This paper investigates the properties of steam cured recycled aggregate concrete (RAC), in an attempt to determine the optimum conditions of the steam-curing cycle for RAC, and incorporating high early strength cement (HESC). Varying conditions of steam curing were employed. The steam-curing cycle was set based on the peak temperature, and the duration for which the peak temperature was maintained. Three peak temperatures were used for steam curing, 50 °C, 60 °C, and 70 °C, maintained for up to two hours. The compressive strength results indicated that the steam-curing cycle employing the peak temperature of 50 °C maintained for one hour with a total duration of four hours was the optimum for strength development, both at the early and late stages of hydration. Determining the optimum steam-curing temperature and duration will help reduce the associated curing cost, thus further economizing the production cost of recycled aggregate concrete.

In this paper, comparative assessment of failure fatigue lives of thin laminated cementitious composites (LCCs) modeled by two modeling approaches—double-parameter Weibull distribution model and triple-parameter distribution model—was carried out. LCCs were fabricated of ordinary Portland cement (OPC), fly ash cenosphere (FAC), quartz sand, and reinforcing meshes and fibers. The failure fatigue life assessment at various probabilities by the two-parameter model was based on numerical calculations whereas the three-parameter model was applied by an open source program—ProFatigue^®. Respective parameters, shape and scale parameters in the two-parameter Weibull distribution model while shape, scale, and location parameters in three-parameter model were determined, and the corresponding probabilistic fatigue lives at various failure probabilities were calculated. It is concluded that the two-parameter model is more accurate in probabilistic fatigue life assessment of double-layer mesh-reinforced LCCs, whereas for single-layer reinforced LCCs, both models could be used at a fair confidence level.

Conventional concrete is a brittle material with a very low tensile strength as a result of compressive strength and tensile strain. In this study, the flexural behavior characteristics of slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs) based on slurry-infiltrated fiber concrete (SIFCON), such as high-performance fiber-reinforced cementitious composites (HPFRCCs), were analyzed to maximize the fiber volume fraction and increase resistance to loads with very short working times (such as explosions or impacts). For extensive experimental variables, one fiber aspect ratio and three fiber volume fractions (6%, 5%, and 4%) were designed, and the flexural toughness and strength were figured out with respect to variables. A maximum flexural strength of 45 MPa was presented for a fiber volume fraction of 6%, and it was found that by increasing the fiber volume fraction the flexural strength and toughness increased. The test results with respect to fiber volume fraction revealed that after the initial crack, the load of SIFRCCs frequently increased because of the high fiber volume fraction. In addition to maximum strength, acceptable strength was found, which could have a positive effect on brittle fractures in structures where an accidental load is applied (such as an impact or explosion).

As jointed plain concrete pavements (JPCP) age in South Korea, the cost of pavement maintenance is increasing annually. To extend the life of jointed concrete pavements through preventive maintenance, this study used 2017 pavement management system data to analyze the effects of traffic volume, alkali–silica reaction (ASR) grade, age, smoothness, and damaged area on the remodeling index (RMI—a measure of expressway pavement condition). In addition, this study evaluates the final RMI as well as the corresponding pavement condition and change in RMI value after conducting preventive maintenance in lieu of resurfacing or overlaying. The results demonstrated that the effect of ASR grade increased as the RMI forecast year increased and that change in surface distress (△SD) increased with age (most intensively when the pavement was 15–20 years of age). Moreover, change in international roughness index (△IRI) increased with age and traffic volume (similarly within 15–20 years of pavement age). Hence, preventive maintenance is a must for sections with high traffic volume and age even if the RMI is low. Finally, performing repairs through preventive maintenance decreases the number of expressway sections requiring resurfacing and overlaying, thus extending the life of the concrete pavement.