Anti-corrosion solutions for interventions to secure the archaeological heritage: GRP structures

Within an archaeological site, operator access to diagnostic and observation activities must take into account various practical aspects, such as the action of corrosive agents, accessibility constraints, and the geological context.  Glass-Fiber Reinforced Polyester (GRP) solutions, such as temporary or permanent structures, are designed on purpose, in compliance with safety regulations, to effectively meet these needs.

This article examines a temporary GRP pedestrian walkway made for the French public institute INRAP – Institut National de Recherches Archéologiques Préventives (National Institute for Preventive Archaeological Research) by P-TREX, a business unit of Fibre Net spa.

Taking advantage of the benefits of using this composite material, P-TREX designs and develops solutions that ensure ever-higher standards of workplace safety in every area of application of its structures, the durability of which represents undisputed long-term cost savings.

Modular and temporary GRP structures for archaeological diagnosis with observation points

INRAP is a French public institution dedicated to research and placed under the supervision of the Ministries of Culture and Higher Education and Research. The purposes of this institute are to identify and undertake the scientific study of archaeological remains (on land and underwater) that might otherwise be destroyed by land development work.

In the case of diagnosis with observation for the detection of deeply buried sites, the operators need a structure that performs well in terms of mechanical strength, chemical resistance, and functionality. In fact, the application context involves its use outdoors—fully exposed to weather and chemicals—and at different sites, therefore frequently moved.

Why use GRP to ensure ever-higher safety standards?

Considering the specific operating conditions and parameters to be met, and in compliance with safety regulations, P-TREX’s design office has planned to develop a modular structure, manufactured entirely from GRP (Glass Fiber Reinforced Polyester).
GRP fabrications are characterized by their undisputed resistance to corrosion.

This characteristic makes GRP structures, whether temporary or fixed, more durable than the same ones made of traditional materials, without the need for special coatings, and therefore more convenient.

The proposed solution was the result of a precise preliminary calculation supported by in-depth analysis to verify compliance with European standards, providing the client with a complete project. The preliminary calculation, based on actual weights and measures, highlights the resistance to specific loads a

Design details

The footbridge is 10 meters long, consisting of two modules of 5 meters each. It is perfect for outdoor use, easy to move, and can be used in either single or double modules, depending on the specific surface requirements involved. Its components are:

• GRP pultruded profiles, characterized by high chemical resistance and mechanical capabilities; these characteristics, combined with the lightness of the material, result in significant savings in installation time and cost.
• Printed GRP grids, open and self-draining, are electrically insulating and therefore particularly suitable for industrial walkways.
• Guardrails, also made of pultruded GRP profiles; are easily installed and provide safety and protection during all operator activities.
• Pultruded profile sliding guide bars, inserted within the structure, to maintain horizontality in the 10-meter module.
• Practical system for lifting the structure, consisting of two U-shaped profiles on each side that allow steel cables to be attached to proceed with lifting.

The modularity of the walkway is an added value: where necessary a single module can be used by simply unhooking the side safety hooks. Furthermore, the modularity, along with the material’s renowned lightness, ensures extraordinary simplicity of installation and movement from one place to another.

Fixed GRP structures for conservative restoration and securing

Along the Via Appia Antica, after the “Quo Vadis?” church, are the catacombs of St. Callistus, among the largest and most important in Rome. They belong to a vast cemetery complex (about 15 hectares of land) consisting of a network of tunnels almost 20 kilometers long and articulated on different levels to a depth of about 20 meters. To make the Cubicle of Orpheus accessible to the technical staff of the Pontifical Commission for Sacred Archaeology and to scholars, a composite fixed structure was created, made of pultruded GRP profiles that are lightweight, strong, and able to withstand the aggressive conditions of high humidity of the Catacombs.