Which of these agents can be used to make the air entrained concrete?

discloses the use of a rosin (gum rosin, tall rosin, wood rosin) as an air-entraining agent for concrete, the resin having been reinforced with maleic anhydride and esterified with polyethylene glycol and subsequently saponified with KOH.

How do you entrain air in concrete?





HOW AIR ENTRAINING WORKS. Fortunately scientists came up with air entraining technology to beat the effects of the freeze-thaw. During the mixing process, constructors add special agents containing a type of detergent to the paste. They create air bubbles inside the concrete.

When an air entrainment agent is introduced into a concrete mix?

Air entraining admixture is usually introduced when it is desired to increase concrete workability without affecting much reduction in compressive strength. It is claimed that, the place-ability of an air entrained concrete having 7.5 cm slump is better than a non-air entrained concrete with a slump of 12.5 cm.

How do you reduce air entrained concrete?

Dusty coarse aggregate will decrease air content. Water softeners can increase or decrease water content depending on the air entrainment composition. Hot concrete temperatures may reduce air content by 25%, while cool concrete temperatures less than 75 degrees Fahrenheit can increase air content up to 40%.

What are air-entraining agents?

Air entraining agent or pore-forming agents are admixtures that are used to incorporate air into the concrete mix. They enhance the workability of concrete and improve resistance against salt scaling or freeze and thawing.

What is air entrained admixture?





Air entraining admixture refers to the admixture that entrains a large number of uniform, stable and closed tiny bubbles in the process of mixing concrete to reduce the segregation of concrete mixture, improve the workability, and also enhance anti-freeze ability and durability of concrete.

How much does air-entrained concrete cost?

So, the cost of an air-entrained 6-bag (564 lb) mix made using gravel coarse aggregate (1800 lb) and sand fine aggregate (1250 lb), as we previously mentioned, is about $75 per cubic yard even including the patriotic fly ash or ground granulated blast-furnace slag. The water is essentially free.

Which admixture produce microscopic air bubbles in concrete?

Air-entraining admixtures

Air-entraining admixtures are used to purposely introduce and stabilize microscopic air bubbles in concrete. Air- entrainment will dramatically improve the durability of concrete exposed to cycles of freezing and thawing (Fig. 6-2).

When should you not use air-entrained concrete?



4.1 Air-entraining agents should not be used in floors that are to have a dense, smooth, hard troweled surface. 6.2. 7 An air entraining agent should not be specified or used for concrete to be given a smooth, dense, hard-troweled finish because blistering or delamination may occur.

How do you increase air entrainment?

Water • Small quantities of household or industrial detergents in the water will increase the amount of entrained air. If hard water (well or quarry) is used to dilute AEA prior to batching, the air content will be reduced.

What is the difference between air entrainment and air entrapment?

When the bubbles are smaller than 0.04 inch, the air is called entrained; larger, and it’s called entrapped. Entrapped air voids are usually irregular in shape while smaller entrained air bubbles are spherical.

How do you calculate air content in concrete?



Air Content – Air content is calculated by subtracting the unit weight, ρ, from the theoretical unit weight, T, divided by the theoretical unit weight, T, multiplied by 100 as shown below.

What is concrete air content?

Concrete having a total air void content of about 6.5% seems optimal. A mix having 6.5% total air voids will have approximately 1.5% entrapped air voids and 5.0% entrained air voids.

What are the methods available for measuring the air content in fresh concrete?

Mainly there are three methods of measuring air contents of fresh concrete.



Pressure Method.

  • Gravimetric Method: …
  • Volumetric Method: …
  • Pressure Method:


How do you test for air entrainment in concrete?




Quote from Youtube video: Close the bleeder valve and pump air into the air chamber until the hand on the dial gauge is on the initial pressure line lightly tap to stabilize the gauge.

What percentage of air should be in concrete?

between 4% and 7%

Entrained air should fall between 4% and 7% of the concrete’s volume. For concrete that will be regularly exposed to freeze/thaw cycles, aim for 6%. Anything less than 4% would not have the durability needed to last through multiple winters. Be careful not to go overboard with air entrainment, however.

How do I check air content?

Method A outlines the principle of the test. A sample of concrete is placed in the cylinder of an air meter in three layers, each being fully compacted by hand or by vibration. The cylinder is filled level with the top. The cover, which has a sealed graduated cylinder fitted, is clamped to the cylinder.

What is the difference between air entrained and non air-entrained concrete?



The water content for an air-entrained mix will be 3 to 5 gallons per cubic yard less than for a non-air-entrained mix having the same slump. The sand content will also be less by about 90 to 125 pounds per cubic yard. As for climate, air-entrained concrete is recommended and used considerably in southern climates.

Is all concrete air entrained?

Air entraining was introduced in the 1930s and most modern concrete, especially if subjected to freezing temperatures, is air-entrained. The bubbles contribute to workability by acting as a sort of lubricant for all the aggregates and large sand particles in a concrete mix.

Do you vibrate air-entrained concrete?

Since air entrained concrete is more cohesive and workable than non-air entrained, there is not as much danger of segregation and air pockets. Accordingly, vibration need not be prolonged. As to appearance, air entrained concrete has an unusually creamy, fatty look.