Alkali-Silica Reaction (ASR) poses a significant challenge to the durability and structural integrity of reinforced concrete structures worldwide. This thesis presents a comprehensive modelling framework that integrates numerical simulations and phenomenological models to predict the long-term behaviour of ASR-affected structures. The framework addresses the progressive degradation of material properties and the structural implications of ASR-induced expansion, using expansion characteristics derived from experimental data.
Several numerical methods exist to simulate ASR effects at the structural scale. Among these, the Dual Mesh Method (DMM) stands out as novel pre-damage method to simulate ASR induced damage in reinforced concrete. Building upon this approach, this research develops the Modified Dual Mesh Method (MDMM), introducing key advancements such as an adapted tensile curve (ATC) to enhance its predictive capabilities.
The MDMM was validated numerically against reinforced concrete beam behaviour, demonstrating its effectiveness in simulating ASR-induced stress generation, crack propagation, and material degradation under incremental expansion conditions. A comparative analysis with the Reduced Material Properties Method (RMPM) highlighted the MDMM's effective ability to account for internal expansion forces and anisotropic behaviour influenced by structural configurations. The results confirmed the framework's accuracy in replicating critical structural responses such as crack propagation patterns and load-deflection behaviour.
Phenomenological models by Larive and Esposito were integrated into the framework, linking ASR-induced expansion with time and material property degradation. These models enabled long-term damage simulations and were applied to a hypothetical bridge pier cap. The simulation successfully captured key aspects of ASR-induced damage, including crack alignment with reinforcement, stress redistribution, and reinforcement yielding, providing insights into the service life thresholds of ASR-affected structures.
While the framework demonstrates promising capabilities, it remains in an early development stage. Limitations were observed, particularly in accurately representing the gradual reduction of elastic modulus associated with ASR progression. Further validation with complete case studies and exploration of diverse structural configurations are recommended to enhance its applicability and reliability.
This research offers a valuable tool for structural assessment, maintenance planning of ASR-affected infrastructure, bridging the gap between experimental observations and predictive modelling of long-term structural performance.

Aggregates make up around 70% of concrete by volume, leading to a high river sand and gravel extraction rate. This depletion of natural resources will soon become unsustainable as the demand will inevitably overcome the availability of natural aggregates. Moreover, about 200 million tons of basic oxygen furnace (BOF) steel slag (LD slag) are produced yearly worldwide and are predominantly disposed of in landfills. The need to find a sustainable alternative to substitute natural aggregates next to the great availability of steel slag opens the opportunity for its usage as aggregate in concrete. However, when used in concrete, LD slag undergoes an expansive reaction, resulting in cracks and concrete failure. This expansive behavior is widely attributed to the expansion of free lime. The instability has been widely investigated on the macro scale, but only a limited number of studies on the microscale investigated such a hypothesis.

The present study provides a thorough microscopic investigation of LD slag and its instability phenomenon. Firstly, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) are used to characterize the steel slag’s chemical composition and phase distribution. In this study, a phase is defined as a portion of a system with similar chemical characteristics. The main phases of LD slag were dicalcium silicate (belite), calcium ferrite with potential alumina content, and wustite phase. During characterization, it was found 2 distinct phase distributions in LD slag particles, the first with small round and isolated belite phases and another with larger belite phases that are interconnected. This difference in phase distribution is attributed to the different cooling rates of the molten steel slag.

Then, possible reasons for the volumetric instability in LD slag were microscopically investigated, namely, the hydration of free lime, belite polymorphic transformation, hydration of magnesium oxide, and release of residual stress. Free lime and belite polymorphic transformation were not observed in the LD slag analyzed in this study and, therefore, were not considered as a mechanism of the volumetric instability. Moreover, Mg-rich phases have been observed in many isolated and interconnected LD slag particles, which are likely mechanisms of damage onset. Lastly, residual stress was qualitatively confirmed, and inhomogeneous hydration was also observed, which supports the hypothesis of redistribution of residual stress as a damage mechanism of concrete with LD slag as aggregate.

All findings and instability generation in concrete have been performed in concrete samples from accelerated curing conditions, such as high-temperature underwater curing. The test was validated by comparing the damage of the laboratory samples to a 15-year-old concrete left outdoors in the field, exposed to actual environmental conditions. It was observed that the damage features were similar, indicating that the accelerated curing conditions could well replicate the damage in real conditions and could predict the behavior of the concrete in practice.

Lastly, mitigation measures have been proposed, focusing on the concrete binder and particle treatment. It was found that the instability is delayed by the increasing development and compactness of the concrete matrix, likely by delaying water ingress. Moreover, by crushing LD slag particles, and thus -partially- releasing the residual stress present, the damage in concrete was reduced, delaying cracking initiation and concrete failure. However, it was found that despite delaying the damage onset, modifying the binder and crushing the aggregates could not ultimately prevent damage and instability.

Building materials generally perform poorly in a high temperature environment. Residential fires and fires in road tunnels are common occurrences. Furthermore, some factories have no option besides exposing their infrastructure to very high temperatures due to the nature of their operation logistics. Therefore, there is a clear need for developing structural materials that can withstand high temperatures ensuring safety during such events. The present thesis deals with thermal shock damage in construction materials. Specifically, the first half of the thesis focuses on the development of an structural material that would fare well on severe cyclic thermal shock conditions found in a steel factory. The second half aims to improve the capacity of engineers and scientists to predict whether a concrete of a given mixture would suffer from spalling under certain heating conditions. Initially, a review of the main effects and chemical changes caused by high temperature was performed on the conventional building materials, followed by some novel materials being currently explored by the civil engineering scientific community. This aided in the pre-selection of material to be tested at later stages. Further, existing theories concerning high temperature spalling, the causes and the main methods of mitigation were reviewed.

The economic and environmental advantages of extrusion-based 3D concrete printing have made it a frontrunner in large-scale buildings. Nonetheless, this approach suffers from a contradictory rheological requirement and a high percentage of Portland cement (PC) in its mixture, which challenges its sustainability. It is claimed that the addition of supplementary cementitious materials (SCMs) to the mixture might solve this issue.
Fly ash (FA), silica fume (SF), Ground Granulated Blast furnace Slag (GGBS), limestone, and calcined clay are examples of such materials. However, the production of certain of these SCMs, such as FA, SF, and GGBS, is restricted, while others, such as limestone and calcined clay, are plentiful. To address these challenges, the purpose of this research was to investigate two developed mixtures: limestone calcined clay cement (LC3-based) and limestone slag cement (slag-based) activated with limestone-based accelerator slurry (with calcium nitrate as an accelerator).
The first phase of this work was the formulation of flowable and pumpable mixtures. The flowability of two cementitious materials (LC3 and slag-based) and limestone-based accelerator slurry was evaluated. For each mixture, the optimum superplasticizer/ accelerator dose was determined to ensure optimum flowability and pumpability. The optimal dose of superplasticizer for the LC3- and slag-based mixtures, as determined by flowability, pumping, and flow curve tests, was 0.6% and 0.3% of the binder’s mass, respectively. The recommended Ca(NO3)2 dose for limestone-based accelerator slurry was 7% of the cement weight.
Part two of this research looked at how combining limestone-based accelerator slurry with cementitious materials affected the mixture’s fresh qualities. Here, the initial setting time and buildability of the formulated mixes were investigated. At last, a printable mixture of LC3 was developed containing just 275 kg/m3 of PC with compressive strength of more than 30 MPa at 28 days of curing.
The third section of this research was devoted to material properties. Here, the development of the mixture’s compressive strength, heat evolution, and hydration product was investigated. The compressive strength development of all mixtures was assessed at 7 and 28 days of curing. In general, the compressive strength of LC3-based mixtures with various accelerator dosages was greater than that of slag-based mixtures with the same accelerator content.
Isothermal calorimetry was employed to investigate the hydration of the mixtures. The
findings for LC3- and slag-based mixtures demonstrated that a larger calcium nitrate dose significantly accelerated the hydration of the fresh mixtures. This acceleration was shown by a quicker induction time, a shifted primary hydration peak to an earlier age of hydration, increased intensity of the primary hydration peak, and greater cumulative heat. Within the first 7 days, LC3-based mixes had a greater cumulative heat evolution than slag-based mixtures.Thermogravimetric analysis (TGA) was used to analyze the amount of calcium hydroxide and hydration water in the investigated mixes at various curing periods, including 1h, 4h, and 168h. In general, the results of the TGA test and isothermal calorimetry were comparable. The final objective of this study was to examine the adaptability of the developed mixture to an actual printing structure. So, the design of a cycle arch bridge in Zaanstad was explored. The results indicate that the developed mixture will be helpful for utilizing in the 3DCP method since the mixture showed encouraging buildability and sustainability behavior.

The chemistry of ground granulated blast furnace slag (GGBFS) is one of the main factors affecting its reactivity. Knowing the composition of GGBFS used in aged concrete may help understand its past performance and estimate remaining service life. It is well known that GGBFS generally react slower than cement clinker. This thesis proposes that partially hydrated GGBFS grains found in aged concrete could be used to determine its chemical composition. The feasibility of using standard-based energy dispersive X-ray spectroscopy (EDS) microanalysis, along with electron imaging, as a tool for quantitative measurement of the chemical composition of GGBFS grains in cement/concrete is explored in this research. X-ray spectra collected from minerals or glasses of known composition are known as standards for quantitative EDS microanalysis. This study initially examined the performance of mineral and slag standards to quantify X-ray spectra obtained from GGBFS-cement paste specimens of known composition. Parameters such as GGBFS properties, experimental conditions, and microanalysis methodologies that affect the EDS quantitative total and accuracy were elaborated. Then, the same standards were used to quantify the unknown composition of GGBFS used in seven concrete specimens collected in the Netherlands representing different service life, which revealed the variation in GGBFS chemistry over the years. Finally, as a supplementary study, the variation in significant hydration products formed due to variation in GGBFS composition in a cement-GGBFS system was predicted using thermodynamic modelling with GEMS. Altogether, it was concluded that standard-based EDS is a solid tool to characterize the chemical composition of GGBFS used in aged concrete.

Experimental research into the spalling behaviour of mortars and if it is possible to predict the spalling resistance. Research is divided into spalling experiments with varying parameters and experiments to analyse and characterize the pore structure. By combining both results, a first step is taken into a formula that is able to predict the spalling behaviour of cement based materials.

Adding extra functionality to cementitious materials will enhance the capabilities of understanding the use of structures where they are used and at the same time increase its life span. The construction industry is one of the most important economic sectors in many countries. Therefore, efforts to improve its productivity can result in significant developments in the economy of a region. Higher productivity can be achieved for instance by means of process automation, by adding value to the product generated with an activity or via the extension of the use of a given asset.....

For economic, scientific and survival reasons, colonisation of other planets is proposed. Mars is the most suitable place to start. To start an early Martian colony, viable In-Situ Resource Utilisation (ISRU) methods of low energy consumption are required to manufacture strong bulk construction materials. Most other studies have used infeasible materials or processes to investigate the possibility of manufacturing construction materials on Mars. This study investigated answers to this problem and assessed the feasibility thereof under strict requirements.

A literature study has specified Martian regolith as the optimal raw resource. The use of water was not feasible. Simulants MGS-1 and JEZ-1 were used as materials analogous to Martian regolith. Spark Plasma Sintering (SPS) has been chosen as the optimal production method considering Martian regolith and the environment. An experimental study has verified the feasibility of the proposed material combined with the proposed method. Standard compressive tests, CT, SEM, SEM-EDS, DSC-TGA, Taguchi Design, MSEL and SPS, accompanied by standard measurements, yielded the following information: uniaxial compressive strength, density (distribution), macro porosity, microstructure, elemental composition, compaction, and energy requirement. Both simulant types were subject to three modifications: particle size, particle size reduction method and drying. Four SPS parameters have been analysed: temperature, duration, applied coating and applied pressure.

The minimum required compressive strength of 1.9 MPa was readily achieved. A maximum compressive strength of 137 MPa was found with an average of 48.50 MPa. Combined with the possible shape geometries of SPS, the manufactured material is expected to be structurally applicable. The measured theoretical energy requirement was 17.07 GJ/m³. The applied energy use was 2.72 TJ/m³. A reference dome requires a feasible theoretical 89.5 kW or infeasible applied 14.3 MW for one year. The latter value was elevated due to experimental factors. The actual energy requirement of a Martian mission is expected to be closer to the theoretical energy requirement due to efficiency improvements. Water vapour was produced during sintering. This is a vital benefit to a Martian colony. To conclude, ISRU bulk construction material manufacturing on Mars, for early colony development, is possible with regolith simulant and SPS.

The first part of this thesis investigated different pre-treatment methods of the fine glass dust in order to increase the reactivity when it was used as a cement replacement in cementitious mixtures. The results showed that the optimal pre-treatment for the fine glass dust was a heat-treatment at 600∘C for 1 hour combined with a grinding treatment of 1 hour. The heat-treatment was efficient in removing the organic compounds from the fine glass dust and the grinding treatment was efficient in reducing the particle size of the fine glass dust. The second part of this thesis investigated the influence of different cement replacement percentages by pre-treated fine glass dust in cementitious mixtures. Results showed that higher FGD percentages resulted in a reduction in compressive strength. However at longer curing ages (between 28 and 90 days) a small increase in strength development was observed. This could be attributed to the pozzolanic activity of the fine glass dust, which caused secondary strength development at later curing ages. It was also shown that significant amounts of secondary products were formed in the mixture with 25% FGD, which caused volume instability of the mixture. For the mixture with 10% FGD no volume instability was observed. The third part of this thesis investigated the suitability of pre-treated fine glass dust for 3D Concrete Printing using the set-on-demand printing technique. For the mixture with 50% FGD in the cementitious mixtures it was found that a superplasticizer (SP) dosage of 0.4% was sufficient to develop a pumpable cementitious mixture. For the mixture with 20% FGD, this SP dosage was found to be 0.35%. As a combination of cementitious mixture with an accelerator slurry with 10% and 8% CaCl2, Mix FGD50- SP0.35-Acc10% and FGD20-SP0.35-Acc8% provided promising results in terms of fast stiffness and strength development. Due to volume instability of the FGD50 mixture, only mix FGD20-SP0.35-Acc8% was tested on printability. This mixture proved to be printable with a nozzle moving speed of 3600 mm/min and a time interval between layers of 18.8 seconds. Therefore a 20% replacement of Portland cement with fine glass dust could be used to develop a printable cementitious mixture for 3DCP. The fourth part of this thesis discussed the applicability of the developed mixture in practice. A concrete bus shelter was used as a case study and it was shown that the mixture developed enough strength to withstand the stresses of the designed structure. The developed mixture FGD20-SP0.35- Acc8% was promising for implementation in 3DCP in terms of sustainable development of the concrete industry and as a new utilization of a byproduct from the glass recycling industry

In this work, an investigation was carried out to assess the use of pH sensitive encapsulation for carbonation triggered release of Sodium Monofluorophosphate (NaMFP) - an inorganic healing agent. To do so, a state-of-the-art review of pH sensitive wall material and a technique to fabricate the same, to encapsulate NaMFP, was performed. The outcome of comparative analyses conducted on prospective shell materials and encapsulating techniques yielded three potential shell materials and two possible techniques. These findings can aid in future experimental investigations to scale up the use of such encapsulation technologies in the construction sector. This would contribute to the research in producing smart cementitious materials that can detect minute changes in their environment and performtargeted healing, without the need for human intervention.

With rapid industrialisation, the infrastructure sector has seen exponential growth in prefabricated concrete elements due to their speedy construction and efficient usage of material. Precast concrete elements have thus observed some deterioration due to increased internal temperature as a result of rapid curing, and also through deliberate heat curing techniques. This has led to researchers in the past to study the effect of such curing conditions on the durability aspect of the binders, especially their impact on Delayed Ettringite Formation. Precast elements such as railway sleepers, exposed to in the humid environment were thus prone to internal sulphate attack and needs to be investigated. Use of Ground Granulated Blast Furnace Slag (GGBFS) as a substitution for binder content in conventional portland cement in the Netherlands has been prevalent since the early 1900s primarily because of its abundant resource from iron industry. The benefits of slag have been then exploited as it was one of the supplementary cementitious systems which along with being a sustainable solution, provides good resistance to environmental degradation such as chloride penetration resistance. However, their advantages surrounding extreme curing conditions have to be studied, unless used at optimised quantities. The research focused on the potential of blast furnace slag systems to undergo internal sulphate attack due to high internal temperatures. The simulation of high internal temperature was done through heat curing inside an oven following which continuous storage under lime solution was carried out in order to saturate the system. Slag systems at low and high substitution levels (20% & 50%) were used along with a combination of coarser and finer surface areas, to investigate their subsequent influence was chosen for the study. Also, since infrastructure industry adopts CEM II & CEM III-A cement type, where the former was low slag concentration with moderate fineness and the latter with higher substitution level of slag in combination with high overall fineness, their potentials for DEF have also been studied. For all the mixes, the influence of high curing temperature and exposure to moisture was studied through microstructural changes, pore size variations and mineralogical composition effect along with fineness on paste specimens. All studies were compared to reference systems of CEM I, which was observed to be the most detrimental due to DEF. Test results indicate that at lower substitution levels of slag secondary ettringite forms in significant quantities in neat systems along with traces of carbo-aluminate phases in the case of slag systems. Also, higher substitution levels does not appear to completely suppress the formation of ettringite after exposure. Its formation in both the cases showed more or less no influence of fineness of slag added, except in the case of pore size distribution. The significant presence of carbo-aluminates was observed in the case of all slag systems that could prove to be beneficial as they do not translate to deteriorative expansion.

Concrete is one of the most widely applied construction materials worldwide. Although traditional construction processes are optimized in terms of efficiency, costs and material use, the main disadvantages are still related to the use of formwork, labour and limited freedom of shapes in architectural design. The future of concrete structures looks promising with the development of 3D concrete printing techniques. Research to 3D concrete printing systems and printable concrete mix designs led to the development of 3D printed bridges, houses and other pioneer structures. On the other hand, the influence of printing process parameters on the mechanical properties of printed elements is still a relevant research topic. The layer-wise construction process inevitably introduces interfaces between adjacent filaments. Therefore the experimental research of this master thesis focussed on the influence of printing process parameters. Samples were tested in tension, compression and tensile splitting. The time interval between printing two filaments was the first parameter to investigate. The results showed significant strength decrease with increasing time intervals. The second variable was therefore the effect of different curing conditions applied to printed filaments with a time interval of three hours. Results showed that it is possible to limit the strength decrease when curing of the printed filaments is applied. Finally, the nozzle standoff distance with respect to the printed filament was a variable in this research, as a nozzle with backflow was used. No significant differences were observed between different nozzle standoff distances. The anisotropic compressive strength and the tensile splitting strength were hardly influenced by the different printing process parameters. 3D concrete printing shows potential, but lack of design and calculation methods are still a limitation for the implementation of this technique in the national codes and guidelines. Therefore, the second part of this research was numerical research to investigate the possibilities to match the properties of a numerical finite element model with the experimental results, to be able to verify the strength of printed structures. The tensile bond strength test and the compressive strength test were simulated and both the interface and filament properties were assigned such that the numerical results matched the experimental results in tension. In compression it was possible to match two of the three loading directions. Finally, a hypothetical case study in Mali was studied. An emergency shelter scenario was chosen because the current shelter solutions are mainly built for short term use. 3D printed shelters benefit from the short construction time, but may provide better indoor climate, and a better feeling of safety, which possibly contributes the well-being of humans. The design of the emergency shelter was based on both the construction procedure, the green strength development of printed filaments, and the final strength of the material. In the end, numerical calculations showed that the shelter fulfils the requirements and complies to the code. The 3D concrete printing technique shows potential for new solutions for humanitarian problems, and possibly let people realize that the investment in 3D concrete printed emergency shelters is feasible.

The investigation of new glass compositions is crucial to expand the possible applications of glass, from the typical applications for building engineering, in the form of cast blocks or floated glass, to more advanced technologies, such as 3D-printed glass or glass to metal connections. Despite the intense research activity and new glass compositions being investigated every day, there has been little innovation or evolution in the composition of architectural glass. This is partially explained by the fact that a substantial part of glass research is not relevant to practical large-scale applications. This thesis is more concerned about the development of compositions with optimized properties than the studies of the short- and intermediate-range structure of a theoretical glass that would hardly find a practical application. Thus, these compositions are inexpensive and appropriate to mass production, utilizing conventional melting techniques. Since the high melting temperatures and the brittleness are two important drawbacks of glass, this work aims to improve both properties. The modification of the properties is achieved via changes in the composition of the glass, using compounds such as phosphorus pentoxide, aluminium oxide and boron oxide. Then, the choice of different glass formers and modifiers contributes to the development of compositions with lower melting and glass transition temperatures. The reduction of the melting temperature allows a saving of energy during the manufacturing and recycling processes. The structures of the glasses differ from the standard soda-lime and borosilicate glasses, leading to a different mechanical behaviour. For instance, an anisotropic structure, which could exhibit a better mechanical performance than standard glasses. Furthermore, these new compositions incorporate up to 35% of slag and fly ash in their formulas. The valorization of these by-products that would otherwise have been previously discarded reduces costs and gas emission. The developed compositions have high water resistance, amorphous structure proved by x-ray diffraction and indentation toughness comparable to a standard soda-lime glass. The coloration of the samples varies depending on the composition and, for the samples containing slag, depending on the melting temperature. In this case, melting at higher temperatures allows the production of colorless glass. The color of the glasses is mainly influenced by the presence of sulfur and iron oxide. In conclusion, this thesis describes the development of new glass compositions containing fly ash and slag. The focus of the work is on the improvement of the properties and a comparison of performance of these new compositions with the glasses currently used in building engineering. The promising results point to the possibility of expansion of the current applications of glass.

The research is focused on investigating regolith as a building material, while implementing the sustainable approach in terms of energy efficiency and material usage, during production process and construction. The context is located within the first manned missions to Mars, and the requirements, towards testing methods allowing for independence from Earth, are implemented.
The studied production process is using compression and thermal treatment as the main processes.The main final product of the research is a novel approach towards the fabrication of martian regolith. The composition of the material is changed in different ways in order to minimize the energy input and required payload for the production process. The compositions with an additional amount of minerals with lower melting point (plagioclase, ferric sulfate), the ones with smaller particle size distribution (amorphous phase elements) or with additional sulfur powder (which could be brought from Earth or extracted in situ in the future) were studied with mechanical tests and microscopic analysis.
The research proved that the change in composition can have a significant impact on the building material characteristics and could be used to optimize the production process. The compressive strength of the produced specimens was ranging between 0,45 – 4,00 MPa.
The structure built in situ was assumed to be external shell structure protecting inflatable, light habitable modules. The outer shell was analysed in terms of resistance towards wind load, gravity and micrometeorites impacts. The construction method and structure type proposed according to the results from experimental research on the material was based on adobe buildings on Earth. The compressive-only structures built with an interlocking system, which protect the crew against wind, radiation and micrometeorites impacts, were studied and designed.

W/C is a fundamental parameter for concrete mix design, it defines the properties in the fresh and hardened state as well as the durability of the material. Nevertheless, once the concrete has hardened, it is very difficult to estimate the W/C in the original mix design, so far only 2 methodologies has been accepted as a standards. Because of this, the aim of the research is to use 4 methodologies, circular polarization microscopy (CPL), thermogravimetric analysis (TGA), UV light microscopy and scanning electron microscopy (SEM) + Powers and Brownyard approach to estimate the W/C of different concrete samples from a Round Robin Test done by the Applied Petrography Group (APG). The results showed that all the techniques have a correlation with the W/C. The CPL on its own and in combination with the UV light can be a feasible technique to estimate this value. Furthermore, since there were several techniques, it was decided to choose which one gave the best results using three guidelines, representativeness, reproducibility and reliability. The technique with the highest score was the combination of CPL+UV light.

In this study, a three-scale characterization of eight 20-years-old reinforced concrete specimens naturally deteriorated due to chloride-induced corrosion was carried out. The main aim of this research was to investigate some relevant parameters to accurately model corrosion of reinforced concrete structures, such as which are the locations where corrosion pits are more likely to initiate as well as if the Elastic modulus of corrosion product depends on the concrete mix that the reinforcement was embedded in. Each scale of characterization had a specific goal: the macro-scale characterization aimed to analyze the state of the specimens after 20 years of outside (unsheltered) exposure through Non-destructive techniques (i.e. potential measurements, corrosion rate, resistivity of concrete), visual inspections and analysis of historical records. Also, since specimens were mis-labelled during the years, the cement type that each specimen was cast with was identified through polished sections of concrete portions analyzed under the Scanning Electron Microscope (SEM). The meso-scale characterization of the reinforcement aimed to quantify the volume loss of the steel as well as to investigate which were the locations where corrosion pits occurred the most. Out of each reinforced concrete specimen, a core of 20 mm diameter and 100 mm height has been drilled, embedding a steel bar of 8 mm diameter. Each core has been then analyzed through X-ray Computed Tomography (CT-scan) and image analysis was performed. Apart from revealing different volume loss for bars embedded in different mixes (i.e. CEM I was the most corroded, CEM III/B the least), this characterization suggested that the most influencing factor for corrosion pits to form is the presence of defects (i.e. air voids) at the steel/concrete interface. Finally, the micro-scale characterization of corrosion product aimed to investigate the relation between Elastic modulus of corrosion product (퐸cp), its micro-structure and its chemical composition, with regard to the different concrete mix that steel was embedded into. 퐸cp was measured through Nano-indentation, while chemical composition was measured through SEM/EDS (Energy Dispersive Spectrometry) elemental mapping and spot analysis. This phase of the research revealed that differences between Elastic modulus of corrosion product generated in different mixes are not significant, and that the relation between 퐸cp and Fe/O seems to be (linearly) proportional. In the last chapter, the findings of the research are summarized and some recommendations are made regarding future endeavors.

The purpose of this thesis is to investigate the short- and long-term behaviour of injected bolted connections (IBCs) with oversize holes for various injection materials. A central theme in this thesis the demountability of IBCs, as a result of which several release agents are tested for their suitability in and effects on IBCs.
Injection bolts have been used successfully in engineering practice using epoxy resin to limit the amount of slip in bolted shear connections with normal clearance holes, but no explicit results are available for connections with oversize or slotted holes. The use of oversize or slotted holes may be beneficial for the (re-)erection process of structures, and thus it is investigated what the effects of such oversize or slotted holes are on the connection behaviour.
First, it is examined if grout is suitable as an injection material in injected bolted connections (IBCs), as well as what precautions are necessary to ensure proper demountability of grout and(epoxy) resin-injected bolted connections. Secondly, the connection behaviour under short-term loading is determined, on the basis of which long-term creep tests are carried out. Finally, a new injection material is developed based on the preliminary conclusions drawn from the short- and long-term tests.
It is concluded that IBCs can be demounted by treating the connection members with a release agent. The results of the experiments show that the long-term behaviour of resin-injected connections is governing the design, but that modelling of this time-dependent behaviour requires additional testing. The short and long-term performance of the newly developed material (resin reinforced with steel shot) in IBCs with oversize holes is significantly better than that of only resin, on the basis of which it is recommended to further investigate the potential and behaviour of this material in engineering applications.

Due to need for finding a reliable semi destructive test to assess the exiting masonry structures in the region of Groningen, the aim of the project is to do a feasibility study on the relation between the microstructure of the mortar and the mechanical properties of replicated masonry walls and see if this technique can be applied to the existing structures on future researches.

Alkali Silica Reaction (ASR) is one of the degradation mechanisms in concrete that poses a threat to the service life of existing structures. This physio-chemical process is progressive and can affect the the strength, stiffness and stability of concrete structures. A lot of mitigation measures are available to prevent the deleterious effects of ASR in new structures. However, assessment and monitoring of ASR in the existing structures still remain a challenge. Thus the main aim of this thesis is to develop a simplified tool for the assessment of existing structures to assist the asset owners in decision making. This is addressed by a combination of petrographic techniques to quantify the damage
and development of a numerical model to predict the remaining service life. Various existing petrographic tools (Damage rating index and image analysis) are investigated and modified to not only identify the ASR signs but also to quantify the damage. A meso-scale numerical model (ASR expansion model) is developed as an extension to the existing Delft Lattice Model to incorporate the effect of ASR by application of randomly distributed internal expansions. A case study (Afsuitdijk, The Netherlands) is used to apply these methods. The model is compared with the findings from the petrographic analysis using a physical parameter 'crack densities'. This model is able to simulate localised network of cracks typical of ASR and expansion strains as a function of time. These expansions are compared with the permissible expansion thresholds set by
RILEM and CUR to assess the remaining service life. Additionally, the numerical model showcases the importance of different boundary conditions by making a comparative study between free expansions and concrete in confined state. Finally, the limitations and drawbacks of this expansion model are discussed critically.