Compatibility of superplasticizers with different cements

The incompatibility between cement and chemical admixtures has increased over the last decade. Specifications calling for the use of admixtures in concrete often results in strange occurrences, i.e, rapid set, retardation, accelerated stiffening, etc. This paper presents the observations of a study on the effect of different superplasticizers with respect to the setting behavior and compressive strength. The hydration behavior of different cements at different time intervals (1, 3, 7, 28 and 360 days) in the presence of superplasticizers has also been analyzed by differential thermal analysis (DTA). The 33 grade ordinary Portland cement has shown retardation with naphthalene-based superplasticizer at the recommended dose (2%) of manufacturer, where as 43 grade OPC has shown retardation with blended polymer-based superplasticizer. Portland Slag Cement and 53 grade OPC has been found to be compatible with all the superplasticizers studied in the present investigation. (C) 2000 Elsevier Science Ltd. All rights reserved.