Longtime Study of Concrete Durability in Sulfate Soils
Appears on pages(s):
air entrainment; beams (supports); blast furnace slag ;
cement factor; cement types; concrete durability; concretes;
long-time study; permeability; pozzolans; shales; steam curing;
sulfate soils; tricalcium aluminates; water cement ratio. --
Eleven year performance data are presented for concrete beams stored in sulfate bearing soil in Sacramento, California. Concrete variables include ASTM cement type, cement factor, air entrainment, pozzolanic replacements for cement, portland blast-furnace slag cement, and steam curing. Results reaffirm the importance of cement type, that is, the tricalcium aluminate content of the cement and, more significantly, cement factor with attendant change in water-cement ratio on resistance to sulfate attack. In this study, the use of 40% replacements of cement by high alumina granulated blast-furnace slags had a generally detrimental effect on concrete durability. Twenty percent fly ash replacements were beneficial in the leaner mixes but generally of little or no value in the richer mixes. Forty percent fly ash replacements were generally detrimental to sulfate resistance, particularly where Types II and V cement were used in richer mixes. Calcined Monterey shale showed similar trends but with a greater dropoff in durability in the richer mixes. Air entrainment and steam curing were beneficial to varying degrees.