concrete curing: plastic shrinkage cracking, bleeding, evaporation, and temperature
DESCRIPTION
Concrete Curing: Plastic Shrinkage Cracking, Bleeding, Evaporation, and Temperature. Jennifer A. Distlehorst Cliff Hobson Dave Meggers John Wojakowski Kansas DOT. Plastic Shrinkage Cracking Analysis of the term. - PowerPoint PPT PresentationTRANSCRIPT
Concrete Curing:Concrete Curing: Plastic Plastic Shrinkage Cracking, Bleeding, Shrinkage Cracking, Bleeding, Evaporation, and TemperatureEvaporation, and Temperature
Jennifer A. Distlehorst Cliff HobsonJennifer A. Distlehorst Cliff Hobson
Dave Meggers John WojakowskiDave Meggers John Wojakowski
Kansas DOTKansas DOT
Plastic Shrinkage CrackingPlastic Shrinkage CrackingAnalysis of the termAnalysis of the term
Plastic - capable of continuous and Plastic - capable of continuous and permanent change in any direction permanent change in any direction without breaking apartwithout breaking apart
Cracking - breaking apart or splittingCracking - breaking apart or splitting
Plastic Shrinkage CrackingPlastic Shrinkage Cracking
Plastic Shrinkage Cracking Plastic Shrinkage Cracking FactorsFactors
Evaporation Rate - Evaporation Rate - Menzel, 1954; Lerch,1957Menzel, 1954; Lerch,1957 Combination of 4 Factors - Concrete and Air Combination of 4 Factors - Concrete and Air
Temperatures, Humidity and Wind Speed Temperatures, Humidity and Wind Speed Critical Value from Lerch, 1957 – 0.2 lb/sq ft/hrCritical Value from Lerch, 1957 – 0.2 lb/sq ft/hr
Bleeding of the ConcreteBleeding of the Concrete Are Today’s Concretes Still the Same? Similar?Are Today’s Concretes Still the Same? Similar? New Value for regular, let alone high New Value for regular, let alone high
performance concrete?performance concrete?
Bleed Test of Concrete Bleed Test of Concrete ASTM C 232ASTM C 232
Bleeding of Concrete and Loss Bleeding of Concrete and Loss of Water at Various of Water at Various Evaporation RatesEvaporation Rates
Cum
ula
tive w
ate
r ble
d o
r evapora
ted,
lb/f
t2
0.2
0.3
0.4
0.5
0.6
0.1
time in hours0 0:43 1:26 2:09 2:52
0.2
0.1
0.05
0.15
bleed water
Laboratory Concrete, Air Entrained
I-635 Example - Hand I-635 Example - Hand PlacementPlacement
0.2
0.3
0.4
0.5
0.6
0.1
bleed water
0.1
Measured evaporation rate 0.07 lb/sq.ft/hr
Cum
ula
tive w
ate
r ble
d o
r evapora
ted,
lb/f
t2
Du
mp
10:
35
Co
nso
lidat
ion
10:
40
Tin
ing
10:
45
Cu
rin
g C
om
po
un
d 1
0:50
time of day10:30 11:00 11:30 12:00
92-95 F,
ADJACENT CURED CONCRETE 106 F 0.
2
I-70 Example -Slip FormedI-70 Example -Slip Formed
0.2
0.3
0.4
0.5
0.6
0.1
bleed water
0.1evaporation 0.12 lb/sq.ft/hr
Cum
ula
tive w
ate
r ble
d o
r evapora
ted,
lb/f
t2
Du
mp
2:0
5
time of day2:00 2:30 3:30 4:00
Co
nso
lidat
ion
2:1
0
Tin
ing
3:0
0
Cu
rin
g C
om
po
un
d 3
:40
3:00
0.2
Louisburg Example - Slip Louisburg Example - Slip FormedFormed
0.2
0.3
0.4
0.5
0.6
0.1bleed water
0.1
0.13 lb/sq.ft/hr
Cum
ula
tive w
ate
r ble
d o
r evapora
ted,
lb/f
t2
Du
mp
1:1
7
time of day1:30 2:30 3:00
Tin
ing
2:1
0
Cu
rin
g C
om
po
un
d 2
:18
2:00
0.2
I-635 Bridge ExampleI-635 Bridge Example
0.2
0.3
0.4
0.5
0.6
0.1
bleed water
0.1
0.05 lb/sq.ft/hr
Cum
ula
tive w
ate
r ble
d o
r evapora
ted,
lb/f
t2
Du
mp
8:5
0
time of day9:00 10:00 10:30
Bu
rlap
10:
45
9:30
Conso
lidati
on
9:0
0
Grade 30, Field Concrete
0.2
If the evaporation rate is If the evaporation rate is greater than the bleeding greater than the bleeding
rate why isn’t there a lot of rate why isn’t there a lot of plastic shrinkage cracking in plastic shrinkage cracking in
our concrete?our concrete? Stiffer, cohesive concrete (used in slip form Stiffer, cohesive concrete (used in slip form
paving & bridge decks) has some tensile strength paving & bridge decks) has some tensile strength to resist the force imposed by the surface tension to resist the force imposed by the surface tension of waterof water
Water reducers used in these mixtures reduce the Water reducers used in these mixtures reduce the surface tension of the watersurface tension of the water
KDOT Bridge Deck Curing KDOT Bridge Deck Curing Specification 90M/R-91-R13*Specification 90M/R-91-R13*
Measure the evaporation rate on the Measure the evaporation rate on the bridge deck regularlybridge deck regularly
Use monomolecular/precure immediately Use monomolecular/precure immediately after the bridge deck finisherafter the bridge deck finisher
Fog immediately behind the tining floatFog immediately behind the tining float Produce a gloss to a semi-gloss sheen Produce a gloss to a semi-gloss sheen
without water runoffwithout water runoff
KDOT Bridge Deck Curing KDOT Bridge Deck Curing Specification 90M/R-91-R13*Specification 90M/R-91-R13*
Apply curing compound to the damp Apply curing compound to the damp wearing surfacewearing surface
Cover with wet burlap for seven daysCover with wet burlap for seven days Use soaker hosesUse soaker hoses Polyethylene sheeting is not allowed Polyethylene sheeting is not allowed
until the evening of the day following until the evening of the day following placement if the temperature is placement if the temperature is forecast to be above 50 Fforecast to be above 50 F
Temperatures of a Slab Temperatures of a Slab BridgeBridge
60
70
80
90
100
110
120
130
140
06/
26/2
003
08:
22
06/
26/2
003
13:
02
06/
26/2
003
17:
42
06/
26/2
003
22:
22
06/
27/2
003
03:
02
06/
27/2
003
07:
42
06/
27/2
003
12:
22
06/
27/2
003
17:
02
06/
27/2
003
21:
42
06/
28/2
003
02:
22
06/
28/2
003
07:
02
06/
28/2
003
11:
42
06/
28/2
003
16:
22
06/
28/2
003
21:
02
06/
29/2
003
01:
42
06/
29/2
003
06:
22
06/
29/2
003
11:
02
06/
29/2
003
15:
42
06/
29/2
003
20:
22
06/
30/2
003
01:
02
06/
30/2
003
05:
42
06/
30/2
003
10:
22
06/
30/2
003
15:
02
06/
30/2
003
19:
42
07/
01/2
003
00:
22
07/
01/2
003
05:
02
07/
01/2
003
09:
42
07/
01/2
003
14:
22
07/
01/2
003
19:
02
07/
01/2
003
23:
42
07/
02/2
003
04:
22
07/
02/2
003
09:
02
07/
02/2
003
13:
42
Tem
per
atu
re,
F
Concrete
Air
Top button at the haunch in a middle pier
AirN N N N N N N = noon
PLASTIC PLACED
15 F
Evaporation retarder applied Evaporation retarder applied immediatelyimmediately
E. Holt, Concrete International , Sept 2000
E. Holt, Concrete International , Sept 2000
(0.1 psf = 0.02 in)
Water applied after 1 hourWater applied after 1 hour
E. Holt, Concrete International , Sept 2000
(0.2 psf = 04 in)