Projects / 5/21/2025

Mapei technology at the service of history

This is how the products for the enhancement project of the southern ambulatories of the Colosseum were created.

The research and development of Mapei products for the repaving of the southern ambulatories of the Colosseum are the result of the joint work of the laboratories. This collaboration led to the formulation of a screed and an adhesive which are essential for the laying of the travertine slabs in the area of the southern ambulacra.

The research and development of Mapei products for the repaving of the southern ambulatories of the Colosseum are the result of the joint work of the laboratories. This collaboration led to the formulation of a screed and an adhesive which are essential for the laying of the travertine slabs in the area of the southern ambulacra.

The main challenge? Reconciling the need to use materials compatible with a context of immense historical and architectural value with the high standards of Mapei products. To meet this challenge, the researchers used technologies previously developed in Mapei laboratories replacing cement with more compatible materials such as NHL hydraulic lime and special hydraulic binders.

The work started about a year ago, when Mapei laboratories were asked to develop a product suitable for one of the most famous monuments in the world, with very stringent requirements.

The screed had to offer performance similar to conventional products but be totally cement-free. The adhesive, on the other hand, had to be suitable for installing natural stone, have a setting time adequate for use in any season, good deformability for outdoor applications, and adhesive properties comparable to the best products on the market. Additionally, it had to be able to support the weight of the travertine, be based on natural hydraulic lime and be white in colour to minimise the risk of staining the stones.

Some existing Mapei products had similar characteristics, but none met all the requirements. However, the work of Mapei's research and development laboratories succeeded in finding the solution.

Products

MAPE-Antique NHL Eco Massetto and MAPE-Antique NHL Eco Adesivo are the two products specifically formulated for this intervention. Both products belong to the renovation and restoration line and are CE marked - the first according to the European standard for screeds EN 13813 classified as CT - C16 - F3 - A1 FL; the second in compliance with UNI-EN 12004, classified as C2F - S1 to guarantee the performance of the adhesive. Both are distinguished by the total absence of cement, replaced with natural lime. MAPE-Antique NHL Eco Massetto is the result of Mapei's expertise in developing cement-free products, introduced to the market over 30 years ago with the Mape-Antique range. It is a mix based on natural hydraulic lime and recycled material, conceived for creating screeds before installing natural stone and stone materials, to be used in combination with gravel. The composition of the screed also makes it an innovative product with low environmental impact.

The product was formulated by adapting knowledge of natural lime-based binders to the need for a product suitable for the preparation of screeds: "Different formulations were carefully evaluated and tested. using different types and quantities of aggregate These mixtures were studied to optimise the product both in terms of application and performance," explains Marta Bovassi, R&D Construction Laboratory.

The challenge was to develop a product that was chemically, physically and elasto-mechanically compatible with the substrates and materials originally used, while also meeting the performance requirements of current standards. The product also had to be easily workable and applicable in various environmental conditions, including installation on substrates with a certain degree of slope.

Thanks to the use of special additives compatible with natural binders, a product was developed with suitable mechanical strength (compressive strength of 16 MPa) and dimensional stability, both essential for the durability of the intervention.

Additionally, the screed has similar setting times to traditional screeds and can be applied with the same laying and finishing techniques used for cementitious products.

MAPE-Antique NHL Eco Adesivo, on the other hand, was developed by reinterpreting Mapei’s quick-setting cementitious adhesives for installing natural stone (such as Keraquick Maxi S1, Granirapid and Elastorapid). In this case too, Portland cement has been replaced with natural lime, while maintaining high performance.

"We chose to combine traditional technologies, such as the use of hydraulic lime, with the most modern formulation techniques necessary to obtain a quick-setting adhesive, thus merging tradition and innovation into a single product," says Matteo Monaco, R&D Coordinator Cementitious Adhesives Laboratory. "The development of the adhesive required only minor adjustments compared to the first formulation we had envisaged”. The product obtained the CE mark as a deformable, rapid-setting, high-performance adhesive - an essential feature to guarantee flexibility and durability even in difficult conditions, such as outdoor applications on lime-based screeds.

A synergy of expertise for an outstanding result

Replacing cement with lime is not an easy task. Although perfectly compatible with ancient materials, lime has a longer setting time, an important factor that must be carefully considered when planning the work. For this reason, a quick-setting adhesive was chosen to compensate for the extended hardening time of the screed.

The development of these two products is the result of a collaboration between the building laboratory, the cementitious adhesives laboratory and the technical support team. The materials were developed in two distinct phases: in the first, the compounds were studied separately and quickly within their respective laboratories. In the second phase, the products were tested together to verify their effectiveness as a combined system. The tests simulated real construction site conditions to evaluate their response. In this phase, Mapei experts evaluated the entire system made up of MAPE-Antique NHL Eco Massetto, MAPE-Antique NHL Eco Adesivo and the travertine slabs, simulating different scenarios: different curing times, application or non-application of adhesive primers, screed covering and natural air curing. All these parameters made it possible to identify the most effective procedure to achieve maximum performance in the delicate setting of the Parco archeologico del Colosseo.