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Engineered cementitious composites (ECC) have been manufactured by mixing the treated municipal solid waste incineration (MSWI) bottom ash (BA), ordinary Portland cement, fne silica sand and Polyvinyl Alcohol (PVA) fber. Characterizations including X-ray fuorescence (XRF) and laser difraction have been performed on four types of BA powders obtained by combined treatments, and the chemical compositions and particle size distribution of those BA powders are derived. The mechanical properties of BA powders in mortar as cement replacement are tested to determine their reactivity. BA powder with highest reactivity completely replaces the fy ash in ECC, and its contribution to strain hardening of composites is investigated. Results indicate that mortar mixed with BA fnes prepared by thermal treatment followed by ball milling has the best mechanical properties. After 28 days of curing, the fexural and compressive strength of this mortar reach 82% and 81% of the reference, respectively. The strength activity index meets the requirement of not less than 70% specifed in the Chinese standards. The increase of BA powder not only reduces the frst crack strength of ECC but also reduces the ultimate tensile strength of the composites. Fortunately, the strain hardening properties of ECC are improved. In addition, the highest ductile tensile properties are obtained in ECC with BA fnes to cement ratio of 2.2. This research provides a strategy in making use of vast resources BA obtained from MSWI. [ABSTRACT FROM AUTHOR]

This paper describes a bi-linear cohesive zone model to simulate fatigue behavior of asphalt concrete. To demonstrate the gradual degradation of cohesive properties of asphalt concrete under cyclic loading, a fatigue damage evolution law was integrated into the cohesive zone model. The model was then implemented in commercial finite element software ABAQUS using a user-defined subroutine. A damage extrapolation scheme was adopted to reduce computational cost for high-cycle fatigue applications. Based on the proposed model, a flexural beam fatigue test was finally simulated. The fatigue lives and other features of damage evolution obtained through numerical analysis are in consistence with experimental data, which indicates that the proposed cohesive zone model could be applied to predict fatigue damage of asphalt concrete with good accuracy. During the fatigue loading process, stiffness decreases linearly while damage accumulates non-linearly and grows faster with the increase of fatigue damage. The duration of crack propagation stage is much shorter than the damage initiation stage. The tensile stress at the crack tip increases with the propagation of fatigue crack. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the residual strength of reclaimed asphalt pavement (RAP) to understand the strength forming mechanism of RAP in cold recycled asphalt mixture. The mechanical properties of the RAP were investigated as compared to the properties of pure aggregates. Triaxial shear tests were conducted to analyze the residual cohesion of asphalt binder in the RAP. The gradation and specific surface area of RAP were analyzed to understand the agglomeration structure of coarse RAP particles. Splitting strength of cement-RAP mixtures was tested as compared to cement-aggregate mixtures. It can be concluded that the RAP in the cold recycled asphalt mixture does not act exactly like "black color" aggregates. The aged asphalt in the RAP has active cohesion although its cohesion strength is much lower than the binder in the hot-mix asphalt mixture. The coarse RAP particles formed by agglomeration of fine particles and the aged binder have important influences on the strength of cold recycled asphalt mixtures. The cement-RAP mixture has much lower splitting strength than the cement-aggregate mixture with the same gradation and cement content. It is important to add new aggregate into the recycled mixture to increase the effective aggregate surface area that can be coated with the new binder. [ABSTRACT FROM AUTHOR]