chap 5

Question 1

x air is intentionally retained in the mix

Answer 1

entrained

Question 2

small voids called x are on purpose

Answer 2

entrained air

Question 3

shotcrete exposed to freezing or thawing should have at least x percent entrained air

Answer 3

4 to 6

Question 4

dry mix without coarse aggregate is x to x parts cement to sand

Answer 4

one, four

Question 5

dry mix with moisture in aggregate should be shot x minutes after mixing

Answer 5

45

Question 6

benefits of predampening dry mix

Answer 6

reduce dust, improve mixing, and reduce static electricity at the nozzle

Question 7

define wet mix shotcrete

Answer 7

wet-mix shotcrete is the process in which the ingredients, incl water, are mixed before intro to the hose

Question 8

if aggregate is gap graded, finer sand wil bypass the x and water will separate from the mix, creating x

Answer 8

larger aggregate, bleed water

Question 9

what happens when bleed water is squeezed from the mix

Answer 9

the aggregate jams, creating a plug in the line

Question 10

best slump?

Answer 10

50-75mm (2 to 3 in)

Question 11

wet mix should be used within x min of first x addition

Answer 11

90, water

Question 12

steel and nonmetallic fibers can be used to improve the x and x of conc

Answer 12

tensile strength, impact resistance