Klaartje De Weerdt
Background and activities
Current research and teaching
The 1st of May 2014 I started as Associate Professor at the Department of Structural Engineering, NTNU Trondheim. I am dividing my time between research and teaching.
In the autumn I teach Building Materials (TBA4123) to the 1st year Civil Engineering MSc students together with Prof. Tore Kvande. In spring I teach Concrete Structures I (TKT4175) to 3rd year Civil Engineering MSc students together with Prof. Jan Arve Øverli. In addition I contribute to the 4th year Concrete Technology I classes (TKT4215), Concrete Technology for Bridge (KT6004) as part of an experience based MSc program, as well as courses organized by the Norwegian Concrete Association.
Our research team is working on topics oriented towards cement hydration and concrete durability, with other words, concrete from cradle to grave.
Why do we need research on concrete? Cement is the glue of concrete. When it reacts with water it forms solid hydrates which glue the aggregates (stones) in the concrete together to form an artificial rock. The production of conventional Portland cement is associated with large amounts of CO2 emissions. One way of reducing these emissions is by replacing part of the Portland cement with supplementary materials such as limestone, fly ash (by product of coal fired power plants), blast furnace slag (byproduct of iron production), or calcined clay. The resulting composite cements behave differently than the conventional Portland cements both in fresh concrete (e.g. flow, interaction with chemical admixtures etc.) and as a hardened material (e.g. durability and mechanical properties). Research is needed to understand the behavior of these composite cements and to give provide a basis to potentially adapt the practice, regulations and test methods.
PhD candidate Alessia Colombo is studying the interaction between composite cements and lignosulphonates, a Norwegian produced water reducing admixture for concrete. Her research is looking into the mechanisms by which cements consume the admixture. This will lead to a better fundamental understanding of compatibility between admixtures and cements as well as the optimal dosing of the admixtures. The PhD study is part of a user driven innovation project funded by Borregaard and the Norwegian Research Council.
PhD candidate Alisa Machner studies the hydration of specific composite cements. She uses techniques such as TGA, XRD, SEM-EDS, calorimetry, and MIP to study the hydration phases and microstructure of the composite cements over time. In a later stage she will look into the durability of these cements. Alisa’s PhD is an Industrial PhD project funded by Norcem and the Norwegian Research Council.
PhD candidate Andres Belda Revert is working with corrosion of reinforcement in carbonated concrete. Reinforcement is generally protected from corrosion by the high pH of the concrete. CO2 from the air can cause carbonation of the concrete which leads to a drop in the pH and the reinforcement is thus no longer protected. Andres is focusing on composite cements which pose challenges regarding carbonation rates compared to Portland cement. He is looking into the determination of the carbonation front and the corrosion rate. Andres’ PhD is part of a larger user driven innovation project supported by the Norwegian Research Council, Norcem and several other industrial partners.
Post Doc Gilles Plusquellec is looking into alkali silica reaction (ASR) in concrete. It is a concrete deterioration mechanism during which reactive silicates in the aggregates react with the highly alkaline pore solution and moisture. Due to this reaction the concrete increases in volume and causes cracking and potentially structural failure. Gilles is focusing on the alkali content or pH in the pore solution of concrete, one of the main driving forces of these reactions. The aim is to establish a reliable method for the determination of the alkali content and/or pH of concrete. This would allow to measure whether there is an alkali/pH threshold above which ASR is likely to cause problems. The project comprises the investigation of both laboratory exposed samples as well as field samples taken from dams and bridges in Norway. Gilles’ project is part of a larger KPI project managed by SINTEF and supported by the Norwegian Research Council, Norcem and several other industrial partners.
Personally I am working with chloride ingress in concrete with composite cements. Chloride induced corrosion is one of the major deterioration mechanisms for reinforced concrete structures exposed to chloride e.g. originating from sea water or deicing salts. The chlorides have to penetrate the concrete cover in order to reach the steel reinforcement and cause pitting corrosion. The binding capacity and microstructure of the concrete are governing parameters regarding the ingress rate and therefore also the service life of the respective concrete structures. Through our research we create a better understanding of mechanisms behind chloride ingress and contribute to establishing improved mechanistic models for the prediction of the ingress and consequently the service life of reinforced concrete structures. We are currently applying for funds within this field.
Through collaboration with other departments at NTNU and SINTEF we have access to large variety of experimental facilities. For analysis of samples we use amongst others TGA, XRD, SEM, calorimetry, rheology, titration, and ICP-MS. For exposure of concrete we have together with SINTEF access to amongst others carbonation chambers, ASR reactors, spray chambers, frost cabinets.
Scientific, academic and artistic work
A selection of recent journal publications, artistic productions, books, including book and report excerpts. See all publications in the database
- (2019) Macrocell corrosion in carbonated Portland and Portland-fly ash concrete - Contribution and mechanism. Cement and Concrete Research. vol. 116.
- (2019) Comparing chloride ingress from seawater and NaCl solution in Portland cement mortar. Cement and Concrete Research. vol. 115.
- (2019) Effect of carbonation on the pore solution of mortar. Cement and Concrete Research. vol. 118.
- (2018) Impact of Accelerated Carbonation on Microstructure and Phase Assemblage. Nordic Concrete Research. vol. 59 (2).
- (2018) The effect of calcium lignosulfonate on ettringite formation in cement paste. Cement and Concrete Research. vol. 107.
- (2018) Reactivity tests for supplementary cementitious materials: RILEM TC 267-TRM phase 1. Materials and Structures. vol. 51:151 (6).
- (2018) Determining alkali leaching during accelerated ASR performance testing and in field exposed cubes using cold water extraction (CWE) and µXRF. MATEC Web of Conferences. vol. 199.
- (2018) Towards the Understanding of the pH Dependency of the Chloride Binding of Portland Cement Pastes. Nordic Concrete Research. vol. 58 (1).
- (2018) Chloride-binding capacity of hydrotalcite in cement pastes containing dolomite and metakaolin. Cement and Concrete Research. vol. 107.
- (2018) Limitations of the hydrotalcite formation in Portland composite cement pastes containing dolomite and metakaolin. Cement and Concrete Research. vol. 105.
- (2018) Stability of the hydrate phase assemblage in Portland composite cements containing dolomite and metakaolin after leaching, carbonation, and chloride exposure. Cement & Concrete Composites. vol. 89.
- (2018) Filler and Water Reducer Effects on Sedimentation, Bleeding and Zeta-Potential of Cement Paste. Nordic Concrete Research. vol. 58 (N88).
- (2018) Determining the free alkali metal content in concrete – Case study of an ASR-affected dam. Cement and Concrete Research. vol. 105.
- (2018) Carbonation-induced corrosion: Investigation of the corrosion onset. Construction and Building Materials. vol. 162.
- (2017) On the effect of calcium lignosulfonate on the rheology and setting time of cement paste. Cement and Concrete Research. vol. 100.
- (2017) On the mechanisms of consumption of calcium lignosulfonate by cement paste. Cement and Concrete Research. vol. 98.
- (2017) Screening of Low Clinker Binders, Compressive Strength and Chloride Ingress. Nordic Concrete Research. vol. 57.
- (2017) Portland metakaolin cement containing dolomite or limestone – Similarities and differences in phase assemblage and compressive strength. Construction and Building Materials. vol. 157.
- (2017) Determination of the pH and the free alkali metal content in the pore solution of concrete: Review and experimental comparison. Cement and Concrete Research. vol. 96.
- (2017) Role of calcium on chloride binding in hydrated Portland cement–metakaolin–limestone blends. Cement and Concrete Research. vol. 95.