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The Faculty of Engineering at Stellenbosch University is one of South Africa's major producers of top quality engineers. Established in 1944, it currently has five Engineering Departments.
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Browsing Faculty of Engineering by browse.metadata.advisor "Babafemi, Adewumi John"
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- Item3D printing of eco-friendly concrete incorporating recycled plastic waste (RESIN8) as fine aggregate(Stellenbosch : Stellenbosch University, 2022-12) Oosthuizen, Jandré Daniel; Babafemi, Adewumi John; Walls, Richard Shaun; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH BSTRACTS: Plastic waste is a massive environmental issue worldwide which cannot be solved in a simple manner. Sand being a natural resource is limited in nature in contrast to the abundance of waste plastics in our environment. This study, therefore, investigates the suitability of creating an eco-friendly 3D printable concrete where recycled plastic waste, in the form of Resin8, is incorporated by replacing different percentages of fine aggregates. Replacement values of 5%, 10% and 15% of natural sand by volume are investigated, which are further characterized by varying Resin8 particle sizes. Particle sizes of Resin8 included are sub-5 mm, sub-1 mm and a combination of the two by mixing them by equal proportions (50/50). The concrete incorporating recycled plastic waste (Resin8) was compared to, and tested against a reference concrete mix which is the standard 3DPC mix at Stellenbosch University. Samples of each concrete mix were also mould cast into 160 x 40 x 40 mm prisms from the same concrete mix that were used for printing to investigate the effect the printing process had on the mechanical properties of the concrete. The rheology, slump flow (workability), buildability, air content and density are some of the fresh properties that were investigated. The mechanical properties of the different concrete mixes were investigated by means of flexural (4-point bending) and compression tests. Due to the anisotropic nature of 3DPC, the printed samples were tested in two different directions; D1 and D3. Porosity analysis by means of Computed Tomography (CT) scans were done on printed and cast samples of the reference mix as well as all sub-1 mm Resin8 printed samples to compare and investigate the effect of Resin8 on the microstructure of the printed concrete. Scanning Electron Microscopy (SEM) analysis was conducted on sub-5 mm and sub-1 mm Resin8 particles used in this study, as well as on the 3D printed samples of the reference mix and all replacement percentages of the combination Resin8 mixes after 28 days. All mixes containing Resin8 performed adequately for use in 3DPC based on characterisation of its fresh properties. It was observed that mixes containing Resin8 were more flowable, which has been validated by an increase in slump flow value when compared to the reference mix, while the buildability was negatively affected by the increased flowability. A lower density was obtained as the percentage of Resin8 replacement increased as expected due to the lower relative density of Resin8 compared to sand. Both the flexural and compressive strength decreased as the Resin8 replacement increased. However, an increase in interlayer bond strength was observed in all Resin8 mixes compared to the reference mix, which could possibly be as a result of excess pore water at the interlayer region due to the hydrophobic nature of plastics. The printing process had little effect on the performance of the 3DPC mixes based on similar flexural and compressive strength results achieved for orientation D3 and the mould cast samples, while orientation D1 yielded the best results. Considering the results obtained in this research, the addition of Resin8 into 3D printable concrete is a feasible option and could potentially lead to great reductions of waste plastics in our natural environment even for low replacement volumes.
- ItemAlkali-resistant glass textile reinforcement of 3D printed concrete(Stellenbosch : Stellenbosch University, 2022, 2022-12) Janse van Rensburg, Johannes Jacobus; Combrinck, Riaan; Babafemi, Adewumi John; Civil Engineering; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Additive manufacturing such as 3D concrete printing (3DCP), has recently gained significant attention due to its numerous benefits. However, 3DCP still has significant challenges to overcome before it can be fully adopted as a feasible alternative to conventional construction methods. The reinforcement of 3D printed concrete elements has proven to be challenging and needs to be addressed. Moreover, there are multiple aspects to this challenge that need to be taken into account, such as the lack of clear space above the filament layer being printed, difficulty in installing the reinforcement in different directions as well as integrating the reinforcement into the printing process. Various strategies have been studied in order to address these challenges, with different materials used as reinforcement before, during or after printing. However, before reinforcement can be applied, the behaviour of the consequent composite materials must first be studied. This study, therefore, investigates the flexural performance and behaviour of two different alkaliresistant (AR) glass textile materials as reinforcement to determine whether it is a feasible solution. During this study, two different methods of printing and applications of the textiles are considered, one where the elements are printed vertically and the textiles are pre-installed, and one where the elements are printed horizontally and the textiles are installed during the printing process. The textiles are applied in two different locations, one at the middle of the depth of the sample and one lower down. Samples are extracted from these printed elements and tested in flexure by conducting fourpoint bending tests 28 days after printing. After conducting these tests, the crack sequence and failure mechanisms of the variations are investigated. Furthermore, an optical microscope is used to gather more information regarding the performance and failure of the various samples. The results show that there is a significant increase in the flexural performance of the samples reinforced with an AR glass Textile A. Textile A is fully impregnated with epoxy resin, with high tensile strength, stiffness, and large cross-section area. Additionally, the application of this textile promotes deflection hardening structural behaviour. However, in contrast, there is a significant increase in ductility with no increase in flexural strength for the samples reinforced with an AR glass Textile B. Textile B is coated with styrene butadiene, with high tensile strength but a small section area. The results further indicate that the samples reinforced lower in the sample experience higher flexural strength with lower ductility and more variability in behaviour. During testing, it is also discovered that voids form underneath Textile A when applied to horizontally printed samples (between the interlayers), and that these voids influence the performance of the samples. The voids further influence the failure mode as well as the cracking sequence. Investigation of the failure of the samples reinforced with Textile A show two failure mechanisms occurring, namely, delamination and shear. Delamination always occurs when the textile is applied in the middle of the depth of the samples, but shear only occasionally occurs for the variation where the textile is applied lower in the sample. Additionally, telescopic failure is detected for Textile B. It is concluded that for both the textiles, the best performance, behaviour and repeatability are observed when the elements are vertically printed, and the textiles are placed in the middle of the depth of the sample. Among others, it is recommended to apply different variations of textiles, use different application techniques (such as retrofitting) and to explore the micro mechanical behaviour of 3DPC elements reinforced with textiles in future studies.
- ItemBehaviour of masonry systems incorporating waste plastic subjected to fire(Stellenbosch : Stellenbosch University, 2020-04) Botha, Ayden Dennis; Walls, Richard Shaun; Babafemi, Adewumi John; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Plastic waste within the built environment is a global concern, with proportions of waste plastic produced in municipal solid waste being more than 10% by the beginning of the millennium. Within the engineering community, the use of construction materials implementing waste plastics has been a recent development that aims to minimise the effect of plastic waste on the environment. One major concern, however, is that addition of plastics has an unknown impact on the fire response and behaviour of recycled construction products. All structures are required to have a fire rating to quantify the resistance of the structure to a fire event. The unknown response of recycled construction materials to fire has resulted in the investigation of several recycled construction systems within this thesis. Systems that were analysed include Ecobricks (a building block made of a plastic bottle that is filled with plastic infill material), adobe bricks (building units made from natural in-situ soils) and RESIN8 bricks (concrete masonry units with added plastic aggregate replacement). The exposure of each of these systems to a heat source representing a small fire allowed their respective response to fire to be examined, both qualitatively and quantitively, and for observed behaviour to be captured. The adaptation of a newly developed system for fire response testing (Heat Transfer Rate Inducing System or H-TRIS) was employed for the experimentation carried out in this thesis. The system used involved the use of electric radiant panels for means of heating experiments (coined as the eH-TRIS). Samples were subjected to constant heat fluxes of up to 35 kW/m² imparted purely by means of radiative heat transfer, without the effect of the convective zone heating the sample. A qualitative assessment of the behaviour of exposed Ecobricks with the use of video and photographic data was performed, as well as quantitative thermal assessment of the associated adobe protection system. A quantitative analysis of the RESIN8 samples was carried out to determine total mass losses, release of energy as well as total heat release rates for samples of increasing replacement plastic content. In addition, the pre- and post-fire compressive strengths of the RESIN8 samples were determined to quantify the effect of fire on the capacity of brick strength. The use of exposed Ecobricks was found to lead to undesirable fire behaviour, including the presence of flaming droplets, high smoke production and sustained burning immediately after ignition. A significant improvement was observed with the use of adobe, with minimal effects of heat transfer impacting on the system. The replacement content of the RESIN8 samples influenced both smoke production and heat transfer, with high volumes of smoke observed for the highest replacement group. Capacity of the RESIN8 units was also found to drop up to 34.7% of original compressive strength, with heat releases ranging from 291 to 3075 kW with an increase in RESIN8 replacement. The research in this paper aims to act as a spearhead into the topic of these systems, as further research will be required into the many other facets (and additional construction materials) that remain.
- ItemFire behaviour of plastic bottle ecobricks as an infill building material(Stellenbosch : Stellenbosch University, 2022-04) Sander, Zara Rose; Walls, Richard Shaun; Babafemi, Adewumi John; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: A global increased awareness of plastic pollution, and the consequences of not addressing said problem, has led to increased interest and adoption of ecobricks as a building material. Ecobricks consist of any size plastic beverage bottle, densely filled with dry, non-recyclable plastic. As a result, places such as schools, shops and crèches around the world are collecting them and using them as an infill material in the construction of private and municipal projects. Construction projects incorporating ecobricks involve placing the plastic bricks inside a timber or reinforced concrete frame. The frame is sometimes covered with steel mesh (“chicken wire”) and plastered with various plaster-mixes. Ecobrick structures have gained popularity, with over 200 schools in Guatemala having been built using ecobricks. With plastics being highly flammable, it is important that the construction and fire engineering industries understand how they may perform when exposed to fire. The problem this thesis aims to answer is: how do ecobrick walls behave when exposed to fire, and how can they be built to ensure that they are safe? As construction using ecobricks is relatively new, minimal research has been done regarding fire safety. Two of the most common methods for constructing homes out of ecobricks were identified. One consists of laying ecobricks horizontally between cob (a clay-straw-sand-mortar mix). The alternative was to stack them vertically and encase them with a mesh and plaster. In this work, various plaster systems were tested, including, (a) traditional cement-sand mortar, (b) lime mortar, and (c) cob. This thesis investigates the placement of bottles, the application of plaster, and the use of mesh layers in relation to the thermal performance of ecobricks in a standard fire test. Six wall samples were built to represent the two different construction methods and three different plasters. The samples were tested in a large-scale furnace where the temperatures were measured through the cross-section of each wall. The temperatures were then compared against 2D thermal modelled wall samples to understand the thermal behaviour of the plaster and ecobricks. The plaster of each wall sample proved to be critical in the fire behaviour of the samples. The most favourable ecobrick and plaster combination, a cob plaster of 40 mm on the horizontal ecobrick wall sample, was able to achieve a one-hour fire rating, where the ecobricks did not melt or ignite. Samples tested with a vertical ecobrick and cement mortar experienced severe flaming and failed after 56 minutes, with some samples failing significantly faster. The lime plaster delaminated early on resulting in rapid failure. Preliminary guidelines for ensuring suitable fire behaviour are presented.
- ItemMechanical properties of eco-friendly one-part metakaolin-based geopolymer concrete with Recycled Glass and Plastic (RESIN8) aggregates(Stellenbosch : Stellenbosch University, 2023-11) Ajayi, Babatunde Luke; Babafemi, Adewumi John; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The high demand for concrete in the construction industry is directly proportional to the demand for Portland cement (PC), which is the binding agent in concrete. However, PC production leads to the emission of its equivalent amount of carbon dioxide (CO2), resulting in global warming. Consequently, a one-part "just add water" geopolymer binder is developed, which is a potential sustainable binder that could substitute PC. Therefore, this study investigates and reports the mechanical performance, microstructural properties, and cost analysis of a one-part metakaolin-based geopolymer concrete (GPC) produced with anhydrous sodium silicate, sodium hydroxide, and calcium hydroxide as alkali reagents. The GPC materials were pretreated and investigated to assess their physical properties (such as water absorption, particle gradation, specific gravity, and moisture content of the aggregates) and the chemical composition and morphology of the precursors. The optimum GPC mix design was obtained using the Taguchi experimental design approach, and the materials were dry-mixed before water was added. Further, the natural sand was substituted by fine waste aggregate (FWG) and RESIN8 (recycled plastic waste containing Resins 1–7), respectively, at a 5% and 10% replacement level. The influence of the recycled aggregates on the fresh and hardened properties of the composite was investigated and reported. Furthermore, the effects of different curing methods, such as climate-controlled curing (CC), water-curing (WC), and ambient-curing (AC) conditions, were investigated on the compressive strength. The samples tested for splitting tensile and flexural strength were subjected to AC conditions. Adding 5% and 10% of FWG and RESIN8 as fine aggregate in concrete enhances its workability. However, the compressive strength of samples with 5% and 10% RESIN8 is reduced by 15.1% and 19% for CC, 15.7% and 24.1% for AC, and 14.7% and 22% for WC, respectively, compared to their respective control GPC samples after 28 days of curing. On the other hand, the addition of 5% FWG improved the performance of the matrices by 8.9%, 3.5%, and 5.3% for CC, AC, and WC, respectively. After 28 days of curing, the strength of CC sample was increased by 13.6% due to the addition of 10% FWG. In contrast, the strength of AC and WC samples decreased by 0.7% and 1.7%, respectively, when compared to the control GPC samples. The compressive strength of AC samples shows a 10.9% improvement, whereas WC samples show a 16.3% improvement compared to the 28-day CC GPC samples. Further, the compressive strength of CC GPC declined after 28 days of curing; hence, the choice of curing condition greatly influences the performance of GPC. The enhanced strength of the AC and WC samples can be attributed to the presence of water within the concrete matrix, which allows for a complete geopolymerisation reaction. In contrast, the CC sample only underwent hydration due to the consistent curing temperature of 24 °C. The inclusion of 5% and 10% RESIN8 led to a 60.6% and 78% reduction, respectively, in the elastic modulus (E-mod) of GPC, while 5% and 10% FWG inclusion led to a 21.2% and 30.3% reduction in the E-mod of 28-day AC GPC, respectively. Using 5% and 10% FWG reduced the cost of GPC by 0.13% and 0.27%, respectively, while 5% and 10% RESIN8 increased the cost by 0.07% and 0.13%, respectively. The increased cost of RESIN8 containing GPC is due to the high cost of producing RESIN8. Conclusively, structural GPC is obtained, and 5% RESIN8 content and up to 10% FWG content have the potential to substitute natural sand in an environmentally friendly one-part metakaolin-based structural GPC. In contrast, 10% RESIN8 could be used for a non-structural concrete component. The use of RESIN8 and FWG in GPC possesses economic benefits and is a viable solution to environmental pollution, protection of aquatic lives and preservation of natural aggregates.
- ItemRheo-mechanical, hardened mechanical characterisation, and tensile creep of limestone calcined clay cement fibre-reinforced printed concrete (LC3-FRPC)(Stellenbosch : Stellenbosch University, 2023-10) Ibrahim, Kamoru Ademola; Babafemi, Adewumi John; Van Zijl, Gideon P. A. G.; Stellenbosch University. Faculty of Engineering. Dept. of Civil EngineeringENGLISH ABSTRACT: Concrete is a widely used and acceptable civil engineering construction material. It contributes significantly to infrastructural development and global economic growth. However, its major challenge is its vulnerability to environmental degradation, pollution, carbon emissions, and cracking, which have detrimental influence on the sustainability of its applications under high demand, low recycling rates, and loading. The scarcity of raw materials, caused by wastage, overuse, and environmental issues, threatens infrastructural development. Hence, research on an emerging technology named 3D printed concrete (3DPC) to reduce waste, but also time and cost associated with the construction of concrete infrastructure is imperative. 3DPC is an evolving construction method and has been proposed as an alternative and environmental-friendly construction method to traditional construction method. The high cement content required for the 3D extrusion process is being reduced by partial replacement with supplementary cementitious materials (SCMs) such as fly ash, slag, and silica fume. However, these SCMs are limited in volume and do not have global spread, implying an urgent need for alternatives, but also care for the longevity of infrastructure. Limestone calcined clay cement (LC3) is a suitable SCM for sustainable concrete because of its global availability and comparable early and later strength gain, as recommended by previous studies. When polypropylene fibres are added to the mix, control of plastic shrinkage cracks, increased toughness, and reduced brittleness of 3DPC can be achieved. The main goal of this study is to investigate the rheology, hardened mechanical properties, and tensile creep of fibre-reinforced 3DPC containing LC3 (LC3-FRPC) by quantifying its layer deformation, but also the orthogonal interlayer bond deformation at different stress levels under sustained loadings. To achieve the goal stated above, this research develops the material mix design satisfying 3DPC requirements for early strength and stiffness, shrinkage cracking resistance and mechanical properties, including interfacial bond. The rheology and hardened mechanical properties of LC3-FRPC were compared to that of the fly ash-based counterpart (FA-FRPC). The strategy for strengthening the interfacial bond of LC3-FRPC with effective microorganisms (EM), which enhances not only the bond strength but also improves mechanical capacities are presented. The mechanical responses were verified by microstructural analysis through scanning electron microscopy augmented by energy-dispersive X-ray spectroscopy and X-ray computed tomography to assess the hydration products of the blended binders and the self-healing action of LC3 and EM in FRPC. Then, the creep and shrinkage deformations in two orthogonal directions, and other parameters associated with creep responses, including creep fracture are also conducted experimentally on LC3-FRPC. The creep specimens were subjected to sustained stresses of 40, 60, and 80% of the direct tensile strength, and 40% of the flexural strength results obtained from the quasi-static tests. The results revealed that FRPC mixtures tested showed good rheological properties, with LC3-FRPC showing improved the workability, open time, and buildability by 1.7%, 15.4%, and 19%, respectively, compared to FA-FRPC. FA-FRPC outperformed LC3-FRPC in compression, tension, and flexure because of its lower water demand, but the bond strength between the interfacial layers is higher in LC3-FRPC than in FA-FRPC, with an increase of 8.1% for tension and 9.8% for flexure. EM-enhanced LC3-FRPC had significantly higher bond strengths than the reference LC3-FRPC in both direct tension (26.1%) and flexure (33.7%), thereby implying a lower level of anisotropy. The effects of the binders, particularly the LC3 and the EM on the strengths of FRPC and the macropores at the interfaces of printed concrete, improved the material by forming more calcite crystals. Finally, for the creep response under sustained loadings, none of the LC3-FRPC specimens fractured in tension and flexure. Instead, higher direct tensile and flexural strengths were recorded for the creep specimens after 225 days loaded at different stress levels.
- ItemRheo-mechanics, durability and microstructural characterisation of slag-nodified metakaolin-based geopolymer concrete for extrusion-based 3D printing applications(Stellenbosch : Stellenbosch University, 2023-11) Jaji, Mustapha Bamidele; Babafemi, Adewumi John; Van Zijl, Gideon P. A. G.; Stellenbosch University. Faculty of Engineering. Dept. of Civil EngineeringENGLISH ABSTRACT: Extrusion-based 3D-printed geopolymer concrete (3DPGPC) is a potential alternative to Portland cement concrete (PCC). Research is sparse on the use of metakaolin (MK) for extrusion-based 3D concrete printing applications. The widespread adoption of 3DPGPC is limited due to the unknown durability properties and the long setting time of a two-part geopolymer system. To address the long setting time, this study modified MK-based 3DPGPC with slag up to 30% for 3D printing due to its high Ca2+ ion content. The printable mixture developed comprises M1 (100% MK-3DPGPC) and M2 (95% MK and 5% slag), beyond 5% slag inclusion; the mixtures stiffened with inadequate open time for printing. To address the stiffening, sodium phosphate is incorporated to achieve sufficient open time for constructability of the new mixtures and to improve structural build-up in the mixtures containing slag, M-S10 (90% MK and 10% slag), M-S20 (80% MK and 20% slag) and M-S30 (70% MK and 30% slag), while the mixture without slag, M-S0 (100% MK), is the control. The slump obtained using a mini-slump cone is in the range of 3–5.5 mm and the slump flow using a slump flow table is between 148–157 mm. The setting time using the Vicat apparatus depicts an open time of 6.8 hours for the control (M-S0), and 1.2–1.3 hours for slag-modified mixtures. Rheology tests using an ICAR rheometer reveal that the initial static yield shear stress (𝜏𝑠,𝑖 ) increased from 1898–1900 Pa and initial dynamic yield shear stress (𝜏𝐷,𝑖 ) evolve from 1452–1482 Pa due to 5% slag inclusion. Also, re-floccution (Rthix) and structuration (Athix) rates improved from 5.16 and 0.2 Pa/s to 5.2 and 0.4 Pa/s, respectively. After 28 days of curing age, 70 mm × 140 mm cored cylindrical-3DPGPC specimens exhibited compressive strength of 23.7–33.13 MPa and splitting tensile strength of 1.79–2.43 MPa. Saw-cut 40 mm × 40 mm × 160 mm beam specimens attained flexural strength of 5.48– 7.29 MPa and an interlayer bond strength of 5.40–6.90 MPa. The durability of 3DPGPC is investigated using the water absorption test, capillary and gel porosity test, oxygen permeability index (OPI), and drying shrinkage tests. After 90 days of curing, the drying shrinkages in the vertical direction are 2.98 and 2.86% for the control specimen (M1) and the slag-modified specimen (M2), respectively. In the horizontal direction, the drying shrinkages are 1.14 and 1.1%, respectively. The vertical strain obtained during drying includes plastic shrinkage, drying shrinkage, and vertical creep due to the sustained weight of the upper layers in the fresh state. Drying shrinkage varied along and across the layers of 3DPGPC, depicting anisotropic behaviour. After 90 days of curing, water absorption decreases to 7.33% and 5.2% in M1 and M2 specimens, respectively. The total porosity of 3DPGPC decreases from 20.5–14.5% after 90 days of curing, while mould cast decreasesfrom 15 to 10% in M1 specimens. Slag inclusion further reduce the porosity of 3DPGPC, and mould cast from 17–10.9% and 11.5–8%, respectively. After 90 days of curing, 3DPGPC specimens cored perpendicular to the printing direction (vertical) exhibits (OPI) of 11.07–11.86 kPa, and specimens cored perpendicular to the printing direction (horizontal) exhibits OPI in the range of 10.99–11.74 kPa, while mould cast specimens exhibit OPI of 11.23–11.92 kPa. CT-scan shows that mould-cast specimens have a total porosity of 4.07% and exhibit spherical pores, while 3DPGPC have a total porosity of 1.81% and exhibit elongated pores due to pumping. CT-scan also reveals that porosity is position-dependent in 3DPGPC due to the presence of voids between 0.1–1.7 mm at the interlayer, whereas mould-cast specimens exhibit randomly distributed voids in the range of 0.1–2.5 mm in diameter. Backscattered electron images show increasing C-S-H, N-A-S-H and C-A-S-H gel formation due to the presence of alumina, silica, sodium in MK and high Ca2+ ion as slag content increases. The BrunauerEmmett-Teller (BET) surface area increases with an increase in slag content from 5–23 m2 /g, resulting in the densified 3DPGPC matrix, thereby improving buildability from 27 layers to 42 layers and enhancing mechanical performance. Nitrogen physisorption test shows that the adsorption and desorption isotherms and the hysteresis loops are within the IUPAC Class IV and H3 types, indicating the presence of mesopores (2–50 nm) and macropores (>50 nm). This research demonstrates that MK-based 3DPGPC can be successfully 3D printed and modified with slag to improve the fresh properties, rheology, mechanical properties, microstructural morphology, pore characteristics, and long-term durability performance. It also reveals that 3DPGPC exhibits anisotropy in orthogonal directions. The results obtained from this study are recommended for numerical modelling strategies.
- ItemStructural reliability of ultra-high performance fibre reinforced concrete structures(Stellenbosch : Stellenbosch University, 2022-12) Simwanda, Lenganji Shadrek; De Koker, Nico; Viljoen, Celeste; Babafemi, Adewumi John; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The current lack of established guidelines for ultra high-performance fibre reinforced concrete (UHPFRC) structures has resulted in their design and construction being based on recommendations adapted from provisions for either conventional reinforced concrete or steel fiber reinforced concrete. Despite these approaches being associated with a fair amount of uncertainty with respect to the performance of the material, the margin of structural safety of UHPFRC structures designed using these guidelines has not been extensively probed in a probabilistic context. Structural reliability provides the most objective and consistent measure of structural safety and allows, in a probabilistic context, comparison of alternative design solutions. As such, it forms a key part of the standardisation of modern structural codes of practice through the prescription of partial safety factors calibrated to conform to minimum levels of safety and is used in probabilistic performance-based design philosophies to target the relevant levels of safety (or performance) directly by explicitly computing the probability of failure. Therefore, to stochastically quantify the level of structural safety in UHPFRC structures, and to take steps towards standardisation for their efficient design, this dissertation presents five studies associated with the development and calibration of methodologies for considering the structural reliability of UHPFRC structures. The first and second studies consider the reliability-based design of UHPFRC beams under the limit states of flexure and shear, respectively. Based on the model uncertainty characterised in these studies, global resistance factors for flexural and shear resistance models of UHPFRC beams are calibrated in the third study. The reliability of existing reinforced concrete beams strengthened with UHPFRC tensile layers is considered in the fourth study. Lastly, a work on Bayesian calibration of temperature-dependent thermal physical properties of UHPFRC and structural reliability of UHPFRC beams under the fire limit state of the load-bearing function is presented.