Which more benefit and economy?
1- Adding fly ash or steel slag with clinker in the kiln in cement manufacture
2- Adding fly ash or steel slag powder as additives in concrete or mortar
Dear Dr Ashraf Heniegal,
As you know, all precast concrete producers can now use a group of materials called “fly ash” to improve the quality and durability of their products. Fly ash improves concrete’s workability, pumpability, cohesiveness, finish, ultimate strength, and durability as well as solves many problems experienced with concrete today–and all for less cost. Fly ash, however, must be used with care. Without adequate knowledge of its use and taking proper precautions, problems can result in mixing, setting time, strength development, and durability.
The concrete containing steel slag powder usually has better durability and later strength development, but longer setting time and lower early strength compared with the Portland cement concrete. The main problem is the low hydration of this powder, and many approaches have been proposed to solve the problem.
Regards,
Dear Dr Ashraf Heniegal,
As you know, all precast concrete producers can now use a group of materials called “fly ash” to improve the quality and durability of their products. Fly ash improves concrete’s workability, pumpability, cohesiveness, finish, ultimate strength, and durability as well as solves many problems experienced with concrete today–and all for less cost. Fly ash, however, must be used with care. Without adequate knowledge of its use and taking proper precautions, problems can result in mixing, setting time, strength development, and durability.
The concrete containing steel slag powder usually has better durability and later strength development, but longer setting time and lower early strength compared with the Portland cement concrete. The main problem is the low hydration of this powder, and many approaches have been proposed to solve the problem.
Regards,
These materials are added as pozzolanic materials . So, the addition of these materials as additives are more benefits and under control .The addition of these materials in cement manufacturing may be lead for undesirable effects in the rotary kilns such as viscosity variation of the mixed raw materials .This variation affect grinding process and other characteristics .
with my best wishes
Dear,
i am suggestion fly ash, which will improve the concrete’s strength, workability and reduces the permeability. ultimately it improves the durability as well as resolve the problems of economy.
Fly ash and steel slag are by-products from certain processes. This creates the environmental problems. Using this materials in manufacturing of cement and production of concrete-mortar gives benefits two ways i.e. it preserves and protects the environment by saving the natural resources, reduces the waste materials and increases the durability of concrete-mortar
Jabbar abbas Jaber and Khalid Mohammed Breesem answers are good and constantly I ensure to use the fly ash as additive to concrete mixes to a certain percentage.
It is rather difficult to differentiate which cement replacement material (CRM) would be more beneficial, also beneficial relative to what? As many others mentioned, there can be several benefits from incorporating CRM in the mix, such as long term performance (strength and durability) but also drawbacks, i.e. decelerated hydration and lower strength at early ages. Generally, in the UK most concretes nowadays contain fa and ggbs with usual practice at 30% and 50% replacement levels respectively. Especially, for fa, for replacement levels above 30% problems may arise, whilst for mass concrete 70%+ ggbs may be used. There are numerous resources for the effects of replacement on concrete properties. Arguably, the greatest benefit is the reduction of carbon footprint of concrete, thus the better CRM might be that which can be used at a higher percentage in concrete for a specific application (taking also into account the availability of material). As far as the economical aspect is concern, prices for ggbs can fluctuate quite substantially based on steel production, and similarly for fa, which depends on availability. Hence, the answer to the second question could be considered as location specific. Hope this is of assistance.
The Most beneficial addition depends on two main factors;
1- the availability of the two materials in cheapest way.
2- the characteristics of concrete mixes required.
- Badges
- Science topic