Table 16. Strength results from three trial admixtures in concrete
with a 420-kg/m3 (705 lb/yd3) cement factor and a 0.43 w/c.
Admixture
Curing
code name-dosage
temperature
Compressive strength--MPa (psi)
(C)
mL/kg (fl oz/cwt)
7 days
14 days
28 days
Control
20
36.0 (5216)
38.4 (5573)
42.0 (6083)
EY-11 100 (150)
20
35.5 (5152)
37.8 (5474)
39.8 (5767)
EZ-3B 100 (150)
20
33.6 (4876)
35.7 (5182)
38.1 (5526)
EZ-4B 100 (150)
20
33.0 (4782)
35.5 (5145)
37.7 (5470)
Control
5
2.8 (410)
3.9 (562)
4.2 (607)
EY-11 100 (150)
5
24.0 (3478)
27.2 (3942)
30.5 (4423)
Table 17. Phase III tasks.
EZ-3B 100 (150)
5
24.1 (3494)
30.1 (4371)
33.8 (4895)
EZ-4B 100 (150)
5
21.8 (3160)
28.0 (4060)
28.4 (4117)
Task
Description
1
Strength vs. temperature
Control
10
0.4 (65)
0.9 (135)
0.9 (127)
2
Corrosion potential
EY-11 100 (150)
10
5.6 (806)
7.6 (1107)
8.7 (1263)
3
Durability
EZ-3B 100 (150)
10
6.7 (973)
8.0 (1160)
10.0 (1448)
4
Equivalent insulation
EZ-4B 100 (150)
10
5.9 (861)
7.7 (1120)
8.1 (1168)
5C (23F), EY-11 promoted strength that ex-
somewhat higher strengths at 5C (23F) than
ceeded that of control concrete cured at 5C (40F).
with EY-11, and could have been a prototype al-
Figure 6 illustrates this result. In that figure, the
ternate for that reason, but it was discovered in
5C (40F) reference strength was based on guid-
time to be relatively unstable (i.e., it tended to
ance given in ACI 1988. For the 365-kg/m3 (611
precipitate out of solution) and was therefore
lb/yd3) cement factor, the EY-11 concrete exceeded
abandoned.
the ACI reference strength at all ages except for
28 days (Fig. 6a). However, this is not considered
a problem because the concrete has the potential
PHASE III: EVALUATION
of recovering full strength when brought back
OF IMPROVED ADMIXTURE
Procedure
The objective of Phase III was to more fully
Table 18. Compressive strength, MPa (psi), of
the EY-11 mixtures. The 365-kg/m3 (611 lb/yd3)
evaluate the best Phase II admixture. Phase III
cement factor had a w/c of 0.48 and the 420-kg/m3
used all Phase I procedures except for one: the
(705 lb/yd3) cement factor had a w/c of 0.43. The
critical strength test. Thus, Phase III consisted of
second number of the ID refers to EY-11 dosage.
four experimental tasks (Table 17). The proce-
dures used in this phase have been explained in
Age--days
Phase I.
Mixture ID
7
14
28
2,0,20
30.5 (4423)
33.0 (4785)
38.4 (5572)
Results and discussion
2,2,20
27.3 (3962)
31.4 (4550)
34.6 (5024)
2,3,20
27.5 (3988)
31.7 (4596)
34.0 (4933)
Task 1: Strength vs. temperature
2,2,5
14.4 (2086)
16.8 (2430)
18.9 (2745)
As was done in Phase I, the concrete was mixed
2,3,5
16.6 (2406)
25.4 (3690)
27.6 (3998)
at room temperature and immediately after cast-
ing placed into 20, 5, and 10C (70, 23, 14F)
2,2,10
4.8 (699)
5.6 (813)
6.7 (965)
2,3,10
5.9 (852)
8.8 (1283)
10.6 (1538)
rooms for curing. Table 18 shows the strength
3,0,20
34.5 (5003)
37.4 (5429)
39.4 (5718)
results for two cement factors. At room tempera-
3,2,20
30.7 (4456)
34.5 (4998)
37.8 (5479)
ture, EY-11 provided concrete of essentially the
3,3,20
32.2 (4671)
36.6 (5307)
39.7 (5761)
same strength as that of the control concrete.
3,2,5
19.4 (2808)
22.4 (3246)
24.2 (3503)
Though the EY-11 did not enhance strength in the
3,3,5
22.7 (3288)
27.6 (4005)
33.1 (4795)
way Pozzutec 20 is capable of, it did not interfere
with strength gain at room temperature, which
3,210
6.1 (887)
6.7 (968)
7.8 (1130)
3,2,10
7.5 (1081)
9.7 (1406)
11.3 (1638)
was an important consideration of this project. At
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