Natural mineral rheology modifiers for lime-based grouts

Natural mineral rheology modifiers for lime-based grouts

Abstract

The properties of injecting grouts are modified by various additives, the two most frequently used being pozzolanic additives to aid the strength development especially in the applications with limited air access and rheology modifiers responsible for good injectability, fluidity, and limited segregation. The most commonly used rheology modifiers are cellulose ethers used to increase viscosity and water retention, mitigating bleeding and segregation, and plasticisers/water reducers to improve fluidity and injectability while reducing the amount of water to values ensuring improved strength and durability. The work studies the effect of natural rheology modifiers on the rheology of lime based grouts. The modifiers used are attapulgite (palygorskite), montmorillonite, sepiolite, and wollastonite; three clay minerals and calcium inosilicate. These minerals affect rheology mainly though their fibrous structure, increasing thixotropy of the solution, improving suspension stability, and increasing yield stress and plastic viscosity. All the natural rheology modifiers studied showed promising results for further utilization in lime-based injection grouts. Sepiolite, in particular, may be suitable solely for its rheology modifying properties, while other additives seem to be more suitable as a combination of filler with added rheology modifying function and wollastonite, due the fibrous structure, also for improving the cohesion of the hardened grout. The rheology modifying function of thesethe additives has to be taken into account while using them in the injection grouts regardless of their main purpose in the mixture.

The properties of injecting grouts are modified by various additives, the two most frequently used being pozzolanic additives to aid the strength development especially in the applications with limited air access and rheology modifiers responsible for good injectability, fluidity, and limited segregation. The most commonly used rheology modifiers are cellulose ethers used to increase viscosity and water retention, mitigating bleeding and segregation, and plasticisers/water reducers to improve fluidity and injectability while reducing the amount of water to values ensuring improved strength and durability. The work studies the effect of natural rheology modifiers on the rheology of lime based grouts. The modifiers used are attapulgite (palygorskite), montmorillonite, sepiolite, and wollastonite; three clay minerals and calcium inosilicate. These minerals affect rheology mainly though their fibrous structure, increasing thixotropy of the solution, improving suspension stability, and increasing yield stress and plastic viscosity. All the natural rheology modifiers studied showed promising results for further utilization in lime-based injection grouts. Sepiolite, in particular, may be suitable solely for its rheology modifying properties, while other additives seem to be more suitable as a combination of filler with added rheology modifying function and wollastonite, due the fibrous structure, also for improving the cohesion of the hardened grout. The rheology modifying function of thesethe additives has to be taken into account while using them in the injection grouts regardless of their main purpose in the mixture.

lime-based grout; rheology modifier; rheology; flow properties; viscoelastic properties

lime-based grout; rheology modifier; rheology; flow properties; viscoelastic properties

ŽIŽLAVSKÝ, T.; VYŠVAŘIL, M.

01.09.2025

Edizioni Quasar

Roma

978-88-5491-636-4

7th Historic Mortars Conference (HMC 2025), Padova

581

583

3

https://hmc2025.com/wp-content/uploads/2025/07/HMC-2025_Book-of-Extended-Abstracts.pdf