Setup of Extruded Cementitious Hollow Tubes as Containing/Releasing Devices in Self-Healing Systems

Abstract

The aim of this research is to produce self-healing cementitious composites based on the use of cylindrical capsules containing a repairing agent. Cementitious hollow tubes (CHT) having two different internal diameters (of 2 mm and 7.5 mm) were produced by extrusion and used as containers and releasing devices for cement paste/mortar healing agents. Based on the results of preliminary mechanical tests, sodium silicate was selected as the healing agent. The morphological features of several mix designs used to manufacture the extruded hollow tubes, as well as the coatings applied to increase the durability of both core and shell materials are discussed. Three-point bending tests were performed on samples produced with the addition of the above-mentioned cementitious hollow tubes to verify the self-healing effectiveness of the proposed solution. Promising results were achieved, in particular when tubes with a bigger diameter were used. In this case, a substantial strength and stiffness recovery was observed, even in specimens presenting large cracks (>1 mm). The method is inexpensive and simple to scale up; however, further research is needed in view of a final optimization.

A Review of Self‐Healing Concrete for Damage Management of Structures

“…Cementitious hollow tubes (CHT) having different internal diameters (2 and 7.5 mm) and a length of 4–5 cm were also produced by extrusion and used as containers and releasing devices for sodium silicate and potassium silicate solutions by Formia et al When tubes with a bigger diameter were used, load recovery indices up to nearly 70% and stiffness recovery indices up to 50% were reached, even in specimens presenting large cracks (>1 mm, Figure ). Moreover, multiple healing seemed possible.…”

Ultrasonic Monitoring of the Interaction between Cement Matrix and Alkaline Silicate Solution in Self-Healing Systems

“…In continuity with previous studies [8,47], the sodium silicate used was provided by Sigma Aldrich and was characterized by a 10.6 wt % proportion of Na${}_2$O, a 26.5 wt % proportion of SiO${}_2$ and a 62.9 wt % of water.…”

Behaviour of Pre-Cracked Self-Healing Cementitious Materials under Static and Cyclic Loading

“…Cementitious tubular capsules were produced in accordance with previous researches [22,[41][42][43] using a polymer-modified cement paste. The powder compounds of the paste were: First, all solid compounds were manually mixed, while all liquid compounds were separately mixed together with an overhead stirrer (RW 20, IKA, Staufen, Germany).…”

“…In the first manufacturing process, already used in previous works [22,[41][42][43], the fresh cement paste was manually extruded. This allowed to obtain ridged tubes of variable length with a hollow ovoid cross section (external diameter of 10 mm and internal diameter of 7.5 mm).…”