strong sensitivity to silica. The results of the complex modulus tests showed that Hot Mixture Asphalt (HMA) mixed with aggregate containing high silica contents gave better results than those mixed with aggregates containing low percentage of silica. The dynamic modulus predictive models of HMA developed shows that it is the properties of bitumen that influence more. However, the effect of silica although low, is very marked at low temperatures and high frequencies.展开更多
Se<span style="font-family:Verdana;">veral studies show that properties of Hot Mixture Asphalt (HMA) mix design materials, aggregate gradation and volumetric properties had an influence on their resist...Se<span style="font-family:Verdana;">veral studies show that properties of Hot Mixture Asphalt (HMA) mix design materials, aggregate gradation and volumetric properties had an influence on their resistance to rutting. However, these properties do not impact in the same way this performance. For a given aggregate type</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> an infinity aggregate gradation type can be observed, and for each type of HMA several types of bituminous binder can be used. This article aims to measure the evolution of resistance to rutting according to the three main classes of National Cooperative Highway Research Program (NCHRP) aggregate gradation (dense-graded, fine-graded and coarse-graded).</span><span style="font-family:""> </span><span style="font-family:Verdana;">To this end, a study was conducted on the measurement of rutting resistan</span><span style="font-family:Verdana;">ce for eight bituminous mixtures manufactured with two bitumen type</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and two types of manufacturing aggregates. The results showed that there is a priority order of these different parameters on the influence of the resistance to rutting. This highlights a competition between the properties of aggregate and type of granular skeleton. Indeed, for the same type of aggregate, asphalt binder type first impact</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> resistance to rutting of the HMA followed by aggregate gradation, volumetric properties of the mix and finally by the angularity of the aggregates. However</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> this order cannot be fixed and can depend of the intensity of each parameter.</span>展开更多
In most countries, there is a low temperature limit to lay down hot asphalt mixes because if it is too cold, it becomes impossible to get proper compaction. For cold recycled bituminous mixture(CRM), there is little i...In most countries, there is a low temperature limit to lay down hot asphalt mixes because if it is too cold, it becomes impossible to get proper compaction. For cold recycled bituminous mixture(CRM), there is little information on the effect of the low temperature on their behavior. The goal of this study is to evaluate, in laboratory, the impact of the compaction and curing temperature on the behavior of CRM. To do so, CRM containing 50%reclaimed asphalt pavement(RAP) and 50% natural aggregates treated with foamed asphalt or bituminous emulsion were mixed and cured at different temperature between 0 and23℃ for up to 10 days before being tested in indirect tension. The results show that for all mixes, a cure at lower temperature means lower tensile strength, but the decrease is more noticeable for emulsion treated materials than for foamed treated mixes. The trend is not as obvious for Marshall stability results. A second cure at ambient temperature was also done, and the analysis of the results showed that the decrease in mechanical performance remains important even after a second cure at higher temperature for all mixes treated with bituminous emulsion, but there is some mechanical gain for mixes treated with foamed asphalt.展开更多
The primary aim of this study is to correlate the impact of aggregates,if any,on the viscoelastic behavior of rejuvenated asphalt mixtures containing very high amounts of reclaimed asphalt pavement(RAP)(>50%).First...The primary aim of this study is to correlate the impact of aggregates,if any,on the viscoelastic behavior of rejuvenated asphalt mixtures containing very high amounts of reclaimed asphalt pavement(RAP)(>50%).First,gradation of 100%RAP was rectified,using a modified Bailey method by adding virgin aggregates to achieve two coarse dense-graded and one fine dense-graded blends.Complex modulus test was then performed from−35 to+35℃and 0.01–10 Hz.In addition to performance grade(PG)testing,extracted and recovered binders from different asphalt mixtures underwent shear complex modulus test within−8℃to high temperature PG and frequencies from 0.001 to 30 Hz.Cole−Cole,Black space,complex modulus and phase angle master curves were constructed and ShiftHomothety-Shift in time-Shift(SHStS)transformation was used to compare the linear viscoelastic behavior of asphalt binders and mixtures.The influence of aggregates on the viscoelastic behavior of asphalt mixtures depends on temperature and/or frequency.The role of asphalt binders in the behavior of asphalt mixtures is more pronounced at high temperatures and the effect of the aggregate structure increases as the temperature falls.The maximum difference(60%to 70%)in the viscoelastic behavior of the binder and mixture based on SHStS transformed Cole−Cole curves is within the phase angle of 15°–20°.展开更多
Asphalt binders play a crucial role in the fatigue cracking resistance of asphalt pavement,making the characterization of their fatigue life increasingly important.To evaluate the fatigue life of asphalt binders,two t...Asphalt binders play a crucial role in the fatigue cracking resistance of asphalt pavement,making the characterization of their fatigue life increasingly important.To evaluate the fatigue life of asphalt binders,two tests have been developed:the time sweep(TS)and the linear amplitude sweep(LAS),both conducted using the dynamic shear rheometer(DSR).Similar to asphalt mixtures,predicting the fatigue life of asphalt binders necessitates the predefinition of fatigue failure criterion and/or fatigue failure definition(failure point).Phenomenological and dissipated energy-based failure criteria are commonly employed to analyze TS test results,while the viscoelastic continuum damage(VECD)model is primarily used to predict fatigue life through the LAS test.Given that the fatigue test temperature significantly impacts the fatigue life of asphalt binders,various methods have been proposed in the literature for selecting the fatigue test temperature.This paper provides a comprehensive review of the fatigue life evaluation of asphalt binders using both TS and LAS tests.It summarizes the different fatigue failure criteria and fatigue failure definitions employed and discusses the selection of fatigue test temperatures.Furthermore,the paper examines the influence of fatigue test conditions,binder chemical composition and/or penetration grade,and bitumen modification on the fatigue life of asphalt binders.Based on the current review,it is recommended to utilize the LAS test on PAV-aged bitumen under strain-controlled conditions to evaluate the fatigue life of asphalt binders.The most relevant failure definition is the peak in stored pseudo-strain energy based on the simplified viscoelastic continuum damage model(S-VECD).Additionally, the authors propose conducting the fatigue test at an intermediate referencetemperature for each country or region, depending on its climate zone.展开更多
文摘The work presented here is a study on the measurement and prediction of the rutting resistance of previously rutted asphalt mixes rehabilitated with a layer of micro-surfacing manufactured with virgin and recycled aggregates at different stages of aging. The experimental procedure consisted of rutting tests on hot mix asphalt slabs already degraded and repaired with virgin and recycled micro-surfacing. Then, the evolution of the behavior of micro-surfacing cast on the hot mix asphalt slabs is observed according to loading cycles of the pavement rutting tester MLPC. Before rutting tests, slabs are subjected to 24 hours at 50°C and aged for 2 days and 5 days at 85°C in the oven. The results showed rutting percentages of 6.3% for hot mix asphalt slabs aged for 2 days and 7.2% for 5 days. These hot mix slabs repaired with virgin micro-surfacing have rutting percentage of about 9.2 % for 2 days of aging and 6.5% for 5 days of aging. While, the HMA slabs repaired with recycled micro-surfacing have rutting percentage of about 8.1% for 2 days of aging and 5.9% for 5 days of aging. These results allowed the development of a prediction model based essentially on three predictor variables including cycle number, rutting state and percentage of water in the micro-surfacing material. The developed model shows a strong correlation between the predicted rutting values and the rutting values measured with the MLPC rut tester. Thermal aging in oven has a positive impact on the resistance to permanent deformation of new asphalt mixes and those rehabilitated with micro-surfacing. The parameters of rutting state and contribution water are significant in the rutting prediction model, while the cycle number remains a non-significant parameter in the model but determinant.
文摘The main purpose of this article is to choose among advanced rheological models used in the French rational design, one that best represents the viscoelastic behavior of asphalt mixtures mixed with aggregates of Senegal. The model chosen will be the basis for the development of computational tools for stress and strain for Senegal. However, the calibration of these models needs complex modulus test results. In opposition to mechanical models the complex modulus can directly characterize the viscoelastic behavior of bituminous materials. Here determination is performed in the laboratory by using several types of tests divided into two groups: homogeneous tests and non-homogeneous tests. The choice of model will be carried out by statistical analysis through the least squares method. To this end, a study was carried out to “Laboratory of Pavement and Bituminous Materials” (LCMB) with asphalt concrete mixed with aggregate from Senegal named basalt of Diack and quartzite of Bakel. In this study, the test used to measure the complex modulus is the Canadian test method LC 26-700 (Determination of the complex modulus by tension-compression). There mainly exist two viewing complex modulus planes for laboratory test results: the Cole and Cole plane and the Black space. The uniqueness of the data points in these two areas means that studied asphalt concretes are thermorheologically simple and that the principle of time-temperature superposition can be applied. This means that the master curve may be drawn and that the same modulus value can be obtained for different pairs (frequency-temperature). These master curves are fitted during the calibration process by the advanced rheological models. One of the most used software in the French rational design for the visualization of complex modulus test results and calibration of rheological models developed tools is named Visco-analysis. In this study, its use in interpreting the complex modulus test results and calibration models shows that, the studied asphalt concretes are thermorheologically simple, because they present good uniqueness of their Black and Cole and Cole and Black diagrams. They allow a good application of the principle of time temperature superposition. The statistical analysis of calibration models by the least squares method has shown that the three studied models are suitable for modeling the linear viscoelastic behavior of asphalt mixtures formulated with the basalt of Diack and the quartzite of Bakel. Indeed their calibration has very similar precision values of “Sum of Squared Deviation” (SSD) about 0.185. However, the lower precision value (0.169) is obtained with the 2S2P1D model.
文摘Pavement design tools are not universal. Indeed, in the sizing of pavements in the USA, the prediction models used in the calculation of the dynamic modulus of HMA are not adapted to the characterization of the mineral skeleton of the HMA mix designed with the French method.<span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">This article aims to assess the predictive models of the dynamic modulus used in the mechanistic-empirical design for their use in the design of bituminous pavements, and to develop new predictive models taking into account the sieve series LC and AFNOR standards. A total of six types of mixtures were subjected to the determination of complex modulus testing by direct tensile-compression on cylindrical specimens (26-700 LC) over a temperature range (5) and frequency (5) data. Dynamic modulus prediction models |</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">*| are studied Witczak model 1999 and model Witczak 2006. These models do not take into account the AFNOR or LC mesh sieve, an approach was made in relation to the US mesh sieve to replace </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">200</span></sub><span style="font-family:Verdana;"> (0.075 mm), </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> (4.76 mm), </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">38</span></sub><span style="font-family:Verdana;"> (9.5 mm) and </span><i><span style="font-family:Verdana;">ρ</span></i><sub><span style="font-family:Verdana;">34</span></sub><span style="font-family:Verdana;"> (19 mm) respectively by the AFNOR mesh </span><i><span style="font-family:Verdana;">P</span></i><sub><span style="font-family:Verdana;">0.08</span></sub><span style="font-family:Verdana;"> (0.08 mm), </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">5</span></sub><span style="font-family:Verdana;"> (5 mm), </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">10</span></sub><span style="font-family:Verdana;"> (10 mm) and </span><i><span style="font-family:Verdana;">R</span></i><sub><span style="font-family:Verdana;">14</span></sub><span style="font-family:Verdana;"> (14 mm). The result is the production of two models whose are evaluated by correlation with the values |</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">*|</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">of modulus measured in the laboratory is satisfactory (</span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.83 respectively </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.71 and </span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;">-value = 0.00). The optimization of these approximate models gave new models with the same frame as the original models and a better correlation with the data observed in the laboratory (respectively </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0. 95 and </span><i><span style="font-family:Verdana;">R</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 0.91 </span><i><span style="font-family:Verdana;">p</span></i><span style="font-family:Verdana;">-value = 0.00).</span></span>
文摘The most famous model known in prediction of dynamic modulus for asphalt concretes<span style="font-family:Verdana;"> is</span><span style="font-family:Verdana;"> the Witczak and Hirsh models. These models didn’t use the mineralogical and chemical properties of aggregates. Witczak models used the passing or refusal percentage to sieve diameters and Hirsh model use</span><span style="font-family:Verdana;">d</span><span style="font-family:""><span style="font-family:Verdana;"> the volumetric analysis. All models developed until now considered that the aggregates were geotechnical conforming to standards. In this study the first mineralogical and chemical properties were considered through the percentage of silica in the rock source of aggregates and the electric aggregate particles charge zeta. Dynamic modulus values used for regression process are determined from complex modulus test on nine asphalt concretes mix designed with aggregate types (basalt of Diack, quartzite of Bakel and Limestone of Bandia).</span><span style="font-family:Verdana;"> Between Twelve initial inputs</span></span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> the statistical regression by exclusion process keeps only seven parameters as input for the model. The mineralogical model showed good accuracy with R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> equal to 0.09. The student test on the model parameters showed that all the parameters included in the model were meaningful with good p inferior to 0.05. The Fisher test on the model showed the same result. The analysis of the sensitivity of the mineralogical model to zet</span></span><span style="font-family:Verdana;">a potential showed that the dynamic modulus increase</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> <span style="font-family:Verdana;">with the positive zeta-potentials and decrease</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> with the negative zeta-potentials.</span><span style="font-family:Verdana;"> The analysis of the sensitivity of the mineralogical model to the silica showed that the dynamic modulus decreases with the increase of the silica.</span>
文摘The mineralogical composition of an aggregate influences its adhesion with bitumen and therefore its dynamic modulus. However, few studies have been conducted on this aspect. One of the most used properties to describe the impact of aggregate on the adhesiveness phenomena is the zeta potential. In this study, the first mineralogical and chemical properties were considered through the percentage of silica in the rock source of aggregates and the electric aggregate particles charge zeta. Dynamic modulus values used for regression process are determined from complex modulus test on nine asphalt concretes mix designed with aggregate types (basalt of Diack, quartzite of Bakel and Limestone of Bandia). The results showed that aggregate with high percentage of silica have higher zeta potential than aggregate with low percentage of silica. The development of a zeta potential predictive model showed a strong sensitivity to silica. The results of the complex modulus tests showed that Hot Mixture Asphalt (HMA) mixed with aggregate containing high silica contents gave better results than those mixed with aggregates containing low percentage of silica. The dynamic modulus predictive models of HMA developed shows that it is the properties of bitumen that influence more. However, the effect of silica although low, is very marked at low temperatures and high frequencies.
文摘Se<span style="font-family:Verdana;">veral studies show that properties of Hot Mixture Asphalt (HMA) mix design materials, aggregate gradation and volumetric properties had an influence on their resistance to rutting. However, these properties do not impact in the same way this performance. For a given aggregate type</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> an infinity aggregate gradation type can be observed, and for each type of HMA several types of bituminous binder can be used. This article aims to measure the evolution of resistance to rutting according to the three main classes of National Cooperative Highway Research Program (NCHRP) aggregate gradation (dense-graded, fine-graded and coarse-graded).</span><span style="font-family:""> </span><span style="font-family:Verdana;">To this end, a study was conducted on the measurement of rutting resistan</span><span style="font-family:Verdana;">ce for eight bituminous mixtures manufactured with two bitumen type</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and two types of manufacturing aggregates. The results showed that there is a priority order of these different parameters on the influence of the resistance to rutting. This highlights a competition between the properties of aggregate and type of granular skeleton. Indeed, for the same type of aggregate, asphalt binder type first impact</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> resistance to rutting of the HMA followed by aggregate gradation, volumetric properties of the mix and finally by the angularity of the aggregates. However</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> this order cannot be fixed and can depend of the intensity of each parameter.</span>
文摘In most countries, there is a low temperature limit to lay down hot asphalt mixes because if it is too cold, it becomes impossible to get proper compaction. For cold recycled bituminous mixture(CRM), there is little information on the effect of the low temperature on their behavior. The goal of this study is to evaluate, in laboratory, the impact of the compaction and curing temperature on the behavior of CRM. To do so, CRM containing 50%reclaimed asphalt pavement(RAP) and 50% natural aggregates treated with foamed asphalt or bituminous emulsion were mixed and cured at different temperature between 0 and23℃ for up to 10 days before being tested in indirect tension. The results show that for all mixes, a cure at lower temperature means lower tensile strength, but the decrease is more noticeable for emulsion treated materials than for foamed treated mixes. The trend is not as obvious for Marshall stability results. A second cure at ambient temperature was also done, and the analysis of the results showed that the decrease in mechanical performance remains important even after a second cure at higher temperature for all mixes treated with bituminous emulsion, but there is some mechanical gain for mixes treated with foamed asphalt.
文摘The primary aim of this study is to correlate the impact of aggregates,if any,on the viscoelastic behavior of rejuvenated asphalt mixtures containing very high amounts of reclaimed asphalt pavement(RAP)(>50%).First,gradation of 100%RAP was rectified,using a modified Bailey method by adding virgin aggregates to achieve two coarse dense-graded and one fine dense-graded blends.Complex modulus test was then performed from−35 to+35℃and 0.01–10 Hz.In addition to performance grade(PG)testing,extracted and recovered binders from different asphalt mixtures underwent shear complex modulus test within−8℃to high temperature PG and frequencies from 0.001 to 30 Hz.Cole−Cole,Black space,complex modulus and phase angle master curves were constructed and ShiftHomothety-Shift in time-Shift(SHStS)transformation was used to compare the linear viscoelastic behavior of asphalt binders and mixtures.The influence of aggregates on the viscoelastic behavior of asphalt mixtures depends on temperature and/or frequency.The role of asphalt binders in the behavior of asphalt mixtures is more pronounced at high temperatures and the effect of the aggregate structure increases as the temperature falls.The maximum difference(60%to 70%)in the viscoelastic behavior of the binder and mixture based on SHStS transformed Cole−Cole curves is within the phase angle of 15°–20°.
文摘Asphalt binders play a crucial role in the fatigue cracking resistance of asphalt pavement,making the characterization of their fatigue life increasingly important.To evaluate the fatigue life of asphalt binders,two tests have been developed:the time sweep(TS)and the linear amplitude sweep(LAS),both conducted using the dynamic shear rheometer(DSR).Similar to asphalt mixtures,predicting the fatigue life of asphalt binders necessitates the predefinition of fatigue failure criterion and/or fatigue failure definition(failure point).Phenomenological and dissipated energy-based failure criteria are commonly employed to analyze TS test results,while the viscoelastic continuum damage(VECD)model is primarily used to predict fatigue life through the LAS test.Given that the fatigue test temperature significantly impacts the fatigue life of asphalt binders,various methods have been proposed in the literature for selecting the fatigue test temperature.This paper provides a comprehensive review of the fatigue life evaluation of asphalt binders using both TS and LAS tests.It summarizes the different fatigue failure criteria and fatigue failure definitions employed and discusses the selection of fatigue test temperatures.Furthermore,the paper examines the influence of fatigue test conditions,binder chemical composition and/or penetration grade,and bitumen modification on the fatigue life of asphalt binders.Based on the current review,it is recommended to utilize the LAS test on PAV-aged bitumen under strain-controlled conditions to evaluate the fatigue life of asphalt binders.The most relevant failure definition is the peak in stored pseudo-strain energy based on the simplified viscoelastic continuum damage model(S-VECD).Additionally, the authors propose conducting the fatigue test at an intermediate referencetemperature for each country or region, depending on its climate zone.
