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The Modular Building System (MBS) is increasingly popular and promoted due to the inherent advantages over conventional construction. Fire performance of a building has become a crucial design consideration because of the recent detrimental fire accidents. However, for modular buildings, there has been less previous evidence of research on the fire performance. Investigations become necessary since double skin wall and floor modular panel systems are involved in MBS in contrast to conventional buildings. Therefore, this work investigates the fire performance of Light-gauge Steel Framed (LSF) modular wall panels with different configurations through numerical analyses. Heat transfer numerical models were developed and validated against the full-scale fire test results comparing the time–temperature response. The validated numerical models were subsequently extended to analyse the fire performance of conventional and modular LSF wall panels. This includes 16 modular wall configurations with single and double fire resistance plasterboard linings and three different insulations, namely rock wool, glass fibre and mineral wool. The structural fire resistance time was determined using the established Load Ratio (LR) vs critical Hot-Flange (HF) temperature correlation. The results demonstrated that there is no noticeable difference in the structural fire resistance time between the modular and the corresponding mapped conventional LSF wall configurations. However, modular wall panels experience enhanced insulation fire resistance up to 170% for single-lined plasterboards and up to 80% for double-lined plasterboard configurations. The analysis also yields that there is no significant influence of the choice of insulation material between rock-wool, glass-fibre and mineral-wool on structural fire resistance.

Concrete-infilled hollow flange cold-formed steel (CF-HFCFS) beams have gained attention in the construction practices owing to many benefits in terms of their structural performances and applicability. The concrete infill ensures better structural performance by restraining the buckling instabilities of thin-walled cold-formed steel elements. However, the shear strength characteristics of CF-HFCFS are not systematically explored yet and hence there is a lack of understanding on the shear strength characteristics of CF-HFCFS beams. Therefore, in this research, shear characteristics were investigated through numerical studies by establishing and analysing three-dimensional finite element (FE) models of CF-HFCFS beams. The developed FE models were verified against the experimental data in terms of failure modes, ultimate shear capacities, and load-displacement characteristics. Then a series of parametric analyses were carried out to investigate the shear behaviour of CF-HFCFS beams against the effects of geometrical (steel thickness, beam depth) and mechanical (yield strength of steel and compressive strength of concrete) properties to further verify the shear characteristics of CF-HFCFS. Lightweight normal and lightweight high strength concrete materials were considered as infill. Also, the influence of the concrete infill on the ultimate shear capacity of the CF-HFCFS beams was evaluated through parametric studies. The ultimate shear capacities were compared against the already available design provisions. Consequently, based on the data established through of parametric analyses, modified design provisions are developed to estimate the ultimate shear capacity of CF-HFCFS beams.

Purpose Fire safety of a building is becoming a prominent consideration due to the recent fire accidents and the consequences in terms of loss of life and property damage. ISO 834 standard fire test regulation and simulation cannot be applied to assess the fire performance of 3D printed concrete (3DPC) walls as the real fire time-temperature curves could be more severe, compared to standard fire curve, in terms of the maximum temperature and the time to reach that maximum temperature. Therefore, this paper aims to describe an investigation on the fire performance of 3DPC composite wall panels subjected to different fire scenarios. Design/methodology/approach The fire performance of 3DPC wall was traced through developing an appropriate heat transfer numerical model. The validity of the developed numerical model was confirmed by comparing the time-temperature profiles with available fire test results of 3DPC walls. A detailed parametric study of 140 numerical models were, subsequently, conducted covering different 3DPC wall configurations (i.e. solid, cavity and rockwool infilled cavity), five varying densities and consideration of four fire curves (i.e. standard, hydrocarbon fire, rapid and prolong). Findings 3DPC walls and Rockwool infilled cavity walls showed superior fire performance. Furthermore, the study indicates that the thermal responses of 3DPC walls exposed to rapid-fire is crucial compared to other fire scenarios. Research limitations/implications To investigate the thermal behaviour, ABAQUS allows performing uncoupled and coupled thermal analysis. Coupled analysis is typically used to investigate combined mechanical-thermal behaviour. Since, considered 3DPC wall configurations are non-load bearing, uncouple heat transfer analysis was performed. Time-temperature variations can be obtained to study the thermal response of 3DPC walls. Originality/value At present, there is limited study to analyse the behaviour of 3DPC composite wall panels in real fire scenarios. Hence, this paper presents an investigation on the fire performance of 3DPC composite wall panels subjected to different fire scenarios. This research is the first attempt to extensively study the fire performance of non-load bearing 3DPC walls.

Purpose In this study, the insulation fire ratings of lightweight foamed concrete, autoclaved aerated concrete and lightweight aggregate concrete were investigated using finite element modelling. Design/methodology/approach Lightweight aggregate concrete containing various aggregate types, i.e. expanded slag, pumice, expanded clay and expanded shale were studied under standard fire and hydro–carbon fire situations using validated finite element models. Results were used to derive empirical equations for determining the insulation fire ratings of lightweight concrete wall panels. Findings It was observed that autoclaved aerated concrete and foamed lightweight concrete have better insulation fire ratings compared with lightweight aggregate concrete. Depending on the insulation fire rating requirement of 15%–30% of material saving could be achieved when lightweight aggregate concrete wall panels are replaced with the autoclaved aerated or foamed concrete wall panels. Lightweight aggregate concrete fire performance depends on the type of lightweight aggregate. Lightweight concrete with pumice aggregate showed better fire performance among the normal lightweight aggregate concretes. Material saving of 9%–14% could be obtained when pumice aggregate is used as the lightweight aggregate material. Hydrocarbon fire has shown aggressive effect during the first two hours of fire exposure; hence, wall panels with lesser thickness were adversely affected. Originality/value Finding of this study could be used to determine the optimum lightweight concrete wall type and the optimum thickness requirement of the wall panels for a required application.

The 3-Dimensional (3D) printing technology in the construction sector has seen an accelerating growth owing to its potential advantages. For this layer-based construction, a detailed investigation on fire performance is necessary. However, there are limited research studies for 3D Printed Concrete (3DPC) walls exposed to fire. Therefore, this paper investigates the fire performance of different types of 3D printed concrete walls using validated Finite Element Models (FEMs). Validated heat transfer FEMs were extended to investigate the fire performance of a range of 3DPC wall configurations (solid, cavity, and composite) under standard fire conditions. The results show that 3DPC non-load bearing cavity walls underperform when subjected to standard fire compared to solid 3DPC walls. The novel composite 3DPC walls with the use of Rockwool as cavity insulation offers superior fire resistance.

Modular Building System (MBS) is an emerging offsite construction technique, which uses prefabricated units, transported, and assembled onsite. In MBS construction process, designing stage is considered as the most significant stage. One of the critical concerns in designing MBSs is to maintain and to ensure the structural integrity of the assembly against critical loading conditions. Connections in the MBSs as a crucial part of the off-site construction, plays a prominent role in providing the essential performance and integrity for the assembled MBS. Hence, it is indispensable to analyse the existing connections used in industry and to investigate the benefits and limitations of their application in MBS construction. A thorough study on connection types will evaluate their capabilities in addressing functional requirements and will exhibit their potential to serve as a benchmark for a range of future modular construction techniques. Thus, this paper presents a review on various forms of inter-modular connection systems used in the contemporary construction industry. It covers the role of connections in the automation of assembly and disassembly of modular units; architectural, structural, and constructional challenges faced by the industry in using them; and their performance under different loading conditions. In addition, numerical studies performed on a selected intermodular connection model is also presented, investigating, and validating the mechanical behaviour of connection and justifying the applicability of such models in predicting connection behaviour. Finally, based on the review, suggestions to address modern construction obstacles by adding new information to the literature and then to overcome challenges in the wide adoption of the MBS in construction industry are presented. The outcome of this study assists in overcoming obstacles and encourages potential growth of MBS and/or off-site construction techniques in building construction industry.

Capillary pressure is frequently measured to evaluate the shrinkage performance of concrete but has been limited to pressures

If concrete is crack free, deleterious substances can be avoided entering the body of the material, that may corrode the rebar or encourage freeze/thaw damage. This paper examines a self healing system of cementitious materials. Microbial induced calcite precipitation was used to heal cracks in concrete with calcite using bacillus bacteria in alkaline conditions to generate a calcite filling material. Self healing of cracked prisms was determined using a water flow and absorption test and the results were expressed to record the healing as a percentage. The findings of the tests showed that a significant degree of self healing had taken place after 56 days after inducing a crack to the concrete prisms and the water flow test was appropriate to determine the degree of self healing taking place. Limitations of this process are such that the process requires a biological laboratory to create the spore impregnated aggregate. Once the aggregate is prepared, the batching process is essentially the same as any normal concrete. A practical use of this system could be developed using cover panels of self healing material to act as permanent formwork, thus placing the healing ingredients where they are needed at a minimum cost. The system has huge potential for the creation of a self repairing sustainable infrastructure.

The use of modular building systems (MBSs) in the construction sector is increasing. MBSs enhance structural performance of buildings, quality control, and construction speed than traditional methods at a lower cost. Additional benefits can be associated with resource efficiency at both the production and construction phases, which may increase MBSs' attractiveness and popularity in the short‐ and long‐term future. In the UK, the government is planning to solve Britain's housing crisis by constructing more than 100,000 modular homes in an effort to meet its target to provide a million new homes by 2020. At the same time, the construction sector is facing post‐Brexit skills shortages, while it is undergoing a technological revolution. One outcome of the latter has been the production of cold‐formed steel (CFS) hollow flange sections, which can be optimised using genetic algorithm and finite element analyses in order to improve the load‐carrying capacity of modular buildings. These optimised CFS beams, employed in MBSs, can light gauge the frame building constructions. This paper presents a review of MBSs and the application of CFS hollow flange steel sections in construction. It then summarises some of the key outputs of numerical studies on the structural behaviour of hollow flange beams to justify its applicability in MBS.

Stainless steel is a high‐performance construction material that combines the strength and stiffness associated with ferrous alloys with the corrosion resistance derived principally from the high chromium content. Its unique combination of properties usually comes at a cost, which puts increased emphasis on ensuring that the material is utilized to the upmost in structural applications. Consequently, in the recent years, an increase in the use of stainless steel in the construction industry has been witnessed, more specifically in exposed architectural applications and where total life economics, durability, improved resistance to aggressive environment, etc. are prime deciding criteria. However, the shear behaviour and capacity of cold‐formed stainless steel beams has not been investigated adequately in the past. Hence, detailed finite element analyses (FEA) were undertaken to investigate the shear behaviour and strength of stainless steel lipped channel beams (LCBs). The developed finite element models were first validated using the shear test results. They were then used in a detailed parametric study to investigate the effects of various influential parameters such as section thickness, depth and grade. Moreover, a parametric study was conducted to emphasize the beneficial effect of strain hardening of stainless steel on shear capacity of LCBs, in particularly for compact sections. FEA results showed that currently available design equations (EN1993‐1‐4) are inadequate to capture the available inelastic reserve capacity of compact stainless steel LCBs, thus suitable equations were proposed to enhance the predictions. This paper presents the details of finite element modelling and analyses of stainless steel LCBs and the development of these new shear design rules.

Cold-formed steel (CFS) members, when subjected to optimisation, can significantly increase their ultimate load carrying capacity leading to a more economical and efficient structural system. This paper presents the details of an investigation on optimisation of CFS beams subjected to bending capacity and an investigation of shear and web crippling capacities of optimised sections. The optimisation was aimed to meet construction constraints reported in Eurocode 3 (EC3). In this research, 4 different CFS sections were considered including the introduction of 2 novel sections (Super Sigma and Smart Beam) which has closer shear center to the web and less susceptible to web buckling. The bending capacity of the available sections were obtained based on the effective width method reported in EC3, while the optimisation procedure was performed using particle swarm optimisation (PSO). The capacities of the optimised CFS beams were also obtained using the nonlinear finite element (FE) analysis and the FE results were compared with EC3. The FE results showed that the Smart beam and Super Sigma claim dual advantage of increase in section moment capacity and restrain against torsional effect than the conventional CFS channel sections with the same amount of material. These optimised cold formed steel beams can be employed in light gauge steel building constructions.

This paper presents the development of novel affordable steel-framed modular units for construction with enhanced overall (healthcare, structural, fire, and lightweight) performance, which ideally suits for emergency response situation, such as current covid-19 pandemic. The nature of quick response and well-prepared strategies are essential to cope with the demand of quicker construction for emergency response structures and if similar situation continues or arises in the future as well. Off-site oriented modular construction is ideal to provide these requirements at very short notice for emergencies. Modular units made of steel components are a leading choice due to the exceptional strength and rigidity for lightweight construction. A new weight optimisation procedure was developed for Cold-Formed Steel (CFS) joists in varying shapes of and results show that weight for per unit length of the joists can be reduced up to 24% without compromising structural capacity. This was verified with validated Finite Element (FE) models. In order to improve the faster jointing method, a novel cut and bend intra-module connection was also introduced. In addition, strap bracing is used for the lateral stability of steel-framed modular buildings. Modular breathing panels are proposed to be employed in corner post modules as sidewalls to improve the indoor air quality and reduce the spread of disease. Based on the comprehensive assessment and numerical results conceptual design of performance improved steel-framed corner post modular unit was proposed to offer short-to-medium (in response to emergencies), as well as long-term solutions for the construction industry.

The bending-shear interaction response of cold-formed stainless steel lipped channel sections has been given inadequate attention in the past. Therefore, this paper investigates the bending and shear interaction behaviour of cold-formed stainless steel lipped channel sections using numerical studies. Finite element (FE) models were developed and validated against the experimental results found in the literature for three-point and four-point loading tests of lipped channel sections of both cold-formed stainless steel and cold-formed steel. The elaborated FE results were used for a comprehensive parametric study that was conducted comprising 60 FE models of three-point loading simulations of stainless steel lipped channels with five different aspect ratios to study the shear response and the bending-shear interaction response. Another 12 FE models of four-point bending simulations were developed to study the bending response. The numerical results were analysed and it is found that the sections with aspect ratios of 1.5 and 2.0 are subjected to the interaction of bending and shear while there is no interaction effect observed in the sections with other aspect ratios. Eurocode 3 and American specifications interaction equations were then evaluated using the numerical results. These design provisions are found to be too conservative for a higher level of applied shear force. Therefore, revised design equations for bending and shear interaction were proposed aiming better prediction accuracy. Further, a statistical evaluation was conducted for the proposed interaction equations and results suggest improved and consistent predictions.

Cracking in concrete structures can significantly affect their structural integrity and eventually lead to catastrophic failure if undetected. Recent advances in sensor technology for structural health monitoring techniques have led to the development of new and improved sensors for real-time detection and monitoring of cracks in various applications, from laboratory tests to large structures. In this study, triaxial accelerometers have been employed to detect and locate micro- and macrocrack formation in plain self-compacting concrete (SCC) and steel-fibre-reinforced SCC (SFRSCC) beams under three-point bending. Experiments were carried out with triaxial accelerometers mounted on the surface of the beams. The experimental results revealed that triaxial accelerometers could be used to identify the locations of cracks and provide a greater quantity of useful data for more accurate measurement and interpretation. The study sheds light on the structural monitoring capability of triaxial acceleration measurements for SFRSCC structural elements that can act as an early warning system for structural failure.

3D Printed Concrete (3DPC) technology is currently evolving with high demand amongst researches and the integration of modular building system (MBS) with this technology would provide a sustainable solution to modern construction challenges. The use of lightweight concrete in such innovative construction methods offers lightweight structures with better heat and sound insulation compared to normal weight concrete. It is worth noting that fire and energy performance has become central to building design. However, there are limited research studies on the combined thermal energy and fire performance of 3DPC walls. Therefore, this study investigates fire performance of 20 numbers of varying 3DPC wall configurations using validated finite element models under standard fire conditions. The fire performance analysis demonstrated that 3DPC non-load bearing cavity walls have substantial resistance under standard fire load and its performance can be further improved with Rockwool insulation. There is significant improvement in terms of fire performance when the thickness of the walls increases in a parallel row manner. Previous thermal energy investigation also showed a lower U-value for increased thickness of similar 3DPC walls. This research concludes with a proposal of using 3DPC wall with Rockwool insulation for amplified combined thermal energy and fire performance to be used in MBS.

Timber beams in historic buildings tend to display signs of mechanical degradation in the form of large bending deformations and reduced capacity, often caused by timber defects. This paper addresses the assessment of the bending resistance of small timber beams subjected to static loads, before and after they have been reinforced using Fibre Reinforced Polymer sheets (FRP). The retrofitting of timber elements using FRP is not a new technique and several experimental research programmes have demonstrated that it is possible to increase the bending capacity of wood beams using FRPs. It is well understood that premature bending failure in timber beams and large bending deformations under loading are often caused by defects (e.g. splay or dead knots, shakes, etc.). This paper presents an experimental work where FRP sheets have been locally applied in the area where defects were noted. The structural response of locally reinforced timber elements when subjected to flexural loading was studied using a series of experiments. The results from the bending tests demonstrate that it is possible to partially restore the bending capacity of defective timber beams with the application of the reinforcement method proposed in this paper.

The shear response of the cold-formed stainless steel lipped channel sections with longitudinal stiffeners has not been investigated adequately in the past. Therefore, this paper presents the details of numerical investigations conducted to study the shear behaviour of longitudinally stiffened cold-formed stainless steel lipped channel sections. Following a validation study of the finite element models of lipped channel sections, the effect of return lips and web stiffeners on the shear response of lipped channel sections was examined through comprehensive numerical parametric studies. In addition, numerical investigations were conducted to study the elastic shear buckling response of the sections and the shear buckling coefficients were back-calculated. It was found that the longitudinal web stiffeners enhance the shear buckling resistance of lipped channel sections considerably with increased stiffener depth. However, the shear capacity increment is not significant compared to plain lipped channel sections. The presence of the web stiffeners is found to be not preventing the out-of-plane buckling of the sections. The evaluation of Eurocode 3 and the direct strength method shear provisions for stainless steel channel sections with longitudinal stiffeners illustrates inaccurate capacity predictions. Therefore, modifications were proposed and comparisons reveal that the proposed provisions enhance the shear resistance predictions with good accuracy over the codified provisions.

Cold-formed steel (CFS) members have been used significantly in light-gauge steel buildings due to their inherent advantages. Optimizing these CFS members in order to gain enhanced loadbearing capacities will result in economical and efficient building solutions. This research presents the investigation and results of the optimization of CFS members for flexural capacity. The optimization procedure was performed using the particle swarm optimization (PSO) method, while the section moment capacity was determined based on the effective width method adopted in EN 1993-1-3 (EC3). Theoretical and manufacturing constraints were incorporated while optimizing the CFS cross-sections. In total, four CFS sections – lipped channel beam (LCB), optimized LCB, folded-flange and super-sigma – were considered in the optimization process, including new sections. The section moment capacities of these sections were also obtained through non-linear finite element (FE) analysis and compared with the EC3-based, optimized section moment capacities. The results show that, compared with a commercially available LCB with the same amount of material, the new CFS sections possess the highest section moment capacity enhancements (up to 65 %). In addition, the performance of these CFS sections when subjected to shear and web-crippling actions was also investigated using non-linear FE analysis.

Modular Building Systems (MBS) has seen an accelerating growth in the construction sector owing to its potential advantages, such as quick erection, improved energy efficiency and less reliant on good weather over conventional construction methods. Therefore, it could be a viable solution to supporting the efforts of solving Britain's housing crisis within a short duration. Construction industries and researchers are working towards better understanding MBS performance at different scales and contexts. To date, research on MBS focused on investigating the structural, social and economic, and safety performances and indicated that there are challenges (Need of lightweight materials and more access space, transportation restrictions, improving structural, fire and energy performances) associated with their use, yet to be addressed. This paper highlights how the incorporation of optimised Cold-Formed Steel (CFS) members with the slotted web can address these challenges. Hence, optimisation technique was employed to enhance the structural performance and to effectively use the given amount of material of CFS members. Lipped channel, folded-flange, and super-sigma have been optimised using the Particle Swarm Optimisation (PSO) method and were analysed using FEM. Results showed that the flexural capacity of the optimised sections was improved by 30–65% compared to conventional CFS sections. A conceptual design of MBS was developed using the optimised CFS members, demonstrating the potential for lighter modules and thus more sustainable structures, reducing the carbon footprint. Therefore, optimisation techniques and slotted perforations would address the aforementioned challenges related to MBS, result in more economical and efficient MBS for inhabitants and construction industries.

This study investigates the effect of 3-dimensional (3D) fibres on the rheological properties of self-compacting concrete (SCC) using three different fibre volume fractions (1%, 2% and 3%). Two different sizes of 3D fibres with perimeters of 115 mm and 220 mm were considered. Rheological properties were determined through slump flow, J-ring, V-funnel and sieve segregation tests. The test results reveal that the addition of 3D fibres decreases the workability of the SCC. 3D fibres with a perimeter of 220 mm have a more adverse effect on the rheological properties of SCC than 3D fibres with a perimeter 115 mm. The balling effect occurred when 2% and 3% fibre volume fractions of 3D fibres with a perimeter of 220 mm were added to the mixture, compromising the workability of SCC.

Fire is one of the severe conditions in which structures may be exposed during their life span. When considering the structural elements, wall panels play a vital role during a fire scenario, since the spreading of the fire could be either controlled or accelerated due to the type of the wall partition. Standard fire tests are generally used to evaluate the fire performance of structural elements. However, the fire tests are expensive and time consuming to carry out. Therefore, numerical methods have been developed to evaluate the fire performance of these structural elements. In this study ABAQUS, finite element software was used to model the fire performance of lightweight foamed concrete and normal weight concrete wall panels. Experimental results of the previous studies were used to validate the models. Parametric studies were conducted using the developed models to evaluate the fire performance of two different types of wall panels under standard and hydrocarbon fire conditions. Lightweight foamed concrete wall panels exhibited better fire performance compared with the normal weight concrete wall panels. Three to five times of fire performance enhancement under insulation criteria could be obtained for wall panels of different thicknesses, by replacing normal weight concrete wall panels with lightweight foam concrete wall panels.

The demand for highly structurally efficient stainless steel is limited to a certain extent by its high initial cost. Therefore, the utilisation of material to the optimum possible level is important. In achieving this, further consideration should be given to enhance the design rules where beneficial effects such as pronounced strain hardening in stainless steel should be taken into account in the design process. In addition to that, a thorough understanding of the structural behaviour of stainless steel sections is also required. However, the shear behaviour and capacity of cold-formed stainless steel lipped channel beams (LCBs) have not been thoroughly investigated previously. Therefore, experimental and detailed finite element (FE) modelling were undertaken to investigate the shear behaviour and strength of stainless steel LCBs. A comprehensive parametric study was also conducted by developing 100 FE models. From the results, the available post-buckling strength in slender stainless steel LCBs was highlighted. Furthermore, the beneficial strength increment due to the strain hardening effect of stainless steel, particularly for compact LCBs in shear, was investigated. Comparisons indicated that current EN1993-1-4 and direct strength method (DSM) shear design rules are too conservative in particularly for compact sections. Thus, existing shear design rules were modified to enhance the overall prediction accuracy for stainless steel LCBs while attention was given to capture the available inelastic reserve capacity.

Structural fire damage can be identified as a common accidental disaster throughout the world which cause thousands of deaths, injuries and millions in property damage each year. Fire represents one of the most severe conditions to which structures may be subjected. Generally, structural elements will be exposed to very high temperature (1200 ℃) during a fire propagation. Fire safety of a structure is measured in terms of fire resistance, which is the duration that a structural member can exhibit resistance with respect to structural integrity, stability and heat transmission. Concrete generally provides better fire resisting characteristics compared to the other construction materials due to its low thermal conductivity, high heat capacity and slower strength degradation with temperature. Cellular lightweight concrete (CLC) is one of the novel type of concrete which can be identified as a better construction material than conventional concrete due to its numerous advantages. However, limited research work has been carried out to determine the fire performance of CLC. Fire response of structural members depends on the thermal, mechanical and deformation properties of the structural material at elevated temperatures. Even though properties at elevated temperatures for normal weight concrete is available in literature, properties of CLC at elevated temperatures (ambient to 1200 ℃) is not thoroughly investigated. Further, CLC fire rating under natural/parametric fire situations and under hydrocarbon fire situations needs to be studied. EN 1992.1.2 provides minimum thickness requirements under standard fire situations for non-loadbearing and load bearing normal weight concrete walls, but for CLC, these values are not available, hence required to be included. Also, parameters and material property limitations related to spalling effect of CLC during fire exposure has not being investigated. Moreover, residual characteristics of CLC walls after fire situations and ability to withstand a second fire situation needs to be assessed.

The use of supplementary cementitious materials (e.g. fly ash and ground granulated blast furnace slag) as a partial replacement of ordinary Portland cement (OPC) in blended cement (BC) concrete has been established in recent years. However, an optimum mix design of BC concrete should not only achieve the targeted mechanical properties but also aim at minimizing the cost as well as environmental impacts. The first step towards an accurate estimate of BC concrete’s environmental impacts is to define an indicative functional unit. Unfortunately, most of the research that uses life cycle assessment (LCA) to compare OPC and BC concrete, selects a simple functional unit without taking into consideration the difference in mechanical properties and durability characteristics. Although several efforts were found integrating the durability characteristics in the environmental impact assessment over the whole life cycle, no consensus was found. In this study, a novel approach to quantifying the environmental impact of BC concrete compared to OPC concrete as a part of a decision making process on the type and mixing proportions of concrete to minimize its environmental impact. Using LCA, the method proposes that performance based parameters are defined: a targeted compressive strength and service life. Predictions should be made of these parameters based on generic user-input data like type of BC, water/binder ratios, binder content and OPC replacement rates. The comparative environmental impact is then quantified accordingly. It is believed that this novel approach allows the user to accurately select and proportion a blended cement concrete mix with the objective of minimizing its environmental impact.

There have been many studies to improve cement integrity under different pressure and temperature conditions where cement degradation is initiated by the mechanical and chemical interactions. Several approaches were presented so far to resolve this issue, many of which are either expensive or inefficient under certain circumstances. In this paper, attempts are made to show the application of Palm Oil Fuel Ash (POFA) as a cheap but efficient supplementary cementing material (SCM) for drilling and completions practices. A series of experiments were conducted to evaluate the changes in the density, free fluid, rheology, weight on cement, compressive strength, matrix structure and composition of the cement modified by POFA. The results obtained indicated that POFA has a hydrophilic surface and can retard pozzolanic reactions. It was appeared that POFA does not significantly change the rheology but may reduce the plastic viscosity. After 24 h and 9 months of curing, 5 wt% POFA based cement appeared to have the highest compressive strength with a very consolidated matrix as observed through XRD, TGA and SEM tests. It was also revealed that nanosilica (NS) may significantly increase the plastic viscosity of the cement while POFA may give a higher strength to the cement in a long curing process. It was then concluded that POFA can be a very good choice to improve the mechanical strength and the matrix structure of the cement under different drilling conditions.

This paper evaluates the feasibility of utilising palm oil fuel ash (POFA) and fly ash (FA) as an Ordinary Portland Cement (OPC) replacement in self-compacting concretes (SCC). The level of OPC replacement is up to 40% based on a 540 kg/m3 mix design. All concrete mixtures were restricted to the following consistency parameter; slump flow of 750 ± 100 mm, T500 of 1.5–4.0 s, J-Ring diameter of 650 ± 100 mm, step height of 5–15 mm and sieve segregation resistance of

[EN] Concrete is the primary building material worldwide with a substantial impact on the built environment sustainability. Hence, it is necessary to assess concrete¿s combined functionality, economic and environmental impact. In this paper, two concrete sustainability assessment frameworks, MARS-SC and CONCRETop, were studied. Building on the identified gaps, a new framework, ECO2 was developed. ECO2 is a multi-criteria decision analysis framework that accounts for carbon sequestration of concrete, impact allocation of raw materials, and the impact from the use and end-of-life phases. Hence, it could be used to optimize the proportions of a concrete mix based on a user-defined sustainability objective. A case study concluded that, due to the whole life cycle scope, the environmental impact calculated through ECO2 is 20% higher than that by MARS-SC and CONCRETop. In case of reinforced concrete, where service life requirements are different, the ranking of the alternatives according to ECO2 will significantly change comparatively., The authors acknowledge no conflict of interest. This work is funded by the Faculty of Engineering and Environment's research development fund (RDF) at Northumbria University, UK.

This paper presents an experimental study on the workability and the heat of hydration in Self-compacting concrete (SCC) incorporating agro-industrial waste and blended aggregates. The control mixture contained only Ordinary Portland Cement (OPC) as the binder while the remaining mixtures incorporated binary and ternary cementitious blends of OPC, palm oil fuel ash (POFA) and fly ash. The replacement of waste was from 10% to 40% by mass of the total cementitious material of the concrete for workability test and limited to 30% and 40% replacement for the heat of evaluation test. Workability i.e. passing ability, filling ability and segregation resistance was determined and semi-adiabatic temperature rise during the initial stage of hydration was measured by thermocouples. It was observed that fly ash mixes required the least amount of super-plasticiser (SP) to obtain a workable SCC, however, POFA mixes had the reverse effect. The ternary use of POFA and fly ash had better workability properties than the POFA mixes and performed the best in terms of segregation resistance. The ternary mixes also had the lowest amount of heat dissipation with peak temperatures occurring earlier than the fly ash mixes. The experimental studies indicate that ternary blend SCC with POFA and fly ash has significant potential when considering a sustainable construction material hence also providing a cleaner production solution for the palm oil industry.

Global warming arising from the release of greenhouse gasses into the atmosphere is one of the biggest issues attracting a lot of attention. One of the conventional problems in sequestration projects is the degradation of Portland cement due to its exposure to supercritical CO2. This paper gives a review on the laboratory work performed to understand changes in the mechanical and transport properties of cement when it is in a CO2 rich environment. The results obtained indicated that pozzolanic material could be useful in enhancing the cement resistance against CO2, although more studies are still required to confirm this conclusion.

This research investigates the fresh state properties and hardened state properties of medium strength, self-compacting concrete incorporating a high volume of class F fly ash as a partial replacement to cement and blended fine aggregates while maintaining satisfactory properties of SCC. The properties of self-compaction investigated are: slump flow, J-ring, L-box, Vfunnel, sieve stability and Visual Stability Index tests. Those of hardened concrete include compressive strength, splitting tensile strength, complete immersion water absorption, apparent volume of permeable voids, sorptivity, and rapid chloride ion penetration tests. The experiments on fresh state properties investigate the filling ability, the passing ability and the segregation resistance of concrete. The results show that fly ash improves workability and decreases the compressive strength as well as splitting tensile strength. Fly ash based SCC shows better resistance to water absorption, apparent volume of permeable voids, sorptivity, and chloride penetration than the control mix.

A UK government report released in 2017 indicated that fly ash (FA) production locally is expected to seize after 2021. This means that for the construction industry to meet its continuously increasing demand for an Ordinary Portland Cement (OPC) replacement, FA would probably need to be either imported or recovered from landfills through energy-intensive processes. Recent reports show that companies in the UK have already started importing FA from several countries from which Germany and China were chosen as case studies to exemplify the closest and furthest respectively. The environmental impact associated with the FA transportation raises concerns about the environmental sustainability of the final concrete product. Therefore, this study focuses on using a life cycle assessment (LCA) tool to analyse the environmental impact of importing FA from Germany and China and compare that to recovering landfilled FA in the UK. The study is the first of its kind to investigate the environmental impact of any of the alternatives. Using a Cradle-to-Gate approach and a mix of primary and secondary data, these alternatives were modelled and compared to conventional OPC and currently available locally sources of FA. Results show that the environmental burden from transporting FA from China to the UK will overcome the environmental benefits of it replacing OPC. It is then concluded that the most promising alternative for cleaner production of blended cement concrete is to recover the 50 million tonnes of landfilled FA from the UK using the Dry-processing technique explained in the study. The second best alternative is to import FA from a country within the Europe region to the UK.

This paper presents the workability properties of Self-Compacting Concrete (SCC) containing a ternary mix binder using Ordinary Portland Cement and agro-industrial wastes i.e; palm oil fuel ash (POFA) and low calcium based fly ash (FA). The mixtures were prepared with 0 to 40% cement replacement using agro-industrial wastes at 10% intervals. Water to binder ratio and cement content is kept constant at 0.38 and 540 kg/m3 respectively. Self-compact-ability parameters investigated were Slump flow, J-Ring, V-Funnel, Sieve Stability and Visual Stability Index Tests. It is found that agro-industrial wastes provide a positive effect on the workability properties of self-compacting concrete.

The aim of this research is to investigate hardened state properties of Self Compacting Concrete (SCC) containing low calcium based fly ash. The mixtures were prepared using various proportions of Class F fly ash ranging from 0% to 30% cement replacement. Water to powder ratio is 0.38 – 0.39 and powder content was kept constant at 540 kg/m3. Properties investigated were strength properties (compressive strength and splitting tensile strength), and durability properties (complete immersion water absorption, apparent volume of permeable voids (AVPV), sorptivity, and RCIPT tests. These tests were done at various days. Results showed that fly ash replacement of up to 30% gave acceptable strength and durability properties for medium strength SCC.

This paper presents an experimental study on the development of normal strength Self compacting concrete (SCC) from uncontrolled burning of rice husk ash (RHA) as a partial replacement to cement and blended fine aggregate whilst maintaining satisfactory properties of SCC. Experiments on the fresh and hardened state properties have been carried out on RHA based SCC from uncontrolled burning. The dosages of RHA are limited to 0%, 20%, 30% and 40% by mass of the total cementitious material in the concrete. The experiments on fresh state properties investigate the filling ability, the passing ability and the segregation resistance of concrete. The experiments on hardened state properties investigate the compressive and the splitting tensile strengths. The water absorption level of the concrete with changing RHA levels has also been monitored. The experimental studies indicate that RHA based SCC developed from uncontrolled burning has a significant potential for use when normal strength is desired. R&D Department, Curtin University Sarawak under CSRF scheme