Title:
Direct and Delayed Dosing: A New Approach to Quantify Ineffective Superplasticizers
Author(s):
Shengnan Sha, Moghul Sirajuddin, Robert J. Flatt
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
394-411
Keywords:
superplasticizers, adsorption, addition, limestone, cement, direct and delayed dosing, D3 method
DOI:
10.14359/51740899
Date:
6/11/2024
Abstract:
It is well known that, in cement suspensions, the consumption of superplasticizers measured by solution depletion includes not only adsorbed and effective superplasticizers, but also those consumed uselessly by intercalation, precipitation, and/or micellization. This paper proposes a new strategy to overcome that experimental limitation: a two-step addition method involving the direct addition of PCE with cement and then the delayed addition of PCE with water and limestone. This is denoted as the "D3 method," which stands for "Direct and Delayed Dosing." The D3 method makes it possible to estimate the ineffective amount of PCE in cement paste due to the complex interactions occurring during early hydration. Results lead to the conclusion that the lost amount of PCE is proportional to the amount of PCE in direct addition to cement.
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