1.0.0 Concrete Ingredients Flashcards
Air-entrained concrete
A concrete mixture with an added agent that creates millions of tiny air bubbles when water is added and the concrete is mixed.
This improves both the workability of the concrete and its resistance to freezing and thawing, but may also reduce the final strength of the concrete.
Bleed Water
A form of segregation in which some of the water in a mix tends to rise to the surface of freshly placed concrete.
Clinker
The material that is produced in a cement kiln after burning. Clinkers are dark, porous, nodules that are ground with a small amount of gypsum to make cement.
Compressive Strength
The measured resistance of a concrete specimen to axial loading, expressed as pounds per square inch (psi), of cross-sectional area; the maximum compressive stress that the concrete is capable of sustaining.
Cured Concrete
Concrete that has hardened and gained its structural strength.
Green Concrete
Concrete that has hardened but has not yet gained its structural strength.
Heat of hydration
The heat generated when portland cement is mixed with water. It is the result of an exothermic chemical reaction between cement and water. Generation of this heat raises the temperature of concrete.
Hydration
The catalytic action water has in transforming the chemicals in portland cement into a hard solid. The water interacts with the chemicals to form calcium silicate hydrate gel.
Mass concrete
Concrete used in dams, spill-ways, and other large structures. It is basically the same as normal concrete except that aggregate up to 6” or more in diameter is used. Admixtures such as water-reducing/water-retarding agents and pozzolans are widely used to decrease heat and cement content and to increase strength.
Plastic concrete
Newly mixed concrete that is in a semiliquid state and portable.
Post-stressed concrete
Concrete placed around steel reinforcement such as steel rods or cables that are isolated from contact with the concrete by encasement and/or a lubricant. After the concrete has cured, tension is applied to the rods or cables to provide great structural strength.
Pozzolans
Siliceous or siliceous-and-aluminous mineral admixtures that in themselves have little or no cementing property. Pozzolans are not cements, but when the particles are very fine and mixed with the calcium hydroxide in concrete and water, they behave like cement, and speed the setting and curing of concrete.
Pre-stressed concrete
Concrete that is placed around pre-tensioned reinforcement steel in a casting bed. When the concrete has cured, the casting bed is removed and the pre-stressed reinforcement applies compression to the concrete, which results in great structural strength. Pre-stressed concrete must never be cut without consulting a structural engineer.
Reinforced concrete
Concrete that has been placed around some type of steel reinforcement material. After the concrete cures, the reinforcement provides greater tensile and shear strength for the concrete. Almost all concrete is reinforced in some manner.
Setting
The process of stiffening as cement becomes unworkable after being mixed with water.
