Nele De Belie

• Ghent University

Over the last century, lime has been quickly replaced by the uptake of Portland cement, mainly due to its faster hardening. Achieving earlier hardening in lime through faster carbonation is thus essential to help overcome one of lime’s limiting qualities. In this work, we isolated and selected strains suitable for use in lime mortars, and used bact...

Microbially-induced calcium carbonate precipitation is a widespread natural phenomenon with numerous applications. Recent advances have shown that bacterial calcium carbonates (BCC) form non-classically via amorphous calcium carbonate (ACC) precursors in the presence of organics, but the role of organics in the formation and nanostructural features...

Replacement of Portland cement is a practical strategy to reduce concrete manufacturing CO2 emissions. However, this approach typically results in a diminished portlandite content in the hardened mix, elevating the risk of carbonation-induced corrosion in steel-reinforced concrete. Carbonation is frequently studied by exposing the samples to elevat...

Concrete manufacturing and recycling must evolve to meet sustainability and carbon reduction demands. While the focus is often on reusing coarse aggregates, fine fractions are also produced during recycling. This study explores using ground fine fractions (0/2) as a partial cement substitute. The fines were characterized for their mineralogical, ch...

Sustainable development relies on the circularity in the built environment, which, in turn, includes recycling construction and demolition waste and using recycled materials. However, using fine recycled fractions is challenging, especially considering the requirements for new building applications. Yet, producing more widely applied recycled coars...

In order to meet the new demand for sustainability and lower carbon emissions for concrete, the production and recycling process has to be adapted. Regarding concrete recycling, the main focus in literature and industry is on the reuse of coarse aggregates. However, the recycling of concrete also generates a fine fraction. In this research, the fin...

In response to the ever-evolving demands of end-users within the construction sector, also due to the heightened global awareness regarding the pivotal role of the construction industry in sustainability ramifications, it has become imperative to wield strategic tools to steer the market toward farsighted choices. A notable example is represented b...

Numerous (inter)national standards are in place for assessing the resistance to carbonation of mortar and concrete. Within the framework of RILEM TC 281-CCC ‘Carbonation of Concrete with SCMs,’ an extensive interlaboratory test campaign (ILT) involving twenty-two participating laboratories worldwide was initiated to compare natural carbonation of c...

The RILEM TC 281–CCC ‘‘Carbonation of concrete with supplementary cementitious materials’’ conducted a study on the effects of supplementary cementitious materials (SCMs) on the carbonation rate of blended cement concretes and mortars. In this context, a comprehensive database has been established, consisting of 1044 concrete and mortar mixes with...

This review presents the scope of current efforts to utilize recycled construction and demolition waste in mortars for masonry. More than 100 articles are divided into groups pertaining to the type of mortar, different binder systems, the type of construction and demolition waste (CDW), and its utilization specifics. Cement-based mortars dominate t...

Replacement of Portland cement is a practical strategy to reduce concrete manufacturing CO 2 emissions. However, this approach typically results in a diminished portlandite content in the hardened mix, elevating the risk of carbonation-induced corrosion in steel-reinforced concrete. Carbonation is frequently studied by exposing the samples to eleva...

This paper delves into the innovative realm of vascularization within concrete, a technique that embeds channel networks into the concrete matrix, mirroring the vascular systems found in living organisms. This approach facilitates the flow of diverse substances throughout the material, significantly expanding the functionalities of concrete beyond...

Lime-based binders, while historically significant, exhibit low strength and slow hardening, which has led to its replacement by cement. Hardening in lime-based materials occurs primarily through carbonation, whereby Ca(OH)2 reacts with atmospheric CO2 and produces CaCO3 cement. This study explores using bacterial additives to accelerate lime harde...

Modern day masonry mortars rely on more than just standard constituents, which by definition include binder, aggregates and water. Due to different requirements imposed onto various types of masonry construction, ready mix mortar manufacturers and even masons and labourers on construction sites add certain additives to their mortar formulations. In...

This study presents the analysis of the crystallization impact in four lime-based mortar mixtures in order to determine the extent of decay during salt crystallization, affected by the use of additives and change in microstructure. For this purpose, non-destructive micro-computed tomography was used to monitor salt crystallization in lime mortar co...

The chemical reaction between CO 2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO 2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation re...

Featured Application Application of superabsorbent polymers in large-scale wall elements, to be used in tunnel systems or ground-retaining structures. Abstract The pursuit of durable and sustainable construction has driven interest in innovative materials, with superabsorbent polymers (SAPs) emerging as a promising solution, especially for the con...

The massive extraction of virgin raw materials has substantially intensified the focus on circular economy of building materials. As a Cradle-to-Cradle service life and circular approach for lime-based construction materials (LBCM) is lacking, the present study evaluates the environmental impact and feasibility of creating a fully recycled second-l...

Several self-healing mechanisms have been developed for applications in concrete. One of the most well-known is the encapsulation of a self-healing agent (resin or other). This technology requires a high level of expertise in order to overcome numerous difficulties: compatibility between the self-healing agent and the shell, watertightness of the s...

Innovative solutions are needed to improve the durability of concrete structures in marine environment. Bacteria-based agents (BAS) and crystalline admixtures (CA) are explored as healing agents to enhance chloride resistance and prevent corrosion. Healing of 100 μm and 300 μm wide cracks was investigated, in combination with two conditioning metho...

A comprehensive decarbonization approach is reported, involving Direct Separation Reactors (DSR) and eco-efficient energy sources in the production of hydrated lime. Environmental and economic impacts are calculated through an in-depth life-cycle cradle-to-grave assessment. Integrating a DSR kiln with carbon capture technologies (CCT) attained a re...

During capillary imbibition, there are changes in the pore structure that reduce the water ingress rate, leading to anomalous behaviour. However, the relation of those deformations with the C-S-H content is still unclear. We performed simultaneous measurements of external deformations and water ingress through neutron radiography. Cement pastes of...

With the continued rise of the world population, it is important to focus on the sustainability of our building materials. Traditional reinforced concrete is prone to cracking and these cracks have a detrimental effect on the durability, thereby limiting the service life. Repair of the damage is often costly and if not done timely the structure nee...

Although the use of supplementary cementitious materials (SCMs) is a well-known practice with over a century of experience, the mechanism of reaction of SCMs remains not fully understood, and further research is necessary. In addition, the incorporation of alkaline activators into cementitious systems with a low content of Portland cement (PC) is g...

Cracks in reinforced concrete are a fast entry point for aggressive substances possibly leading to reinforcement corrosion and concrete deterioration, which leads to a decreased service life and a need for repair. This paper investigates self-healing concrete, which is able to heal the formed cracks. An organic/inorganic hybrid admixture was used i...

Please cite this article as: Etcheverry, J.M., Laveglia, A., Villagran-Zaccardi, Y.A., De Belie, N., A technical-environmental comparison of hybrid and blended slag cement-based recycled aggregate concrete tailored for optimal field performance, Developments in the Built Environment (2024), doi: https://doi.

In this study, a hybrid alkali-activated ground-granulated cement consisting of 70% blast furnace slag (GGBFS) and 30% Portland cement (PC) activated with sodium sulfate was studied. Results were compared with those of a blended system without an activator. The addition of the activator significantly increased the kinetics and degree of reaction of...

The development of innovative cementitious materials such as Ultra High Performance Concrete (UHPC) requires tailored approaches to assess both the environmental and economic impact of structural applications employing them. For this purpose, in this paper, Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) methodologies are integrated into a Du...

Additive manufacturing (AM) can produce complex vascular network configurations, yet limited testing has been done to characterize the damage and healing behavior of concrete with embedded networks for self-healing. In this study, different AM methods and network wall materials were used to produce vascular networks for self-healing concrete prisms...

Mechanical properties of Ultra High-Performance Concrete (UHPC) degrade when exposed to elevated temperatures, even more than ordinary concretes due to its dense microstructure. Concerning, in particular, the special application of nuclear power plants, in which UHPC can find a promising use, concrete can be subjected to moderately high temperature...

Although the circular economy principles date back to the late 1960s, only with the recent stimulus from the European Commission and the Ellen McArthur Foundation has this concept gained attention worldwide. The City Hall of Santiago de Cali (Colombia) is implementing a circular economy model through a sustainable construction handbook and its cert...

In this study, the self-healing of cracks in four alkali-activated slag (AAS) systems modified by superabsorbent polymers (SAPs) is studied. The formation of carbonate precipitate is the main healing mechanism and further AAS hydration is inferior. Self-healing ability in water glass-activated slag (WG-AAS) system is the weakest because Ca²⁺ appear...

Ultra High-Performance Concrete (UHPC) is widely acknowledged for its remarkable mechanical properties, owing to its compact microstructure. The response of UHPC to impact forces plays a vital role in ensuring the safety and longevity of structures, specifically in protective buildings, high-performance pavements and offshore concrete structures. I...

The combination of environmental actions and mechanical load, which most structural concretes are subjected to, has a synergetic effect on the durability of concrete. The comparative test conducted by RILEM TC 281-CCC WG4 demonstrated and quantified the effect of an applied mechanical load on carbonation performance of concrete with supplementary c...

This paper presents an integral parametrized framework to calculate the life-cycle inventory (LCI) in lime-based construction materials manufacturing, utilized for implementing decarbonization strategies in the LCI. The calcination operation is identified as the main source of CO2 emissions, with 0.79 tCO2/t CaO being inevitable (65% of total emiss...

Durability of concrete with supplementary cementitious materials (SCMs) is crucial to the longevity of our built environment. Current research on the carbonation performance of concrete focuses on determining changes in microstructure induced by the chemical and physical interactions of CO2 with the cement phase in samples that do not undergo loadi...

A real-case study is presented aiming at contributing to the understanding of environmental and economic sustainability of lime-based mortars, renders and plasters manufacturing in Europe. A Life Cycle Inventory is presented and used for scenario analysis. The Life Cycle Assessment shows that the binders' production dominates the Climate Change, Re...

In the last decades major advances have been made in the development of self-healing concrete which is able to heal its own cracks without the need for traditional repair interventions, thereby increasing its durability and service life. Recently, more and more self-healing technologies have been applied in demonstrator projects. These demonstrator...

With the current demands for more sustainable and durable structures, the search for smarter and innovative building materials plays a crucial role in the further development of the construction industry. The discovery of the synergetic effect between superabsorbent polymers (SAPs) and cementitious materials gave space to uncountable new possibilit...

Hybrid binders emerge as a solution to further decrease the clinker factor in cementitious systems without unfavorable slow strength development.The Portland cement reduction not only produces greener systems, but also makes them more sensitive to carbonation, especially due to the very limited amount of portlandite available. Therefore, the pore s...

For several decades, the cement industry has been actively seeking alternative raw materials to reduce greenhouse gas emissions and energy consumption. In pursuit of partial replacements for clinker, worldwide research has focused primarily on industrial (fly ash, Si-Mn slag, fired clay-based) and agroforestry (rice husk, sugar cane) waste. The com...

Development of new solutions for masonry mortars is heavily reliant on laboratory-based experimental procedures. This study provides insights into the properties of masonry mortars, prepared by four distinct compaction methods, based on existing standards: tamping, tapping, jolting and vibrating. The particular mortar mix under study has been desig...

The ever-changing needs of the end user in the construction industry, together with the increasing awareness about the great influence of the sector on the worldwide sustainability, require some tools to be employed by the stakeholders to drive the market towards conscious and appropriate choices. An example in this regard are advanced cement-based...

Alkali activation may help to increase the early strength and reduce the setting time of mixtures with high contents of supplementary cementitious materials (SCMs). In this research, the effect of sodium sulfate activator on reaction kinetics, compressive strength and pore structure of hybrid systems produced with 70 wt.% ground granulated blast fu...

The tracking of healing on concrete slabs where dense crack patterns are formed under bending is reported using Acoustic Emission (AE) and Ultrasound Pulse Velocity (UPV). Additively manufactured polymeric networks are designed to distribute a polyurethane agent through capillary actions and under pressure to the open cracks, formed in the slabs. I...

This study evaluated the mechanical properties and self-healing performance of cement mortar containing pulverized clinker, calcium sulfoaluminate (CSA), and Na2SO4. Mechanical properties of cement mortar were investigated by measuring compressive strength, and sealing efficiency were evaluated by a hydrostatic permeability test and a nitrogen gas...

Bacteria-based self-healing concrete has become an effective approach to mitigate microcracks in the concrete structure. However, there are still doubts about when to use vegetative cells or spores of Bacillus sphaericus as a healing agent. Thus, this research aims to give recommendations regarding this choice. Spores and cells were encapsulated in...

Extreme environments are aggressive for concrete structures, hence a performance-based design is crucial to guarantee the durability during the service life. Nonetheless, there is a knowledge gap regarding the influence of cracks on standard and self-healing concrete. This research focuses on monitoring cracked self-healing concrete with two commer...

The capacity of hydrated lime to reabsorb CO2 as it hardens has made it a desirable replacement for cement to produce mortars with an overall lower environmental footprint. Still, research into lime-cement formulations remains limited, especially when it comes to their self-healing capacity. Some studies show that hydrated lime can improve self-hea...

The development of circular economy models for the construction sector brings important challenges and opportunities to research and particularly to make knowledge transfer, for example through public policies. Santiago de Cali, third major city of Colombia (South America), is developing a circular economy model policy, which is mainly based on was...

Although steel reinforcements are used to withstand tensile forces in concrete, cracks are an unavoidable phenomenon. The presence of cracks, in fact, increases the risk for lowering the service life and durability of concrete structures. A critical issue occurs when due to splitting forces, cracks appear in concrete along the tensioned rebars whic...

As an alternative to the usage of axenic bacteria to achieve microbially induced calcium carbonate precipitation (MICP), this study evaluates the usage of two non-axenic biomasses as self-healing agents. A fungi-based consortium (Yeast) and heterotrophic nitrifiers (HTN) were harvested from the incubation of agricultural side streams. The character...

Capillary water absorption tests are widely used in uncracked cementitious materials to assess the quality and durability. Due to the easy execution of the test, it is also frequently used to assess the self-healing efficiency of self-healing concrete and mortar. It is established that the presence of a crack significantly increases the water uptak...

Among the various possibilities to tackle the issue of concrete damage within its structural service life, the biomimetic approach has favoured the development of innovative solutions such as the use of 3D printed vascular networks suitably incorporated into concrete structural elements to inject and convey the most suitable healing agent upon crac...

This study focuses on the evaluation of the efficiency of a low-cost macrocapsule, using commercially available pharmaceutical capsules with specific modifications, for self-healing concrete. The macrocapsules were developed by the Belgian Building Research Institute in a previous study. The healing agent is a resin based on alkyd-urethane, a low-c...

Vascular self-healing concrete is an innovative technology that can potentially improve the durability and longevity of concrete structures. However, limited research is available concerning this type of self-healing compared to intrinsic or capsule-based healing. As the rheology and curing properties of a healing agent can dictate the optimal desi...

Lime-based construction materials (LBM) range from concrete blocks to mortars and plasters used in building new structures or to conserve our cultural heritage. However, little interest has been aroused in the scientific community about their sustainability assessment through Life Cycle Assessment. This research presents a case study carried out wi...

Fe-rich slags originating from non-ferrous metallurgy have shown promising properties as a new type of supplementary cementitious material (SCM). However, their combined use with limestone has not yet been investigated in detail. The goal of this study is to elucidate whether this yields a positive effect as observed for aluminosilicate SCMs with l...

Novel hybrid binder concrete mixes with alkali-activated non-ferrous slag (NFS), either alone or in combination with blast furnace slag (BFS), as partial replacement of Portland cement, and containing 50% recycled aggregates, were successfully manufactured. The compressive strength, carbonation resistance, chloride resistance, frost scaling, sorpti...

Fine recycled concrete aggregate (FRCA) possesses substantial limitations for its use due to its significant porosity. Extensive research on the effect of carbonation on the accessible porosity of coarse recycled concrete aggregate is available in the literature, but FRCA information is scarce. The present paper presents results of the effect of ca...

The required depth of concrete removal should dictate the selection of concrete removal technique and removal energy in repair systems. This study presents a new research approach in the investigation of the impact of concrete removal techniques on the substrate, and as a result, the bond with repair mortar. On the other hand, it introduces a remed...

Advanced design of eco-friendly concrete is very urgent in view of the vital fight against climate change. An interesting eco-efficient strategy is the combination of (1) alternative low carbon hybrid binders with a low clinker factor and the inclusion of alkali activators, (2) substituting natural aggregate by recycled aggregate and (3) securing s...

The objective of this work is to study the freeze thaw resistance of supplementary cementitious materials (SCM) based concrete made from non-ferrous slag (NFS) benchmarked with CEM I 52.5 N and CEM III 42.5 B concrete. NFS is synthesized during the production of Cu metal from Cu scraps. The freeze thaw resistance of NFS concrete containing 70% CEM...

Superabsorbent polymers (SAPs) are novel admixtures in cementitious materials in order to have internal curing. Neutron tomography is used to investigate and to visualize the water release by SAPs with different kinetics over time. This gives insight into the time window for effective internal curing as the results are linked to shrinkage and inter...

Cracking of cementitious materials poses severe problems for the mechanical performance and the durability of concrete structures. Self-healing cementitious materials provide a means of countering these issues, but the testing procedures to assess the self-healing efficiency are mostly impractical for in-situ evaluation. This study concerns the eva...

Bacteria-based self-healing is a promising method due to its effectiveness to completely heal the crack. Expanded clay was chosen as a bacteria protector as it can retain a high amount of bacteria liquid in its pores and it is compatible with the mortar matrix. Most researchers employed bacteria in the form of spores to produce self-healing concret...

Early age cracking is a high risk for low water to cement (w/c) concrete known as the ultra-high performance concrete (UHPC). The lack of water to fully hydrate cement particles at the early age, provides a rapid increase of self-desiccation and autogenous shrinkage which might lead to cracking. However, internal curing agents such as superabsorben...

Recent studies highlighted the need to investigate the sustainability of innovative cement-based composites. In this regard, some works focused their attention on the use of Super Absorbent Polymers (SAPs) blended into the concrete matrix also employed to promote the autogenous healing, which can result into extended durability. In this study the L...

SAPs have been widely studied over the past two decades as new admixtures for cementitious materials. Their ability to absorb and retain water from the cementitious mixture allowed them to be successfully used as internal curing agents preventing self-desiccation and reducing autogenous shrinkage. A lot of research has been developed and important...