Mingzhong Zhang

• PhD, Delft University of Technology, 2013
• Professor (Associate) at University College London

In recent years, an increasing number of attempts have been made on the utilisation of carbon-negative aggregates (CNA) produced from calcium/magnesium-rich solid wastes through carbon mineralisation for low-carbon concrete production. This paper presents an experimental study on the effect of CNA as an alternative to river sand on the engineering...

3D printed engineered cementitious composites (ECC) exhibit remarkable ductility and superior crack control that enhances the load-bearing capacity and toughness of 3D printed structures. Optimising the printing paths across various orientations can effectively reduce the anisotropy in mechanical behaviour of 3D printed concrete. To date, a compreh...

When serving in the marine environment, reinforced concrete structures are prone to be attacked by chloride ingress, which generally co-occurs with varying humidity and temperature changes. Therefore, considering the interaction between moisture transport and heat transfer, and their individual and coupling effects on chloride transport, this paper...

Comparison of three-dimensional (3D) printing and cast methods on the mechanical properties of cementitious materials is the basis for intelligent construction development. To achieve this, a series of experiments including the uniaxial tensile, compressive, flexural and interlayer bonding tests of mould-cast and 3D printed (3DP) specimens are cond...

This paper represents a critical review on alkali-activated materials (AAM) containing organics with high homogeneity at nano-scale (<1 μm). Organics including organosilicons, surfactants, water-soluble polymers and epoxy resins can contribute to performance enhancement and tailorability of AAM based on their molecular characteristics. Hence, AAM w...

The substantial energy consumption and CO2 emissions associated with the production and transportation of concrete and its components have necessitated the search for suitable replacements, particularly waste materials such as plastic, to mitigate their environmental impact. The emergent challenge of employing recycled waste plastics (RWP) in concr...

Pore structure characteristics of cementitious materials play a critical role in the transport properties of concrete structures. This paper develops a novel framework for modeling chloride penetration in concrete, considering the pore structure-dependent model parameters. In the framework, a multi-scale transport model was derived by linking the c...

With the rapid development of alkali-activated concrete (AAC) as a promising sustainable concrete, it is vital to thoroughly understand the microstructural characteristics and micromechanical properties, which determine the macroscopic mechanical properties and structural performance of AAC. This paper presents a critical review on the multiscale m...

Abrasion damage of concrete induced by sediment-laden flow has been a significant durability problem for hydraulic structures. Due to the complexity of dynamic fields and concrete properties as well as the interaction effects between them, many aspects are still subjected to debate despite the tremendous efforts that have been made. In light of thi...

This paper presents a systematic experimental and numerical study on the compressive and flexural behaviour of engineered cementitious composites (ECC) based auxetic structures fabricated through 3D printing. ECC was adopted to tackle the cracking problem and inherent brittleness of plain concrete. Uniaxial compressive and flexural tests on 2D re-e...

Self-healing concrete using encapsulated healing agent has shown great potential in enhancing concrete durability. However, the capsules are expensive to make and can lower the mechanical properties of concrete. In this study, a new type of manufactured aggregate that employs waste-derived fly ash cenosphere as a carrier of healing agent (SH-CS) wa...

As an environmentally friendly material, alkali-activated fly ash-slag (AAFS) is considered as a promising alternative cement because of its excellent mechanical properties and thermal stability. Nevertheless, high temperature induced damage in AAFS can potentially bring serious risks for its practical applications. This paper presents a systematic...

Utilising crumb rubber from waste tyres to replace silica sand in engineered geopolymer composites (EGC) can reduce the environmental impact caused by landfilling and burning the tyres as well as that induced by exhausting the natural resources. This paper presents a systematic study on the effect of partially replacing silica sand with crumb rubbe...

In this paper, microbial induced calcite precipitation (MICP) was adopted as a modifying technology for surface property enhancement of supersulfated cement (SSC) containing phosphogypsum (PG). A series of tests including waster absorption test, mercury intrusion porosimetry (MIP), X-ray diffractometry (XRD), thermogravimetric analysis (TGA) and sc...

Self-sensing ultra-high performance concrete (UHPC) features superior mechanical capacity, excellent erosion resistance, long life cycle, and broad range of stress sensing, and is expected to be a pathway towards next-generation smart cementitious composites. This study presents a novel strategy to achieve electrical percolation and elevate the pie...

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...

This paper presents a systematic experimental study on the effect of shape memory alloy (SMA) fibres (0.25–1% by volume) on microstructure and engineering properties, in particular mechanical properties of polyvinyl alcohol (PVA) fibre (2% by volume) reinforced engineered cementitious composites (ECC). A series of tests were performed to characteri...

This paper presents a systematic numerical study on the structural performance of a newly developed quick-buildable beam-column joint with double-grouted sleeves considering its surface-to-surface contact behaviour between the prefabricated concrete and grouting mortar and strain penetration of the transition rebar. Theoretical analysis is also con...

This study presents a novel strategy to simultaneously mitigate the early-age shrinkage and achieve hydrophobization of metakaolin-based geopolymer (MKG) pastes through the incorporation of organic admixtures including polydimethylsiloxane (PDMS) and sodium methylsilicate (SMS). The pore structure, wettability, moisture/water adsorption capacity, a...

This paper presents a systematic study on the evolution of phase composition, microstructure and micromechanical properties of magnesium phosphate cement (MPC) and their relations to macroscopic mechanical properties. The results indicate that the microstructure of MPC is mainly composed of a crystal region of potassium magnesium phosphate hexahydr...

Accurate prediction of chloride diffusivity in non-saturated cement paste is crucial for durability design of concrete. This paper presents an integrated framework for modelling chloride diffusivity in non-saturated cement paste considering 3D microstructure, water-gas distribution in pore network and electrical double layer effect. Results indicat...

This paper presents a systematic experimental study on the fracture behavior of low-carbon mortars with various contents of carbonated recycled sand and recycled powder (CRS and CRP). Three-point bending tests on pre-notched beams were performed to explore the load-induced fracture processes. Based on the strain and displacement fields measured usi...

Recycled tyre steel (RTS) fibre is favoured as a replacement for industrial steel fibre to reduce the environmental impact and material cost of fibre reinforced cementitious composites as well as a potential substitute for the commonly used polyvinyl alcohol (PVA) fibre to develop sustainable engineered geopolymer composites (EGC). This paper syste...

This paper presents a systematic experimental study on static and dynamic compressive behaviour of 3D octet, re-entrant honeycomb and triangular lattice reinforced ultra-high performance concrete, i.e., O-UHPC, H-UHPC and T-UHPC as well as steel fibre reinforced UHPC (S-UHPC). Mechanical tests were conducted to investigate the static and dynamic co...

This paper presents a comprehensive study on the microstructural evolution and quasi-static and dynamic compressive properties of engineered cementitious composites (ECC) at elevated temperatures (20, 105, 250, 400, 600 and 800 °C). Split Hopkinson pressure bar (SHPB) was adopted to investigate the compressive behaviour of ECC at various strain rat...

CO2 mineralisation by recycled concrete is a novel approach of carbon capture and utilisation to improve the sustainability of concrete products, which has attracted increasing attention in recent years. This paper presents a comprehensive review on carbonation mechanisms related to CO2 mineralisation and hydration, microstructure and multiscale me...

Employing recycled tyre steel (RTS) fibres to replace industrial steel (IS) fibres in ultra-high performance concrete (UHPC) can improve its cost-effectiveness and sustainability. However, the lack of research on dynamic properties of such sustainable UHPC would hinder its application in concrete structures such as protective and defence structures...

To lower the material cost and environmental impact of polyvinyl alcohol (PVA) fibre reinforced engineered cementitious composite (ECC), recycled tyre polymer (RTP) fibres were adopted to partially replace PVA fibres in ECC in this study, with an overall aim to develop sustainable ECC with RTP fibres without significantly affecting the engineering...

This paper presents a systematic study on dynamic splitting tensile properties of polyvinyl alcohol (PVA) fibre reinforced engineered cementitious composites (ECC) after exposure to elevated temperatures up to 800 °C under strain rates of 4.34 to 10.95 s−1. A series of tests were conducted to characterise the weight loss, elastic modulus, uniaxial...

The temperature dependency of specific heat capacity is crucial for thermo-mechanical analysis of fibre reinforced cementitious composites. In this study, a combined experimental and theoretical analysis was conducted to characterise the role of micro fibres in tailoring the specific heat capacity of cementitious composites at elevated temperatures...

The transport properties of concrete are closely related to its heterogeneous features. In this study, by considering the multi-scale microstructural characteristics, the chloride transport properties of concrete are comprehensively analysed. Based on the selected representative elementary volumes from bulk cement paste to concrete, a multi-scale p...

Alkali-activated concrete (AAC) is recognised as a novel sustainable construction material to substitute Portland cement concrete with superior thermal and mechanical performance. However, AAC would suffer significant deterioration when subjected to elevated temperatures due to different damage mechanisms, including thermal incompatibility caused b...

Alkali-activated concrete (AAC) is a promising sustainable alternative to cementitious materials concerning its environmental benefits and satisfactory engineering properties. Given the growing use of limestone and other forms of calcium carbonate as an additive or supplementary precursor in AAC, this review summarises the effect of limestone on th...

Engineered cementitious composite (ECC) featuring extraordinary tensile ductility is a promising option for many structural applications but its large-scale manufacture is not eco-friendly due to its binding ingredient, Portland cement. One of the potential alternatives to ECC is engineered geopolymer composites (EGC) that have been increasingly st...

Alkali silica reaction (ASR) is a long-term factor that causes concrete cracking, and the ingress of harmful agents such as chloride can then be promoted by the ASR-induced cracks. Electrochemical deposition method (EDM) is a promising nondestructive rehabilitation technique which has two-fold advantages of crack repair and chloride removal. In thi...

Partial replacement of the widely used polyvinyl alcohol (PVA) fibre in engineered geopolymer composites (EGC) with recycled fibres can reduce the material cost and improve sustainability. This study investigates the effect of hybrid PVA and recycled tyre polymer (RTP) fibre content on the quasi-static and dynamic splitting tensile behaviour and mi...

Mechanical properties of engineered cementitious composites (ECC) are highly dependent on the pore structural characteristics and fibre-matrix interaction. The relationship between them has not been extensively explored. This paper proposes a practical micromechanical analytical model accounting for pore structure characteristics and crack-bridging...

Ultra-high performance concrete (UHPC) is vulnerable to high temperature-induced damage due to its dense microstructure. To mitigate thermal damage of UHPC, this study develops synergistic flame-retardant polymer (SFRP) fibres by introducing organic-metallic fillers and experimentally investigates the thermal properties, compressive behaviour, and...

The tensile behaviour of engineered cementitious composites (ECC) is highly dependent on their microstructure characteristics. To date, the strain-hardening behaviour of printed ECC in relation to its microstructure is not yet fully understood. This study presents a systematic investigation on the macroscopic mechanical properties of normal and pri...

Strain hardening geopolymer composite (SHGC) is a sustainable fibre-reinforced material that exhibits superior strain-hardening and multiple cracking behaviour under tension. The geopolymer binder synthesised through alkali-activation of aluminosilicate precursors sourced from industrial by-products is chemically stable at elevated temperatures. Th...

To enhance the cost-effectiveness and sustainability of engineered geopolymer composites (EGC), polyvinyl alcohol (PVA) fibres in EGC can be partially replaced with recycled tyre polymer (RTP) fibres. This paper presents a systematic experimental study on the effects of PVA fibre volume fraction (1.0%, 1.5% and 2.0%) and RTP fibre content (0.25%, 0...

Water transport is an important property of concrete, which has the potential to be applied as a representative descriptor to reflect and predict the durability of concrete, especially in engineering. A better understanding of the water absorption behaviour of concrete is still needed. This study presents a systematic experimental and analytical st...

Microbial induced calcite precipitation (MICP) can protect the surface of porous cement-based materials and enhance the durability of concrete, the efficiency of which depends on the near surface property. Therefore, this paper is aimed to investigate the effects of bacterial solution to cementation solution ratio (1:2, 1:1 and 2:1) and different c...

This paper presents a novel meso-scale modelling framework to investigate the fracture process in steel fibre reinforced concrete (SFRC) under uniaxial tension and compression considering its 3D mesostructural characteristics, including different types of fibres, realistic shaped aggregates, mortar, interfacial transition zone and voids. Based on a...

The pore structure plays an important role in determining the performance of solid materials. This paper reviews the studies about the pore structure of geopolymers, a rising kind of eco-friendly low-calcium-content cementitious material. Geopolymers usually show a four-leveled multiscale pore structure. The abundance in nano pores is the key featu...

Landfilled phosphogypsum would cause severe environmental issues, but the waste can be recycled for preparing excess-sulphate cement, an eco-friendly alternative to conventional cement. This paper investigates the effect of metakaolin (0–50%) on early hydration, phase assemblages and mechanical properties of the excess-sulphate phosphogypsum cement...

Strain hardening geopolymer composite (SHGC) is a special group of fibre reinforced geopolymer composites, which exhibits ultra-high ductility and multiple microcracks under tension. This paper presents an experimental study on the effect of polyvinyl alcohol (PVA) fibre content (0%, 1%, 1.5%, and 2%) on engineering properties of fly ash-slag based...

This study presents an integrated multiscale framework for modelling ionic diffusivity in unsaturated concrete accounting for its microstructural features and 3D moisture distribution. The hierarchical microstructure of concrete at multiscale from nano- to meso-scale is mimicked, based on which the fluid-solid interaction and moisture distribution...

This work presents a proof-of-concept study of recycling low-quality urban-fringe construction and demolition waste for the development of sustainable cement-free pervious concrete. Waste was in-situ collected from a local construction site of urban-fringe in Hangzhou, China, and elaborately analyzed for quality assessment. Ground brick powder was...

Geopolymers have been considered as a promising alternative to cementitious materials for 3D printing to enhance sustainability of the construction industry. This paper presents a critical review of the state-of-the-art of 3D printing geopolymers from the perspectives of production process, printability requirement, mix design, early-age material p...

Brick-concrete demolition residue after the primary recycling is generally discarded due to its low quality. Secondary recycling of the brick-concrete demolition residue is urgently required to be solved at present in China due to the large scale constructions and demolitions, and remains a challenging task. In this work, a brick-concrete demolitio...

The accurate prediction of ionic diffusivity in non-saturated limestone blended cement paste is essential for the durability design of blended cementitious materials. This paper presents an integrated framework for simulating the ionic diffusivity in limestone blended cement paste considering its 3D microstructure, water saturation level, and distr...

This paper presents a systematic experimental study on dynamic compressive behaviour of recycled tyre steel fibre (RTSF) reinforced concrete. The use of RTSF can not only enhance the mechanical properties and sustainability of cementitious materials but also reduce the environmental impact of waste tyres. A series of tests were conducted to investi...

A novel precast concrete beam connected using double-grouted sleeves was developed to reduce pouring concrete on-site and expedite construction. This paper presents a systematic experimental study on the flexural behaviour of precast beams subjected to three-point and four-point bending. In total, 11 specimens with different types of grouted sleeve...

This paper presents an experimental and analytical study of the bond behaviour of basalt fibre reinforced polymer (BFRP) bars in geopolymer concrete (GPC). Pull-out tests were conducted on ribbed BFRP bars embedded in GPC cubes considering different bar diameters (6, 8 and 10 mm) and embedment lengths (5d_b, 10d_b and 15d_b) to investigate their ef...

The combined use of low heat Portland cement (LHC), MgO-based expansive agent (MEA) and shrinkage reducing admixture (SRA) is beneficial to reduce the cracking risk of concrete. In this study, the effects of MEA and SRA on the rheological behaviour of LHC paste were investigated using dynamic and static shearing tests. The response surface methodol...

Accurate prediction of transport properties for cementitious materials remains a challenge since it is difficult to experimentally obtain the realistic three-dimensional (3D) pore network of cement paste. In this study, the 3D pore network of cement paste is quantitatively characterized using nano X-ray microtomography coupled with the metal centri...

This paper presents a systematic study on the feasibility of using recycled tyre polymer (RTP) fibres for mitigating the damage of concrete induced by elevated temperatures. A series of tests were conducted to investigate the effect of RTP fibres on mechanical and thermal behaviour, pore pressure build-up and microstructural evolution of concrete e...

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...

Strain hardening geopolymer composite (SHGC) processing superior tensile ductility and multiple cracking is a promising alternative to traditional ductile cementitious composites whereas the extremely high cost of polyvinyl alcohol (PVA) fibres limits its large-scale application. This paper presents a feasibility study of replacing PVA fibres with...

Recycled aggregates can introduce initial defects and damage to prepared concrete. Internal mesocrack formation is a fatal factor influencing the durable and mechanical properties of recycled aggregate concrete. In this study, the internal mesocracks of recycled aggregate concrete (RAC) under uniaxial compressive loading were virtually and quantita...

This paper presents an integrated modelling framework to investigate the effect of curing temperature on hydration, microstructure and ionic diffusivity of fly ash blended cement. A 3D cement hydration model, i.e. CEMHYD3D, was modified by incorporating the parameters representing the temperature-dependent dissolution of Portland cement and fly ash...

This paper presents an efficient experimental-numerical analysis of fracture mechanics in magnesium phosphate cement (MPC) based on the structural and mechanical properties of its constituents including potassium magnesium phosphate hexahydrate (MKP), magnesium oxide (MgO) and pores. At micro-scale, the fracture energy and material strength of soli...

This paper presents an experimental study on impact behaviour and plastic evolution of chiral structure subjected to in-plane impact loading using a Split Hopkinson pressure bar (SHPB). The finite element (FE) model developed in ABAQUS/Explicit was validated and utilized for parametric study, and further developed as an extension of experimental wo...

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...

This paper presents a computational framework for modelling the fracture process in concrete under static and dynamic tensile loading considering its mesostructural characteristics. 3D mesostructure of concrete composed of real-shape coarse aggregates, mortar, interfacial transition zone between them and voids was developed using an in-house code b...

The filler effect is the most important physical mechanism of mineral admixtures in the early hydration of cement whose chemical properties greatly affect the precipitation of C–S–H. In this study, calcite, strontianite, magnesite, dolomite, quartz, whewellite and whitlockite were selected as the fillers. The morphology and reaction kinetics of syn...

This paper presents a meso-scale modelling framework to investigate the fracture process in concrete subjected to uniaxial and biaxial compression accounting for its mesostructural characteristics. 3D mesostructure of concrete consisting of coarse aggregates, mortar and interfacial transition zone between them was developed using an in-house code b...

Strain hardening geopolymer composite (SHGC) is a tailored group of sustainable high-performance fibre reinforced geopolymer composites with strain hardening behaviour and ultra-high ductility. This paper experimentally investigates the effect of fine silica sand content (0-40% by weight of the geopolymer binder) on engineering properties of fly as...