Welcome to Imerys Performance Additives Division

Concrete

Concrete Imerys minerals for reduced porosity and cracking in concrete

Imerys minerals make excellent multifunctional additives in concrete where they reduce porosity and efflorescence, increase cured compressive strength and viscosity control, and prevent cracking.

Metakaolin

Metakaolin is manufactured through the calcination of kaolin to form an amorphous pozzolanic white mineral additive for use in cement based products. The pozzolanic reactivity of metakaolin (French standard NF P18-513) refers to is its ability to react with calcium hydroxide in cement based products. Metakaolin is also included in the European concrete standard for France EN 206-1 as an additive to substitute cement.

Imerys metakaolin provides multiple benefits:

  • Reduced 'cover'

Metakaolin reduces the porosity of concrete allowing a reduction in the 'cover' of concrete needed to protect reinforcing bars from corrosion. It is ideal for road and marine structures exposed to corrosive salts.

  • Higher cured compressive strength

Where high strength concrete is required, Imerys metakaolin increases cured compressive strength of concrete and speeds up curing and early strength development, making it ideal for applications where high strength is required quickly such as airport aprons.

  • Efflorescence

Imerys metakaolin reduces efflorescence by reducing the porosity of the concrete and reacting with lime salts before they reach the concrete surface.

  • Viscosity

Metakaolin can also be used to modify the handling properties of wet concrete, particularly benefiting the viscosity profile and reducing the tendency to bleed, making leveling and achieving a good surface finish easier.

  • Lime prevention in GFRC

In GFRC, metakaolin is used to prevent lime formation which compromises connections between the cement matrix and the GF fibers causing breakdown of pieces.

  • Improved mechanical properties in Portland cement-based concrete

Premium pozzolanic metakaolin products provide improved strength, durability, workability and finish in Portland cement-based concrete.

We recommend our Argical-M product range for concrete.

Wollastonite

Wollastonite is a natural fiber which has a synergetic effect with metakaolin and can prevent or reduce crack formation in concrete.

Imerys wollastonite:

  • Improves early age strength
  • Reduces micro-cracking
  • Increases flexural and compressive strength
  • Provides superior ductility and fracture toughness
  • Provides greater shrinkage resistance
  • Is an excellent extension to macro fibers and textiles o provides ease of mixing and construction
  • Is a sustainable replacement/reinforcement on a micro scale
  • Is a naturally occurring, safe mineral additive

We recommend our Nyad® G product for concrete applications.

SEM photographs of wollastonite
SEM photographs of wollastonite

In comparison with a control mixture, Nyad® G reduces the length of cracks during plastic shrinkage by a factor of 2, area of cracks by a factor of 3, density of cracks by a factor of 2 and width of cracks by a factor of 1.

We offer a full range of bespoke formulation and technical and process support services to help you match the right mineral grade to your application requirement.

Please contact us, we will be only too happy to help

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