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A potentially dangerous building material linked to cases where school roofs have collapsed without warning may have been used in the construction of up to 15 council buildings in Edinburgh, it has emerged.

Concerns over Reinforced Autoclaved Aerated Concrete (RAAC) have resulted in an investigation by the city council who would not confirm if any of the buildings currently being surveyed are educational facilities.

The bubbly, lightweight concrete was commonly used in the construction of roofs and walls in the UK from the 1950s to 80s but is now believed to pose a “risk to life” after incidents of school ceilings caving in.

In a safety briefing notice issued last September, the Office of Government Property (OGP) said the material “is now life-expired and liable to collapse”.

It noted this “has already happened in two schools with little or no notice”.

A Freedom of Information request by the Local Democracy Reporting Service revealed that The City of Edinburgh Council has identified 15 buildings “that may have been constructed” using aerated concrete, also known as Siporex.

The council said it is “currently awaiting a quotation for an external consultant to undertake further intrusive surveys”.

It added it would not disclose which buildings are under investigation – which as well as schools could include community centres, libraries and council offices – until the surveys are complete.

Meanwhile West Lothian Council has agreed to spend £10 million to replace RAAC panels found in three of its primary schools. The worst affected, Livingston’s Knightsridge Primary, was shut with immediate effect in November with after an investigation uncovered extensive structural issues.

If a similarly sum is needed to fix walls and ceilings in local authority-owned buildings across Edinburgh this is likely to cause a headache for the council. This year’s budget for infrastructure investment is already facing a £134million cut, with plans to scale back new school buildings and retrofitting works to plug the gap.

School construction failures in the capital were previously exposed following the collapse of a wall at Oxgangs Primary in 2016, which led to the closure of 17 schools in the city amid significant concerns over building standards.

The potential dangers of Siporex have been flagged with local councils by the UK Government since 2018, after the roof of Singlewell Primary in Kent suddenly gave way. Luckily, no one was injured as the incident happened on a weekend.

The Standing Committee on Structural Safety (SCOSS), which first warned of the problem over 20 years ago, said the following year that ‘sight must not be lost of the fact that the collapse was sudden with very little noticeable warning’.

Furthermore, last summer leaked emails sent to Downing Street by senior officials at the Department for Education said many school buildings  posed a “risk to life” as a result of the RAAC crisis.

by Donald Turvill, Local Democracy Reporter.

The Local Democracy Reporting Service (LDRS) is a public service news agency. It is funded by the BBC, provided by the local news sector (in Edinburgh that is Reach plc (the publisher behind Edinburgh Live and The Daily Record) and used by many qualifying partners. Local Democracy Reporters cover news about top-tier local authorities and other public service organisations.

 

Source: Edinburgh Post

Milbank Concrete Products based in Colchester, North Essex, are one of the UK’s leading manufacturers of precast concrete products with a focus on exceptional customer service.

Throughout the design, manufacturing, delivery and installation stages, Milbank offer one of the most comprehensive and professional service packages, providing a range of precast concrete products including: balconies, beam & block flooring, bespoke concrete products, ground beams, hollowcore flooring, helical stairs, rail products, sea defence & flood solutions, stadia products and straight stairs & landings.

Following on from market research and the identification of the need for an affordable, cost effective and efficient thermal floor arrangement, Milbank Concrete Products have recently launched their new and improved insulated concrete flooring solution, WarmFloor Pro.

WarmFloor Pro offers construction professionals a cost-effective alternative to quickly assembling a thermally insulated concrete ground floor over the industry leading competitor brand, Jetfloor, by Forterra (Bison). Reduced initial construction costs and an increase in energy savings make WarmFloor Pro a compelling alternative to a standard beam and block floor. In combination with its certification and A+ Green Guide rating, WarmFloor Pro is proving to be a must have addition to any new, eco-friendly development where keeping heating costs low is paramount.

WarmFloor Pro is suitable for almost any structure, but is most commonly used in housing, from single dwellings to complete housing developments. It offers a simple, cost effective, concrete insulated flooring solution to self-builders and construction professionals alike. Without the need for any specialist tools or skills, installation of WarmFloor Pro is efficient and streamlined whilst minimising waste and emission rates.

WarmFloor Pro works by combining rigid insulation modules (EPS panels) manufactured from lightweight closed cell expanded polystyrene which is laid in-between prestressed concrete beams (either 155mm or 225mm deep) with an EPS top sheet, damp proof membrane and structural concrete topping. If required, underfloor heating can be incorporated with the pipework attaching to the EPS panels with plastic pegs before the concrete topping is applied.

WarmFloor Pro is comprised of 6 main EPS components that are available in two types of EPS; standard issue in white (0.038W/m²K) or an alternative high-performance platinum in grey (0.031W/m²K). The 6 components are made up of Top Sheets – available in depths of 75-150mm, Infill Panels – available in 533mm for nominal 600mm beam centres and 343mm for reduced beam centres, and End Panels – available in both 178mm and 300mm.

EPS end panels are used for both the start and end of the flooring installation. The end panels are inserted at the start of the row with the straight (1200mm edge) opposite to the beam. All units are 1200mm long and can be cut on site to the required length using basic tools such as a handsaw; (minimum 300mm long).

As every building is different, Milbank are well equipped to design your floor to achieve the specific targeted U-Values (reaching as low as 0.07W/m²K) together with the structural layout of the floor to suit. Milbank then manufacture the concrete components and supply the materials (including the EPS panels) directly to your site. WarmFloor Pro is currently available on a supply only or

supply and installation basis using their vastly experienced installation teams.

WarmFloor Pro Benefits:

  • Easy to install – does not require any specialist tools or skills.
  • Quick to install – each EPS panel is the equivalent length of 5 standard concrete blocks.
  • Cost effective – WarmFloor Pro is designed to save you money. Faster installation speeds combined with reduced waste and excavation removal allow for an increase in overall savings.
  • Bespoke – a wide range of EPS panel depths and grades are available to satisfy your U-value or budget requirements.
  • Sustainable – WarmFloor Pro is designed to last the lifetime of the building while maintaining its exceptional thermal performance.
  • Clean, safe and easy to handle – lightweight EPS panels only weigh around 2Kg.
  • Underfloor heating compatible – heating pipework is simply held in place using plastic pegs that push into the EPS panels.
  • Proven Technology – now in use for over 10 years.
  • Industry compliant – Milbank WarmFloor Pro is Fully certified and has an A+ green guide rating.

For more information on Milbank Concrete Products or to enquire about their extensive range of products including WarmFloor Pro Insulated Flooring, please visit their website or call them on 01787 223 931.

For more information please visit www.milbank.co.uk.

FLI Carlow are the premier total service provider of engineered structural solutions to the Water, Energy, Storm Attenuation and Bespoke markets. Our capacity to design not just the precast units, but the structure into which they integrate and the manufacturing tools used to make them has kept us at the forefront of innovation in our industry.

Semi-precast is the core of our business, a hybrid between traditional in-situ concrete and traditional precast. Although sometimes seen as an under-developed off-site manufactured solution, the semi-precast design philosophy brings enormous improvement to cost and construction efficiency.

The semi-precast approach aims to deliver solutions fully compliant with the operational design requirement. The ideal configuration is not adapted to prefabrication. Whereas we will identify cost and time saving opportunities during the design development phase, we can adapt to the most precise configurations for operational accuracy. In principle, any structure imagined in in-situ concrete can be delivered in semi-precast. Approving Authority confidence is engendered by implementing designs which cannot be disproved by failure to comply in any respect with the specified codes and standards, whether national, international or customer specific. We place wet concrete against hard concrete, the way it’s always been done. The difference is that some of the concrete was manufactured elsewhere and the location of joints and interfaces are unconventional. Regardless, the integrity of joints and interfaces remains uncompromised and verified by design.

The Benefit of Prefabrication

We complete the difficult parts of construction in our factory, under ideal conditions and under quality supervision. Features including pipe-fittings, nibs, corbels, launder-channels, formwork attachments and stability-footings (among others) are eliminated from the site works. Products are delivered to site on a just-in-time basis then taken from the delivery vehicle to their service position in one simple operation without fuss or temporary propping. Small crews achieve amazing productivity by following simple steps and using well designed components and delivery systems.

Tolerance

Precast concrete units can weight in excess of 20 tonnes. Under normal manufacturing tolerances, it could be very difficult to ensure the precision required to maintain accurate alignment and watertight fit. The in-situ joint provides a transition between elements which ensures a complete and perfect fit (in it’s liquid phase) and a completely ‘relaxed’ structure at introduction to service. We don’t stress pieces into alignment or position. The design assumptions are fully realised.

Waterproofing Integrity

At every interface a scabbled surface is prepared. In addition, a smooth dense slot is preserved for the application of hydrophilic strip. This provides ongoing self-healing capability in service. We use only one hydrophilic product; Denso Hydrotite. Hydrotite is resilient to inflation prior to encasement in concrete. It can compress against the surrounding concrete with a pressure of up to 3MPa on contact with water and has been approved by Tokyo Underground for design life up to 100 years. It is also DWI and Materials in Contact approved for potable water applications in the UK. That’s 100 years to first significant maintenance of the structure – no compromise. Sealants used at the mechanical interfaces of traditional precast concrete tanking structures rarely have a service life in excess of 20 years. These features are particularly relevant to storm attenuation, storage, treatment and basement applications,

Structural Continuity

Although relatively short, the in-situ joint is used to enable two-way bending of the structure. This capacity is not available using any other precast approach. Reinforcement lap lengths are designed on a bond-stress basis to ensure full capacity in smaller spaces. Even the interface between the in-situ concrete stitch and the precast unit is designed for the same crack-width control as the body of the structure. This ensures that all elements of the structure provide the minimum standard of waterproofing integrity and full compliance with concrete structures design standards.

By bending in both orthogonal directions, structures are thinner, lighter, economical, require less transport, less craneage and have a lower carbon cost.

Carbon

Our particular concrete mix design delivers very high early strength for efficient production, typically, 25 Newtons at 16 hours. This ensures maximum safety and maximum value by extracting products daily. We use very high concentrations of GGBS (66%) which in conjunction with other energy and carbon saving measures has reduced our carbon cost from 278kg/tonne of concrete manufactured to 182kg/tonne. To ensure the high early strengths despite the use of GGBS we use thermal activation. By adding mixing water at up to 80°C the disadvantage of slow strength development of GGBS is eliminated.

Sulphate Resistance

High levels of GGBS when used in conjunction with limestone cement and limestone powders (for self-compacting behaviour) produce a design chemical resistance class DC4. That’s sulphate resistant concrete at no additional cost.

Value

The precast unit is delivered to site with projecting reinforcement often from five of it’s six faces. All components are 3D modelled prior to manufacture and assembled in model-space prior to fabrication. This eliminates the risk of clashing reinforcement and disruption to programme. Projecting reinforcement leaves very few bars to be placed on site.

Typically the vertical in-situ stitches represent 30% of the volume of the perimeter and internal walls. While precast concrete products are relatively expensive (although value-adding), the concrete used in the joints is locally sourced readymix at approximately £40 per tonne.

The formwork required is very light. Shuttering ply facing with vertical stiffeners is locked against the structure using steel braces and MKK cone anchors. The advantage in this low cost approach is that the formwork is torsionally flexible adapting easily to the surfaces on which they bear. Smooth transitions and tight interfaces are achieved. Through-ties are completely eliminated. These are often a problematic feature of conventional in-situ works.

Length of Joints

The number and length of joints in our solutions are often questioned. Our industry sees joints as the most problematic elements of waterproof concrete construction – more joints, more risk. The rebuttal is that it’s not the number of joints you fear, but the distance between them. Traditional construction methods utilise joints at 6m – 10m centres. Thermal and drying shrinkage accumulate over these lengths and are concentrated at a single interface. The precast unit has long completed its shrinkage when placed on site therefore the shrinkage to be addressed is that occurring over only 500mm. In addition, each interface has the benefit of a factory prepared scabble, reinforcement continuity designed to the higher standards for crack-width control and a self-healing strip at each end. The semi-precast interface is subject to only between 5% and 10% of the movement occurring at conventional joint. As a result, it is significantly better preforming than conventional concrete in this respect.

Rate of Construction

Semi-precast structures are typically completed in 60% to 40% of the time taken to deliver conventional structures. This is where the value lies, both in terms of reduced preliminaries and hugely increased productivity. During the conventionally difficult construction of vertical and suspended works, equivalent productivity per person on site is ten times greater.

For more information please call +44 (0) 1279 423303, email enquiries@flicarlow.com or visit www.flicarlow.com

Cold-applied liquid waterproofing specialist, Kemper System, has helped to preserve a grade II listed building thanks to its Stratex warm roof and Kemperol liquid roofing systems.

Because of the unusual design of St Thomas More Church in the Sheldon area of Birmingham, architects Wood Goldstraw Yorath worked in close consultation with Kemper System to enhance the waterproofing performance by addressing leaks and U/V damage to the existing substrate, whilst also improving drainage and reducing the risk of standing water on the roof.

The structure of the building with its many glass and concrete terraces, saw Kemper System’s Stratex tapered warm roof system being specified along with their solvent-free and odourless Kemperol 2K-PUR waterproofing membrane to refurbish the church’s failing asphalt roof.

The technical team at Kemper System also devised a series of drainage channels to address the volume of standing water on the roof, whereby excess water would be caught and drained off the building.

Contractors, Alliance Technical Services Ltd, a specialist conservation company, not only worked to recover the roof with Kemper’s Stratex warm roof system, but also installed new glazing to the central ribs and high level roof windows, fitted an external downpipe and drainage, and completed concrete repairs and concrete rib replacements.

For the recovering of the roofs with the Kemper designed system, operatives removed the existing chippings on the roof ready to clean and prime the asphalt substrate, and installed a hard top tapered Kempertherm PIR insulation board. This was adhered to each terrace section in such a way to create channels behind and either side of each piece of insulation.

As primarily structural engineers, Alliance Technical Services Ltd undertook thorough product and application training at Kemper System HQ in Warrington before installing the Kemperol 2K-PUR system, to familiarise themselves with the liquid waterproofing product application.

Derek Lowe, Managing Director at Alliance Technical Services Ltd, said: “This was a particularly interesting project for us as the church required remedial works to the concrete whilst also installing an alternative waterproofing solution to ensure the graded building remained watertight. The Kemperol 2K-PUR liquid applied waterproofing system was an ideal solution to work around the complicated structure of the building with its many terraces, outlets and joints. These formally weak areas were able to be fully waterproofed in one seamless, easy application.

“We undertook excellent training at Kemper’s headquarters to ensure we were able to apply the system effectively and efficiently. Thanks to the durability of the Kemperol 2K-PUR waterproofing system, the church’s heritage has been protected and can continue to be enjoyed by its many visitors.”

Technical manager at Kemper System, Ross Smith, added: “This interesting project presented design, specification and installation challenges which were easily solved thanks to versatile qualities of the Kemperol membrane.

“The wet-on-wet, cold applied liquid was the perfect solution to ensure a quick and easy installation, yet providing the reassurance of a sound, waterproof solution for many years to come. Its odourless, solvent-free qualities meant the refurbishment works created little disruption to local residents or those using the church.”

Added to Historic England’s ‘At Risk’ register in 2015, the Roman Catholic Church of St Thomas More was designed by renowned architect, Richard Gilbert Scott – who also designed the Guildhall’s West Wing and Art Gallery – with stained glass by John Chrestien.

For more information please visit www.kempersystem.co.uk.

Aggregate Industries’ Lytacrete solution was the product of choice when it came to helping to introduce an additional floor mid-construction at a new seven story upmarket apartment scheme in Southampton.

Located on Albert Road South, Southampton, the luxury apartment block was originally conceived as a six story scheme. Part-way through construction, plans were redesigned to include an additional floor – creating 20 apartments (7 one bedroom, 12 two bedroom and 1 three bedroom) for the area.

The challenge for Wright Investments was to include another floor without overloading the existing structure that was already in place – no easy feat. However, fortunately this was made possible with the help of Aggregate Industries who suggested Lytacrete – a specialist lightweight solution – in place of conventional weighty concrete.

Helping to revolutionise modern construction, Lytacrete concrete, which is formed using Lytag secondary aggregate, can be up to 50 per cent lighter than traditional comparable materials.
As such, by using Lytacrete, Wright Investments will be able to reduce the dead load of the construction by approximately 7620kN over normal weight concrete whilst maintaining its structural integrity. Crucially for the project, this has enabled reduced size columns, beams and slabs, allowing greater room the developers to add the additional required floor.

Steve Curley from Aggregate Industries comments: “Changing the original design plan mid-way through construction is common, but can present a series of challenges for the contractor. Although there were a number of traditional alternatives available, the use of Lytacrete eliminated the need for expensive re-structuring works to support an additional floor, which most importantly helped keep the project to budget and schedule.”

In production for more than 50 years, Lytag secondary aggregate is made using innovative technology which transforms fly ash into small pellets which are then heated to 1,100°C. The pellets formed are rounded in shape and range in size from 14 mm down to fines and can be used as a superior, consistent, lightweight aggregate.

In total, 420m3 of Lytacrete was supplied for the completion of 7 storeys in the Albert Road South apartment scheme, due for completion in 2018.

For more information on Lytag call 01904 727922 or visit www.lytag.com

Creating flawless brick-faced soffits and lintels has now become much simpler and quicker, thanks to a new lightweight stainless steel based system developed by two industry-leading companies – brick support specialist Ancon Building Products and Ibstock Kevington –national manufacturer of brickwork and masonry special shapes and prefabricated components.

The new Nexus® system combines a specially developed Ibstock Kevington lightweight brick-faced steel unit with Ancon’s tried and tested MDC stainless steel bracket angle support system. The system offers contractors easier handling coupled with maximum adjustability, both vertically and horizontally, for quick and simple alignment on site.

The new system offers considerable benefits over traditional cast concrete alternatives – cutting weight by more than half, which in most cases will allow the brick-faced units to be installed without specialist lifting equipment, and significant savings in installation time – making it particularly appropriate for fast-track or time-limited projects.

Individual Nexus® units are designed and prefabricated off-site to suit different soffit dimensions, even modern deep soffits, so there is no cutting required on-site. They are simply offered up to the pre-fixed and pre-drilled Ancon MDC support system and then bolted into position using T-head bolts. The quality design allows units to be simply adjusted for perfect alignment and, once in position, all that is left is for the brick facing to be pointed for a seamless match with the main brickwork.

Nexus units can be fabricated using virtually any brick or masonry with the chosen product being specially selected and precision cut, generally from the same batch as the main façade to ensure a perfect visual match. Various brick patterns can also be specified to match individual project designs and styles.

All system components are of the highest quality, and engineered for economy and durability, with slips permanently bonded to the high grade stainless steel Nexus system using a BBA accredited bonding system. Nexus has been independently tested for long term durability by Lucideon, the independent global experts in materials testing, analysis and consultancy.

Ibstock Kevington Sales Director, Warren Dean said “Nexus® is an exciting new development that brings together the combined experience and expertise of two major companies – each market leaders in their own area. The advanced design will not only make it easier and quicker to specify and install modern brick-faced soffit and lintel features in a range of different building applications, but the two-part design means it will be far easier to achieve perfect alignment with the main brickwork façade.”

Further details and technical specifications for the Nexus® system are available in a new 4-page brochure, available to download from www.ancon.co.uk/Nexus.