Repeated Creep Test Research Articles

FARKLI DİATOMİT İÇERİĞİ İÇİN ASFALT KAPLAMA PERFORMANSININ DEĞERLENDİRİLMESİ

The majority of steel and reinforced concrete bridges are produced with asphalt pavement. The reason for this is to protect steel and concrete structures from the effects of water and degrading salt additives and to increase their durability. Asphalt bridge superstructures are mostly manufactured with four layers. These layers are the primer bonding layer, waterproofing layer, protection layer and surface asphalt wearing layers. The superstructure must protect the supporting substructure. It should protect the life of the structure and ensure the integrity of the structure against permanent deformation, aging, raveling, water damage and chemical effects. Diatomite additive is used as a performance enhancer in various aspects. It is generally preferred in the region of 5%-15% according to the bitumen mass. The granulometric size and chemical properties of the diatomite additive are other effective factors. In this study, the rutting resistance of conventional and diatomite-modified asphalt pavement for 5% and 10% ratios for selected diatomite additive gradation is investigated. The rutting resistance of the pavements is investigated by repeated creep tests for two different additive ratios on water-damaged and control mixtures. In unconditioned samples, 5% diatomite-modified mixtures; in conditioned samples, 10% diatomite-modified mixtures showed the greatest deformation resistance.

Digital image processing of warm mix asphalt enriched with nanocolemanite and nanoulexite minerals

Digital image processing (DIP) is a method used to view the internal structure of hot mix asphalt. However, in this study, the DIP of warm mix asphalt (WMA), which reduces environmental emissions and saves energy, was been investigated. Firstly, colemanite and ulexite minerals, of which the global reserves are abundant, were ground in a ball mill and nano-sized particles were observed for the first time in TEM micrograph. Secondly, these minerals were added to the foamed WMA in varying amounts of micron/nano-size. Marshall stability and repeated creep tests were performed and the void ratios in the mixtures were analyzed. Thirdly, a DIP system was designed. The primary purpose of this method was to scrutinize the impacts of voids and bitumen ratios around aggregates and the adhesion effect between the bitumen and aggregate. Finally, the void ratios identified by these tests were utilized to compare with those specified by the DIP method. The best deformation resistance for the ulexite appeared to result in a 5 %U + 53 μ mixture, whereas the highest deformation resistance for the colemanite yielded in 5 %C − 25 μ and 10 %C − 25 μ mixtures, according to repeated creep test results. The samples' void ratios identified around the aggregates were the lowest (1.35%) in the 5 %U − 25 μ mixture and the highest (3.72%) in the 10 %U − 25 μ mixture. It was concluded that the designed DIP was quite good in the interpretation of WMA with nanocolemanite and nanoulexite additives.

Evaluation of High-Temperature and Antireflection Cracking Performance of Warm Mixed Recycled Asphalt Mixture

To study the influence of temperature and reclaimed asphalt pavement (RAP) content (0%, 30%, 50%, and 70%) on the high-temperature performance and anti-reflection cracking performance of warm-mix recycled asphalt mixture, triaxial repeated creep tests and overlay tests (OT) based on digital image correlation technology (DIC) were used to analyze the high temperature and anti-reflection cracking performance of recycled asphalt mixtures. Based on the improved Burgers model, a permanent deformation (PD) model was established to evaluate the high-temperature performance of recycled asphalt mixtures. The anti-reflection cracking performance of recycled asphalt was quantitatively analyzed from macro and meso perspectives by using a macro index (load loss rate) and a meso index (vertical strain density DE). In addition, a reflection cracking damage model was developed by cumulative load loss rate relative change rate, and the fractal characteristics of reflection cracks were studied according to the fractal theory. The results show that with an increase in RAP content, the anti-deformation ability of a recycled asphalt mixture is enhanced, and the anti-reflection cracking performance becomes worse. However, with an increase in temperature, the anti-deformation ability of recycled asphalt mixture is weakened, and the anti-reflection cracking performance is enhanced. A PD mechanical model can well describe the high-temperature deformation resistance of recycled asphalt mixtures. The established reflection cracking damage model has high fitting accuracy and accurately describes the reflection cracking damage evolution process of recycled asphalt mixture. In addition, the analysis of the fractal characteristics of reflection cracks shows that the reflection cracks of a recycled asphalt mixture have fractal characteristics of statistical significance. DIC technology can be used to evaluate the anti-reflection cracking performance of recycled asphalt mixtures qualitatively and quantitatively from the mesoscopic perspective, which makes up for the current deficiency in macroscopic evaluation.

Effect of Freeze–Thaw cycles on the pavement performance of SBS modified and composite crumb rubber modified asphalt mixtures

The effect of freeze–thaw cycles on the pavement performance of SBS modified asphalt mixture (SBSMA) and SBS/crumb rubber composite modified asphalt mixture (CCRMA) was studied using a triaxial repeated creep test, semicircular bending fatigue test based on digital image correlation (DIC), and thermal stress restrained specimen test. The mechanical model of the residual strain (RS) of the asphalt mixtures is established, and the residual viscous flow strain (εRvf,N) and residual viscoelastic strain (εRve,N) are separated. Based on the horizontal strain (Exx) of DIC, a new mesofatigue damage variable (D) is proposed. According to the characteristic curve of D, the antifatigue damage parameter (AFDP) is established and the correlation between AFDP and fatigue life (Nf) is analyzed. Simultaneously, a calculation model of the relaxation temperature stress (σRts(T)) of the asphalt mixture at different cooling rates (v) is established based on the finite element method. Results showed that the growth rates of RS, εRvf,N, and D of both asphalt mixtures accelerate, AFDP decreases, and freeze–break temperature (TD) rises with increasing freeze–thaw cycles. However, the growth rates of RS, εRvf,N, and D of CCRMA are always slower than SBSMA, the AFDP is larger than SBSMA, TD is lower than SBSMA, εRve,N is a fixed value under specific conditions, and a good correlation exists between the AFDP and Nf. The pavement performance of the asphalt mixtures worsens after the freeze–thaw cycles, and the influence of a salt freeze–thaw cycles is greater than that of a water freeze–thaw cycles. Moreover, CCRMA has better high-temperature deformation resistance, fatigue damage resistance, and low-temperature cracking resistance than SBSMA. The conversion point temperature (TZ) increases with the acceleration of v, and the σRts(T) calculation model can accurately reflect the σRts(T) of the asphalt mixture at different v.

Effect of Glass Cullet Size and Hydrated Lime—Nanoclay Additives on the Mechanical Properties of Glassphalt Concrete

In this study, the use of glass waste as aggregate in asphalt mixtures was investigated. Maximum glass aggregate size options of 0.075, 2.00, 4.75 and 9.5 mm. were selected. Conventional bitumen, nanoclay-modified bitumen and hydrated lime-modified bitumen were used. Dense graded asphalt mixtures were designed according to the Marshall method. Mixtures were evaluated for low-temperature cracking, resistance to water damage, fatigue, and permanent deformation behavior with repeated creep, indirect tensile strength, indirect tensile fatigue, modified Lottman and Hamburg wheel tracking tests. Increasing glass aggregate size reduced the water damage resistance of asphalt mixtures because of the smooth surface of the glass particles and nanoclay and hydrated lime modification improved the mechanical properties of the asphalt mixtures. Using 2.00 mm sized maximum glass aggregate showed relatively less water damage and deformation properties due to higher internal friction which is due to the greater angularity of the glass particles. In addition, there was a significant correlation between repeated creep test, modified Lottman methods and Hamburg Wheel tracking test from the viewpoint of deformation and water damage assessments.

Laboratory investigation on thermal and road performances of asphalt mixture containing glass microsphere

To decrease the solar radiation heat entering the pavement, glass microsphere (GM) was selected as filler to replace limestone mineral filler (LMF) to improve the thermal resistance of asphalt mixture. The influence of GM on the thermal performance of asphalt pavement was studied by testing the thermal conductivity of asphalt mixture. It is found that the thermal conductivity could be reduced by 23.4%, which was beneficial to improve the cooling effect of asphalt pavement. A series of test, including dynamic repeated creep test, three-point bending test, dynamic modulus test and semi-circular bending test, were used to evaluate the influence of GM on the deformation resistance, low-temperature cracking resistance, dynamic performance and fatigue life of asphalt mixture. The results show that replacing LMF with GM negatively affected the above road performances of asphalt mixture. In further studies the actual rutting resistance of asphalt pavement with GM should be investigated by considering the cooled pavement structure and the elastic/creep performances of asphalt mixture.

An examination of nanoparticle colemanite mineral added warm mix asphalt

Warm mix asphalt (WMA) technologies which enable production at lower temperatures in pavement engineering have been developing. In the present study, the efficiency of colemanite mineral, which the largest reserve is located in Turkey, on the WMA technology was examined. In the first stage, natural colemanite mineral, which is a kind of boron, was milled in a high-energy ball mill for 30 min. The milled powder was sieved by using 53 μm and 25 μm sieves. For the size analysis; powder over the size of 53 μm (C + 53 μm) was preferred for micron size, and powder under the size of 25 μm (C − 25 μm) was preferred for submicron size/nanosize. Particle size distribution (PSD), morphology and element content properties of the powders were measured alternately by using a particle size analyzer, microscopes, and an energy dispersive X-ray spectrometer. In the PSD analysis, d50 values were detected as 91.102 μm for C + 53 μm powder and 7.063 μm for C − 25 μm powder. Additionally, dmin values were found to be 2188 nm for C + 53 μm powder and 275 nm for C − 25 μm powder. In the morphology analysis, the presence of particles below 100 nm (nanoparticles) was observed on a scanning electron microscope. In the elemental analysis, it was determined that there was no contamination in the powders. In the second stage, bitumen and asphalt mixture experiments were conducted. Bending Beam Rheometer test was conducted as the bitumen experiment for colemanite additive. Mixtures were prepared by adding C + 53 µm and C − 25 µm powders at 5% and 10% ratios for both. Marshall Stability, Indirect Tensile Stiffness Modulus and Repeated Creep Test experiments were performed on the produced asphalt briquettes. As a result, it was observed that the colemanite minerals which were stabilized by reducing them into nanosize improved the mechanical properties of asphalt samples.

Effects of Diatomite–Limestone Powder Ratio on Mechanical and Anti-Deformation Properties of Sustainable Sand Asphalt Composite

Diatomite has gained more and more interest as a new resource, since it has potential as a favorable alternative to mineral filler in the construction of asphalt pavement compared with ordinary limestone powder. In this paper, the mechanical and anti-deformation properties of sand asphalt composites with various proportions of diatomite were investigated by a uniaxial compression failure test, a uniaxial compression repeated creep test, and a low-temperature splitting test in order to determine the optimal replacement content of ordinary limestone powder. Five groups of sand asphalts with various volume ratios of diatomite to limestone (0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0) were determined by the simplex-lattice mixture design (SLD) method. The results reveal that the compression strength, anti-deformation properties, and low-temperature crack resistance of sand asphalts are improved through the use of diatomite. Furthermore, the optimal ratio (0.327:0.673) of limestone to diatomite is determined by the SLD method, according to secant modulus and creep strain results.

Effect of aggregate gradation on permanent deformation behavior of a warm mix asphalt

Abstract In this study, the rut susceptibility of warm mix asphalt (WMA) was evaluated by laboratory material characterization tests that included repeated creep testing using universal testing machine (UTM-5P) on WMA and conventional hot mix asphalt (HMA) mixtures. With regard to the fact that aggregate makes up a high proportion of volume and mass of mixtures, this parameter is considered as an important constituent of asphalt concrete. So, one aggregate source, three gradations and three different percentages of Sasobit® content were used to manufacture mixtures. Four creep parameters, namely, flow number (FN), creep stiffness (CS), creep strain slope (CSS) and secondary initial point (SIP), were used to analyze the test results. The primary objective of this research effort was to conduct a comparison between permanent deformation of HMA and WMA mixtures and also to evaluate the effect of aggregate gradation and different Sasobit® contents on introduced creep parameters. Analysis of data shows that the creep behavior of both asphalt mixtures (HMA and WMA) was influenced by aggregate gradation and also by Sasobit® content. Comparison of test results between HMA and WMA exhibits that, in general, WMA mixtures exhibit improved rut resistance compared to conventional mixtures. Also, it is concluded that creep strength of WMA mixes are more susceptible to change in aggregate gradation compared to HMA mixes, while increasing in Sasobit® content produce more stable mixtures. In addition, it is determined that finer aggregate gradations were more influenced by change in the Sasobit® content.

Evaluation of mechanical properties of nano-clay modified asphalt mixtures

Abstract This study aimed to investigate the performance of nano-clay modified asphalt mixtures. This study aimed to investigate the performance of nano-clay modified asphalt mixtures. Three different nano-clay materials were selected and each modifier was used with three different concentrations (2%-3.5%-5%) as substituted for filler. Modified Lottman including hot water conditioning (conditioning 1) and cold water conditioning (conditioning 2) systems were used. Models of water damage were used on half of the identical compacted samples. Cracking, stripping and rutting evaluations were realized with AASHTO T 283 Modified Lottman Test and repeated creep tests (RCT) with Nottingham asphalt tester (NAT). Indirect tensile strength (ITS) tests were realized with control and two types of conditioning systems but RCT were applied with control and Lottman water damage procedure. Nano-clay materials increased rutting resistance of samples with Lottman water damage conditioning method. 2%, 3.5% and 5% nano-clay modified mixtures were found as more rutting resistance than the conventional mixtures according to the AASHTO T283 conditioning. Indirect tensile strength tests were realized with Lottman moisture damage conditioning model. Higher tensile strength values were obtained with 2% and 3% nano-clay modified asphalt mixtures denotes that higher internal friction. Stripping damage of the modified mixtures was interrogated with the ratios of tensile strength concept. In the ratios of tensile strength, 2% each of three nano-clay modified mixtures gives higher ratios. Stripping resistance of the 2% nano-clay mixtures was found as higher than the control conditioned samples based on Modified Lottman Test. It is thought that nano-clay modifiers can be successfully used in view of higher stripping, rutting and cracking resistance with low ratio as 2%. Stripping resistance increased with increasing nano-clay concentrations in view of conditioning 2. As a result of the mechanical test approaches 2% nano-clay content is thought as a suitable ratio in context with stripping, rutting and cracking optimization.

EVALUATION OF SPEED EFFECT OF VEHICLES ON ASPHALT PAVEMENT

The main objective of this study was to investigate the speed effect of vehicles on the Hot Mix Asphalt. These effects were determined in terms of permanent deformation (rutting) and cracking since they are the major distresses in flexible pavement, which are caused due to overloading, speed of vehicles and high temperature variation. In this study, a total of 12 samples were prepared by Marshal Compactor. The Uni-axial repeated creep tests were carryout using a Universal Testing Machine (UTM-5P). The testing were done on asphalt samples for loading pulse period duration of 1,500 ms and pulse width of 200 ms (0.2 sec), 400 ms (0.4 sec), 600 ms (0.6 sec), 800 ms (0.8 sec), 1000 ms (1 sec) and 1,200 ms (1.2 sec). Two replicate samples were tested under each pulse width. The temperature was kept constant for all the samples, which was 40ºC. It was observed that with the increase in pulse width (i.e. loading time) the resilient modulus decreases. This is due to asphalt concrete behavior as visco-elastic material; which behaves like the elastic material at fast moving loads and then behaves like viscous material at slow moving loads. Hence increment in vehicle speed causes the pavement failure pre-maturely. Similarly, with the increase in pulse width the accumulated strain increases, which indicates that the low speed vehicles cause permanent deformation (rutting) to asphalt pavements.

Dynamic mechanical characterizations and road performances of flame retardant asphalt mortars and concretes

To research the dynamic mechanical properties and road performances of flame retardant asphalt mortars and mixtures, four different asphalt mortars/mixtures were prepared: a reference group and three asphalt mortars/mixtures containing composite flame retardant materials (M-FRs) of different proportions. Temperature sweep, frequency sweep, repeated creep test, force ductility test and bending beam rheological test were carried out to research the dynamic mechanical properties of asphalt mortars containing M-FRs; wheel-tracking test, low-temperature bending test and freeze-thaw split test were used to study the road performances of asphalt mixtures containing M-FRs. The results show that high-temperature performances of the three flame retardant asphalt mortars improve greatly, while low-temperature cracking resistances decline. Both high-temperature performances and water stabilities of asphalt mixtures containing M-FRs are quite good and exceed the specification requirements. However, their low-temperature performances decline in different degrees. In summary, besides their good flame retardancy, the flame retardant asphalt mortars and mixtures also exhibit acceptable road performance.

Rheological behavior of basalt fiber reinforced asphalt mastic

The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and the repeated creep tests. The results show that basalt fiber has excellent reinforced performances, such as high asphalt absorption ratio, low water absorption ratio, high tensile strength, high elastic modulus and high temperature stability. The rutting factor of the fiber reinforced asphalt mastic is higher than the plain asphalt mastic and the reinforced effects are more remarkable under high temperature. The rheological performances of the asphalt mastic demonstrate a good linear relationship between different temperature and loading frequency. The creep stiffness modulus of the asphalt mastic at different loading time can be expressed by power function. Improved Burgers model is used to represent the rheological behaviors of the asphalt mastic with basalt fiber and the model parameters are estimated.

Comparative study on the deformation behaviors of cement emulsified asphalt mortars

This study investigates the deformation behaviors of cement emulsified asphalt composite materials (CEACM) with varied cement content. Repeated creep test is implemented to measure the evolution of accumulated strains (\(\gamma_{\text{acc}}\)) with accumulated creep time. Burgers model and piecewise curve fitting are used to obtain the viscous component of creep stiffness (\(G_{\text{v}}\)) and creep compliance. The strain–time curves show that the \(\gamma_{\text{acc}}\) decrease significantly and creep-recovery ratios increase gradually with the increase of C/A. The analysis of \(G_{\text{v}}\) and creep compliance illustrates that the \(G_{\text{v}}\) of CEACM increase by orders of magnitude. A cement asphalt ration (C/A) of 1.0 maximizes the elastic component. Incidentally, for C/A is 1.2, the CEACM demonstrate remarkably rigid behavior.

Rutting susceptibility of asphalt concrete with recycled concrete aggregate using revised Marshall procedure

Natural aggregate is the primary ingredient of asphalt concrete and Portland cement concrete mixtures. Recycled concrete aggregate (RCA) derived from demolition wastes can be used in asphalt mixtures to eliminate potential problems arising from disposing these materials and conserve natural aggregate resources. This study presents methods for using RCA in asphalt mixtures based on repeated creep tests. The standard Marshall mixture design method is revised to prepare specimens satisfying the minimum size and aspect ratio requirement in uniaxial testing. The study shows that addition of RCA can improve the resistance of mixtures to permanent deformation and hence, rutting depending on mixture gradation.

Virgin and aged binder interaction measured on mixture bars via repeated creep in the dynamic shear rheometer

A repeated creep (RC) test was performed on mixture bars in the dynamic shear rheometer (DSR) to investigate the interaction of aged Reclaimed Asphalt Pavement (RAP) binder and virgin binder in different mixtures. The focus of the paper was testing compacted specimens made from 100% RAP and virgin binder. Three RAP sources were tested with three different virgin asphalt contents and two different 100% RAP mixing temperatures. A total of 144 torsion bars were prepared and tested. The overall result of the investigation was that the RC test does not appear optimal for the purpose of evaluating the interaction of 100% RAP mixed with virgin binder. One of the difficulties encountered was preparing torsion bars over a wide range of RAP material properties and virgin asphalt contents. The RC test was able to detect RAP source and virgin asphalt content, but was not able to capture potential differences in mechanical response due to differences in specimen mixing temperature.

Rutting analysis of 100 mm diameter polypropylene modified asphalt specimens using gyratory and Marshall compactors

Compaction technique used in Marshall design does not model the process of actual rolling procedures on site exactly. Carrying out laboratory compaction of dense bituminous mixtures with Superpave gyratory compactors is a more realistic way of simulating actual compaction. In this study, mechanical differences of reference and polypropylene modified asphalt mixtures were compared using Superpave gyratory and Marshall compaction methods by carrying out repeated creep tests utilising universal testing machine. In addition, there is no standard Superpave design procedure for 100 mm diameter samples till date. The other purpose of this study is to propose new standards for the compaction and testing procedures of these 100 mm specimens. Indeed, extensive studies have shown that the design gyration number should be 40 for reference and 33 for polypropylene modified specimens under medium traffic conditions for the similar and specific type of aggregate sources, bitumen, aggregate gradation, mix proportioning, modification technique and laboratory conditions. Moreover, it was shown that, the asphalt samples produced by Superpave gyratory compactor were much resistant to destructive rutting effects than the asphalt specimens prepared by Marshall design.

Evaluation of SBS modified stone mastic asphalt pavement performance

The purpose of this study is to research SBS polymer modified stone mastic asphalt (SMA) pavement performance. With this scope Marshall test (ASTM D1559) test was verified and optimal bitumen contents were calculated with experimental stages. At the optimal bitumen content control and SBS SMA mixtures were evaluated with Marshall Quotient (MQ) approach, repeated creep test (RCT), indirect tensile strength test (ITST), Laboratoire Central des Ponts et Chaussees (LCPC) Wheel tracking tests. According to the MQ results SBS modified samples gives higher values than conventional control mixtures. Higher MQ can be thought as more resistance to the plastic deformation. Controversial results can be obtained with MQ approach for some types of asphalt mixture gradations. Because of structural integrity and stone on stone contact gradation for SMA MQ approach gives more harmonious results. Efficiency of SBS polymer was confirmed with MQ method. Modified samples gave higher indirect tensile strength than control ones. RCT and LCPC wheel tracking test results shows that SBS modified mixtures have lower rutting values than the conventional mixtures.

Rutting prediction of asphalt mixtures modified by polypropylene fibers via repeated creep testing by utilising genetic programming

A novel application of genetic programming (GP) for modelling and presenting closed form solutions to the rutting prediction for polypropylene (PP) modified asphalt mixtures is investigated. Various PP fibers have been utilised for bitumen modification and repeated creep (RC) tests have been carried out. Marshall specimens, fabricated with multifilament 3 mm (M-03) type PP fibers at optimum bitumen content of 5% have been tested under different load values and patterns at 50 °C to investigate their rutting potential. It has been shown that the service lives of PP fiber-reinforced Marshall specimens are respectively longer than the control specimens under the same testing conditions (5 to 12 times). Input variables in the developed GP model use the physical properties of Marshall specimens such as PP type, specimen height, unit weight, voids in mineral aggregate, voids filled with asphalt, air voids, rest period and pulse counts. The performance of the accuracy of the proposed GP model is observed to be quite satisfactory. To obtain the main effects plot, detailed parametric studies have been performed. The presented closed form solution will also help further researchers willing to perform studies on the prediction of the rutting potential of asphalt without carrying out destructive tests for similar type of aggregate sources, bitumen, aggregate gradation, modification technique and laboratory conditions.

Creep Behavior of Geocell-Reinforced Recycled Asphalt Pavement Bases

AbstractThe use of recycled asphalt pavement (RAP) materials for roadway construction is a sustainable approach and has received more attention in the recent years. However, permanent deformation, or rutting, is one of the concerns in the use of RAP as a base course due to traffic loading and creep deformation. To minimize the creep deformation, use of a novel polymeric alloy (NPA) geocell was proposed to confine the RAP. One tensile creep test was conducted at a room temperature of approximately 25°C to investigate the creep behavior of the geocell. Nineteen static plate-loading tests were conducted at a room temperature using a medium-sized loading system to evaluate the applied vertical stress-displacement response, the creep strain—time relationship, and the factors influencing the creep deformations of RAP bases. In order to verify the repeatability of the test method, two repeated creep tests were conducted. Well-graded aggregate cover was used in place of the RAP cover to investigate the cover effe...