The aim of this article is to report a comprehensive review of life cycle assessment (LCA) and life cycle cost (LCC) implication on residential buildings. It discusses the contemporary issues, and ...its relationship and significance of system boundary, assumptions, and reports how it effects on economic and environmental impacts. The tools, frameworks and processes of LCA and LCC of buildings are also discussed. It critically illustrates the existing LCA and LCC studies on residential house designs to determine the causes for the widely varying results of numerous previous studies. It evaluates life cycle cost and life cycle environmental impacts of a case study building, and compares with very similar LCA and LCC studies. Finally, it reports the implications and perspectives of LCA and LCC studies on building designs.
AbstractDeterioration trends derived using discrete condition data are commonly used in management of civil infrastructure assets. However, the high variability of condition data often makes the ...derivation of deterministic models difficult and unreliable. Therefore, reliability-based methods such as Markov chain have been used to establish trends using highly variable condition data. Although these methods have been explored in assets such as bridges and roads, the use of reliability-based methods in deterioration prediction of buildings is less common. The second-largest class of infrastructure assets owned by the local governments in Australia is community buildings. Because most existing community buildings are maturing, the local government agencies seek more reliable asset management strategies. Physical condition–based forecasting is a major component of such asset management approaches. This paper presents the development of a reliability-based methodology for the deterioration prediction of community buildings. The gamma process is considered to be an appropriate approach for predicting building element deterioration because of the associated temporal variability of degradation. The gamma deterioration process presented in this paper is a stochastic process with independent nonnegative increments having a gamma distribution with an identical scale parameter. Building inspection data from one of the local governments in Victoria are used in the model. Further, the paper discusses the analysis of the data and practical application.
This study reports the effect of heat curing at 120 °C on the geopolymeric reaction and strength evolution in brown coal fly ash based geopolymer mortar and concrete. Moreover, an examination of this ...temperature profile of large size geopolymer concrete specimens is also reported. The specimen temperature and size were observed to influence the conversion from the glassy (amorphous) phases to the crystalline phases and the microstructure development of the geopolymer. The temperature profile could be divided into three principal stages which correlated well with the proposed reaction mechanism for class F fly ash geopolymers. The geopolymerisation progressed more rapidly for the mortar specimens than the concrete specimens with 12 to 14 h providing an optimum curing time for the 50 mm mortar cubes and 24 h being the optimum time for the 100 mm concrete cubes. The 50 mm and 100 mm concrete specimens’ compressive strengths in excess of 30 MPa could be obtained at 7 days. The structural integrity was not achieved at the center of 200 mm and 300 mm concrete specimens following 24 h curing at 120 °C. Hence, the optimal curing time required to achieve the best compressive strength for brown coal geopolymer was identified as being dependent on the specimen size.
To avoid premature failures in pavement layers, strong aggregates must be selected for pavement constructions that can bear the accumulation of permanent deformations. Otherwise, rutting happens in ...the pavement layers due to the accumulation of permanent deformations. On the other hand, due to the extensive generation of construction and demolition (C&D) materials around the world, the application of waste materials in civil engineering projects would be considered as an environmentally friendly and cost-effective solution. Although many studies have been performed to examine the performance of the crushed recycle pavement materials, the literature review shows that few studies have been conducted to examine the permanent deformation characteristic of recycled concrete aggregate (RCA) and crushed rock (CR) containing both crumb rubber (R) and crushed glass (CG). In this study, a series of repeated load triaxial (RLT) tests were carried out to evaluate the permanent deformation (i.e. 100000 loading cycles) of RCA and CR incorporating R and CG. The shakedown theory was used to characterize the permanent deformation behaviour of the samples. Also, Werkmeister's criteria were applied to define the shakedown ranges of the samples. The results show that the RCA, RCA +1% R + 5% CG, CR + 1% R + 3% CG and CR + 1% R + 5% CG can be used as base and sub-base material in pavement.
•Four types of construction and demolition waste materials were used in this study.•Different percentages of crushed glass were added to the aggregates containing rubber.•Permanent deformation tests were performed.•The combination of the wastes can be considered for pavement application.
•Recycled crumb rubber is coated with cement paste via a ball milling machine.•Three weight ratios of cement to rubber are designed for different coating quality.•X-ray micro-computed tomography is ...used to analyse pores and crack propagation.•Degree of increase in compressive strength relies on the coating quality of rubber.•Anisotropic compressive property is primarily related to pore shape and orientation.
The modification of a rubber surface, such as cement coating, is an effective method for enhancing the mechanical performance of concrete containing recycled rubber particles. Although this method has been widely investigated for cast concrete, there is limited research on 3D-printed cementitious materials. This study explored the correlation between the compressive strength and microstructural property of 3D-printed rubberised mortar with cement-coated crumb rubber (15 wt% replacement of river sand). Multiple ratios of cement-to-rubber (C/R) were designed to achieve different coating qualities, including C/Rs of 0.25 (CR-0.25), 0.4 (CR-0.4) and 0.55 (CR-0.55). Scanning electron microscopy (SEM) images showed the existence of hardened cementitious shells outside the rubber particles, which effectively improved the interfacial bonding between the rubber surface and the cement matrix. The compressive strengths of the printed specimens did not always improve as the ratio of cement to rubber for coating increased. Moreover, the anisotropy in compressive strength was more obvious in the CR-0.4 and CR-0.55, where the strength in the Y (printing) direction was about 7 % higher than that observed in the Z (layer deposition) direction. X-ray micro-computed tomography (μCT) analysis revealed that the mechanical anisotropy in CR-0.4 and CR-0.55 could be primarily attributed to two factors – pore morphology and pore orientation relative to the external loading direction. For CR-0.25, the rubber-to-matrix interface bonding appeared more critical for the compressive strength. Finally, the printed specimens showed the higher compressive strengths than the cast ones due to the lower fraction of large pores (diameters ≥ 1 mm).
•Three groups of factors for energy efficiency design of building were determined.•Challenges still exist for advanced technologies from cost-effectiveness.•10–28% and 43–71% energy-saving are ...obtained for smart control and lighting systems.•Few studies were taken to integrate occupant behavior into energy efficiency design.•Occupant behaviour interventions and technological updates are urgently needed.
Three main groups of internal and external influencing factors have been identified through this review, including building characteristics, equipment and technologies, and occupant's behaviors. The consideration of only building characteristics cannot guarantee the best energy design of a building, as it could be dependent on the other two groups of factors. Under some circumstances, some of the energy efficiency design solutions did not consider economic or environmental benefits. A wide range of advanced technologies is available for building designers, while challenges still exist from a cost-effectiveness perspective. Many numerical results are hard to validate and confirm the feasibility of those real projects. Comparatively, occupant behavior interventions provide an alternative solution for building users to improve energy efficiency with a relatively low cost and unsophisticated construction procedures. According to those reviewed studies, the ranges of energy-saving are 10–28% and 43–71% through the smart control of the heating, ventilation, and air conditioning (HVAC) and the lighting systems, respectively. The trends of key influencing factors on energy efficiency design have slightly changed over the past few decades. The influencing factors had been mainly investigated in the optimization design and technological updates of buildings previously but now have incorporated the building management of occupant behavior. Few studies have been carried out to integrate the occupant behavior model into the current energy simulation software. Thus, two research directions can be concluded after this review. Building efficiency design needs to be conducted from a systematic view to figure out the underlying issues among different efficient design measures. Energy performance benchmarking of both occupant behavior interventions and the technological updates and building service systems are urgently needed as a guided reference to help the building users to make smart decisions.
Foundation construction involves heavy machine usage which contributes to greenhouse gas (GHG) and non-GHG emissions. The study aims to develop a model to estimate and compare emissions at foundation ...construction and demonstrate its application using two case studies. A process-based quantitative method is established to estimate emissions due to materials, transportation, and equipment usage. The results are analysed under five impact categories including Global Warming Potential, Acidification Potential, Eutrophication Potential, Photochemical Oxidant Formation Potential and Human Toxicity Potential. Analytical Hierarchy Process is employed to obtain weighting factors to assess impact categories under global and local perspectives. Results obtained an average GHG emission of 67%, 19% and 14% from materials, equipment and transportation respectively. This observation signifies the relative higher percentage of emission distribution of equipment and transportation in foundation construction compared to that in the total building construction. Considerable amount of non-GHG emissions such as Nitrous Oxides and Carbon Monoxides were recorded. Global Warming Potential remained the most prominent impact potential from all the perspectives considered, with an overpowering 75% contribution from global perspective. However, this relative importance is reduced to 33.74%–34.85%, with a relative increase in Photochemical Oxidant Formation and Eutrophication Potentials to 32.55% and 31.92% at regional and local perspective. Therefore emissions such as Nitrogen Oxides, Carbon Monoxides and Sulphur Dioxide should be given more consideration at the regional and local perspectives. Results also convey that the emission comparison perspective could change the focus of environmental impacts considerably.
•GHG emissions due to equipment usage are significant in foundation construction.•Considerable amount of non-GHG emissions is recorded in foundation construction.•Global Warming Potential is the most prominent impact category.•Photochemical Oxidant Formation Potential is significant at regional perspective.•Eutrophication potential is significant at local perspective.
•Fly ash geopolymer shows higher corrosion rate than PC concrete with cast-in chlorides.•Higher corrosion rate in cast-in specimens is attributed to a lower pH in geopolymer.•Chloride diffusion rate ...is dependent on the reactivity of the precursor fly ash.•Chloride binding capacity of fly ash geopolymer is dependent on CaO in precursor.•Hematite, akageneite & lepidocrocite are main corrosion products of geopolymer.
This study investigates the corrosion of reinforcement in geopolymer concrete manufactured from three different low calcium fly ashes from Australian power plants. The long term corrosion condition of embedded rebar in fly ash geopolymer concretes containing cast in chlorides (0–5%) subjected to wet-dry cycles, together with specimens exposed to ponding in 3% NaCl were examined. Half-cell potential and linear polarisation resistance techniques were used to measure corrosion up to 540 days of age, and compared with results of a similar binder content PC concrete. Increased levels of corrosion were observed in the cast-in chloride geopolymer specimens compared with the equivalent PC concretes. However, in the case of the ponded specimens the reinforcement in the geopolymer concrete specimens displayed lower corrosion levels than the PC concrete. The higher corrosion rate in the cast-in specimens is attributed to a lower pH in the geopolymer specimens resulting in a higher Cl−/OH− ratio. In the ponded specimens the formation of three-dimensional N-A-S-H and C-A-S-H cross linking in the gel matrix reduces chloride diffusion to rebar depth, resulting in a lower corrosion rate being observed for ponded geopolymer specimens compared to the PC concrete.
Replacing virgin materials with recycled or sustainable materials to reduce energy consumptions and emissions is the focus of contemporary research to reduce building related emissions. Geopolymer ...concrete produced using 100% fly ash is a similar sustainable construction material capable of replacing Portland Cement (PC) concrete. As a replacement for PC, fly ash seems to be a sustainable solution, however the benefits from the production process of fly ash geopolymer (FAGP) concrete is the subject of considerable debate. In addition, factors such as local availability and transportation issues could potentially increase the emission profile of FAGP concrete. Thus, this study aims to evaluate the emission profiles for different types of fly ash in Australia considering availability and transportation. A case study and a scenario analysis are also presented to demonstrate the factors that affect the Green House Gas (GHG) emission profile of FAGP manufacture. The results indicate that to the GHG emission profile for FAGP concrete changes considerably based on the material availability, transportation and mix design. Alkali activators and elevated heat curing processes also significantly contribute the total GHG emissions of FAGP concrete production. The results further signify that the case study location could influence the employment of FAGP concrete in terms of GHG emissions. Further studies are encouraged on optimising the cost, GHG emissions, availability and strength characteristics to strike a balance between in sustainability for selecting the best FAGP type for construction. The results also provide the initial factors to be considered in developing a guideline for employing sustainable materials in the building industry.
•FAGP concrete use in a building was observed 4–9% GHG emission savings.•Optimum use of alkali activated materials in Geopolymer concrete is vital to minimise GHG emissions.•Transportation is major factor to be considered in minimising GHG emissions from FAGP concrete production.•Sustainability of FAGP concrete depends on availability of materials, optimum mix design and pre-fabrication composition.
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