FE- Materials
Bulk Specific Gravity (Gsb)
Bulk dry specific gravity Weight in air of a unit volume of aggregate/ (weight in air of an equal volume of distilled water) Oven dry weight/ (SSD weight - Weight in water)
Bulking
Fine aggregates Undesirable increase in volume caused by surface moisture holding the particle apart
Bulk SSD Specific Gravity
Gsb SSD Weight in air of a unit volume of aggregate including the weight of water within the voids/weight in air of an equal volume of distilled water. SSD weight/(SSD weight-Weight in water)
Apparent Specific Gravity (ASG)
Ratio of weight in air or a unit volume of the impermeable portion of aggregate to the weight in air of an equal volume of gas free distilled water at a stated temperature. oven dry weight/(oven dry weight-weight in water)
Segregation in concrete
Results in Honeycombing Porous layers Surface scaling
water-cement ratio
The ratio of water to cement in a concrete mix, the main factor which determines concrete strength.
Accelerators
Used to speed up setting time and reduces the length of time for curing and protection
VMA
Voids in mineral aggregate
Durability
a measure of the concrete's resistance to extreme weather exposure.
Portland cement
dry powder made by burning limestone and clay followed by grinding and mixing; used to make concrete - one sack =94 lb
Strength
f'c
yield point (elastic limit)
point on the load deformation curve past which deformation is permanent
Ductility
the ability of a substance to deform before it fractures when a load is applied. Can be stretched w/out breaking and drawn into thin wires
heat of hydration
the enthalpy change associated with the hydration process Mixing of Portland cement and water mixture
ultimate strength
the maximum amount of stress a material can withstand without breaking
VFA
voids filled with asphalt
pozzolan
A siliceous material, such as fly ash, that reacts chemically with slaked lime in the presence of moisture to form a slow-hardening cement, named after a natural cement from pozzuoli, an ancient roman town near vesuvius.
Brittle
Break w/out plastic deformation or stretch
Saturated Surface Dry (SSD)
Allows neither absorbing water from nor contributing water to the concrete mix. Aggregate has been soaked in water and has absorbed water into its pore spaces. The excess free surface moisture has been removed so that the particles are still saturated, but the surface of the particle is essentially dry.
air entraining agents
Introduces minute air bubbles in the concrete mix to increase its resistance to freezing improves durability and workability
Bulk Specific Gravity
Mass of oven dried aggregate/ weight of the sample SSD and the weight of the sample in water. Gsb=Wa/(Wssd-Wwater)
Tensile test
Measures the response of a material to a slowly applied uniaxial force. The yield strength, tensile strength, modulus of elasticity, and ductility are obtained.
concrete slump test
Measures the workability of fresh concrete. -WC increases, concrete strength decreases -Higher the slump, greater the water content, the weaker the mix -admixtures increase the slump of the concrete mix w/out affecting the strength -Superplasticizers increase the slump of the concrete while allowing the concrete to be pumped
Toughness
Mechanical property of a material that indicates the ability of the material to handle overloading before it fractures. Material's ability to bend and its resistance to fracture when stress is applied relies on strength and ductility
Hot mix asphalt (HMA)
Mixture of asphalt binder and graded mineral aggregate mixed at an elevated temperature and compacted to form a relatively dense pavement layer.
Retarders
Slows down the setting of a concrete mix in order to allow more time for placing and working the mix
Fatigue
Testing a material until breakage occurs
efflorescence
The irregular and white patches found on the surface of brick.
Proportional/elastic limit
The maximum level of stress that a material can endure and still be able to recover to its original shape
Superplasticizers
also known as plasticizers or high-range water reducers (HRWR), reduce water content by 12 to 30 percent. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction. The effect of superplasticizers lasts only 30 to 60 minutes and is followed by a rapid loss in workability. Added to concrete at the jobsite.
Superpave
an acronym for superior performing asphalt pavements. An asphalt concrete mix-design method for determining the aggregate structure and proportions of aggregate and asphalt cement based upon desired performance
