Table 14. Strength results from Pozzutec 20 (P20) and propylene glycol (PG) and urea with a 420-kg/m3

Results and discussion - SR96_280019

PHASE III: EVALUATION OF IMPROVED ADMIXTURE

SR96_28
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13

Tables 15 and 16 show the results

Table 14. Strength results from Pozzutec 20 (P20) and propylene

glycol (PG) and urea with a 420-kg/m3 (705 lb/yd3) cement factor

of three trial admixtures coded EY-

and a 0.43 w/c.

11, EZ-3B, and EZ-4B. The Table 15

mixtures had a cement factor of 365

kg/m3 (611 lb/yd3) and a w/c of

dosed by weight of

0.48, while the Table 16 mixtures had

active ingredient per

a cement factor of 420 kg/m3 (705

100 lbs of cement

Compressive strength--MPa (psi)

given in percent.

lb/yd3) and a w/c of 0.43. The Table

15 mixtures were tested at 60 and

100 mL/kg (90 and 150 fl oz/cwt),

1.5% P20 + 4.5% PG

while the Table 16 mixes were tested

4.5% P20 + 1.5% PG

at 100 mL/kg (150 fl oz/cwt) only.

1.5% P20 + 4.5% Urea

At room temperature, all three ad-

mixtures provided about the same

1.5% P20 + 4.5% PG

strength results as those attained by

the control. They did not enhance

4.5% P20 + 1.5% PG

strength as much as did Pozzutec

1.5% P20 + 4.5% Urea

20. Though it did not cause enhanced

strength at room temperature at the

1.5% P20 + 4.5% PG

dosage tested, the EY-11 provided

the highest 28-day strength at 5C

4.5% P20 + 1.5% PG

(23F) of all the admixtures tested.

1.5% P20 + 4.5% Urea

(Note that such high dosages will

most likely not be used at room tem-

perature.) Consequently, EY-11 was selected as

capability without diminishing its room-tempera-

the admixture for continued study in Phase III.

ture strength gain. All mixtures used a cement

3 (705 lb/yd3) and a w/c of 0.43.

Another admixture, EZ-3B, appeared to provide

factor of 420 kg/m

At room temperature, the combina-

tion of 4.5% Pozzutec 20 plus 1.5%

propylene glycol provided the best

Table 15. Strength results from three trial admixtures in concrete

strength gain compared to the con-

with a 365-kg/m3 (611 lb/yd3) cement factor and a 0.48 w/c.

trol mixture. It provided a 10%

strength gain over that of the control

code name-dosage

Compressive strength--MPa (psi)

mixture at 28 days, which, unfortu-

mL/kg (fl oz/cwt)

nately, was less than the approxi-

mately 20% strength increase pro-

vided by just Pozzutec 20 in Phase I.

EY-11 100 (150)

At 5C (23F), this same combina-

tion provided a 28-day strength

EZ-3B 100 (150)

equal to 77% of the room tempera-

EZ-4B 100 (150)

ture control mixture. This was better

than with Pozzutec 20 alone in Phase

I where it provided a 5C (23F)

strength equal to only 65% of the

EY-11 100 (150)

room-temperature control mixture at

EZ-3B 100 (150)

28 days. Since neither of these two

freeze-point depressants are rou-

EZ-4B 100 (150)

tinely used by the concrete industry,

they were not considered further in

this CPAR project. However, it did

EY-11 100 (150)

appear that the low-temperature

range of Pozzutec 20 could be ex-

EZ-3B 100 (150)

tended by combining it with certain

EZ-4B 100 (150)

Western Governors University

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