| dc.description.abstract | Time and curing conditions may impact the strength and permeability of concrete. The strength and permeability of concrete with and without supplementary cementitious materials (SCMs) were evaluated as a function of specimen type, season during which construction occurred, and age. Three concrete mixtures were included in the study, a control mixture with 100% portland cement, a mixture with 35% replacement (by weight) of cement with slag cement, and a mixture with 25% replacement with slag and 15% replacement with fly ash. Pavement slabs containing each mixture were cast in the summer, fall, and spring, along with companion 4 × 8 in. cylinders, to determine the effect of seasonal variations in environmental conditions on the strength and permeability of concrete. Cylinders were cured in both the laboratory and the field, and cores were taken from each slab. Specimens were evaluated for compressive strength, void content using the boil test, and ionic conductivity using the rapid chloride permeability (RCP) test at ages of 28, 56, 90, 180, 360, and 720 days. Additional laboratory tests were performed to evaluate the correlation between diffusion coefficient obtained from ponding tests and void content, and ionic conductivity. The study demonstrated that cores and field-cured cylinders have lower compressive strength and greater permeability than lab-cured cylinders. Concrete cast during either hot or cold weather tends to exhibit lower strength and greater permeability than concrete cast closer to 70 degrees Farenheit; mixtures containing fly ash tend to be more affected by lower temperature at early ages. The use of SCMs, however, mitigates some of the effects of hot weather. The results of the boil test do not correlate well with diffusion coefficient or ionic conductivity. | en_US |
