Comparative Study of Influence of Superplasticizers and Superplasticizer/Plasticizer Blends on Slump-loss

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Title: Comparative Study of Influence of Superplasticizers and Superplasticizer/Plasticizer Blends on Slump-loss

Author(s): A. Goncalves and A. Bettencourt-Ribeiro ,

Publication: Special Publication

Volume: 195

Issue:

Appears on pages(s): 321-334

Keywords: concrete; loss (slump); superplasticizer

Date: 7/1/2000

Abstract:
In order to obtain specific concrete properties for distinct applications on site, the use of blends of different admixtures should be considered. During the construction of a roadway bridge, with long and large piles in an aggressive chemical environment, a comparative study was made to analyse the effect of blending of a melamine-based superplasticizer with triethanolamine-based admixtures, and polycarboxylate with lignosulphonate-based admixtures by the other side, on the slump loss of a flowable concrete. The performance of a mixture of plasticizer/superplasticizer was compared with that obtained by the single use of the individual admixtures. A naphthalene sulphonate-based admixture was also investigated. The results show that blending of modified lignosulphonate with polycarboxylate based admixtures in lower dosages, produces a significant synergistic action that provides improvements on slump-loss, with only a small delay in the initial setting time. With polycarboxylate based admixtures it is possible to get significant slump retention without compromising the early strengths