Effect of cross‐linked polycarboxylate‐type superplasticizers on the properties in cementitious system

Abstract

Fluidity and slump loss are main technical indicators for the quality of concrete. They are related to the dispersion of cement and hydration process, and are greatly affected by the structure of superplasticizers (SPs). For the purpose of obtaining SPs with excellent fluidity and slump retention, water-soluble cross-linked polycarboxylate ether copolymers (CLPCs) of acrylic acid and alkenyl alcohol type polyoxyethylene ether were synthesized. In order to gain full understanding of the effect of cross-linked SPs on the properties in cementitious system, properties of the new SPs in cement paste were compared to those of traditional ones without cross-linking agents. Mortar tests showed that CLPC performed obvious slow-release function and kept about 10 mm higher than its initial paste flow after 150 min, while PC incurred loss of 15 mm after 150 min. Adsorption of CLPC on cement resulted in zeta potential being roughly the same as that in the case of PC, and enabled more effective slump retention to cement suspensions by rheological property tests. Ettringite peaks disappeared for CLPC on 1-day curve and reappeared after 35 days, and the intensity of CH peaks for CLPC appeared weaker than Blank and PC after 1 day. The microstructure of CLPC after 1 day showed a very dense structure of smaller and thinner crystallites, which indicated that the early hydration was greatly delayed. V C 2014 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2014, 131, 40856.

Influences of design parameters on the properties of self‐compacting concrete produced with structurally different polycarboxylates

“…Liu et al proposed that the cross‐linked structures could affect generation of C‐S‐H that was gainful for concrete density and compressive strength. In the microstructure of hardened cement paste incorporating cross‐linked polycarboxylate, a very dense structure of crystallites and very few ettringite formation were revealed . In Figure , excellent superplasticizing effect and compressive strength reflection of cross‐linked SP for SCC were seen that is compatible with literature.…”

Synthesis and rapid cement hardening evaluation of polycarboxylate superplasticizers incorporating ester groups in their backbone chain

“…As can be seen from Figure , the compressive strength of the cement mortar containing ESPC2 was significantly higher than that of the PCE sample and the blank sample after curing for 12 and 24 hr. When the compressive strength data is combined with the SEM results, it is evident that ESPC2 can promote hydration more effectively than the conventional PCE during the cement hydration process, and produce more dense AFt and Ca(OH) 2 hydration products, which can enhance the compressive strength of the resultant materials …”

Comb‐like polymer with sulfo groups and its dispersion and rheological properties in aqueous ceramic suspensions

“…The decrease in the apparent viscosity may have been due to the structure and charge density of the copolymer and the ionized anionic carboxylic groups and sulfo groups, which had electrostatic interactions and steric hindrance effects on the kaolin particles …”