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clayshield

Foundation heave protection

Clayshield

The safe, sure way to provide foundation protection Clayshield is the proven solution to protecting foundations against the effects of clay heave and soil movement on the side of deep trench foundations or the side and underside of ground beams.

The Clayshield range includes solid Clayshield compressible fill, for use in deep trench foundations and to the side of ground beams; Clayshield Prestige, which incorporates a protective membrane; Castellated Clayshield, used to protect the underside of ground beams; Pile Collars and the innovative Clayshield Fixing Tool, which enables groundworkers to secure the protective boards in place while remaining outside the trench.

All Clayshield boards are manufactured from expanded polystyrene (EPS), a lightweight, closed cell system with excellent compressibility. The cells in the board contain air, which compress under the pressure of expanding, wet clay soils, acting as a buffer between the ground and the foundation.

Clayshield has a distinctive blue colouring allowing it to be easily identified on site. Clayshield Prestige - This latest innovation improves yet further the resilience of Clayshield during the pouring of concrete foundations by incorporating a protective membrane that enables the boards to resist the impact of the liquid concrete, ensuring they remain firmly in position and also acts as a slip membrane. The laminated layer overlaps the top edge of the board to allow temporary pinning at the top of the trench prior to final fixing to the trench wall.

The Clayshield range is available through a network of insulation distributors and builders merchants throughout the UK.

Application
Position
Clayshield Product
Deep trench foundations
Side
Clayshield / Clayshield Prestige
Ground beams
Side / Underside
Clayshield
Ground beams
Underside
Castellated Clayshield / Clayshield
Piles
Encasement
Pile Collars

Applications

Clayshield is suitable for use in domestic, commercial and industrial foundations in heavy clay soils.

Certification

The solid Clayshield boards have been awarded BBA certificate No: 92/2854. The products are manufactured under a quality management system to BS EN ISO 9001:2000.

Sustainability

The environmental integrity of Clayshield is exceptional:

  • Zero ODP (Ozone Depletion Potential)
  • Zero GWP (Global Warming Potential)
  • CFC, HFC and HCFC free
  • Contains recycled content
  • Boards are 100% recyclable

Durability

The compressible fill properties of Clayshield will remain effective for the life of the building. EPS is a dimensionally stable product, which is resistant to attack from bacteria, mould and fungi, and will not provide nutrient value for insects or vermin. It is also nontoxic and non-irritant. EPS does not bio-degrade and is unaffected by extremes in temperature.

Specification Clause

Clayshield should be described in specifications as: The foundation protection material shall be Clayshield (Prestige), ____mm thick, manufactured to BS EN 13163:2001 by Springvale EPS Ltd. BBA approved (certificate no.92/2854) expanded polystyrene boards to be installed according to Springvale’s instructions. Refer to NBS Plus, clause E20/185 (Compressible Board Sub Structure Formwork) for further information.

Moisture Resistance

EPS is resistant to water and can be installed in wet conditions without compromising its performance or longevity.

NHBC Recommendations

The NHBC publish Technical Standards detailing the recommended protection for trenchfill and ground beam foundations in clay areas. The tables in this literature can be used to determine the required thickness of Clayshield to achieve these recommendations. The data on clay shrinkage potential in this brochure can be viewed in NHBC Standards 2007 but you can also contact the Springvale Technical Office for assistance and advice on foundation design.

Product information - Clayshield / Clayshield Prestige

  Clayshield Clayshield Prestige
Board Size (mm) 2400 x 1200 2400 x 1200
Thickness (mm) 50, 75, 100, 200, 300 50, 75, 100
Effective Depth Deep trenches up to 3m, ground beams up to 600mm
Colour Light blue Light blue with gridded grey laminate

Product information - Castellated Clayshield

 
Castellated Clayshield
Board Size (mm)
1200 lengths, in widths to suit the trench
Thickness (mm)
100, 150, 200, 250
Colour
Light blue

Pile Collars

Diameter (mm)
W (mm)
A (mm)
300
50-150
400-600
400
50-150
500-700
500
50-150
600-800
600
50-150
700-900

Illustrations:

Pile and beam foundation protected by Clayshield
Deep trench foundation protected by Clayshield

Once a site survey has been completed and the prevailing clay type identified, the Engineer can then determine the level and location of protection required for the foundations. Due consideration should be given to the location of trees and the characteristics of the ground beam. The tables below can be used to determine the required thickness of Clayshield to achieve NHBC recommendations. It is important to remember that Clayshield is designed to compress 50% in order to create the required void and therefore this should be allowed for in the overall thickness of Clayshield specified.

Required thickness of Clayshield or Clayshield Prestige installed at the side of ground beams and deep trench foundations

Shrinkage Potential
Plasticity Index (%)
NHBC Void Requirement (mm)
Clayshield / Prestige Thickness (mm)
High
40-60
35
75
Medium
20-40
25
50
Low
10-20
0
Not required

Required thickness of Clayshield board installed to the underside of ground beams

Shrinkage Potential
Plasticity Index (%)
NHBC Void Requirement (mm)
Clayshield / Prestige Thickness (mm)
High
40-60
150
300
Medium
20-40
100
200
Low
10-20
50
100
The thicknesses of Clayshield in each of the tables above are calculated to give a transmitted pressure through to the structure of 35kPa at 50% compression.

Required thickness of Castellated Clayshield installed to the underside of ground beams

Shrinkage Potential
NHBC Void Requirement (mm)
Castellated Clayshield Thickness (mm)
Transmitted Load (kPa)
High
150 250
26
Medium
100 150 or 200
35 or 23
Low
50 100
28
For the purposes of detailing on drawings, Clayheave requirements are often given as the void required under NHBC recommendations. This can be confused with the thickness of board required. Care should be taken to verify any detail where this could be misconstrued. Clayshield should not be used under floor slabs, please contact the Springvale technical office for futher advice.

Site Work

Handling and Storage

Packs of Clayshield are delivered to site wrapped in polythene. Store panels in original packaging under cover and protected from direct sunlight. Keep boards above ground level and out of contact with solvents and materials containing volatile organic compounds such as coal tar, pitch and creosote. Do not expose to naked flame or other ignition sources during storage or installation.

Health and Safety

The material is chemically inert and requires no special treatment. Springvale supply a patented fixing tool toavoid the need to enter a trench in order to fix Clayshield boards. This is in line with Health and Safety and CDM regulations 2007.

Installation Guide

In order to ensure the safety of the installer, Springvale recommend the use of the Clayshield Fixing Tool. This specially designed tool removes the risk involved when fixing Clayshield boards. The operator can operate the tool standing above/outside the trench, avoiding any need to enter the trench. Information on the Fixing Tool and a full installation guide can be downloaded from www.springvale.com or please contact our Technical Advisory Service on 0845 769 7452.

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