Title:
A Summary of Important Characteristics
of Cement and Superplasticizers
Author(s):
K. Yamada
Publication:
Symposium Paper
Volume:
262
Issue:
Appears on pages(s):
85-96
Keywords:
adsorption; particle size; polycarboxylate; poly-naphthalene sulfonate; sulfate; superplasticizers; working mechanism.
DOI:
10.14359/51663224
Date:
10/1/2009
Abstract:
Significant numbers of studies on the working mechanisms of superplasticizers have elucidated many important characteristics of cement. However, because of the lack of general reviews, similar research activities tend to be repeated. Therefore, it is worthy to summarize a research on this issue based on the authors' experiences, including some unpublished miscellaneous but interesting
data, irrespective of its bias or imperfection. The first point is the effect of sulfate ions on the adsorption and dispersing performances of poly- naphthalene sulfonates (NS) and polycarboxylate-type (PC) superplasticizers. With the addition of cations that make insoluble salts with sulfate ion, the dispersing performances of both NS and PC are increased. This emphasizes the importance of absorption. The second point is the effect of carboxylic groups on the initial hydration. A PC with too many carboxylic groups accelerates the initial hydration of cement. This acceleration can be controlled by the addition of soluble sulfate salts. In this case, sulfate ions increase
the dispersing performance of PC. The last point is the importance of fine particles in ultra low water-cement ratio (w/c) range. There is a suitable range of particle size around 1 pm.