Many residential buildings currently under construction will face problems in 30 to 40 years due to defective concrete that is not being tested for durability, according to the president of local NGO Sustainable Built Environment Malta.
Speaking to this newspaper, University of Malta lecturer and architect Ruben Paul Borg said that, while concrete was tested for strength, its durability was often ignored and such tests were very rarely undertaken.
Low durability leads to corroding reinforcement and spalling concrete which, in turn, makes buildings less sustainable by shortening their lifespan.
This has significant economic and social implications, in view of the needs to repair or replace buildings and infrastructure.
The most high-profile, recent examples have been the substandard concrete structures supporting Mater Dei Hospital’s accident and emergency department as well as the ceilings of the dressing rooms at the Tal-Qroqq national pool.
The consumption of concrete was the second highest after water, Dr Borg said, and it was used in buildings and their foundations, as well as in infrastructure such as roads, bridges and quays.
Concrete has a massive impact on the environment due to the consumption of non-renewable resources, energy intensive production processes, transportation and importation of non-renewables such as cement, steel and aggregate. Every structure has a specific design life, after which it needs to be either demolished or dismantled, or better still rehabilitated to conserve resources and reduce construction waste.
The basis of it all is a respect for life cycle engineering
The material’s quality dictates its durability. The basis of the sustainable built environment concept lies in ensuring that a structure lasts longer, Dr Borg says.
“We can’t go without development. Let’s make it clear – in principle we’re against development in outside development zone (ODZ) areas. But we need development, as long as it’s sustainable. The basis of it all is a respect for life cycle engineering, where environmental and social impacts are assessed in conjunction with economic benefits.”
Last week, the NGO organised an international conference titled: ‘Europe and the Mediterranean - Towards a Sustainable Built Environment’, where the subject of sustainability was explored in comprehensive detail.
The use of concrete was continuously on the rise and was necessary for society to develop.
Although often viewed negatively, good-quality concrete was sustainable and could even include recycled industrial by-products to improve its properties. It could be manufactured with local materials, was flexible and easily cast to attain the required geometry, Dr Borg said.
Defects, however, may occur at some point along the manufacturing line and could stem from poor-quality ingredients and aggregates, wrong proportions in the mix, transportation methods, compaction methods, incorrect curing or poor workmanship.
Defective concrete does not adequately protect the steel reinforcements embedded within it, enabling elements such as humidity, carbon dioxide, chlorides and sulphates to permeate the concrete and degrade it.
There were genuine efforts to improve on the quality but certain gaps needed to be urgently addressed, Dr Borg said, highlighting the pressing need for regulations and guidelines in Malta to address quality control.
“We need a culture change to expect higher standards from our buildings and not to accept defects. This collective effort to improve quality needs to be endorsed by all the different stakeholders – not only architects and civil engineers but also contractors, developers and manufacturers.
“If we do not implement quality assurance with our materials and good design, we will face problems within 30 to 40 years’ time. No one bothers to test a building’s performance with time. People seem to be happy to just test the strength. But high strength does not mean high durability.”
Another defect inherent in many Maltese buildings emerges from a penchant for load-bearing walls, which are one of the basic forms of local construction. Such walls bear a load resting upon them by conducting its weight to a foundation structure.
These make our buildings very vulnerable to earthquakes and do not allow for flexibility in the building’s design since any alterations later during the lifetime of the building would need to be extremely extensive ones.
Furthermore, design for deconstruction can improve on resource conservation and reduce construction and demolition waste by enabling reuse – therefore more sustainable construction.
“If, at the design stage, one allows for the changing needs and trends of society, any alternations to a building would not necessitate major structural works,” Dr Borg said.