Over the last two centuries, concrete has evolved as an important construction material, exploited for a wide array of buildings and structures, today considered of cultural heritage significance.

The Qajjenza gas plant folded plate structure is one of a number of remarkable and unique structures in reinforced concrete that are increasingly recognised as key industrial heritage monuments in Malta. However, such recognition of heritage in concrete leads to a growing and urgent need for their protection and conservation.

There is a drive towards a greater understanding of values concerning culturally significant concrete structures. Concrete presents challenges with respect to conservation in view of gaps associated with the understanding of complex degradation mechanisms and advanced restoration requirements.

Such historic structures require conservation methodologies covering key stages from investigation, documentation and assessment to advanced techniques in restoration and monitoring. They present an important and unique opportunity in the recovery of industrial heritage, either through continued use of key assets after restoration or through adaptive reuse.

The underground naval water reservoir in Luqa continues to be used for the storage of water, while the newly restored 1930s water tower at the abattoir has been brought back into operation 90 years after construction following a conservation strategy.

A unique opportunity in the recovery of industrial heritage

Adaptive reuse of such assets presents an equally important approach, as in the case of the newly restored ex-Deutsche Welle radio relay station at Xrobb l-Għaġin, brought back into activity with the launch of the Wildlife Rehabilitation Centre within the Nature Park this month. Such structures demand advanced approaches and additional care in interventions to ensure that actions performed retain their cultural significance in the light of conservation principles.

The conservation of historic reinforced concrete structures is challenging but not impossible. The case of the water tower can, hopefully, inspire other future projects.

The reinforced concrete water tower built in the 1930s at the public abattoir had been set for demolition in 2010 due to severe and extreme degradation of the structure. It was not only spared demolition but was eventually restored and even brought back into operation as a reservoir in 2021.

New advanced technologies, including new self-healing materials, were developed and applied with complex restoration techniques and integration of sensor network systems.

Following the conservation project, it was eventually listed as a Grade 1 National Heritage Monument in 2021 and awarded for industrial heritage conservation. It today also serves as a University of Malta research station in new advanced cement-based composite materials and structural health monitoring.

The 1930s water tower at the public abattoir was set for demolition before it was restored in 2010. Right: The water tower after conservation, now listed as a Grade 1 National Monument.

Likewise, the Qajjenza folded plate presents unique opportunities for restoration and adaptive reuse of the ex-industrial facility. Any reinforced concrete structure on the coast requires care in appraisal and understanding of complex degradation mechanism that neces­sitate advanced methods for recovery and restoration with reference to sound conservation principles.

The Qajjenza structure covers a large unsupported span and was constructed in the late 1960s to replace an earlier structure built in 1958. It was designed by perit Godfrey Azzopardi, the same architect and civil engineer who was responsible for the landmark Fgura parish church, based on a reinforced concrete hyperbolic paraboloid.

Given its industrial legacy and the intrinsic characteristics of the unique structure itself, in the context of the limited number of similar structures on the Maltese islands, the Qajjenza folded plate structure at the gas plant site and its surrounding  merit urgent recognition and protection as industrial heri­tage and their conservation and adaptive reuse.

Perit Ruben Paul Borg is an academic, coordinator of the Industrial Heritage Platform, University of Malta, and honorary secretary of the Malta Industrial Heritage Association.