Portland cement

Question 1

glue that bonds aggregate together to make concrete

Answer 1

cement paste (cement + water)

Question 2

cement paste and sand

Answer 2

mortar

Question 3

cement + water + sand + gravel

Answer 3

concrete

Question 4

process to make portland cement

Answer 4

crushing and grinding of raw materials, heat and melt in kiln that forms cement clinker, add gypsum to clinker and pulverize to fine powder

Question 5

chemical composition of PC

Answer 5

tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite

Question 6

How is fineness important when making PC

Answer 6

smaller particles have more surface area to react with water, fineness controls the rate of hydration (heat and strength game)

Question 7

measures air permeability against known standard material

Answer 7

Blaine test

Question 8

measures sedimentation rate suspended in kerosene

Answer 8

Wagner Turbidimeter

Question 9

specific gravity of cement (w/o air voids)

Answer 9

3.15

Question 10

chemical reaction of cement w water

Answer 10

hydration

Question 11

dominates early stage of hydration

Answer 11

through-solution

Question 12

solid state reaction at cement surface

Answer 12

topochemical

Question 13

Hydration rate: aluminates > silicates

Answer 13

needs balance

Question 14

Hydration of C3S & C2S

Answer 14

makes paste strong

Question 15

Primary Chemical Reaction Chemical reactions that harden cement paste

Answer 15

Fast in the beginning but is long term (decades in dams), Causes heat, which can be a problem if there’s too much

Question 16

Voids in hydration space

Answer 16

interlayer hydration space, capillary voids, trapped voids, entrained air

Question 17

space between atomic layers, shrinkage if humidity is less than 11%

Answer 17

interlayer hydration space

Question 18

w/c too high, decrease strength and increased permeability

Answer 18

capillary voids

Question 19

large pockets caused by handling, decrease strength and increase permeability

Answer 19

trapped voids

Question 20

microscopic bubbles caused by admixtures, increased durability

Answer 20

entrained air

Question 21

change from plastic state to solid state

Answer 21

stiffening

Question 22

premature stiffening within a few minutes

Answer 22

False Set

Question 23

sets that cannot be fixed

Answer 23

quick and flash sets

Question 24

Ability for concrete to retain volume after setting

Answer 24

Soundness

Question 25

Most important property of hydrating cement

Answer 25

water-cement ratio

Question 26

w/c need for hydration

Answer 26

0.4

Question 27

Pros and cons of adding extra water to cement?

Answer 27

improves workability but also causes voids

Question 28

types of PC

Answer 28

I. Normal
II. Moderate Sulfate Resistance
III. High Early Strength
IV Low Heat of Hydration
V. High Sulfate Resistance

Question 29

produce tiny, dispersed air bubbles into the concrete, causes cracking and internal stress, this prevents this from happening

Answer 29

Air Entrainers

Question 30

Air Entrainers decrease strength by 20% but can be compensated with lower w/c ratio

Answer 30

true

Question 31

Three ways to use water reducers

Answer 31

1. ) improve workability using same w/c ratio
2. ) increase strength using lower w/c ratio
3. ) reduce cost at same w/c ratio by reducing both water and cement

Question 32

delay or retard initial set (increase set time), may reduce early strength, usually doesn’t reduce final set time, long haul time

Answer 32

Retarders

Question 33

have the ability to stop and reactivate the hydration process of concrete

Answer 33

Hydration Controllers

Question 34

2 parts to hydration controllers

Answer 34

stabilizer and activator

Question 35

speed up initial and final set times

Answer 35

Accelerators

Question 36

What are accelerators used for?

Answer 36

increase rate of strength gain, reduce the amount of time before finishing operations begin, reduce curing time, plug leaks under hydraulic pressure efficiently

Question 37

Most common accelerator

Answer 37

calcium chloride

Question 38

most common supplementary cementitious Materials

Answer 38

Fly Ash

Question 39

Classes of Fly Ash

Answer 39

N, F, and C