What are the agents used as air entraining admixture?
What are the agents used as air entraining admixture?
Air entraining admixture usually contains rosin resin, alkyl sulfonate, aliphatic alcohol sulfonate, protein salt and petroleum sulfonate, among which rosin resin is widely used.
Under what condition is an air entraining agent needed?
The air entraining agent is needed when the weather is cold, since it has a good ability to combat freeze-thaw damage. When the concrete is mixing, air bubbles naturally entrapped giving the freezing water enough space to expand and eat away concrete.
What is the function of air entraining agents in cement?
Air-Entraining Admixtures and What They Do: Air-entraining admixtures facilitate the development of a system of microscopic air bubbles within concrete during mixing. They increase the freeze-thaw durability of concrete, increase resistance to scaling caused by deicing chemicals, and improve workability.
Which one is not used as air entraining agent?
Which one is not used as air entraining agents? Explanation: Natural resins, fats, oils are used as air entraining agents not alumina.
What is air entrainment made of?
Air entrainment, or free-surface aeration, is defined as the entrainment/entrapment of un-dissolved air bubbles and air pockets that are carried away within the flowing fluid. The resulting air–water mixture consists of both air packets within water and water droplets surrounded by air.
What is superplasticizer made of?
Traditional plasticizers are lignosulphonates as their sodium salt. Superplasticizers are synthetic polymers. Compounds used as superplasticizers include sulfonated naphthalene formaldehyde condensate, sulfonated melamine formaldehyde condensate, acetone formaldehyde condensate and polycarboxylate ethers.
Can you power trowel air entrained concrete?
Hard troweling is also not recommended for air-entrained concrete for several reasons. The primary reason is densification. Densification pushes air out of the surface, leading to a decrease in the air content. This increases the probability of freeze-thaw damage and deicer-scaling damage.
When should air entrainment be used in concrete?
It is beneficial to use air entrained concrete when placing concrete in areas with freeze-thaw conditions. Freeze-thaw conditions occur when the temperature of an environment fluctuates between above freezing temperatures and below freezing temperatures.
Why are Superplasticizers used in concrete?
Superplasticizers (SPs), also known as high range water reducers, are additives used in making high strength concrete. Plasticizers are chemical compounds that enable the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more.
What is Vinsol resin?
Vinsol® resin is a dark reddish-brown, high melting, thermoplastic natural resin extracted from pinewood stumps and refined through a special process. Vinsol resin is produced exclusively by Pinova, Inc. in Brunswick, Georgia, USA.
What is the percentage of air by volume in air-entraining cement?
03-04 %
Explanation: Entertainment of air also improves work ability and durability. It is recommended that air contents should be 03-04 % by volume.