Curling behavior of natural hydraulic lime-cement mortars

A recently published paper aims to identify the parameters influencing the curling phenomenon, and to understand the influence of cement substitution by increasing proportions of Natural Hydraulic Lime (NHL) on the kinetics and the final curling magnitude.

Mason's trowel with mortar lies on the edge of a bucket.
The results of the study showed that NHL leads to a significant reduction in tthe curling's final amplitude and delayed its start time. Source: Voyagerix – -

The developed experimental approach shows that the curling is mainly driven by the progress of the drying front in the specimen depth. A common curve curling-drying depth is observed for all the studied mortars independently of their mix-design. Results also show that NHL leads to a significant reduction in the curling’s final amplitude and delayed its start time due to its influence on the microstructure of studied mortars.

Poroviscoelastic model for reproduction of curling evolution

Based on the experimental results and, mainly, on the spatio-temporal internal relative humidity evolutions, a poroviscoelastic model which incorporates well-accepted mechanisms for shrinkage is proposed. The model is able to reproduce the evolution of curling and to estimate the viscoelastic response of the studied mortars. The curling starts developing as soon as the material develops sufficient rigidity, and its magnitude is mainly related to the viscoelastic-aging modulus which is about the same for all the studied mortars.

The study is published in: Cement and Concrete Research Volume 117, March 2019, Pages 1-15.

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