Development of a web-based information system for cascading utilisation of construction materials

This paper presents a Web-based information system for promoting the cascading utilisation of construction materials in order to mitigate the increasing environmental pressure by the construction industry. First, this paper points out me weaknesses of current waste material exchange systems. Then, a new approach is introduced to reuse demolished materials, by which the utilisation of demolished materials may be ascertained before the demolition is actually produced.. Information technologies, including web-based intelligent and distributed systems, are applied to actua1ise this approach. Finally, the development and implementation of the system is described in detail.

Assessing direct and indirect water requirements of construction

Australia is considered the driest populated continent in the world. Despite this, we consume the largest amount of water, per capita. While little of this water is used for the operation of buildings, buildings are now being designed to use less water. Additionally, rainwater collection and grey water recycling systems offer the potential to significantly reduce demand for fresh water. However, little is known about the water required directly and indirectly (ie., embodied in) construction materials and products. Embodied water comprises the water required directly for construction itself and the water consumed indirectly in the production and delivery of materials, products and services to construction. Water required directly for construction is likely to be insignificant compared to the indirect water required for the manufacture of construction materials and products (ie., through materials and other products required to support construction). There is currently a lack of research into embodied water requirements by the construction sector. The relationship between the embodied water and the operational water is also unknown, apart from a handful of studies based solely on national average statistics known as 'input-output' data. The aim of this paper is therefore to model the water required directly and indirectly by construction, integrating currently available public domain industry data with input-output data. The coverage of the industry data relative to the input-output data was evaluated for a typical commercial building, and was found to be very low.

An assessment of the energy and water embodied in commercial building construction

Growing global concern regarding the rapid rate at which humans are consuming the earth’s precious natural resources is leading to greater emphasis on more effective means of providing for our current and future needs. Energy and fresh water are the most crucial of these basic human needs. The energy and water required in the operation of buildings is fairly well known. Much less is known about the energy and water embodied in construction materials and products. It has been suggested that embodied energy typically represents 20 times the annual operational energy of current Australian buildings. Studies have suggested that the water embodied in buildings may be just as significant as that of energy. As for embodied energy, these studies have been based on traditional analysis methods, such as process and input-output analysis. These methods have been shown to suffer from errors relating to the availability of data and its reliability. Hybrid methods have been developed in an attempt to provide a more reliable assessment of the embodied energy and water associated with the construction of buildings. This paper evaluates the energy and water resources embodied in a commercial office building using a hybrid analysis method based on input-output data. It was found that the use of this hybrid analysis method increases the reliability and completeness of an embodied energy and water analysis of a typical commercial building by 45% and 64% respectively, over traditional analysis methods. The embodied energy and water associated with building construction is significant and thus represents an area where considerable energy and water savings are possible over the building life-cycle. These findings suggest that current best-practice methods of embodied energy and water analysis are sufficiently accurate for most typical applications, but this is heavily dependent upon data quality and availability.

The potential to reduce the embodied energy in construction through the use of renewable materials

The threat of dangerous levels of global warming demand that we significantly reduce carbon emissions over the coming decades. Globally, carbon emissions from all energy end-uses in buildings in 2004 were estimated to be 8.6 Gt CO2 or almost one quarter of total CO2 emissions (IPCC 2007). In Australia, nearly ten per cent of greenhouse gases come from the residential sector (DCCEE 2012). However, it is not merely the operation of the buildings that contributes to their CO2 emissions, but the energy used over their entire life cycle. Research has demonstrated that the embodied energy of the construction materials used in a building can sometimes equal the operational energy over the building’s entire lifetime (Crawford 2011). Therefore the materials used in construction need to be carefully considered. Conventional building materials not only represent high levels of embodied energy but also use resources that are finite and are being depleted. Renewable building materials are those materials that can be regenerated quickly enough to remove the threat of depletion and in theory their production could be carbon-neutral. To assess the potential for renewable building materials to reduce the embodied energy content of residential construction, the embodied energy of a small residential building has been determined. Wherever possible, the conventional construction materials were then replaced by commercially-available renewable building materials. The embodied energy of the building was then recalculated. The analysis showed that the embodied energy of the building could be reduced from 7.5 GJ per m2 to 5.4 GJ per m2 i.e. by 28%. The commercial availability of renewable materials, however, was a limiting factor and indicated that the industry is not yet well positioned to embrace this strategy to reduce embodied energy of construction. While some conventional building materials could readily be replaced, in many instances a renewable substitute could not be found.

Energy analysis of the construction of office buildings /by Graham J. Treloar

Buildings have a significant impact on the environment due to the energy required for the manufacture of construction materials. The method of assessing the energy embodied in a product is known as energy analysis. Detailed office building embodied energy case studies are very rare. However, there is evidence to suggest that the energy requirements for the construction phase of commercial buildings, including the energy embodied in materials, is a significant component of the life cycle energy requirements. This thesis sets out to examine the current state of energy analysis, determine the national average energy intensities < i.e. embodied energy rates < for building materials and assess the significance of using national average energy intensities for the energy analysis of a case study office building. Likely ranges of variation in the building material embodied energy rates from the national averages are estimated and the resulting distribution for total embodied energy in the case study building simulated. Strategies for improving the energy analysis methods and data are suggested. Detailed energy analysis is shown to be a useful indicative method of quantifying the energy required for the construction of buildings.

In situ stabilisation of pavements using cementitious binders

An extensive study was made of the physical properties of a range of cementitiously stabilised materials to determine their suitability for use in in situ pavement construction. This process for recycling existing pavements has considerable environmental and cost benefits. Pavement models incorporating these materials were analysed to determine their structural behaviour.

Lithium doped N-methyl-N-ethylpyrrolidiniumbis(trifluoromethanesulfonyl)amide fast-ion conducting plastic crystals

The incorporation of dopant levels of lithium ions (0.5 to 9.3% by mole) in the N-methyl-N-ethylpyrrolidinium bis(trifluoromethanesulfonyl)amide (P₁₂TFSA) plastic crystalline phase results in increases in the solid state ionic conductivity of more than 3 orders of magnitude at 298 K. Conductivities as high as 10^−-4 S cm⁻¹ at 323 K have been measured in these doped plastic crystal phases. These materials can therefore be classified as fast-ion conductors. Higher levels of Li only marginally increase the conductivity, up to around 33 mol%, followed by a slight decrease to 50 mol%. Thermal analysis behaviour has allowed the partial development of the binary phase diagram for the LiTFSA–P₁₂TFSA system between 0–50 mol% LiTFSA, which suggests the presence of a solid solution single phase at concentrations less than 9.3 mol% LiTFSA. There is also strong evidence of eutectic behaviour in this system with a eutectic transition temperature around 308 K at 33 mol% LiTFSA. A model relating ionic conduction to phase behaviour in this system is presented. The increased conductivity upon doping has been associated with lithium ion motion via⁷Li solid state NMR linewidth measurements.

Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials

 A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill’s 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill’s 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger’s effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multistage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.

The advantages of the construction sector of China and India: a comparison

With the spectacular rise of the Chinese and Indian economies the accompanying growth in these two countries' construction sectors justifies more understanding. There is, however, a lot of unknowns about the two countries' construction sectors from a comparative perspective. This study attempted to identify and compare the comparative/competitive advantages of the two fast-growing economies in construction in pursuit of policy and management implications, which can benefit not only the two countries but also other developing countries. In this regard, a comparative advantage framework and Porter's Diamond Framework were applied to analyze the relative advantages of the Chinese and Indian construction sectors. The comparative analyses showed that China appears better endowed in labor with high productivity. Government intervention was identified as benefiting Chinese firms with support for the development of human resources. China also benefits from superior access to a wide range of inputs, including equipment, construction materials, and technology. The existence of large corporate champions provides scale of economy and contributes to the advantage of the construction sector of China. In contrast, India benefits from the increased competitive rivalry thanks to its more hands-off government policies that focus primarily on providing a good business environment with a favorable tax system, market entry policies, laws and regulations, and code/standard systems. The differences identified provide policy implications to the decision makers of the two countries in further developing their construction sectors. © 2014 American Society of Civil Engineers.

2nd generation concrete construction: carbon footprint accounting

Purpose – Construction contractors and facility managers are being challenged to minimize the carbon footprint. Life cycle carbon‐equivalent (CO2‐e) accounting, whereby the potential emissions of greenhouse gases due to energy expenditure during construction and subsequent occupation of built infrastructure, generally ceases at the end of the service life. However, following demolition, recycling of demolition waste that becomes incorporated into 2nd generation construction is seldom considered within the management of the carbon footprint. This paper aims to focus on built concrete infrastructure, particularly the ability of recycled concrete to chemically react with airborne CO2, thereby significantly influencing CO2‐e estimates.

Design/methodology/approach – CO2‐e estimates were made in accordance with the methodology outlined in the Australian National Greenhouse Accounts (NGA) Factors and were based on the energy expended for each life cycle activity from audited records. Offsets to the CO2‐e estimates were based on the documented ability of concrete to chemically react with airborne carbon dioxide (“carbonation”) and predictions of CO2 uptake by concrete and recycled concrete was made using existing predictive diffusion models. The author's study focused on a built concrete bridge which was demolished and recycled at the end of the service life, and the recycled concrete was utilized towards 2nd generation construction. The sensitivity of CO2‐e and carbonation estimates were tested on several different types of source demolition waste as well as subsequent construction applications using recycled concrete (RCA). Whole‐of‐life CO2‐e estimates, including carbonation of RCA over the 1st and 2nd generations, were estimated and contrasted with conventional carbon footprints that end at the conclusion of the 1st generation.

Findings – Following demolition, CO2 capture by RCA is significant due to the more permeable nature of the crushed RCA compared with the original built infrastructure. RCA also has considerably greater exposed surface area, relative to volume, than a built concrete structure, and therefore more highly exposed surface to react with CO2: it therefore carbonates more comprehensively. CO2‐e estimates can be offset by as much as 55‐65 per cent when including the contribution of carbonation of RCA built within 2nd generation infrastructure. Further offsets are achievable using blended fly ash or slag cement binders; however, this study has focused on concrete composed of 100 per cent OPC binders and the effects of RCA.

Originality/value – Construction project estimates of life cycle CO2‐e emissions should include 2nd generation applications that follow the demolition of the 1st generation infrastructure. Life cycle estimates generally end at the time of demolition. However, by incorporating the recycled concrete demolition waste into the construction of 2nd generation infrastructure, the estimated CO2‐e is significantly offset during the 2nd generation life cycle by chemical uptake of CO2 (carbonation). This paper provides an approach towards inclusion of 2nd generation construction applications into whole‐of‐life estimates of CO2‐e.

The properties of fly ash based geopolymer mortars made with dune sand

Geopolymer cement utilises industrial by-products and is associated with low CO2 emissions. The use of dune sand as fine aggregate could reduce the environmental impact of mining activities. The present study is to examine the feasibility of using dune sand in geopolymer-based construction materials. The geopolymer mortars made with dune sand (DSM) were prepared by using alkali activators of different cations(Na, K and Na/K). In order to compare, the corresponding geopolymer mortars made with normal sand (NSM) were also prepared. It was found that dune sand has little influence on the strength of geopolymer mortars, especially for K based mortars. However, the alkali cation has significant influence on the compressive strength of geopolymer mortars. This influence was found to be correlated to porosity. Low compressive strength is associated with high porosity. For all investigated alkali cations, the tensile strengths of DSM compare favourably to those predicted by the relevant Standards for construction materials. Based on the experimental results, Australian dune sand can be used as fine aggregate for the production of geopolymer based construction materials.

Major factors affecting waste generation on construction sites in Iran

Construction and demolition (C&D) waste account for a large share of total solid waste sent to the environment. As a result, effective C&D waste management has been treated as one of the available avenues towards sustainable development. Yet, C&D waste management within the Iranian construction industry has been literally overlooked by investigators. As one of the first studies in Iran, the main causes of generating C&D waste on construction projects have been identified through a review of literature. Afterwards, the list has been subjected to the scrutiny of 101 experts in the field deploying a questionnaire survey. The findings revealed that important causes of C&D waste generation on construction sites were all associated with lack of skills and experience of construction workers and lack of awareness of the concept of waste and values of construction materials. No discrepancy in terms of causes of waste generation was observed among different tiers of construction companies in the Iranian construction industry. The paper concludes with providing a number of guidelines to address the issues as identified for Iran and other developing countries suffering from the same problems.

Implementation of innovative technologies in small-scale construction firms: five Australian case studies

Purpose - The users of construction technologies such as builders and trades people have been acknowledged as sources of potentially important innovations. These innovations may be in the form of safer, less labour intensive, or cheaper methods and processes. The purpose of this paper is to assess whether the Australian construction industry is providing an environment where user-based innovation is being supported and implemented. Design/methodology/approach - An explorative study was undertaken to provide an insight into actual experiences of the implementation of user-based innovation. The data were collected through faceto- face semi-structured interviews providing case studies on multiple aspects of the implementation of innovative construction technologies. The cases involved a cross section of advances, including product, tool, and system technologies. Findings - The main motivation behind developing the technologies was problem solving. The associated industries of manufacturing and retail, as well as consultants within the construction industry present the greatest barriers to implementation. Originality/value - This research provides a better understanding of the factors that are preventing the successful implementation of user-based innovative construction technologies in small firms.

Overcoming barriers to the reuse of construction waste material in Australia: a review of the literature

Although much has been written on how to improve the management of construction waste and increase the use of recycled materials, little progress has been made to address the reuse of construction waste. Yet there is a consensus in the literature that waste reuse practices have a decisive role to play in improving reduction of waste, and that institutional barriers are the most problematic obstacles to implementing identified reuse strategies. This paper examines the literature from the last 10 years on the issues facing different stakeholders around reuse of construction waste in Australia, and the causes and effects of the institutional barriers encountered. Key texts from before this period are also referenced. The findings reveal that institutional impediments are related to problems outside of the construction industry, such as social, economic and political barriers to change. A number of constraints are identified: lack of interest and demand from clients; attitudes towards reuse practices; and training all of which act as disincentives to a proactive and sustainable application of construction waste reuse strategies. Above all, it is argued that legislation should be better implemented to ensure that all states in Australia are required to implement strategies to reuse waste construction materials.

Concepts, models and analyses of electronic demolition of buildings

The demolition of building structures produces enormous amounts of waste materials. In most current demolition projects, a great number of demolished materials are directly sent to landfill after their primary usage due to the difficulties in finding their next usage immediately. At the same time, because of limited supply of second-hand materials, new and high quality materials are used in construction projects whose design standards can be fitted using the secondary or used materials. However, this is an inefficient method to reduce waste because off the flow nature of the current waste-exchange systems and the demolition procedure. The recent concept using deconstruction rather than destruction for demolishing a constructed facility fails to achieve widespread understanding or acceptance due to various practical limitations. In this paper, for the purpose of envisaging the deconstruction implementations in practice and promoting cascading usages of construction materials, the concept of electronic demolition (e-Demotion, eDemolition) is put forward for the first time. E-demolition is a virtual demolition approach by which the demolition information, progress and outputs are operated before the physical demolition. Furthermore, the authors set up the essential models to implement electronic demolition of buildings from the viewpoints of demolition progress, business, and information. Each model is demonstrated in accord with the conventional demolition practice and subject to the ideal deconstruction implementation. Following the electronic demolition of a real project, the physical demolition can be anticipated with a minimum of construction waste emission.