Coal Ash

CEMGUARD® Fly Ash is a pozzolanic material, captured in electro-static precipitators as a by-product from coal-fired thermal power stations. It consists of small, hard and spherical particles rich in silica (glass) and alumina, with pozzolanic properties. It complements Portland cement upon hydration by reacting with free lime (calcium hydroxide) to form an additional durable binder, namely calcium silicate hydrate. The spherical particles also have a ‘ball-bearing’ effect, which allows concrete to be produced using less water.
CEMGUARD® Fly Ash is subject to processing quality control to regulate its fineness (particle size and distribution, shape and glass content) and unburnt carbon (loss-on-ignition), thus giving quality-assured material which is consistent, predictable and suitable for varied applications. We are working towards CE Marking for CEMGUARD® Fly Ash.
CEMGUARD® Fly Ash is mainly used as a partial replacement of cement in concrete, and has unique properties that benefit both fresh and hardened concrete. Its key advantages include reduced heat of hydration, improved workability, enhanced durability and longer setting time. It can be effectively used where aggregates have poor grading and shape, resulting in bleeding and segregation. It is also suited for mass concrete applications, and in hot and aggressive environments where early-age thermal cracking and durability are major concerns. General replacement of cement with CEMGUARD® Fly Ash in concrete can be 15-35% by weight for normal structures. However, for special structures such as dams, the replacement levels can increase up to 70%. The service life of structures using CEMGUARD® Fly Ash is enhanced by more than 100% on account of superior durability of concrete. Fly Ash use in concrete qualifies for credit under the U.S. Green Building Council's popular LEED® rating system for sustainable construction.