Optimization of Superplasticizer Type and Dosage in Fly Ash and Silica Fume Concretes


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Title: Optimization of Superplasticizer Type and Dosage in Fly Ash and Silica Fume Concretes

Author(s): M. Collepardi, S. Monosi, and M. Valenti

Publication: Special Publication

Volume: 119


Appears on pages(s): 425-444

Keywords: compressive strength; concretes; fly ash; optimization; plasticizers; portland cements; silica fume; Materials Research

Date: 9/1/1989

Purpose was to optimize the type and dosage of superplasticizer in concretes incorporating ASTM Class F fly ash, so that compressive strengths as high as those of superplasticized silica fume concretes could be obtained. Two types of high-range water reducers based on sulfonated naphthalene polymer (SNP) and sulfonated melamine polymer (SMP) both as 40 percent aqueous solution have been used in the presence of fly ash or silica fume to manufacture superplasticized flowing concretes containing ASTM Type I or Type III portland cements. The superplasticizer dosage and the pozzolan addition ranged from the 2 to 4 percent and from 12 to 20 percent, respectively, by weight of cement. The cement factor varied from 255 to 400 kg/m3. The results of the investigation work indicate that only in the presence of ASTM Type III portland cement, superplasticized fly ash concrete can be as strong as the corresponding silica fume concrete, particularly at relatively high cement factors ( ò 300 kg/m3).