C. J. Lynsdale

The University of Sheffield | Sheffield · Department of Civil and Structural Engineering

Slag and other cement replacement materials provide an important route to low carbon footprint concrete construction. These materials are often by-products from other industries, and as such, their quality varies depending on source and processing. This paper examines the influence of a range of parameters on the reactivity of slag and its contribu...

Despite the large amount of research that has been carried out to date on the use of glass fibre reinforced polymer (GFRP) bars in concrete, one factor still hindering their widespread use in civil engineering applications is the lack of comprehensive data on their long-term in-service performance. This paper presents the test results of an experim...

This paper aims to advance research on the use in concrete of a high volume of fly ash, with a high loss on ignition value, aiding in sustainable low carbon footprint construction. To this end, the work explores the benefits that may be achieved in terms of long-term concrete performance from the incorporation of fly ash along with a chemical activ...

To advance existing knowledge on the long term performance of GFRP bars in concrete • To identify and quantify the degradation mechanisms of GFRP in the concrete environment OBJECTIVES • To develop a reliable model to predict the long term performance of GFRP bars in typical concrete environments • To propose simple design recommendations for the l...

This paper presents an experimental study aimed at investigating the long-term tension stiffening and flexural behaviour of concrete elements reinforced with glass fibre reinforced polymer (GFRP) bars subjected to accelerated aging conditions. Six tension stiffening specimens and eight small-scale GFRP RC beams were exposed to different environment...

Although exposure to sulfate and chloride ions separately is known to result in deterioration of concrete and corrosion of steel rebars, the effects of both ions being simultaneously present are ambiguous, with some studies showing the presence of chloride to be beneficial, while in others attack was accelerated. This paper describes an investigati...

Over the past two decades, glass fibre reinforced polymer (GFRP) has been increasingly used as reinforcement in concrete members for civil engineering applications. However, the long-term performance of GFRP bars is still an issue of concern among the engineering community. The main aim of this research is to investigate the effects of harsh enviro...

Following the discovery in the late 1990s of seriously damaged M5 motorway bridge foundations due to thaumasite formation, the standards for buried concrete were changed. Binder types and mix designs to resist aggressive ground conditions are specified; however, in highly aggressive conditions it may be necessary to utilise additional protective me...

Over the past two decades, glass fibre reinforced polymer (GFRP) has been increasingly used as reinforcement in concrete members for civil engineering applications. However, the long-term performance of GFRP bars is still a controversial issue among the engineering community. The main aim of this research is to investigate the effects of harsh envi...

Although glass fibre reinforced polymer bars (GFRP) are increasingly used in civil engineering applications, their long-term performance in concrete structures is still a controversial issue among the engineering community. This paper presents the test results of an experimental study to investigate the inter-laminar shear strength, flexural charac...

A number of alternatives have been explored by the cement industry in recent years to reduce CO2 emissions. One of the alternatives, the subject of this chapter, is an intermediate system between a high volume fly ash concrete and a geopolymer concrete. This concrete includes a hybrid system of 50% OPC–50% fly ash, and an activator. In this study,...

Environmental issues related to CO2 emissions have become a key focus for many different industries, including the cement and concrete industry. An environmentally optimized ‘green’ concrete can provide a much needed alternative to conventional concrete to reduce the carbon footprint of the construction industry. This can be achieved through high P...

ABSTRACT This paper investigates the durability of Glass FRP (GFRP) reinforcement exposed to severe environments and subjected to different levels of sustained load. The test matrix was designed to include 92 GFRP specimens exposed to temperatures varying from 20°C to 60°C for 0, 42, 90 and 270 days. A total of 69 specimens were embedded in concret...

In general, concretes made with blended Portland cement containing high volumes of fly ash provide an alternative to conventional Portland cement concrete to enable carbon footprint reduction. This study evaluates the chemical activation of four fly ashes in blends with Portland cement, by assessing their effects on hydration and compressive streng...

Over the past three decades the use of GFRP bars as more durable alternative materials to traditional steel reinforcement has received a lot of attention in construction. However, given the potential deterioration of glass fibres in alkaline environment, quantifying the durability of GFRP bars in concrete, especially under severe conditions and sus...

Following the discovery in the late 1990s of seriously damaged M5 motorway bridge foundations due to thaumasite formation, the standards for buried concrete were changed. Binder types and mix designs to resist aggressive ground conditions are specified; however, in highly aggressive conditions it may be necessary to utilise additional protective me...

The possibility of attack of buried concrete due to the chemical aggressivity of the ground is of concern in the construction industry. Following the discovery in the late 1990s of seriously damaged foundations due to the formation of thaumasite in bridge structures on the M5 motorway in the UK, changes were made to the standards for buried concret...

The possibility of attack of buried concrete due to the chemical aggressivity of the ground is of concern in the construction industry. Following the discovery in the late 1990s of seriously damaged foundations due to the formation of thaumasite in bridge structures on the M5 motorway in the UK, changes were made to the standards for buried concret...

The effect of chloride on the performance of cement mortars made with CEMI and CEMI blended with 10% limestone filler and subjected to sulfate attack was investigated. The specimens were exposed to the combined action of chloride (0%, 0.5%, 1.0% and 2% of Cl−) and sulfate (0.6% SO42−) for 630 days at 5 ± 0.5 °C. The performance of the mortar cubes...

As part of a study into the controls on the deterioration of concrete due to sulfate attack, mortars (50-mm cubes and 40 × 40 × 160 mm prisms) made with portland cement CEMI, and 90% CEMI + 10% limestone blend were exposed to BRE DS4 sulfate solution based on magnesium sulfate (MgSO4 • 7H2O) under wetting and drying cycles for 18 months at 5°C. The...

The influence of clay composition on the severity of attack due to thaumasite sulfate attack (TSA) on concrete made with CEM I and CEM I blended with 10% Limestone Filler (LF) was investigated. Concrete specimens were exposed to weathered Lower Lias Clay (LLC), for which the water soluble sulfate corresponded to the BRE sulfate class of DS-2, for 1...

This paper describes a long-term investigation into chemical degradation vulnerability of four different types of concrete that were exposed to pyrite rich clay. In this, four 100 mm square by 1.2 m long concrete columns made from Portland cement (PC), Portland limestone cement (PLC), sulfate resisting Portland cement (SRPC) and Portland cement ble...

The consequence of sulfate attack on geopolymer concrete, made from an alkali activated natural pozzolan (AANP) has been studied in this paper. Changes in the compressive strength, expansion and capillary water absorption of specimens have been investigated combined with phases determination by means of X-ray diffraction. At the end of present inve...

Carbonation of ordinary Portland cement occurs naturally. This process is, however, not sufficient for the application of CO2 sequestration due to the very slow kinetics of the diffusion-controlled process. The present study shows that the carbonation can be enhanced in the hardened cement systems blended with blast furnace slag or pulverised fuel...

Environmental issues related to CO2 emissions have become a key focus for many different industries, including the cement and concrete industry. An environmentally optimized ‘green’ concrete can provide a much needed alternative to conventional concrete to reduce the carbon foot-print of the construction industry. This can be achieved through high...

The effect of chloride on the performance of mortars made with CEMI, CEMI blended with 10% limestone filler and CEMI blended with 70% GGBS subjected to sulfate attack was investigated. Mortar cubes, prepared with 0.6 water/binder ratio, were exposed to the combined action of chloride (0 and 0.5 % of Cl- as NaCl) and sulfates (0.6% SO42- as MgSO4.7H...

The effect of chloride on the performance of mortars made with CEMI, CEMI blended with 10% limestone filler and CEMI blended with 70% GGBS subjected to sulfate attack was investigated. Mortar cubes, prepared with 0.6 water/binder ratio, were exposed to the combined action of chloride (0 and 0.5 % of Cl- as NaCl) and sulfates (0.6% SO42- as MgSO4.7H...

The effect of chloride on performance of cement mortars made with CEMI and CEMI blended with 10% limestone filler and subjected to sulfate attack was investigated. The performance of the specimens was assessed by means of visual inspection and loss of mass. In addition, the mineralogy of the deterioration products was determined by infra-red spectr...

The effect of chloride on performance of cement mortars made with CEMI and CEMI blended with 10% limestone filler and subjected to sulfate attack was investigated. The performance of the specimens was assessed by means of visual inspection and loss of mass. In addition, the mineralogy of the deterioration products was determined by infra-red spectr...

In the near future, geopolymers or alkali-activated cementitious materials will be used as new high-performance construction materials of low environmental impact with a reasonable cost. This material is a good candidate to partially replace ordinary portland cement (OPC) in concrete as a major construction material that plays an outstanding role i...

Abstract: The assessment of pozzolanic activity is essential for estimating the reaction of a material as pozzolan. Natural pozzolans can be activated and condensed with sodium silicate in an alkaline environment to synthesize high performance cementitious construction materials with low environmental impact. In this paper, the pozzolanic activitie...

One of the important factors in the use ofportland cement concrete is its durability, and most of the situations where durability is lacking have been identified and strategies to manage durability have been implemented. Geopolymer concrete, made from an alkali-activated natural pozzolan (AANP), provides an important opportunity for the reduction o...

Natural pozzolans can be activated and condensed with sodium silicate in an alkaline environment to synthesize high performance cementitious construction materials with low environmental impact. The nature of the starting materials including mineral composition, chemical composition and crystal structure groups affects the formation of the geopolym...

Natural pozzolans are raw materials from geological deposits with a range of chemical compositions that when combined with suitable alkali activators can be converted to geopolymer cement for concrete production. In this paper the concept of adding mineral additives to enhance the properties of geopolymer cement is introduced. Taftan andesite, a na...

Blended cement pastes are currently used for encapsulation of low level and intermediate level nuclear waste in the UK. However, there is still little information on the long-term durability of those mixes to some chemical attacks. Accelerated testing may predict the long-term durability or at least help the selection of more durable formulations....

The development of alkali-activated binders with superior engineering properties and longer durability has emerged as an alternative to ordinary portland cement (OPC). It is possible to use alkali-activated natural pozzolans to prepare environmentally friendly geopolymer cement leading to the concept of sustainable development. This paper presents...

The reaction of CO2 gas with OPC, OPC-BFS and OPC-PFA composite cement systems were studied using XRD, SEM and TG to investigate the applicability of these materials to immobilise carbon arising from graphite waste. XRD results suggested that calcite formed in OPC system after the carbonation reaction, whereas calcite and vaterite were observed in...

The performance of an Algerian blastfurnace slag has been assessed by examining the parameters influencing reactivity in a comparative study of two slags from different origins. These parameters include chemical composition, glass content, particle size distribution, heat of hydration and microstructural development. Three cement paste systems were...

3:1 BFS:OPC, 9:1 BFS:OPC and 9:1 alkali activated BFS:OPC pastes cured at 20 °C and 60 °C for 90 days were submitted to accelerated carbonation under 5% CO2, 60% relative humidity and 25 ± 5 °C for 21 days. TGA/DTG was used to quantify the amounts of carbonates formed from calcium hydroxide (CH) and calcium silicate hydrate (C–S–H), based on the CH...

Natural pozzolans are raw materials from geological deposits with a range of chemical compositions that when combined with suitable alkali activators can be converted to geopolymer cement for concrete production. In this paper the concept of adding mineral additives to enhance the properties of geopolymer cement is introduced. Taftan andesite, a na...

Blastfurnace slag has been widely used as a successful replacement material for Portland cement, and concrete of enhanced qualities can be achieved as a result. Due to the slag’s slow reactivity, however, the early-age mechanical properties may suffer. This paper reports the results of an investigation, carried out at Chlef University (Algeria), us...

Steel fibre reinforced concrete (SFRC) is known by its excellent performance when compared to conventional concrete. The use of steel fibres in concrete may contribute to improve properties such as crack and impact resistance, shrinkage reduction and toughness, by preventing/delaying crack propagation from micro-cracks to macro-cracks. In some case...

O Concreto Compactado com Rolo (CCR) é conhecido por apresentar elevado custo-benefício quando utilizado em obras especiais, tais como barragens e rodovias. Uma alternativa ao uso de materiais de alta qualidade (responsáveis pela boa qualidade do material) é a adição de fibras de aço no concreto. Torna-se necessário uma elevada quantidade de fibras...

Composite cements containing up to 90% by weight of blast furnace slag (BFS) and 75% by weight of pulverized fly ash (PFA) are used in the UK for encapsulation of low level (LLW) and intermediate level radioactive waste (ILW). The long-term behaviour of such materials may be assessed if some accelerated tests are carried out and also better formula...

This paper presents the findings of a long-term study on the microstructure of Portland cement mortar specimens containing 5%, 15% and 35% limestone filler, as cement replacement, after exposure to a solution of magnesium sulfate at a concentration of 1.44% SO4, for 5 years at 5 °C. The findings are compared to results reported earlier, obtained fr...

The thaumasite form of sulfate attack (TSA) has been recognised in recent years as a distinct mechanism by which degradation of buried concrete can occur in the presence of an external source of sulfate ions. There is, however, disagreement about the role of pH. It has been proposed that attack by sulfuric acid, produced by oxidation of pyrite, is...

The thaumasite form of sulfate attack (TSA) has been observed in mortar prisms made from Portland–limestone cements after laboratory storage in 1.8% magnesium sulfate solution at 5 °C for 5 years. The prisms all showed evident signs of degradation, which increased with increasing limestone content. X-ray powder diffraction indicated that a solid so...

Mortar prisms made with Portland-limestone cement have been stored in air and in 1.8% magnesium sulfate solution at 5 °C and have been examined over a period of 5 years. This paper is primarily concerned with the results obtained at the end of this period. The limestone content in the samples varied from 0% to 35%, but the water to cement plus lime...

There is disagreement about the role of sulfuric acid in the thaumasite form of sulfate attack (TSA) of concrete. Some researchers suggest that thaumasite is formed only at pH above 10.5, whereas others report that the primary cause of deterioration in the affected M5 bridge foundations was sulfuric acid attack followed by neutral TSA. The aim of t...

This investigation is aimed at developing high-performance concrete and form part of an investigation into the optimization of a blended cementitious system for the development of high-performance concrete. Binary and ternary blended cementitious systems based on ordinary Portland cement (OPC), pulverised fuel ash (PFA) and silica fume (SF) were in...

The results presented in this paper form part of an investigation into the optimisation of a ternary blended cementitious system based on ordinary Portland cement (OPC)/pulverised fuel ash (PFA)/silica fume (SF) for the development of high-performance concrete. Cement pastes covering a wide range of PFA/SF blending proportions were investigated. Co...

The influence of aggregate geochemical properties on the development of the microstructure and bond strength at the interfacial transition zone (ITZ) between aggregate and the hydrating cement paste was studied. The mineral phases and microstructure at the ITZs of three commonly used concrete aggregates (quartzite, basalt, and limestone) with contr...

The main focus of this paper is to investigate the applicability of external plate bonding to strengthen in shear reinforced concrete (RC) beams without any internal shear reinforcement. Extensive test data are presented to evaluate the feasibility of the technique when the externally bonded tension plate is made of steel or of glass-fibre-reinforc...

A Portland cement mortar was subjected to elevated temperature curing at 100°C for 12 h and then stored under water at room temperature. Expansions, attributable to delayed ettringite formation, were found to develop over a period of 1 year. Sulfate ions released to the pore fluid at elevated temperatures, and partly sorbed by C-S-H gel, evidently...

The influence of aggregate geochemical properties on the development of the microstructure and bond strength at the interfacial transition zone (ITZ) between aggregate and the hydrating cement paste was studied. The mineral phases and microstructure at the ITZs of three commonly used concrete aggregates (quartzite, basalt, and limestone) with contr...

This paper presents the interim results of an on-going study on the influence of aggressive exposure conditions on the behaviour of epoxy adhesive bonded concrete–glass fibre reinforced polymers (GFRP) joints. The type of specimen used in this study is a push-off double lap shear specimen. Twenty-four of these push-off specimens consisting of concr...

This paper describes part of a large project on aggregate-cement interactions and interface bonding mechanisms in concrete. This part of the study investigates the influence of aggregate physical properties on the nature of aggregate-cement paste interfacial bonding with the aim of establishing the bonding mechanisms as controlled by aggregate phys...

This paper highlights the role played by aggregate with respect to the chemical interactions that take place within the interfacial transition zone between aggregates and cement paste matrix. Four commonly used aggregates with different chemical properties, basalt, limestone, silica sand, and quartzite, were investigated. It was observed that ions...

This paper addresses the structural implications when a glass fiber reinforced plastic (GFRP) plate is bonded externally to a reinforced concrete (RC) beam for flexural strengthening. Full-scale beams were tested in the laboratory to identify the differences in behavior of a GFRP-plated RC beam from that of a steel-plated one, and then special desi...

The interaction between freeze/thaw (F/T) exposure and delayed ettringite formation (DEF) and their combined effect on the performance of heat-cured mortar specimens are reported. The results show that heat-cured mortar, not subject to F/T, starts to expand gradually after a long induction period ([approx]150 days). This period is shortened and the...

This paper presents an example of the use of microcomputers in the study of the durability of reinforced concrete in which silica fume was used to replace part of the ordinary Portland cement. A thermogravimetric balance, a voltage-driven permeation apparatus, a corrosion apparatus and a mercury intrusion porosimeter were connected to the computer...

Coloured concrete can be produced by painting the concrete surfaces after the concrete has hardened or by incorporating colouring agents, i.e., pigments, into the concrete mix when the concrete is plastic. The use of pigments is preferred since the colour becomes an integrated part of the concrete. This paper presents a review of the information av...

Synopsis A permeability cell for measuring the permeability of mortar and concrete to gas is described. The problems encountered and overcome during the development of the cell are discussed. The cell is designed to test 25 mm diameter mortar samples but can also be used for 50mm diameter concrete specimens. Specimens of heights between 10 and 50mm...