Options for achieving a 50% cut in industrial carbon emissions by 2050.

Carbon emissions from industry are dominated by production of goods in steel, cement plastic, paper, and aluminum. Demand for these materials is anticipated to double at least by 2050, by which time global carbon emissions must be reduced by at least 50%. To evaluate the challenge of meeting this target the global flows of these materials and their associated emissions are projected to 2050 under five technical scenarios. A reference scenario includes all existing and emerging efficiency measures but cannot provide sufficient reduction. The application of carbon sequestration to primary production proves to be sufficient only for cement The emissions target can always be met by reducing demand, for instance through product life extension, material substitution, or "light-weighting". Reusing components shows significant potential particularly within construction. Radical process innovation may also be possible. The results show that the first two strategies, based on increasing primary production, cannot achieve the required emissions reductions, so should be balanced by the vigorous pursuit of material efficiency to allow provision of increased material services with reduced primary production.

Comparison of stabilised/solidified mixes of model drill cuttings based on the North Sea and Red Sea Areas

Following the global stringent legislations regulating the wastes generated from the drilling process of oil exploration and production activities, the management of hazardous drill cuttings has become one of the pressing needs confronting the petroleum industry. Most of the prevalent treatment techniques adopted by oil companies are extremely expensive and/or the treated product has to be landfilled without any potential end-use; thereby rendering these solutions unsustainable. The technique of stabilisation/solidification is being investigated in this research to treat drill cuttings prior to landfilling or for potential re-use in construction products. Two case studies were explored namely North Sea and Red Sea. Given the known difficulties with stabilising/solidifying oils and chlorides, this research made use of model drill cutting mixes based on typical drill cutting from the two case studies, which contained 4.2% and 10.95% average concentrations of hydrocarbons; and 2.03% and 2.13% of chlorides, by weight respectively. A number of different binders, including a range of conventional viz. Portland cement (PC) as well as less-conventional viz. zeolite, or waste binders viz. cement kiln dust (CKD), fly ash and compost were tested to assess their ability to treat the North Sea and Red Sea model drill cuttings. The dry binder content by weight was 10%, 20% and 30%. In addition, raw drill cuttings from one of the North Sea offshore rigs were stabilised/solidified using 30% PC. The characteristics of the final stabilised/solidified product were finally compared to those of thermally treated cuttings. The effectiveness of the treatment using the different binder systems was compared in the light of the aforementioned two contaminants only. A set of physical tests (unconfined compressive strength (UCS)), chemical tests (NRA leachability) and micro-structural examinations (using scanning electron microscopy (SEM), and X-ray diffraction (XRD)) were used to evaluate the relative performance of the different binder mixes in treating the drill cuttings. The results showed that the observed UCS covered a wide range of values indicating various feasible end-use scenarios for the treated cuttings within the construction industry. The teachability results showed the reduction of the model drill cuttings to a stable non-reactive hazardous waste, compliant with the UK acceptance criteria for non-hazardous landfills: (a) by most of the 30% and 20% binders for chloride concentrations, and (b) by the 20% and 30% of compost-PC and CKD-PC binders for the Red Sea cuttings. The 20% and 30% compost-PC and CKD-PC binders successfully reduced the leached oil concentration of the North Sea cuttings to inert levels. Copyright 2007, Society of Petroleum Engineers.

Sustainable binders for soil stabilisation

Portland cement is the most commonly and widely used binder in ground improvement soil stabilisation applications. However, many changes are now affecting the selection and application of stabilisation additives. These include the significant environmental impacts of Portland cement, increased use of industrial by-products and their variability, increased range of application of binders and the development of alternative cements and novel additives with enhanced environmental and technical performance. This paper presents results from a number of research projects on the application of a number of Portland cement-blended binders, which offer sustainability advantages over Portland cement alone, in soil stabilisation. The blend materials included ground granulated blastfurnace slag, pulverised fuel ash, cement kiln dust, zeolite and reactive magnesia and stabilised soils, ranging from sand and gravel to clay, and were assessed based on their mechanical performance and durability. The results are presented in terms of strength and durability enhancements offered by those blended binders.

Fracturing of sand in compensation grouting

The phenomenon of fracturing in sand as a result of compensation grouting was studied. Processes of fracture initiation and propagation were explained and a parametric study was conducted in order to investigate the factors that cause sand fracturing to occur. Experimental results indicate that fracture initiation requires the existence of a local inhomogeneity around the injection position. Grout mixture in terms of water-cement ratio and fines content had major roles in sand fracturing, whereas injection rate had a minor influence under the tested conditions. © 2009 Taylor & Francis Group.

The influence of injection conditions and soil types on soil improvement by microbial functions

Research has begun on Microbial Carbonate Precipitation (MCP), which shows promise as a soil improvement method because of its low carbon dioxide emission compared to cement stabilized agents. MCP produces calcium carbonate from carbonates and calcium in soil voids through ureolysis by "Bacillus Pasteurii". This study focuses on how the amount of calcium carbonate precipitation is affected by the injection conditions of the microorganism and nutrient salt, such as the number of injections and the soil type. Experiments were conducted to simulate soil improvement by bio-grouting soil in a syringe. The results indicate that the amount of precipitation is affected by injection conditions and soil type, suggesting that, in order for soil improvement by MCP to be effective, it is necessary to set injection conditions that are in accordance with the soil conditions. © 2011 ASCE.

Design, development, and evaluation of a simple blackbody radiative source

This paper presents a simple design and the testing of a blackbody prototype. The physical properties and geometry of the cavity produce a radiator or blackbody with an emissivity greater than 0.99. The prototype has the advantages of having a traditional spherical cavity made of alumina refractory cement and a radiative emission very close to that of an ideal blackbody. The prototype can be used as a calibration standard for other radiation measuring instruments or sensors. Experimental measurements of radiant flux of the prototype measured with a calibrated infrared radiometer and a wide spectrum radiometer are also presented. The prototype is easy to construct and the material required are available to most research centers, laboratories, industries, and universities. © 2010 American Institute of Physics.

The role of vibration and drainage in femoral impaction bone grafting.

Vibration is commonly used in civil engineering applications to efficiently compact aggregates. This study examined the effect of vibration and drainage on bone graft compaction and cement penetration in an in vitro femoral impaction bone grafting model with the use of 3-dimensional micro-computed tomographic imaging. Three regions were analyzed. In the middle and proximal femoral regions, there was a significant increase in the proportion of bone grafts with a reciprocal reduction in water and air in the vibration-assisted group (P < .01) as compared with the control group, suggesting tighter graft compaction. Cement volume was also significantly reduced in the middle region in the vibration-assisted group. No difference was observed in the distal region. This study demonstrates the value of vibration and drainage in bone graft compaction, with implications therein for clinical application and outcome.

Accelerated ageing of a stabilised/solidified contaminated soil at elevated temperatures

Despite the widespread use of stabilisation/solidification (S/S) techniques, the validation and the availability of predictive modelling of the behaviour of stabilised/solidified soils in the longer-term is very limited. The authors were involved in the assessment of the behaviour of a contaminated site in the UK treated with cement-based in-situ S/S over the first five years after treatment. In parallel, two experimental methods, namely elevated temperatures and combined elevated temperatures and accelerated carbonation, were used in the laboratory to model accelerated ageing of the site soil. A graphical technique, based on the Arrhenius equation, was then used to model the laboratory observations and the in-situ five-year behaviour. The paper presents the details of the two experimental methods used for the accelerated ageing of stabilised/solidified model site soil, the numerical predictive model and a comparison between the results of the two experimental techniques and with the site results. © 2005 Taylor & Francis Group.

Part I: Binders & technologies - Basic principles

The first three reports in this series (Parts I, II and III) deals with binders and technologies used in stabilisation/ solidification (S/S) practice and research in the UK. This first part covers 'basic principles'while the second covers 'research' and the third 'applications'. The purpose of this work, which forms part of the Network STARNET on stabilisation/solidification treatment and remediation, is to identify the knowledge gaps and future research needs in this field. This paper describes the details and basic principles of available binders and technologies in the UK. The introduction in the report includes background on S/S, legislation aspects, overview of STARNET and its activities and details of commonly used binder selection criteria. The report is then divided into two main sections. The first covers binders and includes cement, blastfurnace slag, pulverised fuel ash, lime, natural and organophilic clays, bitumen, waste binders and concludes with proprietary binders. The second part details implementation processes for S/S treatment systems starting with ex-situ treatment systems, such as plant processing, direct mixing and in-drum processing and finishes with in-situ treatment processes, such as mechanical mixing and pressure mixing. © 2005 Taylor & Francis Group.

Performance of magnesia cements in porous blocks in acid and magnesium environments

The performance of porous blocks containing three different reactive magnesia-based cements - namely magnesia alone, magnesium oxide: Portland cement (PC) in 1:1 ratio, cured in ambient conditions, and magnesia alone, cured at elevated carbon dioxide conditions, in hydrochloric acid and magnesium sulfate solution - was investigated. Different aggressive chemical solution conditions were used, to which the samples were exposed for up to 12 months and then tested for strength and microstructure. The performance was also compared with that of standard PC-based blocks. The results showed the significant resistance to chemical attack offered by magnesia, both alone and with PC blend in the porous blocks when cured under ambient carbon dioxide conditions, and confirmed the much poorer performance of blocks made from PC alone. The blocks of solely magnesia cured in elevated carbon dioxide conditions, at 20% concentration, showed slightly lower resistance to acid attack than PC; however, the resistance to sulfate attack was much higher. © 2012 Thomas Telford Ltd.

The efficiency of compensation grouting in sands

Physical model experiments on compensation grouting in sands were performed in two different setups (Cambridge and Delft). The effect of water-cement (w/c) ratio, bentonite content (b.c.) and injection rate on compensation efficiency was investigated. Results show a considerable drop in compensation efficiency resulted from reducing the soil density. Injection in dense sand (R.D. = 93%) resulted in efficiencies between 40-90%, whereas injection in medium-dense sand (R.D. = 60-75%) yielded in reduced efficiencies between 10-40%. When the w/c ratio increased from 0.5 to 1.5 for a given density (R.D. = 93%) and the b.c. of 4%, the compensation efficiency value decreased. Typical efficiencies were between 60% and 40-50% for w/c ratios of 0.5 and 1.5, respectively. The values of compensation and grout efficiencies were almost equal, suggesting that pressure filtration happens mainly during injection. Increasing the b.c. improved the compensation efficiency. When a higher b.c. of 12% to 14% was used, typical compensation efficiencies in dense sand were 78 and 90% for w/c ratios of 1.5 and 1.8 respectively. © 2012 Taylor & Francis Group.

The energy required to produce materials: constraints on energy-intensity improvements, parameters of demand.

In this paper, we review the energy requirements to make materials on a global scale by focusing on the five construction materials that dominate energy used in material production: steel, cement, paper, plastics and aluminium. We then estimate the possibility of reducing absolute material production energy by half, while doubling production from the present to 2050. The goal therefore is a 75 per cent reduction in energy intensity. Four technology-based strategies are investigated, regardless of cost: (i) widespread application of best available technology (BAT), (ii) BAT to cutting-edge technologies, (iii) aggressive recycling and finally, and (iv) significant improvements in recycling technologies. Taken together, these aggressive strategies could produce impressive gains, of the order of a 50-56 per cent reduction in energy intensity, but this is still short of our goal of a 75 per cent reduction. Ultimately, we face fundamental thermodynamic as well as practical constraints on our ability to improve the energy intensity of material production. A strategy to reduce demand by providing material services with less material (called 'material efficiency') is outlined as an approach to solving this dilemma.

Numerical modeling of deep soil mixing excavation support

The finite element method (FEM) is growing in popularity over the pressure diagram/hand calculation method for analysis of excavation systems in general and deep soil mixing excavations in particular. In this paper, a finite element analysis is used to study the behavior of a deep mixed excavation. Through the use of Plaxis (a FEM software program), the construction sequence is simulated by following the various construction phases allowing for deflections due to strut or anchor installation to be predicted. The numerical model used in this study simulates the soil cement columns as a continuous wall matching the bending stiffness of the actual wall. Input parameters based on laboratory tests and modeling assumptions are discussed. An example of the approach is illustrated using the Islais Creek Transport/Storage Project in San Francisco, California. Copyright ASCE 2006.

Relating monolithic and granular leaching from contaminated soil treated with different cementitious binders.

This work employed a clayey, silty, sandy gravel contaminated with a mixture of metals (Cd, Cu, Pb, Ni and Zn) and diesel. The contaminated soil was treated with 5 and 10% dosages of different cementitious binders. The binders include Portland cement, cement-fly ash, cement-slag and lime-slag mixtures. Monolithic leaching from the treated soils was evaluated over a 64-day period alongside granular leachability of 49- and 84-day old samples. Surface wash-off was the predominant leaching mechanism for monolithic samples. In this condition, with data from different binders and curing ages combined, granular leachability as a function of monolithic leaching generally followed degrees 4 and 6 polynomial functions. The only exception was for Cu, which followed the multistage dose-response model. The relationship between both leaching tests varied with the type of metal, curing age/residence time of monolithic samples in the leachant, and binder formulation. The results provide useful design information on the relationship between leachability of metals from monolithic forms of S/S treated soils and the ultimate leachability in the eventual breakdown of the stabilized/solidified soil.

Carbonating magnesia for soil stabilization

This paper investigates the potential for carbonating reactive magnesia (MgO) to serve as a more sustainable soil stabilization method by providing rapid and significant strength development of the stabilized soil through absorbing substantial quantities of CO2. Gaseous CO2 was forced through laboratory-prepared reactive MgO-treated soil samples in a triaxial cell set-up, and their resulting mechanical and microstructural properties were investigated using unconfined compressive strength, X-ray diffraction, and scanning electron microscopy. The results showed that adequately carbonated MgO-treated soils could, in a few hours, reach a similar strength range to corresponding 28 day Portland cement (PC)-stabilized soils. Hydrated magnesium carbonates, namely nesquehonite and hydromagnesite-dypingite, were the main products of the carbonated MgO in the soil, and were responsible for the significant strength development.