Superplasticized Concretes with Slag-Fly Ash-Portland Cement

Synopsis: Composite cements containing portland cement (50%), fly ash (25%) and slag (25%), all interground at a Blaine fineness of about 400 or 500 m2/Kg, were produced. Superplasticized concretes with a slump of 200-230 mm were manufactured by using sulfonated naphthalene (SN) or acrylic polymer (AP). The dosage of superplasticizers was a little higher (10 % more) when finer cements were used. The AP superplasticizer was more effective than that based on SN in terms of lower dosage (20 % less) and lower water-cementitious material ratio (10 % less) at equal workability. Consequently, higher compressive strength were obtained for concretes with the AP admixture rather than with the NS superplasticizer. The better performance of the AP superplasticizer with respect to the SN admixture was independent of the curing temperature (5 ° or 20°) at early (1 day) and later ages (28-90 days). All the concrete mixtures perform very well for the durability behavior in terms of lower CO2 penetration and chloride diffusion. However, due to the lower water-cementitious material ratio (0.29 vs. 0.32) concretes with the acrylic polymer are potentially more durable than those with the naphthalene-based superplasticizer