Module 2 Flashcards
Concrete
Concrete components
Water, Cement, Coarse and Fine Aggregates, Admixtures (optional)
Mortar components
Water, Cement, Fine Aggregates
Cement paste components
Water, Cement
What type of cement is Portland Cement?
Hydraulic cement
Cement components
Limestone, Clay, Iron Ore, Cement rock
What is the first stage of cement?
Mixing (1-2 mins)
What is the second stage of cement?
Induction (1-2 hours)
What is the third stage of cement?
Acceleration (12-24 hours)
What is the fourth stage of cement?
Deceleration (20-25 hours)
What is the fifth stage of cement?
Diffusion Limited
Water Cement ratio
Water/Cement
Specific Gravity
Density of Substance/Density of Water
First type of Aggregate
Coarse Aggregate
Second type of Aggregate
Fine Aggregate
Particles are greater than 1/4 inches, comprise 40-45% of the mixture, and where concrete gets is the compressive strength
Coarse Aggregate
Particles are greater than 3/8 inches, comprise 30-35% of the mixture, and where concrete gets filled up
Fine Aggregate
Denser aggregates
Well-Graded Aggregate
Hollow aggregates
Poorly Graded Aggregate
A characteristic of aggregates where it will give a stronger final concrete
Strong and Hard
A characteristic of aggregates is that it can stand up to wear and tear and weathering
Durable
A characteristic of aggregates is that it doesn’t react with cement
Chemically inactive
A characteristic of aggregates where dirt and clay are not sticking to the mixture
Clean
A characteristic of aggregates where it varies in sizes
Graded
Aggregate that is more workable
Rounded aggregates
Aggregate that is harder to work with but can make the concrete stronger
Angular aggregate
Combining with water
Hydration
Grade of aggregate that has fewer spaces
Well Graded
Grade of aggregate that is loose
Poorly Graded
Grade of aggregate that has no interaction with rocks and has low support
Gap Graded
A crucial component of concrete that holds aggregates together like glue and should be filtered and drinkable
Water
Optional component of concrete
Admixture
Admixture that is added to alter the properties of concrete
Chemical Admixtures
Adding microscopic air bubbles to make the concrete easier to finish
Air Entraining Admixtures
Speed the set time of the mixture
Set Accelerators/Acceleration Plasticizers
Slowing the setting of concrete
Set Retarders/Retanding Plasticizers
Used to produce the amount of water required for a slump
Water Reducer
Augments the strength and density of concrete
Mineral Admixtures
Mineral additives in admixtures
Pozzolanic Materials
Types of Mineral Admixture
Natural Pozzolans and Artificial Pozzolans
Four Properties of Concrete
Workability, Cohesiveness, Strength, and Durability
Three Different States of Concrete
Plastic, Setting, and Hardened
Concrete can be worked and is like “bread dough”
Plastic State
Concrete begins to stiffen, and this takes place after compaction and during finishing
Setting State
A method of keeping concrete at a suitable temperature and moisture level over an extended period of time
Curing
It is how easy concrete is to place, handle, compact, and finish a concrete mix
Workability
Measured by its compressive strength using the compression test
Strength and Durability
Removing air from concrete
Compaction
How well does concrete hold together
Cohesiveness
When does concrete testing occur?
Plastic state
Shows the workability of concrete
Slump Test
Measures concrete strength
Compression test
Slump that falls as one, and the ideal type of slump
True Slump
One side has a lesser slump
Shear Slump
A type of slump which has too much water
Collapse Slump
There are no changes once the cone is removed; too little water
Zero Slump
It is a representative of the concrete supplied
Sampling
A test is done to make sure the concrete is workable and within a set range of the target
Slump test
The difference in color across the surface of the concrete
Color Variation
Network of fine cracks across the surface of concrete
Crazing
Fine powder on the concrete surface
Dusting
Surface of concrete has bits washed away or has dents
Rain Damage
Chipped edges or joints, leaving an elongated cavity
Spalling
A white crystalline deposit found on the surface of concrete
Efflorescence
Too much coarse aggregate is added
Honeycombing
Hollow, low-profile bumps on the concrete surface
Blistering
Cracks that happen before the concrete hardens
Pre-setting Cracks
Cracks that happen after concrete hardens
Hardened Cracks
Forms after the concrete is placed while it is still plastic
Plastic Settlement Cracks
Appear in lines due to low humidity, usually 300-600mm long and 25mm-2m in length
Plastic Shrinkage Cracks
Bending or bulging of formwork may happen during placement and compaction
Formwork Movement
Cracks due to sudden changes in temperature
Thermal Shock
Cracks caused by drying, shrinkage, movement or setting of the ground, or placing higher load on the concrete than it was designed to carry
Hardened Crack
