Concrete Testing Flashcards
tests concrete consistency,
measured @ jobsite.
placed in truncated cone.
Slump Test
Slump Test cone dims
12” high,
8” @ base,
4” @ top,
Slump Test typ. slump
2-6”
tests compressive strength. (psi)
tested as it’s placed,
samples in molds 6”ø, 12” high,
moist-cured, then labtested.
Cylinder Test
Cylinder Test tested on day _ and day __
7
28
7 day is typically ___% 28-day strength.
60-70%
used on existing concrete.
sample is drilled out,
lab tested for compressive strength.
Core Cylinder Test
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”,
nondestructive way to test strength after hardened.
spring loaded plunger snapped against surface,
rebound is measured. (approx reading)
Impact Hammer Test
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
a measure of the consistency of the concrete,
comparable to the slump test.
K-slump Test
test for moisture level prior to
floor finishes
max limit for moisture emission is
3.0 lb per 1000ft2 per 24hr
@73º/50%RH
most common/inexpensive/easy
moisture content test
Calcium chloride test (moisture dome test)
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)
Calcium chloride test requires one test every
1 test per 500-1000ft2
Calcium chloride test sample is tested after
60-72 hrs
measures RH of atmosphere confined adjacent to the concrete floor
pocket of air trapped below vapor-impermeable box,
probe measures RH.
Hygrometer (RH test)
typ Hygrometer reading
typ 75% RH or less
qualitative test
sealing 18x18” membrane to floor, trapping excess moisture.
min 16hrs. visual inspection of floor + membrane.
Polyethylene sheet test
Polyethylene sheet test fails if
visible moisture
(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
Mat Test passes if
mat sample firmly bonded
measuring conductance/capacitance
Electrical Impedance Test
pH scale runs from
0-14
lowest is acidic
higher more alkali
typ concrete pH
12.0-13.3pH
two slabs can have same pH level, but dif. alkalinity, bc
bc alkalinity cannot exist w/o moisture
excess alkalinity can be carried w/
water vapor
finish adhesive re-emulsify (back to liquid)
@ pH 9/10 problems (professional grade = pH 11)
controlled w proprietary coating
surface alkalinity
strongly alkali cement dissolves aggregate.
produces gel-like material = tremendous pressure in surface pores
buckle/blister floor finish
alkali-silica reaction (ASR)
methods of reducing
alkali-silica reaction (ASR)
spec aggregate not susceptible to ASR,
low lime cement,
proper curing,
not finishing w hard trowel surface
ph is tested with
surface test, paper strip/meter.
desired ph levels in concrete
- 5 ideal, and about min conc can have
9. 0 acceptable
grinding portions of concrete,
mixing results w demineralized water,
lab chemical analysis.
titration test (in addition to pH test)
