Robotic spray coating of self-sensing metakaolin geopolymer for concrete monitoring

Abstract

Sensors and new materials can support optimised concrete maintenance, and produce the data needed to justify new, low carbon structural designs. While these technologies are affordable, the process of manual installation in a construction context comes with acute and unfamiliar risks to productivity, personnel safety, and confidence in the quality of workmanship. The installation of smart materials using robotics could address some of these issues, but there are few proofs-of-concept at the time of writing. Here, we present a robotically controlled process for spray coating geopolymers -a class of self-sensing concrete repair materials. By tuning mix design, robotic toolpaths and spray dispenser parameters, we show reliable and automated spray coating of 250 mm 2 patches in a laboratory setting. The cured geopolymer has a compressive strength of 20 MPa, and a bond strength to the concrete substrate of 0.5 MPa. Electrical interrogation of patches, via a set of four electrodes, produces strain and temperature measurements of the underlying concrete substrate with resolutions of 1 µε and 0.2 • C, respectively. This demonstration multifunctional material deposition using robotics is a step towards remote, traceable, and low-risk technology deployment across civil engineering sectors. This could support more widespread adoption of novel concrete health monitoring and repair systems in future.

A low-cost electrical impedance analyser for interrogating self-sensing cement repairs

“…For an extensive presentation of our work on robotic spraycoating of geopolymers, see [20]. Since the subject of this paper is interrogating the geopolymer patches, only a short overview of the deployment process will be provided.…”

“…In recent work, we have demonstrated the capability of both 3D printing [19] and robotic spray coating [20] of a metakaolin geopolymer for concrete non-structural repair with temperature and strain self-sensing capabilities. Impedance measurements were taken using a commercially available electrochemical impedance analyser.…”

Effect of Potassium Phosphate Content in Aluminosilicate Matrix on Mechanical Properties of Carbon Prepreg Composites

“…The variability of their composition makes it possible to prepare materials with different densities and viscosities, depending on which the type of material application also differs. The material can be poured into a container/mold [ 20 , 27 ], sprayed [ 28 ], painted [ 10 ], extruded (3D print) [ 29 , 30 ] or used as a bath (pultrusion) [ 15 ]. The fabrics, used in this study, can be soaked or coated with a binder.…”

3D printed self-sensing alkali-activated coatings for civil infrastructure

“…While it is common practice to incorporate conductive filler such as carbon fiber, carbon nanotubes, carbon black etc. AAM have seen numerous sensing applications without the use of conductive filler [5]- [7].…”

“…This has allowed for more complex designs and numerous applications. Apart from the fabrication of structural elements [13], [16] additive manufacturing has also been used in deploying coatings onto existing infrastructure [5], [7], for insulative applications [17], electronic packaging [18] and architectural purposes [19].…”