Building activities are recognised to produce coarse particulate matter but less is known about the release of airborne ultrafine particles (UFPs; those below 100 nm in diameter). For the first time, this study has investigated the release of particles in the 5-560 nm range from three simulated building activities: the crushing of concrete cubes, the demolition of old concrete slabs, and the recycling of concrete debris. A fast response differential mobility spectrometer (Cambustion DMS50) was used to measure particle number concentrations (PNC) and size distributions (PNDs) at a sampling frequency of 10 Hz in a confined laboratory room providing controlled environment and near-steady background PNCs. The sampling point was intentionally kept close to the test samples so that the release of new UFPs during these simulated processes can be quantified. Tri-modal particle size distributions were recorded for all cases, demonstrating different peak diameters in fresh nuclei (
Branch J, Rawling A, Hannant DJ, Mulheron M (2002) The effects of fibres on the plastic shrinkage cracking of high strength concrete, Materials and Structures 35 pp. 189-194
Plastic shrinkage cracking in concrete usually occurs during the first 5 hours after placing and therefore the mechanics of fibre reinforcement were studied during this period. Two types of polypropylene fibres were mixed at 0.1% by volume. The development of bond strengths and the stresses which the fibres could sustain across cracks were measured by uniaxial tensile tests during the first 5 hours after mixing. Fibre stresses up to 130 MPa at 5 hours were achieved which were equivalent to a composite post-crack strength of 65 kPa. Restrained ring tests were used to assess the amount of cracking which occurred during the first 24 hours in a different high strength mix and, although the results were very variable, the fibres were found to reduce the crack area by between 40% and 85% compared with plain concrete, depending on fibre type.
Nwaubani SO, Mulheron M, Tilly GP, Schwamborn B (2000) Pore-structure and water transport properties of surface-treated building stones, Materials and Structures 33 pp. 198-206
This paper describes the details of a laboratory investigation aimed at ascertaining the effect of penetrating surface treatments on the micro-porosity and water transport properties of three building stones used in the construction of historic buildings and monuments within Europe. The pore-structure and morphology of treated and untreated stone specimens were assessed using a combination of helium autopycnometry, mercury intrusion porosimetry and scanning electron microscopy techniques. Water repellence and transport properties were evaluated using the Karsten tube and magnetic resonance imaging techniques respectively. It was found that surface penetrating treatments have a pore-refining effect on the stone matrix, the extent of internal alteration being dependent on the initial pore-structure. A treatment efficiency index has been established for evaluating the performance of treated surfaces.
Mulheron M (1988) THE RECYCLING OF DEMOLITION DEBRIS - CURRENT PRACTICE, PRODUCTS AND STANDARDS IN THE UNITED-KINGDOM, pp. 510-519
Nwaubani SO, Katsanos A, Mulheron M (2010) Corrosion resistance of reinforced concrete exposed to Calcium-Magnesium Acetate de-icing salt, 2nd International Conference on Sustainable Construction Materials and Technologies pp. 969-977
This paper reports the result of a study aimed at assessing the impact of Calcium-Magnesium Acetate (CMA) solutions on the corrosion of reinforcing steel embedded in concrete. It is part of a larger research to evaluate the efficacy of adopting alternative de-icing chemicals and methods in winter de-icing operations. This part of the study involves the use of half-cell potential and Linear Polarisation Resistance (LPR) techniques to compare the corrosion risk in small-scale reinforced concrete slabs subjected to a ponding regime with distilled water, salt water or CMA solutions over a period of one year. The influence of different de-icers on the corrosion behaviour of the reinforcement are compared. Further work concerning longer term effects is in progress to ascertain the significance of the observed changes on the mechanism of the interaction between CMA solutions and cement paste.
Kakemi M, Hannant DJ, Mulheron M (1996) Techniques for determining some microstructural parameters in glass reinforced cement, Magazine of Concrete Research 48 pp. 229-236
Two important parameters which control the fracture behaviour of glass fibres in cement composites, whether they contain one fibre type or are hybrids of two fibre types, are the perimeter of the glass strands in contact with hydrated cement and the way in which glass filaments fracture in multifilament strands. In scanning electron microscopy (SEM) observations, much improved images were obtained by detecting backscattered electrons rather than secondary electrons. This improvement gave good contrast between the fibre strands and the matrix, hence the perimeter of the glass strands could be determined using an image analyser. The progression of filament fracture within a strand was examined using two techniques, acid dissolution and light transmission through the filaments. These techniques showed that strands tend to fail progressively in hybrid composites containing glass and polypropylene fibres and that glass fracture continues to occur after the peak loan has been reached.
Jesson DA, Mohebbi H, Farrow J, Mulheron MJ, Smith PA (2013) On the condition assessment of cast iron trunk main: The effect of microstructure and in-service graphitisation on mechanical properties in flexure, Materials Science and Engineering A 576 pp. 192-201
The mechanical properties of cast iron used for trunk mains in the water industry have been studied. Specimens have been sourced from nine different pipes, which had been in service for up to 150 years before failure. The bulk microstructures of each cast iron have been analysed with regard to the graphite flake morphology and size. The stress-strain behaviours in tension and compression have been derived from specimens loaded in flexure. Flexural strength data have been obtained for 30 specimens from each pipe (three batches of 10 from different locations along the length and around the circumference of the pipe) and these data have been analysed using Weibull methods. The depth of graphitisation visible on the fracture surface of each sample has been measured. It is shown that the strength of the cast iron samples decreases with increasing depth of graphitisation. When the layer of graphitised material is of reasonably uniform thickness, the strength reduction is modest, but where the section loss is more local, the strength reduction is more significant - for some samples there is a reduction in strength of more than 50% when the depth of graphitisation exceeds 4. mm. Simple strength-of-materials and fracture mechanics approaches are shown to provide reasonable bounds for the data. © 2013 Elsevier B.V.
Boughanem S, Jesson DA, Mulheron MJ, Smith PA, Eddie C, Psomas S, Rimes M (2014) Tensile characterisation of thick sections of Engineered Cement Composite (ECC) materials, Journal of Materials Science
Engineered Cement Composite (ECC) materials have the potential to be used in applications where a level of pseudo-ductility under tensile stress is required. Most previous work has focussed on comparatively thin specimens. For future civil engineering applications, however, it is imperative that the behaviour of thicker specimens is understood. In the present work, specimens containing cement powder, water, polymeric fibres and admixtures were manufactured following two different processes and tested in tension. Multiple matrix cracking was observed during tensile testing, leading to a pseudo-ductile behaviour. Complementary measurements of sample density and porosity suggest that a high porosity could be linked with an enhanced tensile strain-to-failure whereas high density is associated with a high maximum stress. The fibre dispersion, assessed by scanning electron microscopy, indicated that mechanical performance was enhanced with increasing proportion of fibres aligned along the tensile test axis, and this orientation can be linked to the manufacturing process.
McDonald PJ, Aptaker PS, Mitchell J, Mulheron M (2007) A unilateral NMR magnet for sub-structure analysis in the built environment: the Surface GARField., J Magn Reson 185 (1) pp. 1-11
A new, portable NMR magnet with a tailored magnetic field profile and a complementary radio frequency sensor have been designed and constructed for the purpose of probing in situ the sub-surface porosity of cement based materials in the built environment. The magnet is a one sided device akin to a large NMR-MOUSE with the additional design specification of planes of constant field strength /B0/ parallel to the surface. There is a strong gradient G in the field strength perpendicular to these planes. As with earlier GARField magnets, the ratio G//:B0/ is a system constant although the method of achieving this condition is substantially different. The new magnet as constructed is able to detect signals 50mm (1H NMR at 3.2 MHz) away from the surface of the magnet and can profile the surface layers of large samples to a depth of 35-40 mm by moving the magnet, and hence the resonant plane of the polarising field, relative to the sample surface. The matching radio frequency excitation/detector coil has been designed to complement the static magnetic field such that the polarising B0 and sensing B1 fields are, in principal, everywhere orthogonal. Preliminary spatially resolved measurements are presented of cement based materials, including two-dimensional T1-T2 relaxation correlation spectra.
Atkinson K, Whiter JT, Smith PA, Mulheron M (2002) Failure of small diameter cast iron pipes, Urban Water 4 (3) pp. 263-271
The in-service strength degradation, as a result of corrosion, of cast iron water distribution pipes has been investigated. The strengths of 1 m lengths of pipe extracted from the ground have been measured in either 3- or 4-point bending and the size of the controlling defect has been estimated by visual examination of the fracture surface. The application of Weibull statistics to the bend test data demonstrates that there is bimodal behaviour which suggests that there are two populations of flaws present. It is postulated that the larger flaw size population is associated with corrosion pits that form during the process of graphitisation, while the smaller flaw size population is associated with the inherent flaws within the (brittle) cast iron pipe material. A critical pit depth is identified at the transition between the two competing flaw populations, where there is a change in slope on the Weibull plot. It is shown also that the residual strength/pit depth data are described equally well by either of the two conventional analyses, i.e. loss of section and fracture mechanics. © 2002 Thames Water Utilities Ltd. Published by Elsevier Science Ltd. All rights reserved.
Tantele EA, Onoufriou T, Mulheron M (2006) Optimization of preventative maintenance strategies for bridges, Proceedings of the 3rd International Conference on Bridge Maintenance, Safety and Management - Bridge Maintenance, Safety, Management, Life-Cycle Performance and Cost pp. 127-128
The use of preventative maintenance (PM) has been acknowledged as an effective way of reducing the whole life cost of maintaining bridges in good, safe and functional condition. However, there are many uncertainties associated with the need and effectiveness of PM. Such uncertainties if not addressed can lead to incorrect decisions and wastage of resources. In addition optimization procedures are necessary to produce strategies with minimum cost while maintaining the reliability of the bridge at an acceptable level. This paper examines the issue of effectiveness of different PM on reinforced concrete bridges deteriorating due to the corrosion of reinforcement from chloride ions. It investigates the applicability of an optimization methodology, using the principles of genetic algorithm (GA) to identify optimum PM strategies based on their effectiveness and cost. © 2006 Taylor & Francis Group.
Katsanos A, Nwaubani SO, Mulheron M (2010) Sodium acetate: An overlooked, "green" de-icing solution for highways, 2nd International Conference on Sustainable Construction Materials and Technologies pp. 921-930
This study investigates sodium acetate [NAAC], a rather neglected bio-degradable de-icer, which may, however, present a viable solution towards sustainable and environment-friendly winter operations in certain situations. The results presented here are a selection of data obtained by SEM imaging and element mapping, together with X-Ray diffractometry in order to demonstrate the benign nature of NAAC solutions with regard to their interaction with cement pastes. The effect of the inclusion of microsilica in the cement paste in these tests is evaluated through the use of pure OPC and microsilica containing specimens. The results obtained suggest that sodium acetate is an effective de-icer that may deserve as much attention by researchers and the industry, in the same way as other well known alternative de-icers.
Branch J, Hannant DJ, Mulheron M (2002) Factors affecting the plastic shrinkage cracking of high-strength concrete, Magazine of Concrete Research 54 pp. 347-354
Tests were developed to quantify parameters affecting the plastic shrinkage cracking of high-strength concrete of 28-day cube strength in excess of 70 MPa. The parameters measured were tensile stress-strain performance during the first 5 h after mixing and negative pore pressure development and free shrinkage during the first 24 h. Eight high-strength mixes were used containing a variety of supplementary cementing materials such as microsilica, pulverised fuel ash, granulated slag and metakaolin. Two types of superplasticers were included. Plastic shrinkage cracking was assessed using restrained ring tests in which measurements were taken using sealed samples and samples exposed to wind. The research has shown that there is no simple relationship between early age stress-strain curves, negative pore pressure, early age shrinkage and macrocracking in adverse conditions but two factors were always present when plastic cracking was observed, these being microsilica and wind.
Crunkhorn BB, Whiter JT, Ham A, Mulheron M, Smith PA (2004) Assessing the ability of interactive pipe liners to withstand host-pipe failure, JOURNAL OF WATER SUPPLY RESEARCH AND TECHNOLOGY-AQUA 53 (5) pp. 299-312 I W A PUBLISHING
Cox J-A, Jesson DA, Mulheron MJ, Druckman A, Smyth M, Trew H (2015) Municipal Solid Waste as a Resource Pt 1: A case study in specifying composition, Waste and Resource Management
Waste is a complex societal problem that brings together various stakeholders in order
to manage it. However, a lack of sufficient information on the quantities and types of
material in the waste stream can make sustainable waste management difficult. Since
waste in one sector can be valuable as a resource in another, there is a need to
understand the distribution of materials within the resource stream, especially those
that go to landfill. Current work is seeking to address this; whilst much material is
already recycled, this is not the only management option and there remain several
problematic materials/components to be removed from residual waste. This paper, the
first of two case studies, presents a more comprehensive waste composition
specification in order to better manage municipal waste. In developing this approach,
waste composition specifications currently in use have been reviewed and compared
with the solid municipal (household) waste collected at community recycling centres
and from the kerbside. Key primary and secondary descriptors for the better
management of resources arising from municipal waste have been determined, and
the impact of these changes on the information arising from composition analysis is
Chowdhury A, Gillies A, McDonald PJ, Mulheron M (2001) Vapour phase application of hydrophobic coatings to cement-based materials, MAGAZINE OF CONCRETE RESEARCH 53 (5) pp. 347-352 THOMAS TELFORD SERVICES LTD
Logan R, Mulheron MJ, Jesson DA, Smith PA, Evans TS, Clay-Michael N, Whiter JT (2014) Graphitic corrosion of cast iron trunk main: implications for asset management,
Failures of (large diameter) cast iron trunk water mains can be catastrophic in the damage they can cause and it is therefore imperative to understand how cast iron deteriorates in order to help predict those areas of a water supply network which are at greatest risk of failure. Cast irons undergo a localized form of corrosion known as graphitic corrosion. Although a well reported phenomena, the mechanisms of graphitic corrosion are not fully understood. Scanning electron microscopy, in conjunction with energy dispersive x-ray spectroscopy, was used to characterise the microstructure and chemistry of the graphitic corrosion that occurs on the external surface of the pipe during time in service. It was found that that the graphite flakes within the cast iron are deteriorating during the corrosion process. High levels of chlorides are often found at the corrosion interface, within graphitic pits in the pipe wall. The implications of these observations on the development of models used to predict the remaining service life of buried trunk main are discussed.
Tantele E, Onoufriou T, Mulheron M (2005) Effectiveness of preventative maintenance for reinforced concrete bridges - A stochastic approach, Proceedings of the 5th International Conference on Bridge Management pp. 443-451
The effective allocation of resources and prioritisation of maintenance actions for ageing infrastructure systems is an important issue. There are many uncertainties in the decisions making process which may be associated with the deterioration prediction or the effect of various actions on the performance of a system. Such uncertainties if not addressed can lead to incorrect decisions and wastage of resources. This paper examines the issue of effectiveness of preventative maintenance (PM) on reinforced concrete bridges deteriorating due to chloride induced corrosion from de-icing salts. The uncertainties associated with corrosion initiation prediction and the effectiveness of various preventative maintenance actions are incorporated in a stochastic methodology presented in this paper. The proposed methodology was developed as part of a wider study which integrates this model within a proactive preventative maintenance strategy optimisation framework for RC bridges. The development of the stochastic PM effectiveness model is presented and discussed here together with an illustrative example.
Bohris AJ, Goerke U, McDonald PJ, Mulheron M, Newling B, Le Page B (1998) A broad line NMR and MRI study of water and water transport in Portland cement pastes., Magn Reson Imaging 16 (5-6) pp. 455-461
The results of a magnetic resonance spin-spin relaxation analysis and broad-line magnetic resonance imaging (MRI) (gradient-echo and stray-field imaging) study of water and water transport in Portland cement pastes are presented. The effect of varying the cure conditions and the water to cement (w/c) ratio of the sample of mix are discussed. The water sorptivity and the concentration dependence of the hydraulic diffusion coefficient are calculated for samples prepared with a 0.5 w/c ratio and, therefore, an open pore structure. In the case of 0.3 w/c ratio samples, little water transport is observed, and a closed pore structure is inferred.
Nwaubani SO, Mulheron M (1999) The influence of binder type on the properties and corrosion resistance of high performance concrete, pp. 213-225
There are several methods of ensuring high performance and durability of concrete by the use of modem admixtures. Special superplasticising admixtures can be used to produce flowable mortars and concretes of low water-cement content and organic polymers may be incorporated with ordinary Portland cement to produce concrete mixes with improved fresh and hardened properties for special applications. Alternatively, durable concrete may be obtained by adding reactive cement replacement materials. As a consequence there is a need to provide comparative performance data for such materials to enable engineers make an informed decision in selecting materials most suited to specific situations.
Benson TB, McDonald PJ, Mulheron M, Nwaubani SO (1998) The use of magnetic resonance imaging techniques in assessing the uptake of surface treatments and water movement through stone faces, MATERIALS AND STRUCTURES 31 (210) pp. 423-427 R I L E M
Mulheron M, Jones FR, Bailey JE (1986) MOISTURE-INDUCED THERMAL STRAINS IN GLASS-FIBER REINFORCED PLASTIC COMPOSITES, Composites Science and Technology 25 pp. 119-131
Engineered Cement Composites (ECC) materials
have the potential to be used in civil engineering
applications where a level of ductility is required to
avoid brittle failures. However uncertainties remain
regarding mechanical performance, physical
properties, shrinkage and durability. In the present
work, specimens containing cement powder and
admixtures have been manufactured following two
different processes and tested mechanically.
Multiple matrix cracking has been observed in both
tensile and flexural tests and this leads to ?strainhardening?
behaviour. The results have been
correlated with sample density and porosity and it is
suggested that higher levels of porosity do not
necessarily lead to a loss of the strain hardening
capacity. Shrinkage has been investigated and it is
shown, consistent with the literature, that shrinkage
can be reduced both by controlling the initial
environment to which the material is exposed and by
the use of additives. Durability was assessed by
flexure testing of beams specimens aged for
different times. Initial testing (up to one year)
indicates that the specimen retain ductility, although
the initial cracking threshold increases with time ?
which may have implications for longer aging times.
Jones FR, Mulheron M, Bailey JE (1983) GENERATION OF THERMAL STRAINS IN GRP .2. THE ORIGIN OF THERMAL STRAINS IN POLYESTER CROSS PLY LAMINATES, Journal of Materials Science 18 pp. 1533-1539
Lee B, Mulheron M (2012) Fluctuation of bond stress-slip behaviour of deformed bar under displacement control, Magazine of Concrete Research 64 pp. 863-875
The fluctuation of the bond stress as a function of the slip of deformed bar was determined experimentally, under displacement control, using 200 mm concrete cubes with centrally embedded 16 mm deformed bar designed to be in a confined condition. The observed global fluctuation in the bond stress, measured by linear variable differential transformers, was verified by independent measurement of the local strains along the length of the embedded bar using bonded electrical resistance (ER) strain gauges. In the pull-out tests, the failure mode was by shear. The ER strain gauges were installed inside grooves carefully machined in the steel bar to prevent direct friction from the concrete damaging the strain gauges. This approach also prevented damage to the wires and wire/gauge connection during the process of bar slip. The global fluctuation of the bond stress-slip behaviour was determined graphically and analysed using a number of statistical methods and independently verified from the local strain variation along the bar obtained from the strain gauge readings. Based on these observations, the fluctuation in bond stress with slip under displacement control has been shown to be mainly dependent on the transverse rib pattern of the bar.
Logan R, Mulheron MJ, Jesson D, Smith PA, Evans T, Clay-Michael N, Whiter J (2014) Observations on the graphitic corrosion of cast iron trunk main: Mechanisms and Implications,
Failures of large diameter cast iron trunk water mains can be catastrophic in the damage they can cause. It is therefore imperative to understand how cast iron deteriorates in order to help predict those areas of a water supply network which are at greatest risk of failure. Cast irons undergo a localized form of corrosion known as graphitic corrosion. The current work focusses on graphitic corrosion occurring on the external surface of a pipe a forming pits or larger patches of corrosion into the wall of the pipe. It was found that the graphite flakes within the cast iron are deteriorating during the corrosion process. High levels of chlorides are often found at the corrosion interface, within graphitic pits in the pipe wall. Electrochemical Impedance Spectroscopy shows that the corrosion mechanism of cast iron in soils changes when the salinity of the soil rises, which has significant implications for asset management and the mitigation of corrosion.
Keywords: graphitic corrosion, cast iron, water distribution, EIS, chlorides.
Fahimi A, Jesson DA, Mulheron MJ, Smith PA, Evans TS, Clay-Michael N, Farrow J (2014) Managing water infrastructure: Corrosion models for cast iron trunk mains, WIT Transactions on the Built Environment 139 pp. 401-409
Distribution networks are critical in providing continuous potable water supplies to households and businesses. Trunk mains are the major arteries of the distribution network and convey large volumes of water over long distances. Worldwide, much of this infrastructure is made of ageing cast iron and is deteriorating at different rates. Many of these mains are beginning to approach the end of their service lives (with some already exceeding their design life) and consequently out of large populations of pipes, some are failing, although some still have considerable residual life. Trunk main failures can have significant social, health and safety, environmental and economic impacts. It is therefore imperative to prevent the wide-scale failure of trunk mains through the implementation of proactive asset management strategies. Such approaches require accurate condition assessment data across the network in conjunction with deterioration modelling to predict how the assets' condition and performance changes over time. This work, being part of a wider collaborative project, has outlined a deterioration modelling framework on the basis of existing physical probabilistic failure models and research focussing on residual mechanical properties, corrosion and the NDT detection of flaws. The developed deterioration model can be used to characterise individual pipes (deterministic approach), as well as the cohort/network modelling of pipes (probabilistic approach). Deterioration is assumed to be predominantly based on corrosion. Previously this has been dealt with in a rather simplistic manner. The broader work has, on the one hand,shown that corrosion mechanisms are rather different than previously thought and, on the other, that their effect on a given pipe can be variable. A corrosion model capable of simulating the distribution of corrosion properties of the primary defects is to be incorporated within the proposed modelling framework and the development of important aspects of this model are discussed here. © 2014 WIT Press.
Hannant DJ, Branch J, Mulheron M (1999) Equipment for tensile testing of fresh concrete, Magazine of Concrete Research 51 pp. 263-267
The development of equipment suitable for measuring tensile stress-strain curves on fresh concrete is described. With such weak materials, it is essential to eliminate friction effects and this is achieved by the use of air-bearing plates. The objective of the new equipment is to enable data to be obtained to define the rapidly changing tensile stress-strain performance in the first 6 h after water is added at the mixer. This information is important for understanding plastic shrinkage cracking. The equipment is also being used to investigate early-age internal cracking problems which have been observed with high-strength concrete and which are related to the internal tensile failure strain of the cement paste. Some typical tensile stress-strain curves obtained ruing the equipment are shown for two types of concrete.
Boughanem S, Jesson DA, Mulheron MJ, Smith PA, Eddie C, Psomas S, Rimes M Engineered Cement Composite Materials: Characterization for Tunneling Applications,
Cements, which are intrinsically brittle materials, can exhibit a degree of pseudo-ductility when reinforced with a sufficient volume fraction of a fibrous phase. This class of materials, called Engineered Cement Composites (ECC) has the potential to be used in future tunneling applications where a level of pseudo-ductility is required to avoid brittle failures. However uncertainties remain regarding mechanical performance. Previous work has focused on comparatively thin specimens; however for future civil engineering applications, it is imperative that the behavior in tension of thicker specimens is understood. In the present work, specimens containing cement powder and admixtures have been manufactured following two different processes and tested in tension. Multiple matrix cracking has been observed during tensile testing, leading to a ?strain-hardening? behavior, confirming the possible suitability of ECC material when used as thick sections (greater than 50 mm) in tunneling applications.
Mulheron M, Omahony M (1988) THE DURABILITY OF RECYCLED AGGREGATES AND RECYCLED AGGREGATE CONCRETE, pp. 633-642
Katsanos A, Mulheron M, Nwaubani SO (2005) Prolonging bridge life through innovative approach to deicing operations, Proceedings of the 5th International Conference on Bridge Management pp. 541-548
This paper provides a brief review of the adverse effects of rock salt on reinforced concrete bridge structures, the roadside natural environment, the life cycle of highway structures, and the attendant financial cost implications. It addresses the issue of whether the adoption of an alternative method of winter operations for highway bridges, combined with the use of alternate de-icing salts, could constitute a viable, cost-effective and sustainable solution. The University of Surrey and Anglia Polytechnic University in the UK are currently evaluating the effects of two biodegradable de-icers; Calcium Magnesium Acetate (CMA) and Sodium Acetate (NAAC), on the behaviour of reinforced concrete Highway bridge structures. Initial results obtained from this study are presented and discussed with respect to the optimum condition for their application on highway structures. Conclusions are drawn on the basis of the practical implication for the life cycle of corrosion-prone highway structures and the natural environment. The need for further investigation is identified.
Boughanem S, Jesson DA, Smith PA, Mulheron MJ, Eddie C, Psomas S, Rimes M (2011) Engineered cement composites properties for civil engineering applications, ICCM International Conferences on Composite Materials
Engineered Cement Composites (ECC) materials have the potential to be used in civil engineering applications where a level of ductility is required to avoid brittle failures. However uncertainties remain regarding mechanical performance, physical properties, shrinkage and durability. In the present work, specimens containing cement powder and admixtures have been manufactured following two different processes and tested mechanically. Multiple matrix cracking has been observed in both tensile and flexural tests and this leads to "strain-hardening" behaviour. The results have been correlated with sample density and porosity and it is suggested that higher levels of porosity do not necessarily lead to a loss of the strain hardening capacity. Shrinkage has been investigated and it is shown, consistent with the literature, that shrinkage can be reduced both by controlling the initial environment to which the material is exposed and by the use of additives. Durability was assessed by flexure testing of beams specimens aged for different times. Initial testing (up to one year) indicates that the specimen retain ductility, although the initial cracking threshold increases with time - which may have implications for longer aging times.
Belmonte HMS, Mulheron M, Smith PA (2007) Weibull analysis, extrapolations and implications for condition assessment of cast iron water mains, FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES 30 (10) pp. 964-990 BLACKWELL PUBLISHING
Jones FR, Mulheron M (1983) THE EFFECT OF MOISTURE ON THE EXPANSION BEHAVIOR AND THERMAL STRAINS IN GRP, Composites 14 pp. 281-287
Boguszynska J, Brown MCA, McDonald PJ, Mitchell J, Mulheron M, Tritt-Goc J, Verganelakis DA (2005) Magnetic resonance studies of cement based materials in inhomogeneous magnetic fields, CEMENT AND CONCRETE RESEARCH 35 (10) pp. 2033-2040 PERGAMON-ELSEVIER SCIENCE LTD
McDonald PJ, Mitchell J, Mulheron M, Monteilhet L, Korb JP (2007) Two-dimensional correlation relaxation studies of cement pastes., Magn Reson Imaging 25 (4) pp. 470-473
Two-dimensional nuclear magnetic resonance relaxation correlation studies of cement pastes have been performed on a unilateral magnet, the Surface GARField. Through these measurements, the hydration process can be observed by monitoring the evolution of porosity. Characteristic relaxation time distributions have been observed in different cement pastes: fresh white cement, prehydrated white cement and ordinary Portland cement. The observed T(1)/T(2) ratio in these cements has been shown to agree with expectations based on high field values.
Jones FR, Mulheron M (1983) INFLUENCE OF VULCANIZATION AND MOISTURE ON THE THERMAL-EXPANSION OF UNSATURATED POLYESTER RESINS, Kautschuk Gummi Kunststoffe 36 pp. 300-300
Bohris AJ, McDonald PJ, Mulheron M (1996) The visualization of water transport through hydrophobic polymer coatings applied to building sandstones by broad line magnetic resonance imaging, JOURNAL OF MATERIALS SCIENCE 31 (22) pp. 5859-5864 CHAPMAN HALL LTD
BLACK S, LANE DM, MCDONALD PJ, HANNANT DJ, MULHERON M, HUNTER G, JONES MR (1995) THE VISUALIZATION OF THE INGRESS OF POLYMER TREATMENT COATINGS INTO POROUS BUILDING-MATERIALS BY STRAY-FIELD MAGNETIC-RESONANCE-IMAGING, JOURNAL OF MATERIALS SCIENCE LETTERS 14 (17) pp. 1175-1177 CHAPMAN HALL LTD
McDonald PJ, Mitchell J, Mulheron M, Aptaker PS, Korb J-P, Monteilhet L (2007) Two-dimensional correlation relaxometry studies of cement pastes performed using a new one-sided NMR magnet, CEMENT AND CONCRETE RESEARCH 37 (3) pp. 303-309 PERGAMON-ELSEVIER SCIENCE LTD
Jenneson PM, Clough AS, Hollands R, Mulheron MJ, Jeynes C (1998) Profiling chlorine diffusion into ordinary Portland cement and pulverized fuel ash pastes using scanning MeV proton micro-PIXE, JOURNAL OF MATERIALS SCIENCE LETTERS 17 (14) pp. 1173-1175 SPRINGER
Abstract Building activities generate coarse (PM10 d 10 ¼m), fine (PM2.5 d 2.5 ¼m) and ultrafine particles (<100 nm) making it necessary to understand both the exposure levels of operatives on site and the dispersion of ultrafine particles into the surrounding environment. This study investigates the release of particulate matter, including ultrafine particles, during the mixing of fresh concrete (incorporating Portland cement with Ground Granulated Blastfurnace Slag, GGBS or Pulverised Fuel Ash, PFA) and the subsequent drilling and cutting of hardened concrete. Particles were measured in the 5?10,000 nm size range using a GRIMM particle spectrometer and a fast response differential mobility spectrometer (DMS50). The mass concentrations of PM2.5?10 fraction contributed
Cox J-A, Druckman A, Jesson DA, Mulheron M, Smyth M, Trew H (2015) MSW as a Resource Pt 2: A case study in sustainable management, Proceedings of the Institution of Civil Engineers: Waste and Resource Management
WX Weight of material to be managed by a particular option
Waste is intricate to manage. With greater attention now being paid to the use of waste as a resource, there is an increasing need to develop sustainable and secure management options for the most complex material resource streams. In order to achieve this, it is necessary to look to those materials, which due to their complex structure have not traditionally been recycled, and so remain in the residual waste stream.
This paper presents a methodology that has been developed to enable local authorities, or their equivalents, to assess the environmental and economic feasibility of collecting complex material streams separately, in order to improve their management of municipal solid waste. The methodology utilises available data from a number of sources, to determine the feasibility of options available.
The methodology is applied to a case study in Surrey, England, in relation to the management of Absorbent Hygiene Products. Currently this waste is collected as part of the residual stream, and dealt with either through landfill or energy from waste. The result of applying the new methodology suggests that the optimum solution is the separate collection of Absorbent Hygiene Products and subsequent the sterilisation and recycling.
Lee B, Mulheron M (2015) Measurement of bar strain during pull-out tests: use of electrical resistance gauge methods under large displacement, MAGAZINE OF CONCRETE RESEARCH 67 (10) pp. 523-531 ICE PUBLISHING
Mulheron M, O'Mahony MM (1990) Properties and performance of recycled aggregates, Highways and transportation 37 (2) pp. 35-37
The research work reported was carried out in 1987 as part of a four-year programme sponsored in part by the Institute of Demolition Engineers on the recycling of demolition debris. The physical and mechanical properties of crushed concrete and demolition debris from a variety of sources were examined to assess the suitability of these aggregates for use as granular sub-base materials. In particular, sieve analyses and compacted density tests were conducted, during the construction of a road in Portsmouth, to compare the use of crushed concrete and limestone as the upper part of the capping layer. The authors review recent research on the recycling of crushed aggregates, examining their physical and mechanical properties and gauging their suitability as sub-base materials for roads.
Crunkhorn BB, Whiter JT, Mulheron M, Smith PA (2005) Behaviour of an interactive pipe liner under conditions that may occur following ring fracture of host main, PLASTICS RUBBER AND COMPOSITES 34 (7) pp. 305-310 MANEY PUBLISHING
Kakemi M, Hannant DJ, Mulheron M (1998) Filament fracture within glass fibre strands in hybrid fibre cement composites, Journal of Materials Science 33 pp. 5375-5382
In the study of hybrid fibre cement composites containing continuous polypropylene fibres and glass fibres, it is important to know the fracture behaviour of the glass fibre strand in order to minimise the discrepancies between experiment and theory. A new technique of light transmission through the glass fibres has been developed in order to obtain independent information about the failure of individual glass filaments within a strand. The technique gave quantitative results showing that in the hybrid composite, about 80% of the glass filaments were broken somewhere in the strands before the maximum stress in the composite was reached. This was in contrast to the composite reinforced with glass fibres alone where only about 30% of the filaments were fractured before the ultimate stress. The fractures of the glass filaments in the hybrid composite were more evenly distributed than in the singly reinforced composite which enabled greater strains to be achieved in the hybrid composite at the maximum stress. (C) 1998 Kluwer Academic Publishers.
Jones FR, Mulheron M, Bailey JE (1983) GENERATION OF THERMAL STRAINS IN GRP .1. EFFECT OF WATER ON THE EXPANSION BEHAVIOR OF UNIDIRECTIONAL GLASS-FIBER REINFORCED LAMINATES, Journal of Materials Science 18 pp. 1522-1532
Grey cast iron water pipe networks have been installed around the world, often 100?180 years ago. Cohorts (which can be defined by age, size, casting technology and geographical location, to specify but a few groups) degrade at different rates due to environmental and in-service issues, which can lead to a significant loss in mechanical performance. Hence, the management of these assets can be extremely problematic in terms of identifying priorities. The current paper considers the causes of such degradation, the consequences for defining accurate and up-to-date condition assessment protocols and hence the type and urgency of rehabilitation strategies. It follows that understanding the integrity/life expectancy of water networks requires non-destructive evaluation (NDE) of large-diameter cast iron trunk mains, with particular reference to the kinds of defects that are likely to be present and the issues that make assessment difficult. From this, recommendations are outlined for asset managers required to specify NDE protocols, based on an understanding of the nature of the material and conditions in the field.
Every day, water networks across the developed world are relied on by billions of people to provide them with
a fresh supply of water. Many of these networks are comprised of pipes made from grey cast iron and may
have been in service for up to 150 years. Despite their age, some parts of these networks continue to operate
with little degradation, whereas in other areas they degrade rapidly: more recently laid pipes are being outlived by their forerunners. In such networks, it is the trunk mains (pipes between 12-60? [300 mm to 1500 mm] in diameter) that are of great concern, since they pose the greatest risk of failure and are already bursting more frequently.
Accurate NDE is required to enable the mains in poor health with the highest risk of failure to be identified
and replaced before they burst. A review of the published literature has shown that whilst there are many NDE
techniques to choose from, many are not practical for application to the mains. The review process also
highlighted the kinds of defects present in grey cast iron and an initial stress analysis using strength models
and material data published in the literature has suggested defect sizes approaching 5 mm must be able to be detected to prevent catastrophic pipe failure.
Ultrasonic inspection has been investigated and shown to work effectively on uncorroded cast iron. Speed of
sound values between 4100 ? 4600 m s-1 have been observed across several pipes. A speed of sound of 2950 ± 80 m s-1 has been measured for graphitic corrosion, however, inspection on corroded main has not been possible.
A complementary magnetic technique, with the potential to scan pipe rapidly in order to identify mains in need
of further investigation, as well as providing supplementary condition data, has been trialled and shown to detect corrosion layers up to 6 mm thick.
A methodology using a 3D scanner to accurately determine the ?ground truth? pipe condition has been developed. This methodology proved to be successful and provided corrosion measurements that were in-keeping with those obtained through standard pit depth measurements. Further, the data showed that traditional pit depth measurements do not always find the deepest external corrosion pits, particularly where the surrounding geometry is complicated.
This methodology was used in a live comparison exercise of two, commercially available techniques. This
comparison highlighted problems with the surface preparation required by some techniques, which can be
quite damaging, and with some proprietary post-processing algorithms ? the raw data can be more useful.
From this assessment process, it has been possible to specify very detailed schedule for the testing of new NDE
techniques in the future.
Large diameter trunk mains are the life line of the water supply system. They convey large volumes of water between treatment works and local distribution networks, sometimes over quite significant distances (tens to hundreds of kilometres). Compared to smaller diameter distribution mains, trunk mains tend to have low failure rates, but when they do fail, the consequences are potentially much more significant, with direct, indirect and societal costs.
Worldwide, a significant proportion of trunk mains are still made of aging cast iron material. Remarkably, these aging assets have in some cases outlived the pipes that replaced deteriorated parts of the network. Even so, many cast iron pipes are beginning to approach, or have already exceeded, their design life: consequently, out of a large population of pipes, some are failing whilst some still have considerable residual life.
Asset management, in this context focussing on the targeted replacement of degrading main, requires tools and models for the prediction of the future performance of the network. Several mechanistic deterioration models have been developed in recent years, which attempt to predict the condition of cast iron pipes, but few methodologies have specifically targeted water trunk mains. Nevertheless, the requirement has remained for a robust deterioration and failure model for cast iron trunk mains, worldwide.
This project, being part of a wider, collaborative project between Thames Water Utilities and the University of Surrey, has reviewed existing failure models for cast iron trunk mains and sought to modify these based on information arising from other areas of the project. This has included, new understanding of the corrosion of cast iron trunk main, the use of fracture mechanics to predict failure and non-destructive evaluation data gathering techniques has provided significant insight into improvements that can be made to failure models.
In particular, the present research has shown how traditional loss-of-section approach to the residual strength of corroded pipes can be used alongside a fracture mechanics approach, in order to provide boundaries to the failure ?envelope?. This novel methodology has been incorporated as part of an enhanced modelling framework, which has shown to improve the failure predictions across the network. The enhanced model also enables more detailed analysis of sections of the pipes that have been surveyed on site.
The fitness of ageing cast iron pipe is a problem for both clean water and wastewater networks. Whilst considerable effort has been put into understanding the condition of cast iron mains that carry potable water, wastewater systems have received less attention. Compared with clean water mains, wastewater trunk sewers typically have thinner walls, are often of lesser casting quality, and typically are exposed to a harsher and more complex internal and external environment. It has been established that corrosion is a leading cause of deterioration in cast iron mains. Research has shown that when predicting residual load capacity in clean water main, a loss-of-section approach is not applicable when dealing with corrosion pitting, which is more discrete and notch-like. This research examines the use of both loss-of-section and fracture mechanics models to provide a failure envelope for a ring from a pipe under combined vertical loading and internal pressure. Internal corrosion, defect size, and morphology of this corrosion have a significant effect on the residual strength of the pipe. The failure envelope predicted is rather different to that previously reported for clean water mains, which is not unexpected given the differences in component geometry and operational conditions.