Guohao Fang

Shenzhen University · Institute for Advanced Study

A novel microcapsule-based self-immunity system for reinforced concrete is proposed. Its feasibility for hindering the corrosion of steel rebar by means of lifting the threshold value of [Cl(-)]/[OH(-)] is discussed. Precisely controlled release behavior enables corrosion protection in the case of depassivation. The release process is characterized...

X-ray computed microtomography (X-ray μCT) method is proposed to trace the corrosion features of steel bar in cementitious materials. Three-dimensional corrosion morphology (including morphology of steel corrosion, corrosion products and cracks formation) are characterized and reconstructed. Experimental results demonstrate that X-ray μCT can track...

To promote the high-temperature application of alkali-activated fly ash-slag (AAFS), it is vital to thoroughly understand the performance of AAFS at elevated temperatures. This paper presents a systematic study on the multiscale microstructural evolution in AAFS paste in terms of nanostructure, chemical composition and morphology changes characteri...

In this study, we produced alkali-activated slag/red mud (AASR) pastes using sodium silicate as the alkali activator. The effects of Bayer red mud (RM) on the engineering and micro-properties of alkali-activated slag pastes were investigated. It was found that the decreased fluidity and the increased setting time of the fresh AASR pastes were achie...

Solid waste is considered a promising resource to manufacture environment-friendly building materials. A huge amount of sand-washing slurry is generally generated from construction sites and plants, and its improper accumulation can pose a major threat to the ecology and the environment. To reuse this sand-washing slurry, a porous cold-bonded ceram...

Cracks promote the rapid ingress of water into concrete and shorten the service life of concrete structures. As different deterioration factors form cracks of different sizes, it is necessary to study the water penetration mechanism in cracks. In this study, the capillary absorption process of cement pastes with different crack sizes was monitored...

Alkali and carbonate-enriched lime mud (LM) is a solid waste produced during alkali recovery in the paper-making industry. In the present work, high-volume LM was upcycled in fly ash and silica fume-blended Portland cement (FSPC), and its positive roles were investigated through hydration kinetics analysis, X-ray diffraction, thermogravimetric anal...

This paper presents an in-situ investigation of the microstructure evolution of fly ash and slag particles in alkali-activated fly ash-slag paste using X-ray microcomputed tomography. Results indicate that the dissolution of fly ash and slag particles is not uniform especially for the particles with large size due to the heterogeneous distribution...

This paper systematically investigates the micromechanical properties of interfacial transition zone (ITZ) in alkali-activated fly ash-slag (AAFS) concrete using nanoindentation, backscattered electron microscopy and energy dispersive spectroscopy. Results indicate that the micromechanical properties of ITZ depend on the chemical composition of rea...

Current demand for highly sustainable concrete, e.g. alkali-activated fly ash-slag (AAFS) concrete, urges understanding the links between microstructure and micromechanical properties of this binder. This paper presents a systematic investigation into the microstructure and micromechanical properties of AAFS paste from nano-scale to micro-scale. Na...

This paper investigates the mechanisms of microstructure evolution of interfacial transition zone (ITZ) in alkali-activated fly ash-slag (AAFS) concrete using scanning electron microscope. Results indicate that the formation of original ITZ depends on the so-called “wall effect”, leading to a deficit of large grains and a higher effective alkaline...

To mitigate autogenous shrinkage that may cause early-age cracking of alkali-activated fly ash-slag (AAFS) concrete, internal curing using superabsorbent polymers (SAP) is employed in this study. AAFS pastes with different SAP dosages (0-0.5%) and slag replacement ratios to fly ash (15-30%) are investigated. Experimental results indicate that with...

A novel type of microcapsule-based self-healing material which holds promise for crack-healing of concrete in a marine environment is designed and prepared, in which the calcium sulfoaluminate cement (CSA) is used as the healing agent. In the present work, X-ray microcomputed tomography (X-ray μCT) is innovatively applied to study the crack-healing...

Alkali-activated fly ash-slag (AAFS) concrete is a new blended alkali-activated concrete that has been increasingly studied over the past decades because of its environmental benefits and superior engineering properties. However, there is still a lack of comprehensive studies on the effect of different factors on the fresh and hardened properties o...

This paper aims to provide a better understanding of autogenous shrinkage of alkali-activated fly ash-slag (AAFS) pastes at very early age (<24 h). The autogenous shrinkage of AAFS pastes with 10%, 20% and 30% slag replacement ratios of fly ash is measured. The results show that increasing the slag content in AAFS pastes would accelerate the chemic...

Grouted splice sleeve connection is a crucial component in modular/prefabricated building structures. However, the reliability (e.g., crack-induced durability issues) of the grouting materials in the splice sleeve connection during their service life is hardly assessed. The external maintenance strategy is usually unimplemented. A capsule-based gro...

A novel chemical self-healing system, with sodium monofluorophosphate/ethyl cellulose microcapsules, is designed with the objective of inhibiting rebar corrosion in concrete materials under NaCl solution. The corrosive behavior is traced and analyzed in 3D visualization by the method of micro X-ray computed microtomography (X-ray lCT). Environmenta...

X-ray microcomputed tomography (X-ray μCT) method is proposed to trace steel corrosion and corrosion-induced cracking in cement paste. Experimental results show it can track the time-dependent development of steel corrosion and corrosion products, as well as the subsequent initiation and propagation of corrosion-induced cracks. Furthermore, the inf...

Two kinds of chemically-triggered self-healing systems with novel microcapsules are designed to protect rebar from corrosion in concrete. X-ray micro-computed tomography (XCT) method is employed to non-destructively visualize the protection performance and quantitatively evaluate the efficacy of the self-healing system in a wet-dry cyclic accelerat...

In this paper, a kind of novel ethyl cellulose (EC)/calcium hydroxide microcapsule to establish a self-immunity system based on increasing hydroxyl content for the reinforced concrete is proposed. The capacity for lifting the threshold value of [Cl⁻]/[OH⁻] in this system is feasibly evaluated. Different dosages of microcapsules are placed in the so...

In this paper, electrochemical impedance spectroscopy (EIS) is adopted as a nondestructive testing method for tracing the hydration procedure of aluminophosphate cementitious (APC) materials. A newly proposed electrochemical model is used to explain the hydration related features. The experimental results show that the electrochemical impedance beh...

ID No : 44 ABSTRACT This paper presents work toward the studying of a new family of self-healing cementitious material. This innovative system features the design of microcapsules with calcium sulfoaluminate cement (CSA) as healing agent. The aim of this study is to comprehensively monitor the whole crack-healing process of microcapsules based self...

ID No : 45 ABSTRACT This paper presents work toward the studying of a new family of self-immunity material that hold promise for cementitious material, expecially for reinfrocement concrete. This innovative material features the design of chemical self-immunity system for preventing the steel corrosion in reinforcement concrete. A novel type of mic...

To fulfil initially the intellisense and self-healing of concrete for corrosion of reinforcement by means of microcapsule technology, a novel chemical self-healing system based microcapsule technology was designed for cementitious composites, which was accompanied by a chemical trigger mechanism. The fundamental issue of this system was the smart r...