Scientists have designed a “skin” that senses when concrete structures are damaged

Image: Bittbox via Flickr, reproduced under creative commons.

Concrete is pretty great, isn’t it? It’s strong, it’s cheap, it’s easy to use. Let’s hear it for concrete!

On the downside, though, it’s also prone to cracking – if there are swift changes in temperature, for example, or if it’s bearing too much weight. Cracks in concrete structure are annoying at the best of times, but if said structure is holding, say, nuclear waste, they can also be disastrous.

So a team of scientists from North Carolina State University and the University of Eastern Finland have developed plans for a “skin” that would flag up cracks or damage to the concrete’s surface. Their idea involves installing electrodes at the edges of a structure, then applying electrically conductive copper paint across the concrete. The electrodes would emit a constant, low-level current across the surface of the painted “skin”, monitored by a computer. If the surface was weakened, cracked or damaged, the paint would become less conductive, and the computer would sense a change in the signal. You can even analyse the data to produce a map of the damage.

Here’s a cracked piece of concrete, alongside a computer rendering of the damage:

Image: Aku Seppänen.

So far, the researchers have only tried the method out on small, 1m long pieces of concrete, but they’re hoping to test on bigger areas. Dr Mohammad Pour Ghaz, one of the paper’s co-authors, said the team were keen to show the method could work on “real-world structures”.


So what happened at Habitat III?

Habitat III's secretary general Joan Clos treated delegates to his famous performance of the Macarena. Image: Getty.

Habitat III – the United Nation’s global conference on the future of cities – has come to a close. About 30,000 people gathered in Quito, Ecuador, last week to discuss the key issues facing cities today and sign off on the New Urban Agenda – the global strategy which will guide urban development over the next 20 years.

For four days, the Casa de la Cultura Benjamín Carrión – where most of the conference events took place – buzzed with action. A range of diverse voices was heard in the conference precinct: from high ranking UN conference officials, to activists who fight every day for a more just city. UN-Habitat can take credit for a diverse and generally inclusive conference which delivered an optimistic – though somewhat ambiguous – outlook on the future of cities.

An inclusive conference

Efforts to make the conference inclusive – it was free and anyone could register – materialised in a big jamboree of all kinds of people interested in urban affairs (as well as complaints about long queues). The overall message of the conference emphasised the need to address social, economic and material inequalities in cities and urban areas.

Disadvantaged groups were widely represented at Habitat III. Most side events included representatives of the urban poor, such as organisations like Shack/Slum Dwellers International.

International organisations which had previously ignored the significance of cities in international development – such as UNIDO and the Red Cross – pleaded to join an increasingly popular (and highly lucrative) urban field.

Yet international experts often appeared oblivious to the enormous progress that the poorest urban communities have made to organise themselves and finance their futures. During the sessions, questions from Ecuadorian students raised eyebrows, pointing towards unexamined assumptions that international experts take for granted – such as what makes a city “smart”.

The New Urban Agenda

The main outcome of Habitat III was that UN nation states agreed on the New Urban Agenda (NUA): a non-binding document, which will guide policies over the next 20 years with the goal of making cities safer, resilient and sustainable and their amenities more inclusive.

The foundation for the 24-page document was a collection of papers written by six policy units, made up of experts from around the world. The NUA itself emerged from a consultative process, whereby UN-Habitat collected the inputs of a diverse community of urban scholars, leaders, planners and activists.

UN-Habitat director Joan Clos in action. Image: Ministry of Natural Resources, Rwanda/Flickr.

The key message of the NUA was “leaving no one behind”. This points towards a vision for the future of cities, where diverse urban aspirations of prosperity and sustainable development are linked by a desire for equality.

Yet the document did not escape criticism. Its reliance on experts generated scepticism about whether the NUA could actually integrate grassroots perspectives. Meanwhile, the consensual approach – which involved redrafting the NUA a total of five times – has led to the avoidance of polemic issues. For example, LGBTQ rights were excluded from the NUA at the request of a group of 17 countries, led by Belarus.

The impact of the NUA will depend on how it is put into practice. Neither the NUA nor Habitat III have clarified how the ideals outlined should be achieved. So for the moment, the text can be thought of as a series of important goals – the consequences of which will only become evident during implementation.

Urban leaders

The role of city governments in implementing the NUA was one of the big issues discussed at Habitat III. The World Mayors’ Assembly which preceded Habitat III asserted two key demands. One was that city, metropolitan and regional governments should have a seat at UN negotiation tables and be able to take decisions without the interference of national governments.

Barcelona Mayor Ada Colau takes the stage. Image: Jose Jacome/EPA.

The other was that mayors want direct access to international finance. Some proposed that 20 per cent to 25 per cent  of global finance for development – in instruments such as the Green Climate Fund – should be allocated directly to cities.

But the NUA is created by and for national governments. As a result, it often appears to prioritise the role of national policies which strategically coordinate urban development at the national level. This focus may become an obstacle for local governments seeking to implement the goals.

The right to the city

The consensus around the “right to the city” – an idea championed by Ecuador and Brazil – was historical. The “right to the city” generally refers to the capacity of urban citizens to influence processes of urban development, and make a city they want to live in.

Social movements have promoted the “right to the city” to denounce urban processes that generate injustices, such as gentrification, privatisation of public spaces, forced evictions and the mistreatment of urban refugees. But the inclusion of the “right to the city” in the NUA meant watering it down, because it is not explicitly recognised as a universal human right. Instead, the NUA merely encourages governments to enshrine the right to the city in their laws.

Contradictions are already beginning to emerge around the right to the city. For instance, one representative from the Senegal delegation kicked off a high level round table on financing sustainable urban development by explaining that informal settlements are often situated on high-value land. This value, he argued, can be cashed by local governments if dwellers are willing to relocate.

However, this representative did not explain that this means of gathering finances often entails local governments leading a process of urban gentrification. Research on forced evictions has documented the tremendous negative impacts that relocation has on the livelihoods and well-being of displaced people. This is just one of many contradictions which will become visible as the NUA is implemented.

Habitat III brought together thought leaders on the future of urban areas, fostering dialogue and collaboration. It will have a lasting impact on efforts to address urbanisation – one of the global challenges of our time.

Vanesa Castán Broto is senior lecturer in environment and sustainable development at UCL.

This article was originally published on The Conversation. It's part of a series on publicly funded UK research at the UN Habitat III summit in Quito, Ecuador. It is a collaboration between the Urban Transformations Network, UK Economic and Social Research Council and The Conversation UK. Read the original article.The Conversation