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control mixture was designed for a 28-day compressive strength of 5800 psi
without any fly ash. However, other mixtures were designed with various
percentages of fly ash as a partial replacement of cement. ASTM C618, Class
C fly ash from Pleasant Prairie Power Plant was used in these tests.
Table 4-19 shows the mixture proportions for the various mixtures, including
fresh concrete properties. For this study, the water-to-cementitious materials
ratio and air content for the primary mixtures were maintained at about 0.35 ±
0.02 and 6 ± 1%, respectively. The mixtures that did not meet these target
parameters were called secondary mixes. The primary mixtures were used to
make major conclusions, while the secondary mixes were used to study the
effect of air content on concrete strength and permeability (28).
The concrete mixing procedure was performed according to ASTM C192
procedures, and specimens were also cast in accordance with ASTM C192
“Making and Curing Concrete Test Specimens in the Laboratory” procedures.
Compressive Strength Test Results
Compressive strength tests were measured per ASTM C39 “Standard Test
Method for Compressive Strength of Cylindrical Concrete Specimens”
procedures. Air and water permeability was measured in accordance with the
Figg Method. Chloride ion permeability was measured according to ASTM
C1202 “Standard Test Method for Electrical Indication of Concrete’s Ability
to Resist Chloride Ion Permeability”.
Compressive strength results are shown in Table 4-20 and on Figures 4-10 and
4-11. Fly ash with up to 35% cement replacement and replaced on a 1.25 fly
ash per 1.00 cement weight ratio, showed results similar to the reference
concrete at a 3-day age. Beyond 30% cement replacement, the mixtures
exhibited lower compressive strength when compared to the reference
mixture. At the 28-day age the concrete showed strength levels comparable to
the control mixture.
We Energies 78
Coal Combustion Products
Utilization Handbook