Numerical study on the chemical and electrochemical coupling mechanisms for concrete under combined chloride-sulfate attack

Cementitious materials exposed to marine and saline environments are commonly threatened by a combined attack of sulfate and chloride ions. This study developed a numerical framework to investigate two combined coupling mechanisms of 1) coupled solid-liquid chemical reactions for competitive chloride-sulfate attack and 2) electrostatic multi...

Numerical study of interactive ingress of calcium leaching, chloride transport and multi-ions coupling in concrete

In circumstances with wastewater and seawater, the behavior of multi-ions including calcium, chloride and others in concrete attracts attention. The present study investigated the multiple mechanisms that could happen under the special field situation above, including calcium leaching, chloride transport and multi-ion coupling. To realize the...

A Numerical Study of Moisture and Ionic Transport in Unsaturated Concrete by Considering Multi-ions Coupling Effect

Understanding the transport mechanisms within unsaturated porous media is essential to the durability problems associated with cement-based materials. However, the involvement of multi-ions electrochemical coupling effect, especially under unsaturated condition makes the transport mechanisms even more complex. In this study, the moisture and...

Influence of coarse aggregate settlement induced by vibration on long-term chloride transport in concrete: a numerical study

High-frequency vibration helps to improve the compactness of concrete, but also causes the settlement of coarse aggregates (CAs) and then affects the durability of hardened concrete. In this paper, a numerical study combining multi-phase CA settlement model and multi-component ionic transport model is performed to understand the influence of...

Surface Modification of Steel Slag Aggregate for Engineering Application in Asphalt Mixture

The proper disposal of steel slag has always been a great challenge for the metallurgical industry in China and around the world. In this work, the steel slag aggregate (SSA) was surface pretreated (PSSA) and applied into asphalt mixture. The adhesive behavior between the bitumen and five different types of aggregates (i.e., limestone, diorite,...

Driving factors of land surface temperature in urban agglomerations: A case study in the pearl river delta, china

Land surface temperature (LST) in urban agglomerations plays an important role for policymakers in urban planning. The Pearl River Delta (PRD) is one of the regions with the highest urban densities in the world. This study aims to explore the spatial patterns and the dominant drivers of LST in the PRD. MODIS LST (MYD11A2) data from 2005 and...

An experimental and numerical investigation of coarse aggregate settlement in fresh concrete under vibration

Fresh concrete needs vibration to compact, fill the mould and reach a dense state. During the compaction process, coarse aggregates (CAs) tend to settle, affecting the homogeneity and eventually the long-term durability of hardened concrete. In this study, a 3-D, multi-phase numerical model for fresh concrete is developed for better...

A Time-Space Network Model for Collision-free Routing of Planar Motions in a Multi-Robot Station

This article investigates a new collision-free routing problem of a multirobot system. The objective is to minimize the cycle time of operation tasks for each robot while avoiding collisions. The focus is set on the operation of the end-effector and its connected joint, and the operation is projected onto a circular area on the plane. We...