Concrete Testing Flashcards

1
Q

tests concrete consistency,
measured @ jobsite.
placed in truncated cone.

A

Slump Test

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2
Q

Slump Test cone dims

A

12” high,
8” @ base,
4” @ top,

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3
Q

Slump Test typ. slump

A

2-6”

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4
Q

tests compressive strength. (psi)
tested as it’s placed,
samples in molds 6”ø, 12” high,
moist-cured, then labtested.

A

Cylinder Test

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5
Q

Cylinder Test tested on day _ and day __

A

7

28

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6
Q

7 day is typically ___% 28-day strength.

A

60-70%

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7
Q

used on existing concrete.
sample is drilled out,
lab tested for compressive strength.

A

Core Cylinder Test

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8
Q

steel ball dropped on freshly laid concrete,
penetration is measured,
compared to half the values of the slump test.

A

Kelly Ball Test

aka “ball penetration test”,

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9
Q

nondestructive way to test strength after hardened.
spring loaded plunger snapped against surface,
rebound is measured. (approx reading)

A

Impact Hammer Test

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10
Q

¾” tube that contains a floating scale.
tube placed on wet concrete,
scale pushed into mixture and released,
distance the scale floats is read.

A

K-slump Test

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11
Q

a measure of the consistency of the concrete,

comparable to the slump test.

A

K-slump Test

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12
Q

test for moisture level prior to

A

floor finishes

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13
Q

max limit for moisture emission is

A

3.0 lb per 1000ft2 per 24hr

@73º/50%RH

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14
Q

most common/inexpensive/easy

moisture content test

A

Calcium chloride test (moisture dome test)

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15
Q

place standard mass of substance below a plastic cover, seal to concrete floor.
after 60-72 hours, weighed vs pre-test weight.
1 test per 500-1000ft2

A

Calcium chloride test (moisture dome test)

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16
Q

Calcium chloride test requires one test every

A

1 test per 500-1000ft2

17
Q

Calcium chloride test sample is tested after

A

60-72 hrs

18
Q

measures RH of atmosphere confined adjacent to the concrete floor
pocket of air trapped below vapor-impermeable box,
probe measures RH.

A

Hygrometer (RH test)

19
Q

typ Hygrometer reading

A

typ 75% RH or less

20
Q

qualitative test
sealing 18x18” membrane to floor, trapping excess moisture.
min 16hrs. visual inspection of floor + membrane.

A

Polyethylene sheet test

21
Q

Polyethylene sheet test fails if

A

visible moisture

22
Q

(sim. sheet test)
24x24” sample of vapor retardant finish.
applied w adhesive, edges are sealed w tape.
@ 72 hrs a visual inspection is made

A

Mat Test

23
Q

Mat Test passes if

A

mat sample firmly bonded

24
Q

measuring conductance/capacitance

A

Electrical Impedance Test

25
Q

pH scale runs from

A

0-14
lowest is acidic
higher more alkali

26
Q

typ concrete pH

A

12.0-13.3pH

27
Q

two slabs can have same pH level, but dif. alkalinity, bc

A

bc alkalinity cannot exist w/o moisture

28
Q

excess alkalinity can be carried w/

A

water vapor

29
Q

finish adhesive re-emulsify (back to liquid)
@ pH 9/10 problems (professional grade = pH 11)
controlled w proprietary coating

A

surface alkalinity

30
Q

strongly alkali cement dissolves aggregate.
produces gel-like material = tremendous pressure in surface pores
buckle/blister floor finish

A

alkali-silica reaction (ASR)

31
Q

methods of reducing

alkali-silica reaction (ASR)

A

spec aggregate not susceptible to ASR,
low lime cement,
proper curing,
not finishing w hard trowel surface

32
Q

ph is tested with

A

surface test, paper strip/meter.

33
Q

desired ph levels in concrete

A
  1. 5 ideal, and about min conc can have

9. 0 acceptable

34
Q

grinding portions of concrete,
mixing results w demineralized water,
lab chemical analysis.

A

titration test (in addition to pH test)