Eduardus A.B. Koenders

Technische Universität Darmstadt | TU · Department of Civil and Environmental Engineering Sciences (Dept.13)

A reactive transport model was employed to investigate the influence of multiple hydrate phases during acetic acid attack on Portland cement paste. The simulation accounted for the dissolution of primary cement hydrates like Ettringite, Portlandite and C-S-H, along with the formation of silica gel products impacting diffusivity. The simulations pri...

Concrete poured as linings of geothermal tunnel would deviate normal curing condition. A multiscale model based on continuum micromechanics, accounting for temperature-dependent factors, is established from the cement paste level to the concrete level. This model predicts the physical properties and compressive strength of concrete and is validated...

This study employs computational chemistry to investigate the detailed mechanisms behind the dissolution of thermally activated clays, which are emerging as a promising supplementary cementitious material (SCM) for enhancing concrete properties and reducing carbon footprint. Specifically, the study employs first principles methodology for obtainin...

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...

Low-grade limestone (LGL) is not used to produce cement clinker, but this leftover material in cement quarries increases the water demand when used as a filler in concrete production. In this study, the effect of six commercial superplasticizers on the performance of cement mixes containing 35% LGL and 2% gypsum was investigated. The optimal doses...

This study focusses on the bond between asphalt and concrete. The bond is a decisive factor for the transfer of traffic loads. A lack of bond between the layers can quickly reduce the load-bearing behavior and thus lead to pavement failure. In the literature, the bond between asphalt pavements and concrete substrates is usually analyzed using mecha...

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...

Addition of different types of phase change materials (PCMs) to cement-based materials for thermal energy storage has been broadly investigated in the literature. Many studies have researched the addition of organic PCMs and the thermal performance of the PCM-cement system. However, drawbacks such as leakage and poor thermal conductivity of the PCM...

In the realm of cementitious materials, integrating nanoclay shows promise in enhancing properties relevant to additive manufacturing. This paper presents a novel mathematical model that combines simple empirical dissolution/nucleation Avrami-like kinetics with a thixotropic kinetics equation. To analyze the initial exothermic peak, two sets of the...

This research aimed to enhance the impregnation of carboxylate styrene butadiene rubber (XSBR) polymer on jute yarns, thereby improving the mechanical properties of textile-reinforced cementitious composite (TRCC). An experimental investigation on the use of cellulose microcrystals and nanofibrils as additives to XSBR admixture was conducted. Four...

The urgent need to address climate change has pushed Europe to the forefront of environmental legislation initiatives, such as the Environment Action Program (EAP) within the European Green Deal and the disclosure of Environmental Product Declarations (EPDs) in the construction sector. The cement industry plays a vital role in this transition becau...

This study investigates the effects of carbon nanomaterials (CN), specifically nanohorns (CNHs) and nanotubes(MWCNTs), on geopolymer carbon nanocomposites (GCN). The research investigates 0.2%, 0.5% and 1.0% ofCN and two curing conditions to understand their impact on the microstructure, morphology, and performanceof GCN. Analytical techniques such...

In the pursue of environmentally-friendly binders for the construction industry, metakaolin (MK) has emerged as promising material, with its hardening performance primarily driven by pozzolanic reactions. However, in systems containing MK and calcium hydroxide (CH), transformation reactions from metastable to stable phases, particularly in excessiv...

The incorporation of carbon fillers into geopolymers enhances conductivity, forming intricate networks for integrated energy conversion in construction materials. This study employs a novel computational modeling approach to investigate the electrical conductivity of geopolymer-graphite composites. Utilizing a particle-based Monte Carlo method, per...

Geopolymers offer a potential alternative to ordinary Portland cement owing to their performance in mechanical and thermal properties, as well as environmental benefits stemming from a reduced carbon footprint. This paper endeavors to build upon prior atomistic computational work delving deeper into the intricate relationship between pH levels and...

The water–cement/binder ratio and the admixture of water-reducing agents strongly affect the rheological properties of cement pastes. This study develops mathematical models to predict the apparent viscosity of cement pastes with varying water-cement/binder ratios and polycarboxylate-based superplasticizer content by introducing the power law shear...

The exposure of concrete structures to acid attack is a growing concern. This study employs thermodynamic modeling to investigate the changes in phase assemblage of powdered cement pastes subjected to a wide range of sulfuric and acetic acid concentrations. A modeling approach utilizing IPHREEQC implemented through Matlab is presented, and the obta...

A titration method is used to analyse the acid neutralization/consumption capacity (ANC) of cement binders, which involves plotting the steady‐state pH against the amount of acid added to a diluted suspension of hardened cement samples. Despite ANC being employed for several decades, there is no reported application of ANC for metakaolin‐based geop...

Enhancement of metakaolin graphene coated geopolymer wettability. • A decrease of surface energies of gra-phene/geopolymer with MD and DFT methods. • The contact angle between water nano-droplet and geopolymer surface rises to 79 •. • The diffusion coefficient of water drops and is equal to 0.131 10 − 10 m 2 /s. • The interfacial chemical bonding h...

Improving the durability of metakaolin aluminosilicate materials (named geopolymer) is a key challenge in the building industry. One approach to enhancing these materials resistance to water infiltration and other aggressive agents is to modify their surface properties. This study investigates the atomic-level interfacial interactions between a nan...

Despite the extensive research conducted in BIM applications in construction and the built environment, fields such as demolition and circularity of construction and demolition waste (CDW) materials can still be subject to significant breakthroughs stemming from BIM-inspired frameworks. The circular economy concept in the context of CDW aims to min...

This is a Cover Profile publication. Invited for this issue's Front Cover are the groups of Eddie Koenders and Markus Stöckl. The cover feature illustrates a chimney made of Sn‐modified geopolymer‐bricks. Functionalized geopolymers can be applied as hybrid material for construction and as an electrode for CO 2 electrolysis to formate. The cover was...

The aim of this study was to assess the characteristics of fly ash foam concrete containing two varying temperature ranges of microencapsulated phase change materials (PCMs): PCM28D (26–30 °C) and PCM43D (41–45 °C). In total, five different fly ash foam concrete samples were prepared, and the unit weight of cement was substituted with varying perce...

The Front Cover of ChemElectroChen journal illustrates a chimney made of Sn-modified geopolymer-bricks. Functionalized geopolymerscan be applied as hybrid material forconstruction and as an electrode forCO2 electrolysis to formate. The coverwas designed by one of the authorsJürgen Schuster and the designerVerena Stöckl. More information canbe found...

Geopolymer nanocomposites incorporating carbon nanotube (CNT)/graphene-based nanomaterials have become an exciting area of research because of their exceptional interface compatibility, providing improved mechanical, electrical, and thermal properties for next-generation construction materials. Accordingly, geopolymers are superior candidates for t...

Graphene-based materials are considered excellent candidates to implement cementitious nanocomposites due to their mechanical properties. This paper presents a comprehensive interface interaction that ends up with computing the elastic properties for four models of the C−S−H gel, taking tobermorite 14 Å as an example, with reduced graphene oxide (r...

Technologies that can contribute to the reduction of greenhouse gases are mandatory, and those based on solar energy are good candidates to achieve this. In this sense, massive solar thermal collectors are suitable technologies for supplying the primary energy demand of buildings. To design these devices, it is necessary to fully understand the phy...

The increasing concerns regarding global warming and the scarcity of raw materials in the construction industry have led to a growing need for alternative low-carbon binders to partially replace ordinary Portland cement. To assess the suitability of pozzolans as supplementary cementitious materials (SCMs), the R³-test has been introduced and succes...

Life Cycle Assessment (LCA) modelling of several scenarios are time consuming if performed manually and the results are typically calculated as a single time point estimate. Furthermore, uncertainty in the input variables is high, making comparisons between different solutions challenging. This work introduces an LCA-algorithm tool that improves up...

To achieve a successful transition to a sustainable carbon and energy management, it is essential to both reduce CO2 emissions and develop new technologies that utilize CO2 as a starting substrate. In this study, we demonstrate for the first-time the functionalization of geopolymer binder (GP) with Sn for electrochemical CO2 reduction (eCO2RR) to f...

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...

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...

Energy demand for heating and cooling represents a large part of building´s (residential and non-residential) energy consumption around the world. Development of thermal insulating construction elements with thermal energy storage and release capacity could be one way of reducing this consumption while maintaining thermal comfort inside the buildin...

The major concern of the modern cement industry is to minimize the CO2 footprint. Thus cement based on belite, an impure clinker mineral (CaO)2SiO2 (C2S in cement chemistry notation), which forms at lower temperatures, is a promising solution to develop eco-efficient and sustainable cement-based materials, used in enormous quantities. However, the...

In this paper the Tang’s model (Cem. Concr. Res. 1999), updated by introducing the pore geometry factor, was calibrated on through diffusion (steady-state) test results obtained from literature. This enabled to propose a new improved approach for estimating the intrinsic friction parameter ψ, that accounts for concentration dependent ionic interact...

In recent years, the global need on alternative binders for the construction industry has driven the development of novel testing methods for evaluating the reactivity of supplementary cementitious materials (SCMs). One method that has attracted particular attention is the so-called R3-test, that measures the reactivity of SCMs while eliminating th...

The mechanical and microstructural properties of carbon nanomaterial reinforced geopolymers are investigated regarding carbon nanomaterial type, carbon nanomaterial content, and curing conditions. For this purpose, three types of carbon nanomaterials (CN) were investigated: pristine carbon nanotubes (P-CNT), functionalized carbon nanotubes (F-CNT)...

Metakaolin (MK) has emerged as a highly promising supplementary material in low carbon binders for the construction industry. In wide range of applications, from lime to cement–based materials, its hardening performance relies on the pozzolanic reactivity between MK and calcium hydroxide (CH), resulting in the formation of diverse calcium-aluminate...

A performance-based approach for assessing the environmental impact of masonry buildings is proposed. This new method combines Life Cycle Assessment and operational energy (OE) simulations to compare the cradle-to-use environmental performance of a reference building composed of single core masonry walls made of Calcium Silicate Bricks (CSB) and Cl...

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...

This study investigates the shear behavior of reinforced concrete (RC) beams that have been strengthened using carbon fiber reinforced polymer (CFRP) grids with engineered cementi-tious composite (ECC) through finite element (FE) analysis. The analysis includes twelve simply supported and continuous beams strengthened with different parameters such...

Thermal loading, especially in fire scenarios, challenges the safety and long-term durability of concrete structures. The resulting heat propagation within the structure is governed by the heat conduction equation, which can be difficult to solve analytically because of the nonlinearity related to the thermophysical properties of concrete. A semi-a...

Metakaolin (MK) is a high-quality, reactive nanomaterial that holds promising potential for large-scale use in improving the sustainability of cement and concrete production. It can replace cement due to its pozzolanic reaction with calcium hydroxide and water to form cementi-tious compounds. Therefore, understanding the dissolution mechanism is cr...

This work presents a 3D off-lattice coarse-grained Monte Carlo (CGMC) approach to simulate the nucleation of alkaline aluminosilicate gels, their nanostructure particle size, and their pore size distribution. In this model, four monomer species are coarse-grained with different particle sizes. The novelty is extending the previous on-lattice approa...

Technologies based on phase change materials (PCMs) are promising solutions to reduce energy consumption in buildings and related greenhouse gas emissions. However, the performance of passive PCMs in buildings is highly dependent on the melting temperatures employed, as well as the climate where the building is located. Therefore, the present contr...

The growing global energy demand requires solutions that improve energy efficiency in all sectors. The civil construction sector is responsible for a large part of global energy consumption. In this context, phase change materials (PCMs) can be incorporated into construction materials to improve the energy efficiency of buildings. The purpose of th...

Two bio-oleogels were investigated. These materials were produced with a combination of canola and soybean oil with 4, 6, 8, and 10% of beeswax (by weight). Sensible heat storage capacity, melting parameters, and enthalpies were investigated by the differential scanning calorimetry (DSC) test. An ordinary DSC dynamic test was performed. Cycles of h...

The actual effectiveness of phase change materials (PCMs) in achieving building energy savings strongly depends on the number of entire phase change cycles they undergo within a year. While advanced building performance simulation tools are available, evaluating and enhancing the annual effectiveness of PCMs can be challenging. This research aims t...

International project PoroPCM involves partners from Germany, Czech Republic, Spain and Japan with the objective to develop new multifunctional Phase Change Materials modified porous cementitious nanocomposite (PoroPCM). Such material can be utilized for storing heat energy in the insulation layer of buildings compared to commonly used insulation m...

Concrete structures are increasingly becoming exposed to organic acid attack conditions, such as those found in agriculture and food-related industries. This paper aims to experimentally verify the thermodynamic modeling of cement pastes under acetic acid attack. For this, a modeling approach implemented in IPHREEQC via Matlab is described, and res...

This work aims to introduce a new multiobjective optimization method for designing insulating cementitious foams combined with phase change materials (PCMs) to improve the energy performance of buildings. To achieve this, the multiobjective Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and EnergyPlus software are dynamically coupled. Paramet...

The increasing use of renewable energy sources has highlighted the importance of energy storages, and in particular of latent heat thermal energy storages (LHTESs). Among the phase change materials (PCMs) that can be used in such systems, sugar alcohols (SAs) are considered potential substances that may lead to interesting applications in the LHTES...

Cement clinkers containing mainly belite ( -C2S as a model crystal), replacing alite, offer a promising solution for the development of environmentally friendly solutions to reduce the high level of CO2 emissions in the production of Portland cement. However, the much lower reactivity of belite compared to alite limits the widespread use of belite...

The hysteresis of phase change materials (PCMs) is a temperature delay of the enthalpy curves between the melting and solidification. This work assesses the impact of modelling the PCM hysteresis on the building performance simulation. To this end, a series of PCM models, considering and not the hysteresis phenomenon, are implemented in EnergyPlus...

A major concern in the modern cement industry is considering how to minimize the CO2 footprint. Thus, cements based on belite, an impure clinker mineral (CaO)2SiO2 (C2S in cement chemistry notation), which forms at lower temperatures, is a promising solution to develop eco-efficient and sustainable cement-based materials, used in enormous quantitie...

Air pollution is still among the biggest environmental health threats for humans in Europe. Traffic, industry, and agriculture are the main responsible sources that are emitting air pollutants, that is, nitrogen oxides (NO×), sulfur dioxide (SO2), carbon monoxide (CO), and particulate matter (PM). Moreover, indoor volatile organic compounds (VOCs),...

This work reports a detailed experimental study that has the purpose of investigating the thermal energy storage (TES) performance of cement pastes enhanced with novel microencapsulated phase change materials (MPCMs). Three water-to-binder ratios and three MPCM volume fractions, leading to a total of nine different mixtures, were investigated at th...

A cement-based device that can meet, partially or completely, the heating loads of a building by absorbing the solar radiation and converting it into thermal energy can be defined as a Massive Solar-Thermal Collector. The absorbing material for the incoming radiation is made of a cementitious composite, generally concrete, and flowing water inside...

The study is focused on ultra-light foam concrete (FC) aimed as a thermal insulation material. Two important properties of such material were investigated: compressive strength and thermal conductivity. In the conducted tests, the influence of the air-dry density (200–500 kg/m3), type of foaming agent (synthetic and protein) and binder type (ordina...

Thermal energy storage using phase change materials (PCMs) is a promising technology for improving the thermal performance of buildings and reducing their energy consumption. However, the effectiveness of passive PCMs in buildings depends on their optimal design regarding the building typology and typical climate conditions. Within this context, th...

This paper reports a comprehensive experimental investigation of cement pastes enhanced with Microencapsulated Phase Change Materials (MPCM) for Thermal Energy Storage (TES) purposes. The experimental plan considers three water-to-binder ratios and three MPCM volume fractions, for a total of nine different MPCM paste mixtures. The water-to-binder r...