Control of slump loss in superplasticized concrete

The slump loss characteristics of concrete containing different amounts of sulphonated melamine formaldehyde (SMF) admixed with two types of polymers were investigated. The addition of 2% polymer to SMF retarded the slump loss. The setting times although retarded were found to satisfy the requirements of the ASTM standards.Addition of the polymer to a commercial superplasticizer formulation further extended its slump loss capability. The final setting times were within the limits specified by ASTM but the initial setting times were significantly higher than the specified ASTM limits.The control of slump loss in the presence of polymer may be related to the retarding action on the formation of ettringite from the C3A+Gypsum reaction in cements.