Question

The cement concrete from which entrained air and excess water is removed after placing it in position is called.

• A. Lightweight concrete
• B. Pre-stressed concrete
• C. Air entrained concrete
• D. vaccum concrete

Answer 1

The correct option is D vaccum concrete

Vaccum Concrete - Concrete with water content more than the required quantity is poured into the formwork. The excess water is then removed out with the help of a vaccum pump without waiting for concrete to undergo setting.
$\cdot$ It improves the compressive and tensile strength.
$\cdot$ Make concrete to resist abrasion and impact.
$\cdot$ Reduce the shrinkage
$\cdot$ Make low permeable and higher durable.
$\cdot$ Lightweight concrete -Concrete that have a density lesser than $1920\frac{kg}{m^3}$ will be categorized as light weight concrete. the use of lightweight aggregates in concrete design will give us lightweight concrete. It is used as the construction of building blocks.
$\cdot$ Air entrained Concrete - these are concrete types into which air is intentionally entrained for an amount of $3$ to $6$ % of concrete. The air entrainment in the concrete is achieved by the addition of foams or gas-foaming agents.