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To improve the availability of reclaimed asphalt pavement (RAP) in recycled hot mix asphalt (HMA), this study is focused on the mechanical performance of recycled HMA, which is beneficial for environmental conservation and consistent with the concept of sustainability. To alleviate the heterogeneity of the material composition of recycled HMA and enhance the usability and applicability of research means, micromechanical modeling is used to examine the modulus of recycled HMA, which is a critical parameter for asphalt pavement analysis. In this investigation, a four-layer built-in micromechanical model was constructed and derived to characterize recycled HMA. The micromechanical model indicated that the modulus of recycled asphalt was the main factor influencing the modulus of recycled HMA. Thus, the following study took the modulus of recycled asphalt as the main study subject. The frequency sweep test and three-point flexure beam test for recycled asphalt were designed and conducted to clarify the change trend of influence factors and further verify the reasonability and feasibility of the micromechanical model. Considering the diffusion behavior of the rejuvenator, the change trends of the factors are explored. The curing time apparently influences the modulus of recycled asphalt, followed by the curing temperature and the rejuvenator proportion. Finally, analytical results from micromechanical model matched well with the experimental results. The results of this study may be valuable for predicting the dynamic moduli of recycled HMA. • A four-layer built-in micromechanical model for recycled HMA is derived and validated. • The modulus of recycled asphalt prominently affects the modulus of recycled HMA. • The diffusion behavior of rejuvenators is considered in modulus research. [ABSTRACT FROM AUTHOR]

• Rutting Lab Test Comparisons – Practicality, Simplicity, and Repeatability. • Correlation of lab results with Field Rutting Performance. • Rutting Prediction Potential and Field Correlations. • HMA Screening Criteria using different Rutting Lab Test. Rutting or permanent deformation (PD) is one of the most critical distresses occurring in hot-mix asphalt (HMA) pavements. However, despite all of the recent efforts aimed at producing new test methods and better road materials, HMA rutting is still prevalent, particularly in hot regions and/or on highways with heavy truck-traffic loading. Laboratory testing to screen HMA mixes against rutting during the HMA mix-design stage thus constitute a vital step towards optimizing field performance. In this Texas case study, five laboratory test methods were comparatively evaluated for quantifying and screening four HMA mixes' rutting resistance potential relative to their field performance on in-service highway test sections under conventional traffic loading and climatic conditions. The five test methods included the dynamic modulus (DM), flow number (FN), repeated load permanent deformation (RLPD), simple punching shear test (SPST), and Hamburg wheel tracking tester (HWTT), respectively. The four HMA mixes evaluated included commonly used Texas fine-, coarse-, and porous-graded mixes. The data for the study, both laboratory and field performance including climate (temperatures) and traffic loading, were all extracted from Texas flexible pavements and overlays database, namely the Texas Data Storage System denoted as the DSS. Overall, all the laboratory test predictions correlated well with the actual measured field performance data, with the HWTT and SPST tests exhibiting superiority over the other test methods. As theoretically expected, the coarse-graded HMA mix out-performed the other mixes, with the fine- and porous-graded mixes being at the lower end of the spectrum. [ABSTRACT FROM AUTHOR]

• Clarify the effects of mixture gradation and polishing on nanoindentation results. • Characterize the age-hardening behavior of asphalt mixtures using nanoindentation. • Describe the vertical aging gradient in asphalt mixtures by nanoindentation. Understanding the aging behavior of asphalt mixtures is of great significance to the design, construction and maintenance of asphalt pavements. Numerous studies have been conducted on the aging phenomenon and its effects on mixture properties. However, conventional testing methods focus mainly on the global view or average value of the performance of aged mixtures, while the inner aging gradients are seldom addressed. The aging gradient, referring to the differences of aging effects in asphalt mixtures due to different accessibilities to aging conditions, represents the true aging behavior of asphalt mixtures. Hence, a micromechanical testing technique, nanoindentation, was used in this paper to investigate this issue. The effects of mixture gradation and polishing in sample preparation process on nanoindentation results were explored first. Then the vertical changes of modulus of asphalt mastic in asphalt mixture samples were characterized by nanoindentation to describe the aging gradient in different aged mixture samples. Dynamic modulus test was also performed for data supplement and comparison. Results show that gap-graded mixtures are suitable for nanoindentation test and a careful and standard polishing treatment will not affect the reliability of nanoindentation data. Nanoindentation can well characterize the age-hardening behavior of asphalt mastic and the aging gradient in long-term aged asphalt mixtures is approximately in a logarithmic curve form. Nanoindentation modulus results indicate that 8d of laboratory long-term aging in this paper can only affect the upper sections of dense asphalt mixtures. This paper suggests that nanoindentation can achieve a quantitative, mechanical and precise characterization of aging gradient in asphalt mixtures and is therefore promising in further research of asphalt materials. [ABSTRACT FROM AUTHOR]

Highlights • BOF slag has a great potential of recycling. • BOF slag is a heterogeneous and complex material. • Mechanical properties of the different phases were determined using a coupled SEM-microindentation system. • The macro-mechanical properties were estimated from mixing laws and compared to macroindentation results. • The BOF Slag recycling can be optimized based on the knowledge of their mechanical properties. Abstract Steel slags are industrial by-products of an integrated steel plant, characterized by their high calcium, siliceous and ferrous content. They prove useful in many fields, such as civil engineering and in the process of steelmaking for the iron-rich phases. For a better valuation, it is important to optimize the separation of its phases. To separate these phases, mineral processing technologies such as grinding followed by magnetic separation are used. The overall goal of this work is to determine the mechanical properties of each phase to improve grinding performance. The results show that all compounds have been clearly identified and mechanically characterized, which has led to a better understanding of BOF (Basic Oxygen Furnace) slag. Finally, a mixture law using the mechanical properties calculated from each phase made it possible to estimate the overall mechanical properties of the BOF slag. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CR blending properties with bitumen are highly influenced by the production process of CR. • High pressure water jet technology produces CR with rougher and larger surface area. • Larger rubber particle size (<1000 µm) increased the cold temperatures ductility. • CR increased modulus at higher temperatures and lowered it at lower temperatures. Abstract The quality of the bitumen modified with crumb rubber (CR) largely depends on the process parameters when blending CR with bitumen. The larger the specific surface of the CR particles, the better the final properties of the CR-modified bitumen. A novel high-pressure water jet (WJ) based technology has been shown to produce CR with a rougher and larger surface area compared to other traditional techniques such as mechanical shredding (ME) or cryogenic processing (CG). This, in turn, resulted in superior low temperature properties when used as modifier in bitumen. Specifically, the results showed a clear tendency of WJ technology to improve the strength in fracture toughness tests at −10 °C more so than CG and ME. The larger rubber particle size (<1000 µm) the higher the ductility of the material investigated showing improved performance under cold temperatures. From the rheological analysis, it can be concluded that addition of CR to bitumen increases the complex modulus at high temperatures and reduces stiffness at low temperatures. In comparison to SBS polymer modified bitumen there is a flattening of the complex modulus curve indicating less temperature susceptibility. This implies enhanced rutting resistance at high temperatures and enhanced low temperature cracking resistance at low temperatures for CR modified bitumen compared to neat and SBS modified bitumen. [ABSTRACT FROM AUTHOR]

Mixed solids (precursors) containing equal portions of ground granulated blast-furnace slag (GGBS) and sewage sludge ash (SSA) by weight were activated by mixed alkaline solutions that was comprised of sodium hydroxide and sodium silicate in prescribed proportions to prepare geopolymer pastes in a dry-mixed form. Tests were carried out to provide data on compressive strength and microstructural properties of the geopolymer pastes synthesized from different mass ratios of alkali to the mixed solids, i.e., Na 2 O content, and different molar ratios of SiO 2 to Na 2 O in the mixed alkaline solution (i.e. different moduli). The results showed that the maximum compressive strength of 32.8 MPa at 28 days could be achieved at the optimal Na 2 O content of 4.0% and a modulus of 0.95. Analyses of the microstructures of the geopolymer pastes by XRD, QXRD, FTIR, SEM and EDX revealed that SSA participated in the geopolymerization process and the quartz and hematite crystals in it were largely dissolved in the reaction. The microanalyses also revealed that the main reaction product of the optimal geopolymer mixture was a C-(N)-A-S-H type gel with Fe substitutions. The drying shrinkage of all specimens were less than 0.06% at the age of 14 days. Testing for metal(loid)s showed that SSA could be used with GGBS as precursor materials for geopolymerization with no leaching problems. This work provides a potential option to recycle SSA and builds up a theoretical basis for proportioning design in utilizing GGBS and SSA in dry-mixed geopolymers. [ABSTRACT FROM AUTHOR]

The silting of dams requires periodic dredging campaigns to maintain their functional capabilities. In Algeria, more than 32 million m 3 of sediment are deposited every year. In this paper, we investigate the case of the Bakhadda dam in western Algeria, whose dredged sediments can be valorised as an eco-geo-material for building construction in the form of compressed earth blocks (CEB). Preliminary hydro-mechanical study showed the need to amend the natural sediment with sand fraction up to 30% to reach the recommended characteristics of the standards, as granulometry, plasticity and mechanical properties. To achieve high mechanical strength, compaction energy equivalent to modified optimum proctor + 25 blows was required. The hydro-mechanical properties of the manufactured CEB were then studied. Water content effect on their mechanical properties was highlighted. In fact, the strength increases when water content decreases due to an increase in suction. Using the measured drying-wetting paths, relations were established between small strains modulus and water content and suction. Results of this study have led to the valorisation of natural dredged sediments in CEB which respond to the recommendations. Based on the hydric and mechanical tests carried out, the behaviour of CEB in situ was determined. [ABSTRACT FROM AUTHOR]

This paper describes the use of Spectral Analysis of Surface Wave (SASW) for characterizing rail track ballast and foundation layers. Surface wave testing on a rail track is more complicated than on soil sites or pavements due to the presence of large ballast void spaces, crossties, and rails as well as the complex variation of shear-wave velocity and Young’s modulus with depth. Young’s modulus is presented for both clean and fouled ballast in wet and dry conditions using the results of surface wave testing and SASW. Young’s modulus can be used to assess tie and track support at different locations, e.g. tie center and edge, under the applied loads. A portable surface wave system is described as well as its expansion to measure Young’s modulus under two ties in the same test. [ABSTRACT FROM AUTHOR]

A Mechanistic-Empirical (M-E) design based pavement quality or performance prediction methodology incorporating nondestructive test such as Ground Penetrating Radar (GPR) and Falling Weight Deflectometer (FWD) tests is demonstrated in this study. To facilitate, three pavement sites, namely, US285, US54, and I-40 in New Mexico are selected for nondestructive tests such as GPR and FWD. It is observed that the GPR predicted AC layer thickness is more consistent than base layer thickness. The FWD test was also conducted on the same locations, and like GPR, backcalculated layer moduli also shows varying level of inconsistency in different pavement sections. Based on the GPR and FWD tests, each of these three sites is divided into two major areas: one with the mean and the other with the minimum layer thicknesses and modulus. Layer thicknesses as well as moduli are incorporated to the AASHTOWare-ME software to determine load related distresses such as bottom-up crack and rut. Based on the amount of bottom-up cracks, the US54 pavement section is predicted to fail during 15th year of its service life, and the time of failure can be very early in the area with minimum layer thickness and modulus. Based on the rut prediction, pavement sections in US54 and I-40 is predicted to fail early. Finally, this methodology is recommended to implement to perform pavement quality assessment incorporating GPR and FWD tests in both project and network levels. [ABSTRACT FROM AUTHOR]

This paper describes the use of Spectral Analysis of Surface Wave (SASW) for characterizing rail track ballast and foundation layers. Surface wave testing on a rail track is more complicated than on soil sites or pavements due to the presence of large ballast void spaces, crossties, and rails as well as the complex variation of shear-wave velocity and Young’s modulus with depth. Young’s modulus is presented for both clean and fouled ballast in wet and dry conditions using the results of surface wave testing and SASW. Young’s modulus can be used to assess tie and track support at different locations, e.g. tie center and edge, under the applied loads. A portable surface wave system is described as well as its expansion to measure Young’s modulus under two ties in the same test. [ABSTRACT FROM AUTHOR]

• Flexural tensile strengths calculated with tensile and compressive differences are reduced by nearly 20 % when compared to those calculated without tensile and compressive differences. • A power function decay model of the tension–compression moduli of cement stabilized macadam was established in the four-point bending fatigue test. • The fatigue damage model of cement stabilized macadam was established and its accuracy was verified. Cement stabilized macadam (CSM) is a mixture created by combining cement as a binding material, water, and various particle sizes of minerals. The cement stabilized macadam material exhibits different moduli in tension and compression due to both its mechanical properties and the mechanical response in the asphalt pavement structure. To explore the strength, modulus and fatigue damage characteristics of CSM under different tensile and compressive modulus, this paper carried out the research. The calculation formulas for flexural tensile strength and tension–compression modulus were derived based on the difference in tension–compression modulus. A four-point bending strength test of CSM was carried out. Four-point bending fatigue tests with varying stress ratios were performed. It reveals deterioration laws of tension–compression modulus during fatigue process. The double logarithmic fatigue equation of CSM, as well as its nonlinear fatigue damage evolution equation, are established based on fatigue life results. The results of an analytical solution for fatigue life of rectangular section beams based on damage mechanics were obtained and compared to the results of four-point bending fatigue tests. The results reveal that the modulus of CSM differs in tension and compression. The calculated flexural tensile strength with the tension and compression difference is nearly 20 % lower than without the difference. The calculation approach that does not account for the difference in tension and compression overestimates the flexural tensile strength of CSM. The tension–compression moduli of CSM exhibit a power function decay law in the four-point bending fatigue processes. In the first stage, the dynamic modulus decays at a steady rate, accounting for 90 % of total fatigue life. The second stage in the life ratio of 0.9 occurs when the decay rate of the modulus rapidly increases and enters the stage of sharp decay. Based on the results of the four-point bending test, the modulus decay model was created. The decay parameter m has an exponential relationship with the stress ratio. The relative errors between the mean values of fatigue life tests and the predicted values of the analytical solutions range from 10.8 to 30.6 percent. The established fatigue damage equation for CSM can better reflect its fatigue damage evolution law. The research findings have great significance to solve the determination of pavement materials parameters based on the difference in tension and compression modulus. It also has a specific reference value for asphalt pavement design theory and calculation method when the varied modulus of tension and compression are considered. [ABSTRACT FROM AUTHOR]

• Validate the accuracy of nanoindentation in the characterisation of aging properties of asphalt materials. • Establish the relationship between DSR and nanoindentation viscoelastic analysis results based on interconverted creep compliance. • Non-destructive testing of the aging gradient of real pavements using nanoindentation. The aging of asphalt pavements has a serious impact on their road performance and service life., Therefore, it is necessary to characterise the aging behaviour of the actual pavement in service. The aging behaviour of asphalt pavements is difficult to characterise accurately due to the macroscopic nature of the aging indicators obtained by conventional testing methods. Nanoindentation (NI), as an emerging microscopic tool, has been increasingly used in the field of asphalt materials. It is necessary to verify the accuracy of nanoindentation in characterising the aging behaviour of asphalt materials. In this paper, a total of ten samples were selected for testing, corresponding to five states of aging for styrene-butadiene-styrene (SBS) modified and matrix asphalt respectively. The effects of aging on the micro-modulus and viscoelastic properties of the asphalt mastic samples were mainly characterised by means of nanoindentation. This is combined with Dynamic Shear Rheometer(DSR) frequency sweep tests and an attempt to establish a relationship between DSR and NI. Macroscopic characterisation of the aging behaviour of asphalt mastic is achieved. On this basis, the aging behaviour of the actual pavement was characterised using nanoindentation. The results show that the creep compliance of the asphalt mastic back-calculated by the DSR complex shear modulus is in good agreement with the nanoindentation creep compliance results. The accuracy of the nanoindentation characterisation of the aging performance is thus verified. The closer the aging of the actual pavement to the road surface the more pronounced the aging becomes. [ABSTRACT FROM AUTHOR]

• LWDs can facilitate deflection-based compaction control of open-graded aggregates. • No significant difference was observed between results from the two LWDs used. • Compaction in a mold can induce boundary effects for open-graded aggregate materials. • Nine seating drops ensured adequate contact between LWD plate and aggregate surface. • Five seconds of jackhammer compaction worked well for both aggregate materials. • Excessive compaction was found to destabilize the aggregate matrix in some cases. An ongoing research study is focusing on developing deflection-based compaction criteria for open-graded aggregate materials using Portable Impulse Plate Load Test Devices, such as the Light Weight Deflectometer (LWD). LWD tests were conducted on two different aggregate materials (ASTM # 4 and ASTM # 57) in cylindrical molds and a cubic wooden box with sides of 1.22 m. A scaled-up mold with a diameter of 304.8-mm was constructed and used for laboratory testing. Three different methods of compaction were used, and LWD testing was conducted after different levels of compaction. Nine (9) seating drops were necessary for LWD testing on open-graded aggregates. LWD testing in a mold was meaningful only for the large-diameter mold. Five seconds of compaction using a jackhammer was deemed to be adequate for stabilizing the aggregate matrix. Future tasks for this study have also been outlined in this paper. [ABSTRACT FROM AUTHOR]

Highlights: [•] Long rest periods and few loading cycles result in improved healing. [•] The effect of terminal cases on healing is greater than the effect of rest periods. [•] We established a universal healing evaluation index for asphalt binder. [•] The healing ranking of binders suggested by HIm-c, HIem-c and HIvm-c are the same. [•] The healing ranking of the binders is the same as the ranking of the corresponding. [ABSTRACT FROM AUTHOR]

Abstract: Pavement modulus and shear slip stiffness are two important parameters in determining the mechanical behavior of steel deck pavement. This paper proposed a new method to estimate these two parameters based upon elasticity and composite theory. A composite beam model with incomplete shear interaction was first established, from which equations for calculating beam deflection and pavement strain were deduced in terms of pavement modulus and shear slip stiffness. The equations were solved by a numerical approach to analyze the effect of parameters on deflection and strain distribution. Analytic results indicate that the influence of pavement modulus on strain distribution along beam depth at the mid-span section is more significant than that of the interfacial shear stiffness, but within the same order of magnitude. Moreover, the slip strain increases with the reduction of pavement modulus or shear stiffness. To verify the proposed model, a bending test was conducted on a steel deck–pavement composite beam at normal temperature. Based on the proposed method, a numerical back-calculation approach—discrete search iteration approach was established with detailed flow chart. Pavement modulus and shear slip stiffness were back-calculated from the test results of displacement and strain. It shows that pavement modulus is higher when shear slip along the deck–pavement interface is considered than that when shear slip is not considered. It was further concluded that pavement strain distribution could be predicted more realistically using the slip stiffness together with the exact pavement modulus. This study improves current simulation method of the behavior of a steel deck–pavement composite structure. The exact shear stiffness calculated based on the proposed method can also provide an index for bonding evaluation. [Copyright &y& Elsevier]

Abstract: Dynamic Mechanical Analysis was conducted on a polyurethane adhesive at different constant heating rates up to 100°C, covering the glass transition range. Different storage modulus degradation curves were obtained from different heating rates. The different temperature gradients through the specimen thickness, resulting from the different heating rates, did not explain these differences. The application of kinetic theory, however, enabled the modeling of the observed modulus degradation. The glass transition of a structural adhesive was considered as a kinetic process, during which secondary bonds break progressively, depending on their dissociation energy. Based on these results, it was demonstrated and concluded that modulus degradation is not only temperature-dependent but also time-dependent and therefore depends on the thermal loading history, which has to be taken into account to obtain reliable results. [ABSTRACT FROM AUTHOR]

• Basaltic crushed rock, pumice and recycled concrete aggregates were tested in the study. • Micro-indentation tests and Weibull analysis were implemented to measure hardness and modulus. • The data indicated the important influence of loading history on the measured hardness and modulus. • A qualitative analysis was performed examining the influence of the microstructure of the aggregates. • Elastic and plastic fractions from the load–displacement curves were quantified. Micro-indentation experiments were performed to study the correlation, both qualitatively and quantitatively, between microstructural characteristics and mechanical properties of three types of aggregates, including basaltic crushed rock, vesicular volcanic rock composed of pumice and recycled concrete aggregates. Emphasis was placed on the measurements of micro-hardness and modulus, and the influence of number of loading cycles. Despite the highly vesicular structure leading to edge chipping during indentation, pumice showed lower variability in indentation hardness and modulus values compared to basalt and recycled concrete aggregate. The number of indentation cycles had different influence on the crystalline structured recycled concrete aggregate and basalt compared to the amorphous structured pumice in terms of hardness and modulus values. Weibull statistics was used to support the important influence of the microstructural and textural characteristics of the aggregates on the bulk properties of the specimens, and different statistical parameters were introduced to characterise the aggregates. [ABSTRACT FROM AUTHOR]

• Machine learning models to link chemical information to phase mechanical properties. • Use easily obtainable imaging/chemical maps as inputs. • Demonstrates the applicability (or lack thereof) of ML models to complex microstructures. • Suggests potential options to overcome inaccuracies in multiple-material binders. This paper demonstrates the use of normalized intensities of chemical species obtained from energy-dispersive X-ray spectroscopy (EDS) as inputs to machine learning (ML) models, in order to predict the nanoindentation moduli (M) of different phases in a cementitious matrix. Single and multi-component blends belonging to conventional and ultra-high performance (UHP) pastes are evaluated using a variety of ML models. It is shown that the relative intensities of Ca, Si, and Al can be used to accurately predict the phase moduli in well-hydrated pastes with limited microstructural complexities, using all the ML models investigated. When data sets belonging to multiple binders or those for UHP pastes consisting of multiple materials and low degrees of reaction are considered, the accuracy of ML predictions are found to be significantly lower. This is partly attributable to the presence of mixed phases with widely differing chemistry-property relationships, and the lack of data for higher stiffness phases that exaggerate the skew-sensitivity of ML models like ANN. Potential data augmentation strategies to tide over some of these effects are suggested. [ABSTRACT FROM AUTHOR]

Motivated with sustainability and economic factors, there is a rapid increase in the use of recycled asphalt pavement (RAP) material in the construction of new asphalt pavements. This necessitates the development of better understanding of the interaction between recycled and virgin binders, as well as studying the influence of this interaction on the properties of the blended binder. This paper provides in-depth evaluation of these properties at various scales using chemical, mechanical and rheological tests. This study involved the use of binders with different proportions of RAP (0, 15, 25, 35 and 100%). The chemical characterization of these binders was carried out using Fourier Transform Infrared Spectroscopy (FTIR), and the results showed that higher peak levels of C O and S O bonds were observed with the increase in RAP binder content. Atomic Force Microscopy (AFM) imaging of these binders showed that the surface roughness increased with an increase in RAP content especially when the RAP proportion exceeded 25%. The multiple stress creep recovery (MSCR) test was used to measure the rutting resistance, and the linear amplitude sweep test (LAS) was used to evaluate the fatigue resistance. There was slight improvement in rutting resistance with an increase in RAP content; however, the fatigue resistance degraded with the addition of RAP. The moduli/stiffness of virgin, RAP and blended binders was determined using Dynamic Shear Rheometer (DSR), Nanoindentation (NI), and AFM. The moduli obtained from these three techniques increased exponentially and at similar rates up to 25% of RAP. However, the dynamic modulus from DSR increased at a higher rate than the nano-scale moduli at higher RAP contents. This finding suggests that the nano-scale interactions were not influenced by the increase in RAP content as the DSR measurements of dynamic modulus and fatigue life values imply. The nano-scale understanding of blended binder offers opportunities for better engineering and accommodation of RAP in asphalt mixtures. [ABSTRACT FROM AUTHOR]

• Morphological and stiffness of asphalt binders with high reclaimed asphalts were evaluated. • An Atomic Force Microscope (AFM) was used to evaluate nanoscale properties. • Rejuvenators are very effective to reduce the hardness of stiff asphalt binders. • The effects of rejuvenator are seen in the surface images obtained from the AFM. • Modulus values of stiff binders reduce significantly when rejuvenators are used. A properly formulated rejuvenator is a possible remedy for asphalt pavements with a high percentage of Reclaimed Asphalt Pavement (RAP), which is traditionally too stiff to resist premature damage due to fatigue cracking. Rejuvenated asphalt binders with high RAP have traditionally been evaluated by micro- and macro-level test methods, which are transcendental in providing binders' molecular level properties that govern their performance properties. This paper presents the usefulness of an Atomic Force Microscope (AFM) and its nanoindentation technique to observe morphological and nanomechanical properties of rejuvenated asphalt binders with high RAP. A commercial rejuvenator is applied in a Performance Grade (PG) (PG 64-22) binder blended with different percentages (25%, 40%, and 60%, by the weight of the blended binder) of a bulk RAP. The rejuvenated asphalt binder blends were subjected to routine tests such as Penetration, Rotational Viscosity (RV), and Dynamic Shear Rheometer (DSR) as well as the AFM-based PeakForce Quantitative Nanomechanical Mapping (PFQNM™) analysis. As expected, the routine test results reveal that the rejuvenator reduces the stiffness of the RAP-modified binders. The effects of rejuvenator on the RAP-blended binders are evident in the morphological images and nano-level mechanistic data. Based on the AFM test results, it is observed that modulus values of RAP blended binders reduced significantly when the rejuvenator was used. The findings of this study will benefit the pavement professionals for assessing the effectiveness of rejuvenators in asphalt binders with high RAP contents. [ABSTRACT FROM AUTHOR]

• High alkali dosages lead to obvious reduction in flexural strength after 7 days. • High moduli contribute to rapid setting and high compressive strength. • Increasing curing time improves resistance to chloride penetration. • Low alkali dosages provide continuous development in strength after 28 days. Cement industry has become one of important sources of greenhouse gas emission. Compared with the cement, alkali activated slag (AAS) possesses comparable mechanical properties and lower carbon emission during its production. It can thus be employed as an alternative binder for low-carbon construction. This paper investigated the effect of alkali contents, moduli, and curing time on flexural strength, compressive strength, drying shrinkage, setting time, and resistance to chloride penetration of AAS. Alkali contents ranging from 2% to 6%, moduli of 0.6, 0.9, and 1.2, and curing time of 7, 28, 90 and 180 days were adopted in the test. Test results have shown that high alkali contents shorten setting and accelerate development of compressive strength, but cause large drying shrinkage, deterioration in flexural strength and resistance to chloride penetration of AAS. Alkali contents ranging from 3% to 4% in AAS can achieve the setting time, flexural and compressive strength comparable to cement. Increasing moduli can accelerate setting, improve compressive strength and lower chloride penetrability, but increase drying shrinkage and reduce flexural strength of AAS. Continuous curing after 28 days can significantly improve flexural strength, compressive strength and resistance to chloride penetration of AAS mortar with alkali contents of 2–3%. Using 28-day compressive strength as an index for classification will underestimate the AAS with low alkali contents. Analytical models considering effect of alkali contents and moduli are proposed to predict relationships between flexural strength and compressive strength of AAS mortar and achieve a good correlation with experimental results. [ABSTRACT FROM AUTHOR]

• Slant shear apparatus developed for testing asphalt concrete. • Shear tests conducted at different temperatures and shear strain rates. • Time-temperature superposition principle is confirmed. • Shear modulus and strength values to be used for different loading conditions. Asphalt concrete is a viscoelastoplastic material and its behavior depends on temperature and time. Asphalt concrete used as impervious core in embankment dams is subjected to different loading conditions at different temperatures. A shear apparatus is described and used to investigate the stress-strain-strength behavior of asphalt concrete by carrying out shear tests at different temperatures and shear strain rates. The domains of shear modulus and shear strength values of asphalt concrete are established by applying the time-temperature superposition principle. Shear modulus and shear strength values of asphalt concrete for different loading conditions are compared. The documented behavior can be used in the design of the asphalt core in embankment dams. [ABSTRACT FROM AUTHOR]