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Flashcards in Concrete Testing Deck (34)
1

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

Slump Test

2

Slump Test cone dims

12” high,
8” @ base,
4” @ top,

3

Slump Test typ. slump

2-6"

4

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

Cylinder Test

5

Cylinder Test tested on day _ and day __

7
28

6

7 day is typically ___% 28-day strength.

60-70%

7

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

Core Cylinder Test

8

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

Kelly Ball Test

aka “ball penetration test”,

9

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

Impact Hammer Test

10

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

K-slump Test

11

a measure of the consistency of the concrete,
comparable to the slump test.

K-slump Test

12

test for moisture level prior to

floor finishes

13

max limit for moisture emission is

3.0 lb per 1000ft2 per 24hr

(@73º/50%RH)

14

most common/inexpensive/easy
moisture content test

Calcium chloride test (moisture dome test)

15

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

Calcium chloride test (moisture dome test)

16

Calcium chloride test requires one test every

1 test per 500-1000ft2

17

Calcium chloride test sample is tested after

60-72 hrs

18

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

Hygrometer (RH test)

19

typ Hygrometer reading

typ 75% RH or less

20

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

Polyethylene sheet test

21

Polyethylene sheet test fails if

visible moisture

22

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

Mat Test

23

Mat Test passes if

mat sample firmly bonded

24

measuring conductance/capacitance

Electrical Impedance Test

25

pH scale runs from

0-14
lowest is acidic
higher more alkali

26

typ concrete pH

12.0-13.3pH

27

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

bc alkalinity cannot exist w/o moisture

28

excess alkalinity can be carried w/

water vapor

29

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

surface alkalinity

30

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

alkali-silica reaction (ASR)

31

methods of reducing
alkali-silica reaction (ASR)

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

32

ph is tested with

surface test, paper strip/meter.

33

desired ph levels in concrete

8.5 ideal, and about min conc can have
9.0 acceptable

34

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

titration test (in addition to pH test)