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Building the future with self-healing concrete and biocement

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After water, concrete is the most widely used substance on Earth. With applications from housing and industry to coastal defence and infrastructure, concrete and cement are at the cornerstone of life, quite literally.

Unfortunately, the construction industry also has a major environmental impact. Cement production alone generates up to 8% of global carbon emissions, more than aviation (2.5%) although less than the agriculture sector (12%), according to one report.

Innovative thinking is needed to make construction materials more sustainable, while keeping them affordable and versatile. Some in the industry are using new technologies to make concrete ultra-durable, while others are turning to biology to make sustainable biocement.

New types of sustainable concrete are key to providing the foundations for other sustainable infrastructure, such as wind farms, said Professor Liberato Ferrara, a professor of structural analysis and design at the Polytechnic University of Milan in Italy.

‘If we think of all the needs that we have now for the energy transition, I would say that we cannot do this without concrete,’ he said.

Punishing settings

He led a project called ReSHEALience, which set out to develop ultra-high-durability concrete (UHDC). Such concrete is able to withstand extreme conditions and self-heal when used for construction in punishing settings like marine environments and geothermal energy plants.

‘These environments are among the most aggressive situations that you can have for concrete structures,’ said Prof Ferrara.

The tailored recipes are what gives these concrete mixes their strength and durability, including components such as crystalline additives, alumina nanofibres and cellulose nanocrystals.

Concrete inevitably cracks during its service life, but one of the features of crystalline mixtures is that they stimulate self-healing. By reacting with water and constituents in the concrete, they form needle-shaped crystals that grow to fill the cracks. The nanofibres mixed through it add mechanical strength to the material and help to enhance its toughness, allowing it to endure extreme conditions. 

UHDC has been tested as a durable substitute for traditional wooden rafts in mussel farming, and to make parts of floating wind-turbine platforms in coastal areas. It has also been tested in the harsh conditions of a geothermal power plant, where its performance improved on traditional methods of construction.

Its use in the restoration of an old water tower in Malta demonstrates the concrete’s potential for the maintenance of heritage architecture.

Sustainable material

‘The pilots are matching expectations from all points of view,’ said Prof Ferrara. ‘We succeeded in demonstrating that UHDC is intrinsically a sustainable material. It allows the use of less material to build the same structure, so in the end the environmental footprint and economic balance is better.’

The material slashes resource use both by reducing the amount of material needed in the first place and by lasting much longer, with Prof Ferrara predicting that it may have the potential to last up to 50 years before requiring significant maintenance. 

It can be produced in a wide variety of locations for many different applications using local materials. Moreover, crushed UHDC shows promise as a recycled constituent to produce new concrete with the same mechanical performance and durability as the parent concrete.

The increasing urgency of meeting sustainability goals calls for fresh ways of looking ‘holistically’ at construction, Prof Ferrara added.

‘It’s about spreading a new way of thinking for concrete structures’ that considers the whole value chain and service life of the planned structures, he said. ‘You have to think of the structural design, the procurement of materials, and the materials’ durability and life cycle. If you do not think like that, you will always have partial information and innovation will not break through.’

Biocement

Elsewhere, researchers are looking at quite different ways of innovating in the construction sector, harnessing the natural processes of living organisms.

For rail companies, the settlement of soils over time in embankments beneath railways can create serious problems and add to maintenance costs and passenger delays. 

Mechanical methods for firming up ground materials or chemical-based stabilisers are usually employed as a solution. However, these can be disruptive and costly, have environmental side-effects and generate carbon emissions.

The NOBILIS project is therefore getting bacteria to do the work, viewing the ground as a living organism rather than a nondescript mass to be moved by bulldozers.

The idea is that stronger soil, created through a process called ‘biocementation’, can reduce the need for earthworks and materials like concrete.

Bacteria-built

In the process of biocementation, the bacteria’s growth and metabolic activity are stimulated by providing them with nutrients and so-called cementing agents. The resulting enzymes produced by the bacteria catalyse reactions that ultimately form substances such as calcium carbonate, which bind the soil particles together.

The technique has been recognised as having potential in soil with larger particles, such as sandy soils, including forming beach rocks to protect against coastal erosion and for other applications in civil or environmental engineering.

However, a bigger challenge emerges with finer-grained soils like clay and peat, due to more restricted movement of bacteria, water and other substances. Undeterred, NOBILIS is seeking to explore ways to use biocementation on a wider range of soils.

Recent work in East Anglia, UK has demonstrated the possibility of biocementing peat soils. The NOBILIS project will aim to scale up this work through trials in the field, said Professor Maria Mavroulidou, a geotechnical researcher and project lead at London South Bank University (LSBU).

Paradigm shift

Prof Mavroulidou said this kind of biology-inspired approach requires new ways of thinking and faith in unfamiliar techniques.

‘To tell a practising civil engineer that you’re going to use bacteria to cement the ground raises eyebrows,’ she said, because it’s a paradigm shift for the industry.

Wilson Mwandira, an environmental engineering researcher, also at LSBU, said NOBILIS is investigating techniques to lock up carbon dioxide in the soil as biocementation occurs, as well as looking at the potential of using more indigenous bacteria in the process.

Using bacteria already present in the soil would avoid having a negative impact on organisms already in the environment, explained Mwandira. ‘If you bring new bacteria into a community, you are going to have a disruption in the system,’ he said.

The hope is that such biocementation techniques will become more widely applicable to construction work in general. ‘We’re also trying to extend the technique more generally to other geotechnical materials found in foundations under buildings and civil-engineering construction,’ said Professor Michael Gunn, a geotechnical engineer also at LSBU. ‘All construction requires some form of ground improvement.’

He thinks that it could take a number of years for the techniques to be used in a more routine way, but that it is essential such innovative methods are explored to address long-term challenges in construction.

‘A significant proportion of greenhouse gas emissions in the form of carbon dioxide is down to the construction industry,’ he said. ‘So we need to move away from the traditional processes.’

The research in this article was funded by the EU. This article was originally published in Horizon, the EU Research and Innovation Magazine.  

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‘Immensely bleak’ future for Afghanistan unless massive human rights reversal

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Women in a waiting room of a clinic in Afghanistan. © UNICEF/Alessio Romenzi

The international community must dramatically increase efforts to urge the de facto authorities in Afghanistan to adhere to basic human rights principles, a group of UN independent rights experts said on Friday. 

“The future is immensely bleak for Afghans if more is not done by the international community to ensure the Taliban changes its modus operandi and complies with its human rights obligations,” they said in a statement

The experts recalled that following the Taliban takeover last August, they had appealed for the international community to take “stringent actions” to protect Afghans from violations such as arbitrary detention, summary executions, internal displacement, and unlawful restrictions on their human rights. 

Failure to deliver 

“One year later, we reiterate this call,” they said. “Despite making numerous commitments to uphold human rights, the Taliban have not only failed to deliver on their promises, they have also reversed much of the progress made in the past two decades”. 

Moreover, the humanitarian and economic crisis in Afghanistan, which has already caused immeasurable harm to millions, shows no signs of slowing down. In fact, it is predicted to worsen, they added, partly due to the interruption of international assistance and the freezing of Afghan assets abroad.  

Attack on women and girls 

The experts said the Taliban have committed a “plethora” of human rights violations, with the virtual erasure of women and girls from society, as well as their systematic oppression, being particularly egregious.  

“Nowhere else in the world has there been as wide-spread, systematic and all-encompassing an attack on the rights of women and girls – every aspect of their lives is being restricted under the guise of morality and through the instrumentalization of religion. Discrimination and violence cannot be justified on any ground”. 

Regrettably, there is little indication that the human rights situation is turning a corner, they said. 

No confidence 

“Indeed, the daily reports of violence – including extra-judicial killings, disappearances, arbitrary detention, torture, heightened risks of exploitation faced by women and girls including for the purposes of child and forced marriage, and a breakdown in the rule of law – gives us no confidence that the Taliban has any intention of making good on its pledge to respect human rights.”

Citizens now have no means for redress as the Afghanistan Independent Human Rights Commission has been abolished, along with other independent oversight mechanism and institutions.  

The administration of justice has also been compromised. The applicable law is unclear, and judges and other officials have been replaced, which has especially affected women. 

Peace prospects dim 

The experts pointed to other violations, such as the curtailing of press freedom, and the rise in attacks on religious and ethnic minorities, some of which were claimed by the ISIL-KP terrorist group. They also and highlighted how journalists, activists, academics and artists have either left the country, quit their work, or gone into hiding.

Furthermore, in the absence of an inclusive and representative government, prospects for long-lasting peace, reconciliation and stability will remain minimal.  

“The de facto authorities seek international recognition and legitimacy. Regrettably, they continue to abuse almost all human rights standards while refusing to offer even a modicum of respect for ordinary Afghans, in particular women and girls,” said the experts. 

Most recently, the Taliban appeared to have been harbouring the leader of Al Qaeda. Ayman al-Zawahiri was killed last week in a US drone strike, which the experts said also raises concerns of a violation of international law.  

“Until it demonstrates significant steps towards respecting human rights, including by immediately reopening girls’ secondary schools and restoring their access to a quality education, they should not be on a path to recognition.” 

Action by the authorities 

In addition to honouring their international obligations, the experts have called for the Taliban to fully implement human rights standards, including respecting the rights of women and girls to education, employment and participation in public life.   

The de facto authorities should immediately open all secondary schools for girls, and lift restrictions on women’s mobility, attire, employment and participation. The rights of minority communities must also be upheld. 

The Taliban are also urged to “respect the general amnesty and immediately stop all reprisals against members of the former government’s security forces, other officials and civil society, especially human rights defenders, including women”. 

Furthermore, human rights monitors and humanitarians should be allowed free, unhindered access throughout the country, including to sensitive locations such as detention facilities.

They also called for the Afghanistan Independent Human Rights Commission, bar associations, and other relevant unions, to immediately be reinstated and allowed to operate freely and independently. 

International appeal

The experts also outlined steps the international community should take. 

They include insuring civilians have equitable access to humanitarian aid, and supporting ongoing initiatives by Afghan women towards a strategy to promote the rights of women and girls, with clear benchmarks and expectations. 

Countries are also urged to maintain and/or adopt sustained and robust humanitarian exemptions within sanctions regimes to ensure compliance with international human rights and humanitarian law.  

“Such measures should be fit for purpose, ensure that sanctions measures do not interfere with protected humanitarian action under international law, and function to remediate the current humanitarian crises and to prevent sanctions from continuing to exacerbate the humanitarian human rights crises being faced by the Afghan people,” they said. 

Role of UN experts 

The 20 experts who issued the statement were all appointed by the UN Human Rights Council

They include Richard Bennett, UN Special Rapporteur on the situation of human rights in Afghanistan, and other Special Rapporteurs who monitor and report on issues such as the situation of human rights defenders worldwide. 

These independent experts receive their mandates from the Council and operate in their individual capacity. They are neither UN staff, nor are they paid for their work. 

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IAEA: ‘Very alarming’ conditions at Ukraine’s Zaporizhzhia nuclear power plant

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image made from a video released by Zaporizhzhia nuclear power plant

The situation at Ukraine’s Zaporizhzhia nuclear power plant has deteriorated rapidly to the point of becoming “very alarming,” Director General of the International Atomic Energy Agency (IAEA) Rafael Mariano Grossi warned the Security Council on Thursday afternoon.

“These military actions near such a large nuclear facility could lead to very serious consequences,” Mr. Grossi said at the meeting requested by Russia, which was marked by resounding calls to allow the Agency’s technical experts to visit the area amid mounting safety concerns.

IAEA has been in frequent contact with both Ukraine and Russia to ensure that it has the clearest picture possible of the evolving circumstances.

Europe’s largest nuclear plant shelled

Providing an overview, the IAEA chief said that on 5 August, the Zaporizhzhia plant – Europe’s largest – was subjected to shelling, which caused several explosions near the electrical switchboard and a power shutdown. 

One reactor unit was disconnected from the electrical grid, triggering its emergency protection system and setting generators into operation to ensure power supply. 

The senior UN official said that there was also shelling at a nitrogen oxygen station.  While firefighters had extinguished the blaze, repairs must still be examined and evaluated.

No immediate threat

He said that the preliminary assessment of IAEA experts indicate that there is no immediate threat to nuclear safety as a result of the shelling or other military actions. 

However, “this could change at any moment,” Mr. Grossi cautioned.

Overarching goal

He recalled his recent address to the ongoing Tenth Review Conference of the Parties to the Nuclear Non-Proliferation Treaty, where he outlined seven indispensable pillars that are critical for nuclear safety and security.

These included aspects dealing with the physical integrity of the plant, off-site power supply, cooling systems, and emergency preparedness measures. 

“All these pillars have been compromised if not entirely violated at one point or another during this crisis,” flagged the IAEA chief. 

“Any nuclear catastrophe would be unacceptable and thus preventing it should be our overarching goal”.

He asked both sides to cooperate with the UN atomic agency. 

“This is a serious hour, a grave hour, and the IAEA must be allowed to conduct its mission in Zaporizhzhia as soon as possible”.

Trading Blame

Presenting his case, the Russian delegate said Ukrainian forces used heavy artillery against Zaporizhzhia on 5 August, shelling the plant during a shift change to intimidate staff – their own citizens. 

He upheld that on 6 August, those forces attacked with cluster munitions, and on 7 August, a power surge occurred, blaming. 

The Russian Ambassador blamed Kyiv for refusing to sign a trilateral document issued by IAEA, stressing that Moscow strictly complies with the IAEA Director General’s seven principles. 

In turn, Ukraine’s representative said that the withdrawal of Russian troops and return of the station to the legitimate control of Ukraine is the only way to remove the nuclear threat at Zaporizhzhia. 

The Ukrainian Ambassador insisted on the need to send a mission to the site and has negotiated modalities with the Agency. 

“Despite their public declarations, the occupiers have resorted to manipulations and unjustified conditions for the site visit,” he said. 

Given the militarization of the site by Russian armed forces, such a mission must include qualified experts in military aspects.

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Dozens missing after migrant boat sinks in Aegean Sea

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Volunteers help refugees arriving on the island of Lesbos, in the North Aegean region of Greece. (file) © UNICEF/Ashley Gilbertson

Dozens of people are said to be missing after a boat of migrants and refugees sank in the Aegean Sea on Wednesday off the Greek island of Karpathos, according to the UN refugee agency, UNHCR.

“Very sad news from the Aegean: Dozens of people are missing after a boat sank off the island of Rhodes this morning (Wednesday),” UNHCR’s office in Greece said in a tweet.

News media reported that the vessel sank at dawn after setting sail from southern Türkiye yesterday, heading for Italy.

29 rescued

A major search and rescue operation is underway,” said UNHCR.

According to news reports, the Greek Coast Guard said that an air and sea rescue operation saved 29 people, all men, from the waters between Rhodes and Crete.

The media also cited the Greek authorities in reporting that the rescued are from Afghanistan, Iraq and Iran.

The wrecked boat had sailed from Antalya, located on the southern coast of neighbouring Türkiye.

Still searching

News media quoted a Greek Coast Guard press official who said that those rescued affirmed that the voyage began with 80 people on board – so up to 50 are still missing.  

UNHCR confirmed the number of missing.

Deadly route

Since the beginning of the year, UNHCR has said that more than 60 people have died in the eastern Mediterranean.

Aegean Sea crossings between the Greek islands and Turkish coasts are often perilous – taking the lives of many migrants and refugees who travel on makeshift boats with hopes of arriving in Europe.

Since January, 64 people have died in the eastern Mediterranean, and 111 in 2021, according to data from the International Organization for Migration (IOM).

The last shipwreck in the Aegean Sea, which took place on 19 June, took the lives of eight people off the island of Mykonos, according to the IOM.

Every more deadly crossing

While the number of refugees and migrants crossing the Mediterranean to reach Europe is lower than in 2015, the journeys have become increasingly more deadly.

Throughout last year, the UN counted 3,231 migrants and refugees dead or missing in the Mediterranean Sea, and 945 people so far this year.

Successful voyages

At the same time, 70,325 migrants did manage to reach Europe, of which 65,548 individual crossings were reported in the Mediterranean, according to UNHCR.

Since the beginning of the year, Italy received the largest number of arrivals – 43,740, followed by Spain – nearly 17,000, Greece – 7,261, and Cyprus – 2,268.

Last year there were 123,300 arrivals, and in 2020, 95,800. Previously, 123,700 crossed the Mediterranean in 2019, and 141,500 in 2018.

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