Influence of Polycarboxylate Superplasticizer on the Properties of Cement-Fly Ash Cementitious Materials and Concrete

Abstract

Concrete materials often crack due to the temperature field caused by the early heat of hydration, affecting structural safety and normal use. To solve this problem, this paper proposes the method of incorporating polycarboxylate superplasticizer to improve its performance and explore the influence of polycarboxylate superplasticizer on the properties of cement-fly ash composite cementitious materials and concrete. Ordinary silicate was used to prepare cement-fly ash composite cementitious materials. Through isothermal conduction calorimetry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and other testing methods, the influence of polycarboxylate water-reducing agent on the heat of hydration of cementitious materials was studied. In addition, the hydration products and microscopic morphology of the cementitious materials were analyzed, and the changes in the concrete properties due to the addition of polycarboxylate superplasticizers were discussed. The results showed that the polycarboxylate superplasticizer could delay the onset time of the hydration heat peak of the slurry and reduce the hydration heat peak, inhibit the crystallization of Ca(OH)2 and AFt, improve the density of the slurry, and reduce the amount of chemically bound water. In addition, it could delay the overall hydration process of the cementitious material, where the adiabatic temperature increase rate and the early drying shrinkage rate of the concrete slowed down, and the mechanical properties and impermeability of the concrete improved.

Innovative self-healing concrete using polycarboxylate ether: a fused deposition modeling approach with 3D-printed polylactic acid vascular networks

“…This has the potential to enhance compressive strength. The polycarboxylate water-reducing agent (PCE) is composed of polymer backbones containing carboxyl groups, resulting in a substantial decrease in water content compared to conventional alternatives [44][45][46].…”

Polycarboxylate-based superplasticizer with added silica sub-microspheres for use in Portland cement materials

“…The carboxylate group present in the polycarboxylate may have the ability to easily form a complex with the hydrated Ca 2+ present in the cement, this increases the bond strength between cementitious materials and allows reducing the amount of mixing water needed, shrinkage in capillary and internal pore size, this translates into more compact microcracks that improve the resistance of the mortar (J. Chen et al, 2022). The compressive strength of SsM decreased slightly in 6.5 % at 3 days of cured , compared with RM, however, increased 13.9 and 3.6%, at 7 and 28 days, respectively.…”

Mechanical properties of recycled concrete aggregates with superplasticizer

“…They suggested that a number of criteria, including the properties of RCA, the presence of fines in RCA, and the required workability in mix design, are important in figuring out the best proportions for the replacement of Natural Aggregate (NA) by RCA. Concrete becomes more mechanically strong as the water-to-cement ratio is lowered, but it also becomes less workable [11]. Additionally, the workability of RAC is reduced by RCA's enhanced water absorption.…”