Concrete Flashcards
is a construction material made from a mixture of water, aggregates, Portland cement and in some cases chemical admixtures.
Concrete
What is the Composition of Concrete
Water + Cement + Aggregate + Air
What Condition of Water needs to be used in mixing
Water that must be used is good water which means as good enough to drink, it is free from trash, organic matter or excessive minerals/ chemicals.
It is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties.
Cement
It occupy 60% to 80% of the volume of concrete. Sand, gravel, crushed stone are primary used that is free from silt and/or organic matter.
Aggregate
It helps to control amount of air that modifies the elastic properties of concrete regarding workability, segregation, bleeding and finishing quality and increase durability of concrete.
Air-entraining admixture
It enables a given fresh concrete mix to have higher workability without increasing the water content which results in faster rate concrete placement, easy placement in relatively poorly accessible locations without vibration and reduction in cement content.
Water reducing admixture
It speeds up the initial set of concrete.
Accelerating admixture or Accelerators
It was used to delay the setting of cement and hardening.
Retarding admixture or Retarders
It is a type of concrete mix that is prepared using approximate proportions of ingredients rather than precise measurements by weight or volume. It is often used in small-scale construction projects or in situations where detailed testing and quality control may not be critical.
NOMINAL MIX
The nominal mixes of fixed cement-aggregate ratio (by volume) differ largely in strength and lead to under- or over-rich mixes. Due to this, at least compressive strength is contained in various specifications.
STANDARD MIX
