Generation Aggregates - PFA for grouting

Cheaper and easier to use than sand cement grouts, Pulverised Fuel Ash (PFA)grouts normally consist of PFA, Portland cement and water. They bring the environmental benefit of a reduced need for primary aggregates and high cement contents, meaning cost savings for customers, improved durability and reduced CO₂ emissions.

The self-hardening properties of PFA also allow for the production of low strength grouts containing only PFA and water.

PFA grouts have the ability to:

• reduce the permeability of the ground
• increase the shearing resistance and subsequent strength and durability of the ground
• fill inaccessible voids
• be used for mass infill and bridge infill

The benefits of PFA grouts include:

• reduced bleeding: typically less than 1%
• increased yield: typically 0.7 to 1.0 tonnes of PFA to 1.6 tonnes of a primary aggregate such as sand to produce a cubic metre of grout
• ease of use
• increased strength
• increased resistance to chemical attack
• delayed set – remains fluid for up to 4 hours

RWE Power International has supplied PFA for use in many successful grouting projects, including support for a viaduct carrying the busy Liverpool Street to Ipswich railway line in East London.