SUPPLEMENTARY CEMENTITIOUS MATERIALS

In the construction industry, Supplementary Cementitious Materials (SCMs) used as construction and building materials are added to concrete mixtures for various reasons including improving durability, reducing permeability, increasing the strength of concrete, or influencing other concrete properties.

SCMs are added to the concrete as a partial replacement for Portland cement. Provide strength with the help of construction and building materials.

Supplementary Cementitious Materials are typical byproducts of construction industrial processes and their use can contribute to environmental and energy conservation practices in the construction industry.

1. Fly Ash

Fly ash used in concrete

The use of fly ash in portland cement concrete (PCC) has many benefits to improve concrete performance in cementation. Fly ash use in concrete improves the workability of plastic concrete and the strength and durability of hardened concrete.

Fly Ash directly works with the construction building materials to improve the building strength and stability also its effect on the construction cost as well.

The resulting benefits are as follows:

• Improved workability
• Decreased water demand
• Reduced heat of hydration
• Increased ultimate strength
• Reduced permeability
• Improved durability

2. Ground Granulated Blast Furnace Slag

What is Ground Granulated Blast Furnace Slag?

A composite mineral binder was prepared by mixing ground granulate blast furnace slag (GGBS) and steel slag. its ratio of GGBS/steel slag is 1:1 or 3:2 by mass.

Ground Granulated Blast furnace Slag (GGBS) is a material whose main use is in concrete and is a by-product of the blast furnaces used to make iron.

The process involves cooling the slag through high-pressure water jets, this leads to the formation of granular particles. The granulated slag is further processed by drying and then grinding in a vertical roller mill or rotating ball mill or roller press to a very fine powder, which is called GGBS.

Ground Granulated Blast Furnace (GGBS) inherent chemistry gives it several advantages being environment-friendly, it offers:

• Reducing thermal cracks due to lower heat of hydration
• High resistance to attack by sulfates and other chemicals (see factsheet)
• Better workability, making placing and compaction easier
• Improved cohesion
• High resistance to chloride ingress thus reducing the risk of steel reinforcement corrosion
• Higher long-term strength
• Higher flexural strength
• Improved durability and hydration.

JSW Cement is the company that manufactures and supply of the Ground Granulated Blast Furnace slag.

Also read: Types of structure in civil engineering

3. Silica Fume

What is Silica Fume?

Silica fume, is a by-product of the ferrosilicon industry. it is a very reactive pozzolan.

Concrete containing silica fume can have very high strength and can be very durable. Silica fume is available from suppliers of concrete admixtures in the construction world.

It may be added directly to concrete as an individual ingredient or in a blend of portland cement and silica fume.

The Silica Fume Association (SFA) was formed in 1998 to assist the producers of silica fume in promoting its usage in concrete.

Uses of Silica fume

• Highway bridges, parking decks, marine structures, and bridge deck overlays are subject to constant deterioration caused by rebar corrosion current, abrasion, and chemical attacks. 
• Silica fume will protect concrete against deicing salts, seawater, traffic, and heavy impact. 

Key benefits include:

• Very low permeability to chloride and water intrusion
• High electrical resistivity (20 to 100 times greater compared to ordinary concrete)
• Increased abrasion and impact resistance on decks, floors, overlays, and vertical structures
• Superior resistance to chemical attack from chlorides, acids, nitrates, and sulfates

Also read: how to calculate the number of bricks, sand and cement in brick masounary work?

4. Calcium Carbonate

Calcium carbonate (CaCO₃) powder is a common filler in many industries, including in the cement industry where it is used in the production process. 

Carbon-negative Precipitated Calcium Carbonate (PCC), produced from CO₂ emissions,

It can be used as a means of offsetting the carbon footprint of cement production while potentially providing benefits to cement hydration, workability, durability, and strength.

Types of calcium carbonate

• Natural calcium carbonate: natural CaCO₃ can be obtained from calcite and aragonite in mines. Waste CaCO₃ powder is produced as a byproduct in stone sawing factories with a typical particle size of 0.5 – 1 µm. CaCO₃ powder can be produced from the reaction of carbon dioxide with calcium hydroxide: Ca(OH)₂ + CO₂ –> CaCO_3.
• Precipitated calcium carbonate: the precipitated CaCO₃ has a high purity (98 – 99%) and can be produced with a specific crystal morphology.

Calcium chloride provides other benefits as well:

• Improves workability
• less water is required
• Improves strength of air-entrained concrete
• Reduces bleeding

Also read: What is structural engineering, what is the scope of structural enigneering?

4. Natural Pozzolans (calcined clays, shale, and metakaolin)

Natural Pozzolans (Calcined Clay, Calcined Shale & Metakaolin) as Supplementary Cementitious Materials (SCMs)

Natural Pozzolans are used in a vast range in partial substitution of cement in concrete and mortar.

Its pozzolanic behavior improves the performance of concrete and mortar strength and durability.

The minimization of carbon dioxide emissions in the cement industry is due to the increasing involvement of NP(Natural Pozzolans). It’s helpful to achieve the goal of reducing global carbon emissions.

The different proportions of NP as partial substitute results in enhancing the comp. strength, water absorption, sorptivity etcetera, and it gives the resistance to the structure of mortar and concrete to the action of the harmful solution.

Conclusion

We can learn about the 4 diff types of byproducts used in the concrete to increase the concrete stability, strength, and performance as a part of the Supplementary Cementitious Materials. The most common material is fly ash and Ground Granulated Blast Furnace Slag (GGBS) widely used in concrete. Also, silica fume is important for larger structures in the construction industry. PIGSO Learning always helping you to improve your research interest, skill, and knowledge in the construction industry.