The zeta potential of cement and additions in cementitious suspensions with high solid fraction

Lowke, Dirk; Gehlen, Christoph

doi:10.1016/j.cemconres.2017.02.016

Cited by 102 publications

(29 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Pérez-Nicolás et al [27] indicated that air lime particles exhibited positive zeta potential values due to the positive charge of the portlandite crystals. In the presence of pozzolanic addition, the expected formation of C-S-H compounds has also been observed to yield high positive values of zeta potential: The negative charge caused by the silanol groups' (Si-O-H) deprotonation in the C-S-H phases is strongly sheltered by the adsorption of the Ca 2+ ions [27], recognized as potential-determining species [48], leading to a positive overcharging phenomenon.…”

Section: Properties Of the Fresh Groutsmentioning

confidence: 99%

Combination of Polymeric Superplasticizers, Water Repellents and Pozzolanic Agents to Improve Air Lime-Based Grouts for Historic Masonry Repair

et al. 2020

View full text Add to dashboard Cite

This paper presents the experimental procedure to develop air lime-based injection grouts, including polymeric superplasticizers, a water repellent agent and pozzolanic agents as additives. Our research focuses on the development of grouts to improve various characteristics simultaneously by combining different additions and admixtures. Aiming to improve the injectability of the grouts, in this study, different polymeric superplasticizers were added, namely polycarboxylated-ether derivative (PCE), polynaphthalene sulfonate (PNS) and condensate of melamine-formaldehyde sulfonate (SMFC). As a water-repellent agent, sodium oleate was used to reduce the water absorption. The enhancement of the strength and setting time was intended by using microsilica and metakaolin as pozzolanic mineral additions. Compatibility between the different admixtures and action mechanism of the different polymers were studied by means of zeta potential and adsorption isotherms measurements. Diverse grout mixtures were produced and investigated by assessing their injectability, fluidity, stability, compressive strength, hydrophobicity and durability. This research led to several suitable mixtures produced by using more than one component, to enhance efficiency and to provide better performance of grouts. According to the results, the grout composed of air lime, metakaolin, sodium oleate and PCE was found to be the most effective composition, improving the mechanical strength, injectability and hydrophobicity.

show abstract

Section: Properties Of the Fresh Groutsmentioning

confidence: 99%

Combination of Polymeric Superplasticizers, Water Repellents and Pozzolanic Agents to Improve Air Lime-Based Grouts for Historic Masonry Repair

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Nevertheless, given the high ionic strength, pH, calcium and sulfate concentration of the pore solution, these charges remain limited and the zeta potentials are in range -7mV -+12mV [39], thus triggering the flocculation. The zeta potentials of mineral additions such as quartz, limestone and fly ash also remain in this range [39]. Indeed, both cement hydrates and silica fume possess a small positive surface charge in spite of the high pH due to the high concentration of calcium [40].…”

Section: Effet Of Nano-silica On the Rheology Of The Cement Pastementioning

confidence: 99%

Effect of nano-silica particles on the hydration, the rheology and the strength development of a blended cement paste

Lavergne

Belhadi

Carriat

et al. 2019

Cement and Concrete Composites

135

View full text Add to dashboard Cite

The aim of the present work is to evaluate the effect of nano-silica (NS) on the hydration, the rheology and the strength development of cement pastes. The advance of chemical reactions is monitored by mean of isothermal calorimetry and thermogravimetric analysis: adding nano-silica particles speeds up the hydration of the cement paste but alter its workability. Indeed, the effect of the nano-silica particles on the hydration kinetics can be modelled by accounting for its high specific surface and a flocculation model based on the DLVO theory is proposed so as to investigate the stability of nano-silica suspensions in the fresh cement paste. As a consequence, the dosage of nano-silica can be optimized to promote the early age strength. Lastly, a ternary blend incorporating fly ash can be designed so as to provide an early age strength similar to that of the cement while lowering the induced CO 2 emissions.

show abstract

“…This molecular structure causes two complementing effects: The carboxyl groups of the backbone are deprotonated in cement typical pH range (~12.6) and thus negatively charged [6]. In aqueous suspensions, mineral particles show surface charges depending on several experimental parameters such as pH-value and electrolyte composition [7]. Beside van der Waals forces, this phenomenon is the basis for an electrostatic interaction between the charged polycarboxylate backbone and the surface of the particles, resulting in an adsorption of the polymers [8].…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Wetzel

Middendorf

2020

Materials

View full text Add to dashboard Cite

The adsorption of superplasticizer molecules to particle surfaces in cementitious systems is a very important aspect for the desired liquefaction of pastes and concretes. This way, the comb shaped polymers shield attractive forces between the particles and induce a well-dispersed, homogeneous suspension. These admixtures allow the usage of fine fillers even in combination with low amounts of mixing water, and thus, are the basis for modern high performance concretes. However, the adsorption does not cause beneficial effects only: The polymer covered particle surfaces, especially clinker, are hindered to interact with water, thus hydration is retarded. This is the reason for lower early strength and is very disadvantageous for certain applications. Today it is known that the molecular structure of the polymers, for instance the chain length and charge density, affects the retardation strongly. The complexity and diversity of cementitious systems is the main reason why research in this field is quite empiric and time as well as cost intensive. To investigate the adsorption of superplasticizers in various systems in-situ, a fluorescence microscopic approach was applied: By staining the polymers with fluorescent dye they become localizable and the adsorption quantifiable. This work shows the influence of molecular structure to adsorption characteristic of different polymers and the correlation to the retarding effect of superplasticizers, especially concerning the presence of silica fume, which is indispensable for ultra-high performance concrete (UHPC).

show abstract

The zeta potential of cement and additions in cementitious suspensions with high solid fraction

Cited by 102 publications

References 36 publications

Combination of Polymeric Superplasticizers, Water Repellents and Pozzolanic Agents to Improve Air Lime-Based Grouts for Historic Masonry Repair

Combination of Polymeric Superplasticizers, Water Repellents and Pozzolanic Agents to Improve Air Lime-Based Grouts for Historic Masonry Repair

Effect of nano-silica particles on the hydration, the rheology and the strength development of a blended cement paste

Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC

Contact Info

Product

Resources

About