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Air-entrained concrete is made by adding a detergent (an air-entraining admixture) to stabilize air bubbles trapped during mixing. In fresh concrete, the air bubbles reduce the water demand of the concrete and make the mix stickier, which helps to reduce segregation and reduces bleeding when air content is around 3%. If the air content is higher, the increased stickiness makes the concrete more difficult to finish, and the bubbles can lead to blisters and delaminations on steel-troweled surfaces. As the concrete hardens, the cement paste sets around these bubbles, leaving bubble-shaped voids in the hardened concrete.