Real and perceived barriers to steel reuse across the UK construction value chain

© 2017 Elsevier B.V. Although steel reuse has been identified as an effective method to reduce the carbon and energy impact of construction, its occurrence is shrinking in the UK. This can be partly explained by the many barriers which have been identified in the literature, but a detailed analysis of how these barriers affect different parts of the supply chain is still lacking. We show that there is a contrast between perceived higher costs and time required to employ reused steel and the assessments of realised projects. Using a novel ranking method inspired from the field of information retrieval (tf-idf), we have analysed interviews of actors across the supply chain to determine the acuteness of the perception of each barrier. We show that demolition contractors, stockists, and fabricators face specific barriers which each need to be addressed at their level. This is in contrast with more generic barriers present throughout the value chain which we show are probably more perception than reality. Finally, we suggest how supply chain integration could facilitate reuse and make it economically viable at scale

A new method to estimate the lifetime of long-life product categories

Increased recycling and reuse rates are a central part of the objectives laid out by the COP21. Nonetheless, the practical implementation of what has been called the circular economy, as well as its true potential are not easily established. This is because the impact and implementation time scales of any intervention depend on knowing the lifetime of products, which is frequently unknown. This is particularly true in construction, responsible for 39% of worldwide emissions, 11% of which are embodied. Most MFA models will simply assume a range of plausible life expectancies when bottom-up data is lacking (e.g. for buildings). In this work, we propose a novel method of identification using the high quality but highly aggregated trade data available, and use it to establish a “mortality curve” for buildings and other long-lasting products. This identification method is intended to provide more reliable inputs to existing MFA models. It is widely applicable due to the general availability of the underlying data. Using it on UK trade data, we identify product classes at 1 year for packaging/home scrap, one around 10 years for vehicles/equipment, and around 50 years for construction. The identification approach was then validated using classical approaches using bottom up data for vehicles

Options to make steel reuse profitable: An analysis of cost and risk distribution across the UK construction value chain

Although steel reuse has been identified as an effective method to reduce the carbon and energy impact of construction, it is in effect only a marginal practice. A detailed analysis of the costs and risks of reuse in practice in the uk is lacking. We found that although there is a sufficient spread between the price of steel scrap and new steel, this difference cannot be captured by the demolition contractors. Rather, reused steel is somewhat more expensive than new elements, except in certain circumstances such as when the reused elements are available from a nearby site, or when testing elements can be avoided. Further, we show that neither the costs of steel reuse, nor the risks, nor its benefits are spread equitably throughout the construction industry supply chain: most of the substantial and capital-intensive changes required for the widespread adoption of steel reuse are concentrated on steelwork contractors and stockists. Based on this analysis, we suggest helping the emergence of a specialised stockist.This research was supported by Innovate UK, project ‘Supply Chain Integration for structural steel reuse’, ref. 132106; EPSRC Material demand reduction: NMZL/112, RG82144, EPSRC reference: EP/N02351X/1

Usability of mortar for predicting shear strength development at rest of fresh self compacting concrete

Determining the relationship between the rheological parameters of the model mortar and the rheological parameters of SCC (Self-Compacting Concrete) was the aim of the work. The static yield stress and the thixotropy coefficient AT were determined, which are important due to the development of the shear strength at rest and the formwork pressure generated during SCC casting. Shear strength of SCC reflected as static yield stress gs at rest develops mainly due to a self-compaction ability of SCC. And in the longer term, gs develops due to the progressive hydration of the cement and the disappearance of the HRWR impact (loss of fluidity). The static yield stress gs depends on w/c ratio, the type of HRWR (High Range Water Reducers) and cement. SCCs with a higher w/c ratio develop static yield stress gs faster, but up to 40 min the influence of w/c ratio decreases. The stiffening of SCC due to thixotropy increases the shear strength of SCC, but at the same time, it slows down the self-compaction of concrete. Thixotropy coefficient AT depends primarily on w/c ratio, and with the same w/c, on the type of cement and HRWR. The thixotropy coefficient AT increases in the initial period of SCC being at rest. The SCC with higher w/c ratio are characterized by higher thixotropy coefficient AT but at the same time by lower static yield stress gs. The significance of the thixotropic effect for shear strength disappears in time

Testing the greenhouse gas emissions reduction potential of alternative strategies for the english housing stock

Buildings account for around a third of global energy and process emissions, but have been delivering much smaller emissions savings than other sectors. Although clear standards of new building construction and retrofitting options have been developed and are able to reduce building emissions, there is need for a clear prioritisation of policy options capable of delivering the greatest reduction in emissions at minimal costs. This requires an assessment of the trade-offs between new construction and retrofitting in terms of the pace of adoption of improved building standards and the emissions savings achieved to meet current climate targets. In this paper, a dynamic material flow analysis is used to explore the impact of combined mitigation strategies on both new and existing buildings capable of reducing embodied and operational emissions in the English domestic housing stock. The results show that progress in the use of low carbon materials in construction and the deployment of zero-carbon buildings at scale would not be enough to deliver a reduction of building emissions of the scale required nationally (–66% from current levels by 2050). Improvement in building standards for both new and pre-existing construction is essential to meet targets, but its costs are likely to be unreasonable without a reduction in the demand for floor area per capita by promoting flexible design of buildings, house sharing or telecommuting, which are likely to produce far-reaching implications in social organisation and urban planning.EPSR

A home for all within planetary boundaries: Pathways for meeting England's housing needs without transgressing national climate and biodiversity goals

Secure housing is core to the Sustainable Development Goals and a fundamental human right. However, potential conflicts between housing and sustainability objectives remain under-researched. We explore the impact of current English government housing policy, and alternative housing strategies, on national carbon and biodiversity goals. Using material flow and land use change/biodiversity models, we estimate from 2022 to 2050 under current policy housing alone would consume 104% of England's cumulative carbon budget (2.6/2.5Gt [50% chance of < 1.5 °C]); 12% from the construction and operation of newbuilds and 92% from the existing stock. Housing expansion also potentially conflicts with England's biodiversity targets. However, meeting greater housing need without rapid housing expansion is theoretically possible. We review solutions including improving affordability by reducing demand for homes as financial assets, macroprudential policy, expanding social housing, and reducing underutilisation of floor-space. Transitioning to housing strategies which slow housing expansion and accelerate low-carbon retrofits would achieve lower emissions, but we show that they face an unfavourable political economy and structural economic barriers

Mapping material stocks of buildings and mobility infrastructure in the United Kingdom and the Republic of Ireland

Understanding the size and spatial distribution of material stocks is crucial for sustainable resource management and climate change mitigation. This study presents high-resolution maps of buildings and mobility infrastructure stocks for the United Kingdom (UK) and the Republic of Ireland (IRL) at 10 m, combining satellite-based Earth observations, OpenStreetMaps, and material intensities research. Stocks in the UK and IRL amount to 19.8 Gigatons or 279 tons/cap, predominantly aggregate, concrete and bricks, as well as various metals and timber. Building stocks per capita are surprisingly similar across medium to high population density, with only the lowest population densities having substantially larger per capita stocks. Infrastructure stocks per capita decrease with higher population density. Interestingly, for a given building stock within an area, infrastructure stocks are substantially larger in IRL than in the UK. These maps can provide useful insights for sustainable urban planning and advancing a circular economy

The effect of calcareouc fly ash on the efficiency of air entraining additives

W artykule omówiono wpływ dodatku popiołu lotnego wapiennego (PLW) jako dodatku typu II na efektywność działania wybranych domieszek napowietrzających (AE) oraz domieszek napowietrzających w obecności superplastyfikatora (SP). Celem podjętych badań było rozpoznanie wpływu PLW na I efekt działania domieszek napowietrzających. Przedstawiono metodykę i wyniki badań napowietrzenia zapraw cementowych z dodatkiem PLW w zależności od stopnia jego domielenia, w stanie laboratoryjnego zmieszania. Metodami oceny efektywności działania AE były: normowa metoda ciśnieniowa oraz nienormowa metoda wskaźnika piany. Analizowano wpływ następujących czynników: rodzaj popiołu lotnego wapiennego (4 partie), jego ilość jako 10, 20 i 30 % zamiennik masy cementu, aktywację popiołu poprzez przemiał (dostawa, domielenie), rodzaj AE (3 domieszki o różnej bazie chemicznej), rodzaj SP (2 rodzaje). Uzyskane wyniki badań wykazują, iż obecność popiołu lotnego wapiennego powoduje zmniejszenie ilości powietrza w zaprawie. Efektywność działania domieszek napowietrzających w jego obecności uzależniona jest od partii zastosowanego popiołu oraz jego rodzaju (dostawa, domielenie).This article discusses the effect of the addition calcareous fly ash as Type II addition in structural concrete on the efficiency of some air entraining additives (AEA) and admixtures with AEA and superplasticizer (SP). The paper presents the methodology and results of air content of cement mortar with the addition of calcareous fly ash. Methods for assessing the effectiveness of aeration additives were: pressure method and foam index method. The influence of the following factors: the type of calcareous fly ash (4 different delivery), 10, 20 and 30% replacement by weight of cement, ash activation by milling (without and with milling), the type of AEA (3 admixture of various chemical-based), the type of SP (2 types). Results show that the presence of calcareous fly ashes reduces the amount of air in the mortar. The effectiveness of additives in the presence of aeration depends on milling calcareous fly ash addition

Office floor live load- past, present, and future.

Buildings and construction industry are estimated to account for nearly 40% related CO2 emissions. The introduction of strict targets for near-zero energy buildings mean that embodied energy is approaching 100% of total energy consumption. One of the Circular Economy strategies aimed at reducing the use of resources is to prolong the life of the product. With a goal of minimum embodied energy in buildings and make them more flexible in adaptation to maximize their life, every step of the design process must be very carefully examined. In structural design codified rules set out how to calculate the design effect of actions (e.g. imposed loads) on an element, which must be less than or equal to the resistance of that element. The U.S., Canada and the UK codes indicate 2.4 or 2.5kN/m2 as live loads for office floors. Despite this, the area weighted average of imposed loading in 95 office buildings completed in the last 20 years was found to be 4.2kN/m2 (including allowance for partitions). This same value was first introduced in 1862 by The Laws of New York State. In the UK it is common practice to assume 5kN/m2 (including allowance for partitions), a value that is equal to that in The London Buildings Acts 1909. Previous studies have shown that loads introduced in current codes are almost impossible to exceed during a building’s life. Furthermore 0.5kN/m2 reduction in design loads could result into a 20% reduction in the building costs and a 14% reduction in the overall embodied carbon of the structure. Research was undertaken to find what causes the decision to assume higher values than codes indicate. It was found that floor load capacity is the one of the factors that is used to grade office space. However, no guidelines introducing load requirements for such classification were found. It might be concluded that the higher load capacity is perceived as a “flexibility” measure and is connected to higher expected rent. It causes over specification and consequently higher energy intensity in construction without clear impact on building life extension