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.

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.

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.

In the last decade, maintenance and adaptive reuse, of the existing building stock, have gained ground in the construction sector. For the adaptive reuse of a building, it is required to analyze, meticulously, the existing structure. Unreinforced masonry structures are indicative of the Dutch built environment. For the assessment of their structural capacity, the European Standard EN 1996 is, currently, applied. Masonry walls of high slenderness, often, comprise the structure of existing buildings, in the Netherlands. It has been noticed that the EN 1996 norm underestimates the vertical resistance of slender walls. This study attempts to extend the applicability of the EN 1996 norm to slender masonry walls, since the norm serves for the assessment of existing structures. Particularly, the research objective is to find an appropriate verification method for existing slender masonry walls, in one-way bending. Literature research is, initially, conducted, with respect to alternative formulas for the calculation of the vertical resistance of slender masonry walls. The formula in the EN 1996 norm and the alternative formulas are reviewed, considering a case study. The case study is one of the slenderest interior masonry walls, that form the structure of a relevant existing building block in Amsterdam. The latter was constructed in the late 19th – early 20th century. The engineering firm STRACKEE BV Bouwadviesbureau provided the technical drawings of the building block. Reference values for the vertical resistance, of existing slender masonry walls, are necessary to develop an appropriate formula for their verification. Therefore, the next step of the research is the numerical analysis. The response of slender masonry walls, subjected to combined vertical and lateral loading, is estimated according to the results of FE analysis. The case study is the reference for the geometry of the FE model. Indicative, for the construction period, properties of masonry are the input for the initial material model. Further, models of slender masonry walls with different geometrical and material properties are analyzed. Specifically, a parametric study is done, to define the influence of geometrical and material properties on the vertical resistance. Based on the FE analysis results, a new formula is proposed. The formula estimates the vertical resistance of existing slender masonry walls, subjected to combined vertical and lateral loading.

Steel fibre reinforced concrete (SFRC) is nowadays used as a construction material for pavement and industrial floors in The Netherlands. The common used SFRC mixture, is concrete strength class C30/37 mixed with circa 35 kg/m3 of steel fibre. The details of the concrete composition mixed with steel fibres are ignored. The mechanical tests result of the experimental program accomplished in this thesis emphasized on the decisive role of the concrete composition and quality on the mechanical properties.

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.

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.

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.

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.....@en

Chemical degradation of cementitious materials is a serious threat to the durability and performance of concrete structures. External sulfate attack is one of the situations that may cause gradual but severe damage. Sulfate ions present in seawater, rivers, groundwater and industrial effluent can penetrate into the hardened concrete, and react with cement hydration products to form ettringite as well as gypsum crystals, if stronger sulfate concentrations are available. Such formations result in a solid volume increase and cause local expansive pressure within the pore network. Although the solid volume increase may initially reduce the porosity of cement paste, it will cause cracking at a later stage as the generated expansive pressure exceeds the tensile strength of cement paste. This, in turn, leads eventually to a total strength loss and an increased permeability of concrete. External sulfate attack in a saturated situation is a complex issue in which ionic transport, expansive reactions and mechanical damage interact with each other. These phenomena may be accompanied by significant macroscopic expansion and severe mechanical damage. However, the theories concerning the exact origin of the expansive pressure are still under debate. In recent years, the crystallization pressure theory has become the most widely cited hypothesis, and ettringite formation from monosulfate is also generally considered as the major cause, but more evidences for this mechanism are still needed. Moreover, the magnitude of the expansive pressure at different scale is still missing, since direct measurement of the expansive pressure on the walls of nanopores is highly challenging. Also the expansion behaviors of larger scale specimens are lack of complete experimental data fromthe literature. Furthermore, the process of crack initiation and propagation is seldom discussed. The development of pressure gradient has been largely neglected in the current literature. In this thesis, an attempt is made to increase the body of knowledge related to cement paste expansion and degradation due to external sulfate attack. Laboratory experiments and numerical simulations were used during the study. External sulfate attack under continuous immersion condition is a slow diffusion process. Even though high water/cement ratios and high sulfate ion concentrations have been adopted as acceleration methods, research shows that the attack depth remains shallow even after several months. Therefore, specimens with a small thickness along the diffusion direction could be preferred for experimental research in order to ensure a faster exposure of the entire cross-section. In this study, small cement paste pipes with a wall thickness of 2.5 mm were prepared and immersed in sodium sulfate solutions with SO42− ion concentrations of 1.5 g/L and 30 g/L. Three types of longitudinal restraints were applied on the specimens before exposure, which were created by a spring, a thin or a thicker stainless steel bar that was centered in the hollow specimens in order to facilitate the non-, low- or high-restraint condition. Strain gauges were used for the measurements of restrained expansions and generated stresses, with the purposes of increasing the measurement accuracy and obtaining continuous experimental results. The free expansion until 420-day immersion was measured periodically. The restrained expansion and corresponding generated stress until 810-day immersion were quantified continuously. The pore size distribution, sulfur distribution and crack pattern were also periodically analyzed. According to the MIP measurements, the pores with diameters between 10 nm and 70 nm were continuously filled during the immersion tests, and strong sulfate solution lead to a faster filling, which supports the crystallization pressure theory. The sulfur distributions at 0-day, 21-day, 70-day, 105-day, 133-day and 189-day immersion in strong and weak sulfate solutions were acquired based on SEM-EDS microanalysis, which can reflect the gradient of the local expansive pressure distribution at the corresponding immersion days. The corresponding expansions under three types of restraint were also obtained. The specimen immersed in strong sulfate solution under high-restraint condition (7 mm - 30 g/L) was almost damaged after 565-day exposure with the largest generated stress of 13.4 MPa. Several vertical cracks were found after 581-day immersion based on the image analyses of CT scanning results. The specimen immersed in strong sulfate solution under low-restraint condition (3 mm - 30 g/L) was almost damaged after 628-day exposure with the largest generated stress of 11.2 MPa. One main vertical crack was found after 765-day immersion. The crack development of the unrestrained specimen immersed in strong sulfate solution (30 g/L) was also studied by CT scanning at 189-day, 294-day, 343-day, 420-day and 469-day exposure. A combination of the horizontal cracks which started some distance away from the exposed surface and the vertical cracks which started from the exposed surface was observed. However, no visually noticeable cracks were observed for the specimens immersed in weak sulfate solution (1.5 g/L) up to 807-day immersion. The generated stresses of specimens under low-restraint condition (3 mm - 1.5 g/L) and high-restraint condition (7 mm - 1.5 g/L) after 807-day immersion were 8.8 MPa and 11.1 MPa, respectively. The complex process of crack initiation and propagation during material degradation at microscopic scale was studied by SEM - EDS microanalysis. The damage evolution of unrestrained specimens immersed in strong sulfate solution (30 g/L) was investigated experimentally. The specimens before sulfate exposure and after 70-day, 105-day and 133-day immersion were studied. Image analysis was applied. The localization process of the subparallel cracks near the exposed surface at the depth of about 250 μm was studied. Progressive precipitation of gypsum crystals inside the localized cracks was observed. The change of sulfur gradient versus exposure time was analyzed. Based on that, the change of expansive pressure gradient versus exposure time was discussed. Numerical models can be of use in understanding complex problems. Delft lattice model was used in this thesis. In order to obtain the realistic mechanical properties of lattice elements, the experimental and numerical studies on the mechanical properties of cement paste pipes just after 90-day curing was done prior to further simulations. Two types of specimens are subjected to uniaxial tensile loading, which are unnotched and single notched specimens. Two main results were obtained through experiments. The first one is the Young’s modulus and tensile strength of unnotched specimens. The second one is the complete stress-strain curves of single notched specimens. A 3D lattice model with a mesh resolution of 0.25 mm/voxel was constructed to simulate the two types of specimens subjected to uniaxial tensile loading. After fitting with the experimental results, the local mechanical properties of cement paste lattice elements were obtained. Afterwards, a numerical study on expansion and degradation processes of the specimen immersed in strong sulfate solution under high-restraint condition (7 mm - 30 g/L) was performed. After comparing with the experimental results in previous chapters, the magnitude of local expansive pressure caused by external sulfate attack was discussed. The experimental setup and techniques (such as strain gauge measurement system, SEM-EDS analysis and X-ray computed tomography) employed in this thesis can be used in the same or similar way for further studies on external sulfate attack or some other degradation problems. Also, the experimental results presented in this research can be used for further numerical studies.@en