Various tests, focusing on the effects of the type and composition of cementitious materials (ordinary Portland cement, fly ash, slag, low-heat cement, and their combinations) on the mechanical properties and durability of high-strength concrete, were performed to provide experimental data for the application of high-strength concrete to prestressed bridges. Firstly, mix proportions were designed based on a number of trial mixes, taking into account their applicability to prestressed bridges. Mechanical properties, such as compressive strength, modulus of elasticity, splitting tensile strength and flexural strength, were determined. Durability related properties, such as temperature of hydration, resistance to chloride-ion penetration, resistance to freezing-thawing, autogenous and drying shrinkages and creep, were also determined. The effects of cementitious materials on the various properties of high-strength concrete have been demonstrated.

Many studies have been conducted using carbon-based nanomaterials (CBNs) for improving the electrical conductivity and mechanical properties of cementitious composites, but their practical use is yet to be achieved. Several methods have been attempted to secure the dispersibility in the cementitious composite matrix of CBNs, such as multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). In this study, MWCNTs and GNPs were noncovalently functionalized using melamine, a low-cost chemical, and ball milling, a simple process commonly used in industrial fields. Additionally, MWCNTs and GNPs having one- and two-dimensional shapes were mixed with the cement paste to examine their effect on electrical conductivity and compressive strength. Following the experiment, it was shown that the electrical conductivity was improved via the noncovalent functionalization of MWCNT and GNP. The compressive strength increased up to approximately 0.30–0.60% of the CBNs content; however, for CBN content higher than 0.60%, the compressive strength decreased. The hybrid MWCNT and GNP mixture had a negligible effect on the electrical conductivity and compressive strength.

This numerical study investigated the effects of different reinforcing details in beam-column joints on the blast resistance of the joints. Due to increasing manmade and/or natural high rate accidents such as impacts and blasts, the resistance of critical civil and military infrastructure or buildings should be sufficiently obtained under those high rate catastrophic loads. The beam-column joint in buildings is one of critical parts influencing on the resistance of those buildings under extreme events such as earthquakes, impacts and blasts. Thus, the details of reinforcements in the joints should be well designed for enhancing the resistance of the joints under the events. Parameters numerically investigated in this study include diagonal, flexural, and shear reinforcing steel bars. The failure mechanism of the joints could be controlled by the level of tensile stress of reinforcing steel bars. Among various reinforcing details in the joints, diagonal reinforcement in the joints was found to be most effective for enhancing the resistance under blast loads. In addition, shear reinforcements also produced favourable effects on the blast resistance of beam-column joints.

Water supply facilities such as waterworks systems are facilities that supply residential and industrial water essential for humans to live and it is essential for these facilities to be prepared for earthquake hazards. In the present study, new hydraulic analysis procedures that can complement problems in existing model were proposed for performance quantification under seismic hazards. Detailed procedures for estimating the serviceability of water supply networks using pressure dependent demand (PDD) and pressure dependent leakage (PDL) techniques were proposed. The developed methodologies can simulate many pipe leakage and breakage situations more realistically. The methodologies were applied to representative pipe networks to investigate the models and new performance quantification indicators were additionally presented. The developed models are judged to be usable as a basic tool finding for guidelines because they can simultaneously quantify the amount of leakage calculated from the viewpoint of suppliers as well as the water availability of consumers when an earthquake hazard has occurred.