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The strength and dilatancy of sand are mainly influenced by the void ratio, confining pressure and stress path. In engineering, the stress-strain relationship of sand in three-dimensional stress state is complicated, where the state-dependent properties of sand are difficult to be described by traditional constitutive models. Thus, fractional plastic models based on different fractional derivatives were developed to capture such state-dependent behavior of sand. This paper attempts to make a comparative study of the fractional models based on two typical fractional derivatives, i.e., the R-L derivative and Caputo derivative. The results show that the different types of fractional derivatives are mainly reflected in the different order of differentiation and integration, which will have a significant impact on the calculation of plastic flow direction, stress-dilatancy ratio and fractional order parameter β in the constitutive model. By determining the constitutive parameters of the two models, the constitutive behaviors predicted by different models were compared with the corresponding test results of saturated sands under different initial mean pressures and different stress paths. The models can reasonably simulate the test results of saturated sands, where the dilatancy characteristic can be captured. Compared with R-L model, Caputo model can predict more volumetric strain in the dilatancy process, and has better prediction effect. Overall, the predicted effects of the two models are close, with a maximum difference of about 7 %. • Fractional plastic models based on different fractional derivatives were developed. • Two typical fractional derivatives are compared between R-L and Caputo derivative. • Stress-dilatancy relationship for different types of fractional order models were analyzed. [ABSTRACT FROM AUTHOR]

• Setting time and engineering properties of BCSA concrete are studied. • Citric acid delays initial set from 15 min to as long as 3.5 h. • Retarding hydration does not affect the mechanical strength. • Design codes accurately predict the modulus of elasticity and tensile strength. This paper discusses the setting time and engineering properties (compressive strength, tensile strength, and modulus of elasticity) of belitic calcium sulfoaluminate (BCSA) cement and concrete. BCSA is an emerging alternative cement known for, among other things, its rapid setting behavior. This has long supported its use as a concrete repair material, but BCSA is also attractive for structural applications. Nevertheless, little information is available on the engineering properties of BCSA concrete. This paper quantifies the influence of mixture parameters on BCSA cement setting times, showing that they can be tightly controlled by altering the dosage of a citric acid retarder. It also quantifies the influence of mixture parameters and curing age on compressive strength, proposing predictive models and showing that retarding the hydration of BCSA does not affect its long-term strength. Finally, this paper measures the modulus of elasticity and tensile strength of BCSA concrete and attempts to predict these properties based on the compressive strength. Results suggest that predictive equations from ACI 318, CSA A23, and Eurocode-2 tend to predict the engineering properties of BCSA cement rather well. Together, these results support the feasibility of integrating BCSA cement into practical concrete construction. [ABSTRACT FROM AUTHOR]

Abstracts Environmental sustainability in transportation infrastructures can be achieved by using recycled materials. Commonly, road and airport pavement construction is identified as a greatly polluting factor for greenhouse gas and odor emissions. This paper presents a case study concerning two rehabilitation methods adopted in a reconstruction project of two taxiway pavements in a major Italian airport. The paper describes the entire process of rehabilitation works starting from the preliminary investigations to the final quality controls. It includes the pavements design phase and the materials optimization and environmental assessment, which is the core of the research. The findings show that recycling does not necessarily result in lower performance. In fact, up to 65% of CO 2 e emissions were saved by constructing the recycled pavements. Performance was instead comparable to a standard asphalt pavement. Finally, the paper shows the eco-efficiency of including low-energy treatments and sustainable strategies into pavement construction to enhance environmental savings and cost effectiveness in airport construction practices. [ABSTRACT FROM AUTHOR]

• Methods to evaluate the protective ability of rust layers on weathering steels (WS). • Corrosion problems in WS structures. • Testing, inspection and maintenance of WS structures. • Advanced WS. • Painting of WS. The atmospheric corrosion of weathering steel (WS) has been extensively discussed in the scientific literature, but a comprehensive overview of this topic from an engineering viewpoint is currently lacking. The present publication seeks to fill this gap, providing engineers, designers and steel manufacturers with an insight into the current state of knowledge on this important structural material and presenting key research findings in a way that promotes their practical application. The Part II of this review sets out the methods available to evaluate the protective ability of rust layers and describes testing, inspection and maintenance techniques. The paper ends with a number of examples of corrosion problems in WS structures, an overview of new advanced WS, and considers the painting of WS in highly corrosive atmospheres. [ABSTRACT FROM AUTHOR]

• CLSM made using silty soil as only aggregate is feasible for structural fills. • The flowability of CLSM decreases with the increasing RM content. • The optimal mass ratio of RM/cement is 0.5 for engineering properties of CLSM. The aim of this paper is to investigate the feasibility of controlled low-strength materials (CLSM) made from silty soil as the only aggregate, together with local red mud (RM) and portland cement as binder on structural fills. The results indicate that water to solid ratio of 0.46 satisfies the flowability and initial setting time demand, and the RM content less than 7.5% satisfies the strength and impermeability demand. RM has a significant influence on the engineering properties of CLSMs. At 3 d, the properties containing unconfined compressive strength, direct shear strength, and impermeability decrease with the increase of RM content. However, these properties initially increase and then decrease with the increase of RM content from 7 to 28 d, the optimum mass ratio of RM to cement is 0.5. The mechanism is summarized as a filler effect, an alkali environment effect, and a pozzolanic effect. [ABSTRACT FROM AUTHOR]

The composite material TRC results from the combination of a fine-grained cement matrix and a textile reinforcement. This composite has good mechanical properties and, depending on the nature of the matrix, good acoustic isolating properties and fireproofing can be considered. One of the potential applications of this new generation composite deals with sandwich panels via thin facings. Although studies of TRC sandwich panels are rare, it is the finite element approach which is quite preferred for studying their quasi-static mechanical behavior. Although interesting and useful, this approach requires excellent mastery of computer software given the many nonlinearities that should be included. This paper aims to provide a non-linear calculation procedure of TRC-facings sandwich panels with the following main properties: (i) the use of materials “real” behavior law (ii) the use of numerical methods (iii) the application of arbitrary combination loads and (iv) allowing to study both global and local behavior. This procedure is based on (i) the cross-section and length of the panel meshing and (ii) the non-coupling of bending, shear and local bending effects of the mechanical behavior of the panel. A sensitivity study is further performed to evaluate the evolution of the relative error depending on the mesh size. Finally, using the results obtained from an experimental campaign on TRC-facings sandwich panels, a theoretical/experimental confrontation on a global scale (load-deflection behavior and failure mode) and local (strain development) will be performed. This will permit us, on one hand, to emphasize the good reproduction of the results given by the method on a global scale and, on the other hand, some limitations to the local scale where possible explanations are proposed. [ABSTRACT FROM AUTHOR]

• Healing efficiency theory developed based on geometric probability. • New self-healing capsules, called engineered aggregates, are introduced. • Self-healing efficiency calculated for different cracking conditions. • Effect of size, shape and dosage of capsules on healing efficiency is evaluated. This paper presents optimal self-healing configurations in concrete using a new concept referred to herein as engineered aggregates (EA). EA are hollow particles designed to carry healing agents into the cracks in concrete. The concept of EA has been developed by the authors as a cost-effective method for self-healing in conventional concrete without having to modify the existing materials or mixing procedures. EA have an internal brittle capsule carrying the healing agents and they are covered with a cementitious coating. They are similar in size to a concrete coarse aggregate and they are added during the mixing process replacing a portion of the coarse aggregates. Similar to other self-healing materials with cast in capsules, one of the basic requirements of EA is that when concrete cracks, the cementitious coating and the embedded brittle capsule break to release the healing agents into the cavity of the crack. The goal of this study is to identify the optimal shapes and sizes of EA that can be effectively used in self-healing concrete while minimizing the volume fraction of the added healing agent (and thereby EA). The tools of geometric probability are used to determine the probability of intersection of cracks with EA and the probability of healing of cracks with different geometries: a single crack, parallel cracks, mapping cracks and multiple discrete penny-shape cracks. As such, the optimal size and shape of EA are selected based on the density and type of cracking that might occur in concrete. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PU prepolymers can chemically react with the base asphalt. • The PU has superior high-temperature stability, adhesion strength, and durability to asphalt. • The anti-aging performance of PU sealants is always a great concern. • High-density PU foam injection has been implemented as an alternative to the conventional cement. • PU-bonded mixture can improve the performance and extend the service life of pavements. In the past decades, Polyurethane (PU) as an emerging polymer material has been widely used to construct, repair, reinforce, and protect civil engineering infrastructures. Meanwhile, various PU-based materials are increasingly employed in pavement engineering for new construction and maintenance, due to their excellent physical and chemical properties. In this review paper, the synthesis method, chemical structure, and engineering properties of PU materials were first introduced briefly. Secondly, the practical applications of PU materials in pavement engineering at present were summarized, mainly including PU-modified asphalt, PU-bonded mixture, PU sealant, and PU foam injection. Finally, the potential economic benefits and environmental impacts of utilizing PU materials in pavement engineering were further discussed towards sustainability. [ABSTRACT FROM AUTHOR]

• Experimental study is incorporated within performance-based durability engineering. • Both exposure and deterioration models are verified by experimental data. • Effects of 2D chloride transport and non-uniform corrosion on PBDE are investigated. • Effects of changing climate and repair input on decision information are studied. Reinforced concrete (RC) structures under marine atmospheric environment usually suffer from chloride ingress, which could impair structural serviceability and performance within the service life. Performance-based engineering, as an approach to design structures with predictable and defined performance, has attracted increased attention. In this paper, the developed probabilistic performance-based durability engineering (PBDE) approach is used as a novel attempt to integrate different computational modules (i.e., exposure analysis, deterioration, repair analysis, and impact/consequence analysis) within the durability assessment and management process of RC structures incorporating the experimental results. To begin with, a probabilistic environmental model is developed using the measured data to account for global warming, the seasonal and daily variation of temperature, etc. Additionally, deterioration analysis is conducted considering two-dimensional chloride transport and non-uniformity of corrosion. The experimental studies are conducted to verify the relevant numerical results. Subsequently, consequence analysis is performed to aid the maintenance process of RC structures. Uncertainties associated with material properties, model, and environmental scenarios, as well as the effect and cost of maintenance actions, are incorporated within the developed framework, which is illustrated using a real-world example. Compared to the traditional durability assessment approach, non-uniformity of corrosion, 2D convection-dominated chloride transport model, and climate change effects are assessed in a probabilistic manner. [ABSTRACT FROM AUTHOR]