Impact of zeta potential of early cement hydration phases on superplasticizer adsorption
نویسندگان
چکیده
The zeta potential of early hydration products of cement was found to be a key factor for superplasticizer adsorption. A highly positive zeta potential results in a strong superplasticizer adsorption whereas a negative zeta potential does not allow adsorption. Synthetic ettringite precipitated from solution shows a highly positive zeta potential, hence it adsorbs great amounts of negatively charged superplasticizer. Monosulfate (AFm) has a less positive zeta potential. Therefore, it adsorbs smaller amounts of superplasticizers. For syngenite, portlandite and gypsum, the zeta potential is around zero or negative. These phases do not adsorb superplasticizers. Consequently, a hydrating cement grain is best represented by a mosaic structure, with superplasticizer molecules mainly adsorbed on ettringite and some on monosulfate and C–S–H nucleated at surface. © 2007 Elsevier Ltd. All rights reserved.
منابع مشابه
The ettringite – superplasticizer interaction and its impact on the ettringite distribution in cement suspensions
Synopsis: In terms of workability of cement based materials, ettringite formation is of major importance. Thus, the interaction between polycarboxylate-ether based superplasticizers (PCE) and various pure cement clinker and hydrate phases is investigated by means of rheological, adsorption and zeta potential measurements. Microstructural analysis of fresh pastes is carried out using cryo-micros...
متن کاملThe influence of cement composition on superplasticizers’ efficiency
Fundamental interactions between polymeric superplasticizers and cement are studied. Cements with different alite-, belite-, C3Aand C4AF-contents are used. The use of commercially available superplasticizers like melamine formaldehyde sulfite(MFS) and β-naphthalene sulfonic acid formaldehyde-(NSF) resins is investigated. These superplasticizers (industrial products) are characterized by means o...
متن کاملStudy on the Structural Model of Calcium Silicate Hydrate based on Computer Simulation
Calcium Silicate Hydrate (C-S-H) is the main hydration product of Portland cement, it has an important impact on the properties of cement and causes a wide range of study. In recent years, superplasticizer, of which the main component is organic macromolecules, has become an important component in preparation for high performance concrete. Molecular dynamics simulation of cement hydration produ...
متن کاملPoly(carboxylate ether)-based superplasticizer achieves workability retention in calcium aluminate cement
Calcium aluminate cement (CAC) suffers from loss of workability in less than an hour (~15 minutes) after first touch of water. Current superplasticizers that are utilized to modify the viscosity of cement admixtures are designed to target ordinary Portland cement (OPC). The high affinity between these superplasticizers and cement particles were found to be detrimental in CAC systems. Utilizatio...
متن کاملThe Hydration Products of a Refractory Calcium Aluminate Cement at Low Temperatures
Calcium aluminates (CA) are the most important hydraulically setting cements used for preparing refractory castables, because they develop high strength at very early ages after placements. The anhydrous phases of this kind of cements are CA, CA2 and traces of C12A7 and alpha-alumina. The major hydraulic phase in all of the CA cements including ciment fondu...
متن کامل