World class facilities allow key mechanical properties of materials to be examined with an ultra-high positioning precision on the micro to nanoscale.

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Nanotechnology based research at the Advanced Concrete and Masonry Centre has been world-leading for many years.

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With the award of a Research Development Grant from the Scottish Higher Education Funding Council of over 500,000 UK pounds, the ACM Centre will maintain this profile and build for the future. The Scottish Centre for Nanotechnolgy in Construction Materials, or NANOCOM Centre, is unique in the UK and will provide Scotland with a unique research resource.

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More information will be made available here as soon as possible. In the meantime please contact the ACM Centre for more information at the addresses and numbers given in the Contacts page.

Characterisation of mortars in historic buildings.
Biological deterioration of natural building stones.
Development and testing of modern conservation lime mortars.
The Experimental Lime Kiln (ELK)

The concept of self-compacting concrete was proposed by Okamura in 1986 and the prototype was first completed in the word in 1988. Since then, various investigations have been carried out and the concrete has been used in pratical structures, mainly by large scale construction companies. The required workability for casting depends on several factors, such as the type of construction, the selected placement and consolidation methods, the shape of formwork, and the congestion nature of the reinforcement. With the increasing use of congested reinforcements in mat foundations and moment-resisting reinforced concrete structures, there is a growing interest in specifying highly flowable concrete.

SCC often incorporates several mineral and chemical admixtures, in particular a SP and a viscosity-modifying admixture (VMA). The SP is used to insure high fluidity and reduce the water-powder ratio (W/P). The VMA is incorporated to enhance the yield value and viscosity of fluid mixture, hence reducing bleeding, segregation, and settlement.

More recently, much greater volumes of SCC have been used in major Japanese civil engineering structures, such as a massive LPG storage tank or huge anchorages for the 2km-span Akashi-Kaikyo suspension bridge. The anchorgaes contain a complex mixture of dense reinforcement and cabling that had to be encased in 512,000m3 and 250,000m3 of SCC each.

The required stability of fresh concrete depends on the rheological properties and placement conditions. With the increased consistency necessary to ensure proper spread of the cast concrete away from the placement point and around various obstacles and reinforcement, there is an increased risk of segregation and washout. Such stability must be high when the concrete is subjected to some free fall in water, as when the concrete is used for the repair of relatively shallow areas that make it impossible to ensure that the bottom of the placement device remains immersed in freshly cast concrete. The risk of water dilution also increases when the concrete is cast in circulating water. Dropping a highly workable concrete, even a short distance, through moving water can lead to a significant level of water dilution that can negatively impact mechanical properties and durability.

AWAs are incorporated to enhance the resistance of fresh concrete to water erosion, segregation. The majority of AWAs consist of water-soluble polymers.

The specific advantages of AWA underwater concrete include the following:
Compared to ordinary concrete, antiwashout underwater concrete is highly resistant to the washing action of water and rarely separates, even when dropped through water.
Its yield stress is small and its viscosity high, so the concrete components don’t segregate and it displays high fluidity.
As a result of the high fluidity, its self-leveling ability is improved.
Almost no bleeding occurs.
The properties required for underwater concrete placed by conventional tremie, pump with free fall and skips are:
specified strength and durabilty
self-compaction
self-levelling or flow resistance (depending on placing conditions)
washout resistance
cohesive to reduce segregation.

A limited number of opportunities (10-15) are available for short, 10 minute, presentations on current research during an “open session”. Please submit 1 page abstracts by the 15th of December to be considered for the open session.

DEADLINE for registration and submission of abstracts for open session – 15th DECEMBER 2004

Background to the workshop

Full consideration of a complex, heterogeneous and coupled nature of cementitious composites is increasingly needed to explain the behaviour of cementitious materials under extreme conditions (e.g. high temperature) or their durability in long term exposures. Similarly, the same arguments apply in the engineering and design of novel cementitious materials with specific performance characteristics in mind, where an integration of computational modelling strategies bridging different scales and micro/nano characterisation of cementitious materials represents one of the principal research challenges in computational mechanics.

The Centre for Microstructural Modelling and Chararacterisation of Cementitious Materials represents an interuniversity initiative between the Computational Mechanics Group (CMG) at the University of Glasgow and the Advanced Concrete and Masonry Centre (ACM) at the University of Paisley, supported by the EPSRC Research Funding Council in the UK. One of the main aims of this Centre is to contribute towards an integration of recent advances in multiscale computational modelling and novel micro/nano characterisation techniques, especially in cases of exposure to extreme conditions. This aim is in line with the interests of the RILEM TC-197 Committee on Nanotechnology in Construction Materials.

The centre is a partner in the Glasgow Research Partnership for Engineering funded by the Scottish Funding Council, as part of the Mechanics of Materials and Structures and Bioengineering Joint Research Institute. In 2004 a collaboration with the Mechanics and Materials group at Civil Engineering at the University of Glasgow saw the establishment of the Centre for Microstructural Modelling and Characterisation with funding from the EPSRC.

Research Focus

The group’s activities focus on the characterisation of construction materials at a range of scales from the nano to the macro-scale. The aim is to improve our fundamental understanding of the structure-property relationship and processes within materials, that control mechanical and durability behaviours across these scales. The staff expertise is complimentary to permit an expansion of such research work focussing on the cycle of characterisation through modelling to design of new materials. Additional research focuses on the properties of natural geomaterials and their relationship to performance in construction environments

Key themes are:
· Verification of new special materials designed and manufactured with desirable properties and performance characteristics, as a result of modelling activities, closing a full cycle of investigative-modelling activity.
· The investigation of special materials, for example high performance and self compacting concrete, traditional lime mortars tailored for compatibility, materials in extreme environments, control of durability through direct fabrication or adapted properties of existing materials.
· Development of an interdisciplinary approach to sourcing and interpretation of materials issues in building conservation, and their functional properties.
· Realising waste reuse and the development of binders for alternative cements in and novel geopolymers in support of environmental agendas.

It sounds like advertising a new product but, in most respects, high performance concrete is not fundamentally different from the concrete that we have been using in all along, because, it does not contain any new ingredients and does not involve new practices on site. In the 1970s, when the compressive strength of concrete used in the columns of some high-rise buildings was higher than that of the usual concretes used in construction, there is no doubt that it was legitimate to call these new concretes ‘high-strength’ concretes. They were used only because their strength was higher than that of usual concretes generally specified at that time.
Actually, high performance concrete evolved gradually over the last 15 years or so, mainly by the production of concrete with higher and higher strengths: 80, 90, 100, 120 MPa, and sometimes even higher.

However, when the superplastizer began to be used to decrease the water/cement or water/binder ratios rather than being exclusively used as fluidifiers for usual concretes, it was found that concretes with a very low water/cement or water/binder ratios also had other improved characteristics, such as higher flowability, higher elastic modulus, higher flexural strength, lower permeability, improved abrasion resistance and better durability. Finding aggregate that meet the minimum standard requirements for usual concrete in the 20 to 40 MPa range is fairly easy; however, when targeting 75 MPa, a number of problems arise. Performance can be limited by certain aggregates, such as gravels that are too smooth and not clean enough, those containing too many soft and crumbly particles, soft limestones and hard aggregates with poor shape characterised by flat or elongated particles. Aiming for a design compressive strength of 100 MPa imposes even greater restrictions on selecting aggregates, cements and superplastizers. Successfully producing a 100 MPa concrete requires:
A very strong, clean, cubical coarse aggregate (with some exceptions for some glacial gravels)
A cement that performs outstandingly well, both rheologocally and in terms of strength
A superplastizer that is totally compatible with the selected cement

Example projects that make use of HPC:
Water Tower Place (1970), Chicago, Illinois, USA (60 MPa)
Norway’s Gulfaks offshore platform (1981) (70 MPa)
Hassan II mosque (1986), Casablanca, Morocco (95 MPa)
Sylans and Glacieres viaduct (1986), France (60 MPa)
Scotia Plaza (1988),Toronto, Canada (70 MPa)
Two Union Square (1988), Seattle, Washington, USA (90 MPa)
Joigny bridge (1989), France (60 MPa)
The ‘Pont de Normandie’ bridge (1993), France (60 MPa)
Hibernia offshore platform (1996), Newfoundland, Canada (70 MPa)