Strength and Durability of a 70% Ground Granulated Blast Furnace ...

Table 17- ASTM C 989 Reference Cement Requirements
Parameter
Level
Minimum 28 day strength(psi) 5000
Minimum Total Alkalies (%) 0.60
It should be noted that the project Type II cement’s strength and alkali content levels are
lower than that which is required by ASTM C 989 for the reference cement used for SAI
determination. And, sulfate of slag is allowed to be as high as 4.0%, which is
considerably greater than the level that was present in the slag used in this study. Thus,
reactivity of the cement-slag system could be expected to be lower than if a cement and
slag system with more slag activator content had been used.
Sand. The fine aggregate used for the mortar cubes was an uncrushed silica sand. It was
significantly finer than that required by ASTM C 778 64 . The extra surface area may have
been responsible for the increased water demands that were required to meet flow
requirements. Table 18 shows the C 778 sand requirements and the sand gradation used
in this study as reported from the supplier, U.S. Silica.
Table 18- Graded Sands
Sieve
ASTM C778
% Passing
This Study
% Passing
#16 100 100
#20 96-100 100
#30 99.9
#40 65-75 95.4
#50 20-30 80.4
#70 49.4
#100 0-4 15.4
#140 2.4
#200 0.1
The bulk specific gravity SSD was measured as 2.648 and the absorption was 0.1%.
Equipment
A detailed account of the batching, curing, and testing procedures, as well as the
equipment used, is included in Appendix A.
The batches were mixed in a 4.7 l [5 qt] Hobart mixer. The mortar was cast in 50 mm [2
in.] cube rigid steel gang molds of 3 cubes each. The loading device was a 890,000 N
[200,000 lb] Tinius-Olsen servo-hydraulic controlled universal testing machine with a 64
mm [2.5 in.] square bottom platen and a spherically-seated 90 mm [3.528 in.] diameter
upper platen.
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