CE 337 FINAL EXAM QUESTIONS AND CORRECT
ANSWERS
Hydration - Answers - term used to describe the CHEMICAL REACTION between
cement powder and water
curing - Answers - management of temperature and moisture
Characteristics of hydration - Answers - exothermic reaction, surface reaction, cement
grains reduce in size as products are formed
mortar - Answers - water, cement, FA
paste - Answers - water, cement
concrete - Answers - water, cement, FA, CA
concrete is a multi-scale composite - Answers - millimeter scale, micrometer scale,
nanometer scale
states of concrete and duration of each - Answers - fresh/plastic state (2-4 hours),
hardening state (4-8 hours), hardened state
entrained air - Answers - chemically added
entrapped air - Answers - naturally occurring
unit weight of concrete - Answers - 140-150 lb/ft3
28-day compressive strength (psi) - Answers - 3000-6000 psi
28-flexural strength - Answers - 500-750 psi
coefficient of thermal expansion - Answers - 4-6 micro e fahrenheit
permeability - Answers - 10^-3 - 10^-4 mm/sec
temperature of kiln in production of PC - Answers - 2700 degrees fahrenheit
Gypsum (chemical formula) - Answers - CaSO4 . 2H2O
Tri-Calcium Silicate - Answers - C3S (3CaO.SiO2)
, Di-Calcium Silicate - Answers - C2S (2CaO. SiO2)
Tri-Calcium Aluminate - Answers - C3A (3CaO. Al2O3)
Tetra-Calcium Alumino Ferrite - Answers - C4AF (4CaO. Al2O3.Fe2O3)
Type I concrete name - Answers - ordinary portland cement
Type II concrete name - Answers - low sulfate resistant cement
Type III concrete name - Answers - high early strength cement
Type IV concrete name - Answers - low heat of hydration cement
Type V concrete name - Answers - high sulfate resistant cement
specific gravity of cement grains - Answers - 3.12-3.16
particle size - Answers - less than 0.045 mm
1 bag of cement (weight) - Answers - 94 lb
surface area - Answers - 1500-2000 ft2/ lb
hydration of silicates reaction - Answers - C3S + water -> CSH + CH + heat
CSH - Answers - Calcium silicate hydrate, strength giver, fibrous, grows for the surface
of the grain, large surface area
CH - Answers - Calcium hydroxide, crystalline, embedded in CSH matrix, provides
alkalinity, fills pore space, no significant impact on strength
stages of hydration - Answers - initial mixing, dormancy, hardening, cooling,
densificiation
which stages of hydration are diffusion controlled? - Answers - Stages 4-5 (cooling and
densificiation)
which stages of hydration are chemically controlled? - Answers - Stages 1-3 (initial
mixing, dormancy, hardening)
Stage 1 of hydration - Answers - mixing or initial hydrolysis (about 15 minutes,
associated with a spike in heat, gel like coating of the cement grains begin)
Stage 2 of hydration - Answers - nucleation or dormancy (about 2-4 hours, water is
being saturated with OH- ions, concrete can be transported, placed and finished)
ANSWERS
Hydration - Answers - term used to describe the CHEMICAL REACTION between
cement powder and water
curing - Answers - management of temperature and moisture
Characteristics of hydration - Answers - exothermic reaction, surface reaction, cement
grains reduce in size as products are formed
mortar - Answers - water, cement, FA
paste - Answers - water, cement
concrete - Answers - water, cement, FA, CA
concrete is a multi-scale composite - Answers - millimeter scale, micrometer scale,
nanometer scale
states of concrete and duration of each - Answers - fresh/plastic state (2-4 hours),
hardening state (4-8 hours), hardened state
entrained air - Answers - chemically added
entrapped air - Answers - naturally occurring
unit weight of concrete - Answers - 140-150 lb/ft3
28-day compressive strength (psi) - Answers - 3000-6000 psi
28-flexural strength - Answers - 500-750 psi
coefficient of thermal expansion - Answers - 4-6 micro e fahrenheit
permeability - Answers - 10^-3 - 10^-4 mm/sec
temperature of kiln in production of PC - Answers - 2700 degrees fahrenheit
Gypsum (chemical formula) - Answers - CaSO4 . 2H2O
Tri-Calcium Silicate - Answers - C3S (3CaO.SiO2)
, Di-Calcium Silicate - Answers - C2S (2CaO. SiO2)
Tri-Calcium Aluminate - Answers - C3A (3CaO. Al2O3)
Tetra-Calcium Alumino Ferrite - Answers - C4AF (4CaO. Al2O3.Fe2O3)
Type I concrete name - Answers - ordinary portland cement
Type II concrete name - Answers - low sulfate resistant cement
Type III concrete name - Answers - high early strength cement
Type IV concrete name - Answers - low heat of hydration cement
Type V concrete name - Answers - high sulfate resistant cement
specific gravity of cement grains - Answers - 3.12-3.16
particle size - Answers - less than 0.045 mm
1 bag of cement (weight) - Answers - 94 lb
surface area - Answers - 1500-2000 ft2/ lb
hydration of silicates reaction - Answers - C3S + water -> CSH + CH + heat
CSH - Answers - Calcium silicate hydrate, strength giver, fibrous, grows for the surface
of the grain, large surface area
CH - Answers - Calcium hydroxide, crystalline, embedded in CSH matrix, provides
alkalinity, fills pore space, no significant impact on strength
stages of hydration - Answers - initial mixing, dormancy, hardening, cooling,
densificiation
which stages of hydration are diffusion controlled? - Answers - Stages 4-5 (cooling and
densificiation)
which stages of hydration are chemically controlled? - Answers - Stages 1-3 (initial
mixing, dormancy, hardening)
Stage 1 of hydration - Answers - mixing or initial hydrolysis (about 15 minutes,
associated with a spike in heat, gel like coating of the cement grains begin)
Stage 2 of hydration - Answers - nucleation or dormancy (about 2-4 hours, water is
being saturated with OH- ions, concrete can be transported, placed and finished)
