Title:
Performance of Superplasticizers in
Blended Cement Systems
Author(s):
I. Papayianni and F. Karkantelidou
Publication:
Symposium Paper
Volume:
262
Issue:
Appears on pages(s):
17-34
Keywords:
blended cement systems; fly ash; polycarboxylate; porosity; slag; strength; sulfonated naphthalene formaldehyde; superplasticizers; water/cementitious material ratio.
DOI:
10.14359/51663220
Date:
10/1/2009
Abstract:
The combination of different type of blending materials with portland cement such as natural pozzolans, fly ashes, and slags provides high flexibility in designing concrete mixtures with several technical advantages and low cost.
However, their addition influences the properties of fresh concrete and causes
problems of compatibility in blended cement systems containing superplasticizers that are usually used either for reduction of water demand or for increase of workability.
In this study, two of the widely used type of superplasticizers, one based on
sulphonated naphthalene formaldehyde condensate (SNF) and another based
on polycarboxylate polymers (PC), were tested with ten blended cement mixtures containing 20, 30, 50, or 80% portland cement replacement with one or more of the above-mentioned supplementary cementitious materials.
The action of superplasticizer on cement pastes was monitored by making zeta
potential, pH, and temperature measurements as well as by using DTA-TG method for determining the hydration and hardening process. Porosity and strength development were also measured at different ages. The aim of the research work was to find which type of superplasticizer was more suitable for each type of binder system.
The highest reduction of water demand was achieved with polycarboxylate polymer superplasticizer. Results show that compared to the plain portland cement system, the decrease of water/binder ratio with superplasticizer addition was lower in blended cements.