Physical Properties of Aggregates
Aggregate Properties.ppt (Size: 2.23 MB / Downloads: 232)
What is an AGGREGATE
Aggregate: the inert filler
materials, such as sand or
stone, used in making
Physical Properties of Aggregates:
1.Unit Weight and Voids
2. Specific Gravity
3. Particle Shape and Surface Texture
4. Shrinkage of Aggregates
5. Absorption and Surface Moisture
6. Resistance to Freezing and Thawing
Void content affects mortar requirements in mix design; water and mortar requirement tend to increase as aggregate void content increases
Void contents range from 30-45% for coarse aggregates to about 40-50% for fine aggregates.
Absolute: the ratio of the weight of the solid to the weight of an equal volume of water (both at a stated temperature)
• refers to volume of the material excluding all pores
Apparent: ratio of the weight of the aggregate (dried in an oven at 212- 230ºF for 24 hours) to the weight of water occupying a volume equal to that of the solid including the impermeable pores
• volume of solid includes impermeable pores (but not capillary pores)
Resistance to Freezing and Thawing
Important for exterior concrete.
• Affected by an aggregate's high porosity, absorption, permeability and pore structure.
• If aggregates or concrete absorbs so much water that when the water freezes and expands the concrete cannot accommodate the build up of internal pressure, pop–outs may occur.