Recent Submissions

  • New offsite production and business models in construction: priorities for the future research agenda

    Goulding, J.S.; Pour Rahimian, F.; Arif, M.; Sharp, M.D. (Taylor and Francis, 2014-03-11)
  • Assessing sustainability of employee suggestion schemes: a framework

    Lasrado, Flevy; Arif, Mohammed; Rizvi, A. (Emerald, 2015-11-16)
  • Creating a better healing environment in Qatari healthcare sector: Exploring the research agenda for the future

    Alhorr, Yousef; Arif, Mohammed; Bano, Tabassum; Egbu, Charles; Mazroei, Ahmed; Elsarrag, Esam (Elsevier, 2015-06)
  • Understanding knowledge sharing in the Jordanian construction industry

    Arif, Mohammed; Mohammed, Al-Zubi; Gupta, Aman Deep (2015-07-13)
  • Knowledge sharing maturity model for Jordanian construction sector

    Arif, Mohammed; Al Zubi, Mohammed; Gupta, Aman Deep; Egbu, Charles; Walton, Robert O.; Islam, Rubina (Emerald, 2017-01-16)
  • Developments in the United Kingdom Dispute Resolution Process

    Akintoye, Akintola; Renukappa, Suresh; Lal, Hamish (ASCE, 2015-02)
    It is generally recognized that the U.K. construction industry is associated with low profit, delay in payments, cash flow concerns, short-term relationships compared with other industries, and high levels of business failure. In particular, claims and disputes have proliferated in the industry largely due to unfair payment practices. Therefore, to encourage a swifter and more economic method of resolving construction disputes by way of adjudication, the U.K. Housing Grants, Construction and Regeneration Act 1996 (HGCRA) came into force on October 1st, 2011in England andWales, and November 1st, 2011 in Scotland. This study presents the HGCRA 1996 Act—highlighting its strengths and weaknesses—along with the new 2009 Construction Act. The study additionally presents awareness of the new Act, key reasons for amending the HGCRA 1996 Act, and the impact of key changes in the Act on the dispute resolution process. The paper concludes that the new Act is perceived as being more effective at improving cash flow in the construction supply chain and is expected to encourage parties to resolve disputes by adjudication—but it will have to overcome the historical fact that integration of such proposed changes in construction may be a complex issue.
  • Effect of wind characteristics on gas dispersion in porous media

    Wilkinson, Stephen (International Society for Porous Media, 2017-05)
    Greenhouse gases have the key role in global warming. Soil is a source of greenhouse gases such as methane (CH4). Radon (Rn) which is a radioactive gas can emit form soil into the buildings and causes health concerns. Different soil properties can affect gas emissions inside/from soil including temperature, humidity, air pressure and vegetation (Oertel et al., 2016). It’s shown in many cases that pressure fluctuations caused by wind play an important role in transport of gas in soil and other porous media. An example is: landfill gas emissions (Poulsen et al., 2001). We applied a novel experimental equipment for measuring controlled wind turbulence on gas transport in porous media. This set-up was utilized to evaluate the effect of wind turbulence on gas transport in relation to the depth of porous medium. Experiments were carried out with binary diffusion of CO2 and air as tracer gases with average vertical wind speeds of 0.02 to 1.06 m s-1. 13 different wind conditions with different speed and fluctuations were applied. Five oxygen sensors were places inside sample at different depths to measure air transportation within porous media and total of 39 experiments were carried out. Gas transport in porous media is described by advection-dispersion equation. Gas transport is quantified as a dispersion coefficient. Oxygen breakthrough curves as a function of distance to the surface of the porous medium exposed to wind were derived numerically with an explicit forward time, central space finite-difference based model to assess gas transport. We showed that wind turbulence-induced dispersion of gas is an important transport mechanism that can increase gas transport with average of 45 times more than molecular diffusion under no-wind condition. Power spectrum density is calculated for all the 12 wind conditions to determine strength vibration of all the wind speeds.
  • Construction industry legal risk identification for SMEs

    Charlson, Jennifer; Oduoza, Chike (Sweet and Maxwell, 2016)
  • An analysis of passive earth pressure modification due to seepage flow effects

    Hu, Zheng; Yang, Zhongxuan; Wilkinson, Stephen Philip; Wilkinson, Stephen; Zhejiang University, 12377, Department of Civil Engineering, Zhejiang University, B700, Anzhong Building, 866 Yuhangtang Road, Hangzhou, Zhejiang, China, 310058, ;; Zhejiang University, Department of Civil Engineering, B712 Anzhong Building, Zijingang Campus, Zhejiang University, 866 Yuhangtang, Hangzhou, China, 310058, ;; University of Wolverhampton, 8695, Department of Civil Engineering, Wolverhampton, West Midlands, United Kingdom of Great Britain and Northern Ireland; (NRC Research Press, 2017-09-13)
    Using an assumed vertical retaining wall with a drainage system along the soil-structure interface, this paper analyses the effect of anisotropic seepage flow on the development of passive earth pressure. Extremely unfavourable seepage flow inside the backfill, perhaps due to heavy rainfall, will dramatically increase the active earth pressure while reducing the passive earth pressure; thus increasing the probability of instability of the retaining structure. In this paper, a trial and error analysis based on limit equilibrium is applied to identify the optimum failure surface. The flow field is computed using Fourier series expansion, and the effective reaction force along the curved failure surface is obtained by solving a modified Kötter equation considering the effect of seepage flow. This approach correlates well with other existing results. For small values of both the internal friction angle and the interface friction angle, the failure surface can be appropriately simplified with a planar approximation. A parametric study indicates that the degree of anisotropic seepage flow affects the resulting passive earth pressure. In addition, incremental increases in the effective friction angle and interface friction both lead to an increase in the passive earth pressure.
  • MICP and Advances towards Eco-Friendly and Economical Applications

    Rajasekar, Adharsh; Moy, Charles K.S.; Wilkinson, Stephen (IOP Publishing Ltd, 2017-07)
    Biomineralization is a natural process aided by living organisms. Due to its applicability in ground improvement and bioremediation, Microbially Induced Calcite Precipitation (MICP) is an interdisciplinary field of study combining engineering, chemistry and microbiology. Bioremediation has been applied widely for contamination containment or removal, in this case it will be containment. MICP can also be applied to improve the efficiency of insitu bioremediation. Urease is an enzyme which can facilitate increased calcite precipitation. However the production of urease by bacteria and thus the resulting carbonate precipitation are inhibited by environmental factors including calcium concentration, bacterial concentration, pH and temperature. Under good conditions MICP can be used for heavy metal and radionuclide immobilization. However technologies such as bioconsolidation and biocementation require improvement such as time and cost. This paper highlights the application of MICP in addition to suggested improvements to make it more eco-friendly and sustainable.
  • Stimulation of Indigenous Carbonate Precipitating Bacteria for Ground Improvement

    Rajasekar, Adharsh; Moy, Charles K S; Wilkinson, Stephen (IOP Publishing, 2017-05)
    Calcite minerals are precipitated in soil through biomineralisation which can be either organic or inorganic in nature. Biomineralisation can be employed to improve ground conditions in its natural state. Usually, studies of applied biomineralisation are highly interdisciplinary involving expertise from engineers, chemists and microbiologists. In this paper, we study the potential of biomineralisation from indigenous bacteria present in soil. The soil samples were collected from a high permeable zone and the bacteria that inhabit the soil were stimulated at a temperature of 15°C. A cementation solution consisting of 500mM calcium chloride, urea and nutrient broth at a pH of 7.5 was added to the soil samples. Inorganic precipitation was found to be dominant and was more efficient when compared to organic precipitation. Carbonate precipitation data indicated that inorganic precipitation were 1.37 times better at carbonate formation in comparison to organic precipitation. Scanning Electron Microscopy analysis identified cementation bonds formed between soil particles. It was deducted that organic precipitation is dependent on temperature, and may take an extended time at such low temperature. The preliminary data presented in this paper suggests that the implementation of biomineralisation with in-situ microbes is promising but requires further laboratory and field investigation before being considered for engineering application.
  • Effect of air turbulence on gas transport in soil; comparison of approaches

    Pourbakhtiar, Alireza; Papadikis, K; Poulsen, T G; Bridge, J W; Wilkinson, Stephen (Geophysical Research Abstracts, 2017-05)
    Geophysical Research Abstracts (GRA) is the conference series publishing the abstracts accepted for the General Assemblies of the European Geosciences Union (EGU). It links the annual conference programmes listing programme groups, included sessions, and their contributions. The abstracts underwent an access review by the session conveners.
  • Effect of partial replacement of cement with slag on the early-age strength of concrete

    Tang, Kangkang; Khatib, Jamal; Beattie, Greg (Institution of Civil Engineers, 2017-02-17)
    Concrete structures are popularly used to provide open space areas that are often incorporated into the design of sports, social and industrial structures. One of the concerns with concrete structures, especially long-span concrete structures, is early-age thermal expansion and subsequent contraction as a result of the exothermic cement hydration reaction. Thermal contraction, externally restrained by vertical structural elements such as columns and shear walls, may cause thermal cracking if it exceeds the tensile strength of the concrete. The early-age thermal loading of cast-in-place concrete can be estimated through isothermal calorimetry, semi-adiabatic calorimetry and finite-element modelling (FEM). This paper discusses the efficiency of using FEM, based on the isothermal calorimetry results, for predicting early-age temperature development of in situ concrete. In addition, this work quantifies the beneficial effect of using ground granulated blast-furnace slag as a partial replacement of cement in structural concrete. The simulation results, validated via semi-adiabatic calorimetry, indicate reduced thermal loading due to the presence of slag. This can be taken as an advantage of using such slag in structural concrete.
  • Effect of wind turbulence on gas transport in porous media: experimental method and preliminary results

    Wilkinson, Stephen; Pourbakhtiar, Alireza; Poulsen, Tjalfe; Bridge, Jonathan (Wiley, 2017-01)
    Summary We demonstrate a novel experimental arrangement for measuring wind turbulence-induced gas transport in dry porous media under controlled conditions. This equipment was applied to assess the effect of wind turbulence on gas transport (quantified as a dispersion coefficient) as a function of distance to the surface of the porous medium exposed to wind. Two different strategies for the measurement of wind-induced gas transport were compared. Experiments were carried out with O2 and CO2 as tracer gases with average vertical wind speeds of 0.02–1.06ms−1. Oxygen breakthrough curves as a function of distance to the wind-exposed surface of the porous medium were analysed numerically with a finite-difference-based model to assess gas transport. We showed that wind turbulence-induced gas transport is an important transport mechanism that can be 20–70 times larger than molecular diffusion-induced transport. Wind conditions and properties of the porous medium had strong controlling effects on this relationship. Importantly, we show that even though wind-induced gas transport is greatest near to the wind-exposed surface, it can have marked effects on the variation in gas concentration at much greater depths.
  • Active earth pressure acting on retaining wall considering anisotropic seepage effect

    Hu,Zheng; Yang, Zhongxuan; Wilkinson, Stephen (Springer, 2017-01)
    This paper presents a general solution for active earth pressure acting on a vertical retaining wall with a drainage system along the soil-structure interface. The backfill has a horizontal surface and is composed of cohesionless and fully saturated sand with anisotropic permeability along the vertical and horizontal directions. The extremely unfavourable seepage flow on the back of the retaining wall due to heavy rainfall or other causes will dramatically increase the active earth pressure acting on the retaining walls, increasing the probability of instability. In this paper, an analytical solution to the Laplace differential governing equation is presented for seepage problems considering anisotropic permeability based on Fourier series expansion method. A good correlation is observed between this and the seepage forces along a planar surface generated via finite element analysis. The active earth pressure is calculated using Coulomb’s earth pressure theory based on the calculated pore water pressures. The obtained solutions can be degenerated into Coulomb’s formula when no seepage exists in the backfill. A parametric study on the influence of the degree of anisotropy in seepage flow on the distribution of active earth pressure behind the wall is conducted by varying ratios of permeability coefficients in the vertical and horizontal directions, showing that anisotropic seepage flow has a prominent impact on active earth pressure distribution. Other factors such as effective internal friction angle of soils and soil/wall friction conditions are also considered.
  • Impact of knowledge management on construction projects

    Olayinka, Raymond; Chinyio, Ezekiel; Renukappa, Suresh; Suresh, Subashini (INSTITUTION OF CIVIL ENGINEERS (ICE), 2016-12-05)
    The implementation of knowledge management strategies on construction projects can accrue benefits such as improved performance and continuous improvement. However, many projects are still not utilising knowledge management fully and are thus plagued with inefficiencies, repetition of mistakes and lack of lessons learnt. Poor skills, design changes, errors and omissions contribute to the internal failure cost element of the overall cost of poor quality on construction projects. This study aimed to investigate the extent of the impact that knowledge management has in reducing the cost of poor quality and used a mixed-methods approach. In-depth interviews were conducted with 25 construction industry experts on knowledge management across the UK, followed up by a questionnaire survey of 114 respondents. The data obtained were analysed using thematic analysis and descriptive statistics. It was found that knowledge management had a positive impact in reducing the cost of poor quality, in particular in the area of knowledge transfer through apprenticeships and mentoring. This implies the importance of managing the tacit knowledge of employees through ‘socialisation’ initiatives. This study contributes to the existing body of knowledge by providing a knowledge management framework for reducing the cost of poor quality on construction projects.
  • Effect of desulphurised waste on long-term porosity and pore structure of blended cement pastes

    Khatib, Jamal M.; Wright, Lee; Mangat, Pal S. (Elsevier, 2016-09)
    This paper presents some results on the porosity and pore size distribution of cement paste containing simulated desulphurised waste (SDW) cured for 90 d. The SDW was chosen for the investigation due to the variability in chemical composition of real desulphurised waste as explained in previous papers. The SDW is a combination of 85% fly ash and 15% gypsum. The cement in the pastes was replaced with 0, 20 and 40% SDW. The water to binder ratio was 0.5. The binder consists of cement and SDW (by weight). After 90 d of curing, the porosity and pore size distribution tests were conducted on the pastes. Increasing the amount of SDW leads to an increase in the pore volume of the paste. There is no clear trend on the effect of SDW on the size of the pores.
  • Complete Genome Sequence of Carbonic Anhydrase Producing Psychrobacter sp. SHUES1

    Li, Mengmeng; Zhu, Xuejiao; Huang, Minsheng; Achal, Varenyam; Wilkinson, Stephen (2016-09-13)
    Recent advances in biotechnology have allowed the study of new bacterial strains, which can produce enzymes that can be used in the bioremediation of heavy metals. Microbially induced carbonate precipitation (MICP) is a recent well-recognized process that has the potential to precipitate heavy metals, mainly those with a valency of +2 (Kumari et al., 2016). There are two enzymes, urease, and carbonic anhydrase, that play an important role in the MICP process. The role of carbonic anydrase (EC 4.2.1.1) in MICP is generally underestimated and most of the studies in past mainly focus on urease-producing microorganisms (Li et al., 2013, 2014; Kumari et al., 2014). In the present study, Psychrobacter sp. SHUES1 was isolated from frozen alkaline soil sample collected at Shanghai, China. This bacterium produced lipase and protease at 4°C in a plate assay. The ability of Psychrobacter sp. to show extracellular lipolytic activity at low temperatures is widely known (Xuezheng et al., 2010); however, the remarkable property of this strain was in the precipitation of heavy metals including cadmium and zinc in parallel to the MICP process. Therefore, to know the type of enzyme or genes involved in the process of metal precipitation, this research aims to sequence the whole genome of Psychrobacter sp. SHUES1, and thus provide a genomic insight into its behavior. Genomic DNA from Psychrobacter sp. SHUES1 was extracted using the DNeasy Blood & Tissue Kit (Qiagen, USA), and its quantity and quality were evaluated on the Qubit. The extracted DNA was subjected to whole-genome shotgun sequencing using the NEBNext Ultra DNA Library Prep Kit (Illumina, San Diego, CA). Library construction was performed with the following process: DNA fragmentation, end repair, adding “A” to the 3′ end, adaptor ligation and amplification. After library construction, the generated cluster was sequenced on an Illumina HiSeq2500 sequencing system, according to a paired end 2 × 125 nt multiplex program. 13,716,515 raw reads resulted in 13,144,818 quality-filtered trimmed reads, yielding a not less than 3 Mb genome size. De novo genome assembly was performed using SPAdes-3.5.0. After purification, the assembly produced 3,115,590 bp of sequence across 115 contigs with an N50 of 47,049 bp, with a longest sequence of 182,144 bp, and a G+C content of 43.5% (Table 1). Gene prediction and annotation were carried out using Prodigal_v2.6.1, blastp in the National Center for Biotechnology Information (NCBI) “nr” database. Gene ontology (GO) functional annotation of genes was carried out using the blast2GO algorithm, dominated by the following features: biological process (44%), molecular process (42%), and cellular component (14%). Clusters of Orthologous Groups (COG) annotation was carried out in the NCBI COG database using rpsblast. A total of 2627 protein-coding genes, 45 tRNA-coding genes, and 6 rRNA genes were predicted in the draft genome. TABLE 1 www.frontiersin.org Table 1. Genome features of Psychrobacter sp. SHUES1. The most significant finding of the whole genome sequencing of Psychrobacter sp. SHUES1 was the presence of carbonic anhydrase gene in it. Carbonic anhydrase participates in all physiological processes dealing with CO2 and HCO3, such as cellular pH regulation, calcification, acid, and ion transport (Smith and Ferry, 2000; Achal and Pan, 2011). It catalyses the interconversion of CO2 and HCO3, which ultimately promotes the precipitation of calcium carbonate in the presence of Ca2+ ions. Although there are a number of genome sequences of Psychrobacter sp. deposited in NCBI database, this is the first characterization of the genome sequence of strain SHUES1, which produces carbonic anhydrase which has a significant role in metal bioremediation based on the ability to promote the precipitation of metal carbonates. This sequencing result also suggests the importance of carbonic anhydrase in the MICP process which is a novel element in this field of research. The present study is especially valuable in the area of biomineralization based on MICP processes, in the bioremediation of metals and in the development of microbial concrete (biocement). Urease is the main enzyme responsible in such studies; however, in our study the urease gene was not present in Pyschrobacter sp. SHUES1. This indicates the importance of carbonic anhydrase, as a less studied secondary enzyme for the MICP process. It is hoped that this research will encourage other researchers to look for this carbonic anhydrase precipitation pathway when carrying out MICP studies.

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