Superplasticizers (SPs) are also known as high- range water reducers that are additive used in making high strength concrete. Plasticizers are chemical compounds that enable the production of concrete with approximately 15% less water content. Superplasticizers allow a 30% or more reduction in water content.
It is chemical admixtures that are added to the concrete to improve their flowing ability, they help to reduce the amount of water in the concrete and to improve the strength and durability of concretes.
They achieve a reduction in water content without loss of workability.
Here we will learn about Superplasticizer, types of superplasticizers, advantages & disadvantages of superplasticizer.
Introduction to superplasticizer:
Superplasticizer is also known as high range water reducers, it produces extreme workability flowing concrete.
It has the efficiency of dispersing fine-grained particles like cement, fly ash, ground granulated blast furnace slag, and silica.
They increase slump for ease of placement, creates the denser and more durable concrete.
Types of Superplasticizer:
1.Sulphonated Melamine – Formaldehyde Condensates (SME):
Sulfonated melamine formaldehyde condensates are often preferred superplasticizers in the precast industry because they do not dim the cement setting.
2.Sulphonated Naphthalene Formaldehyde Condensates (SNF):
Sulphonated Naphthalene Formaldehyde is a high range water reducer.
3.Modified Lignosulphonates (MLS):
Lignosulfonates or sulfonated lignins are water-soluble anionic polyelectrolyte polymers, they are byproducts of wood pulp using sulfite pulping.
Polycarboxylate superplasticizer- Carboxylated Acrylic-Ester Co-polymers (CAEC):
Polycarboxylate superplastics, also known as high-grade water reducers, they are chemicals that are used where well-dispersed particle suspensions are required.
These polymers are used as dispersants to avoid particle aggregation to improve the flow characteristics or rheology of solid applications such as suspensions.
Superplasticizers are mainly used in pumping concrete, casting heavily reinforced members and precast elements of concrete.
Advantages of Superplasticizer:
1. Superplasticizers reduces the water content.
2. It reduces the cement content.
3. Also, increases the workability of concrete.
4. It reduces the permeability of concrete.
5. They are easy to placement.
6. Increased long terms.
7. It develops the early strength.
Disadvantages of Superplasticizer:
1. Slump loss are greater than conventional concrete.
2. Addition cost for admixture.
3. They increase air entrainment in concrete.
Uses of Superplasticizer:
- Superplasticizers disperses cement provides plastics with higher initial strength than free concrete with the same W/C ratio.
- Set retards are adductors that cause delays in the setting time of wet concrete mixes.
- Air entrances are added to solid forms millions of small non-coalescing air bubbles, thus formed are deliberate ones are called perforated air.
Also read: Papercrete, Geosynthetics, Geotextile & Admixture
A high-performance superplasticizer can be prepared by using bio-polymer chitosan as a raw material by chemical performance.
This greatly improves the strength of high strength concrete with the presence of silica fume.