Looking south for new ideas

The corruption scandals that put large construction firms on the front pages of newspapers across Brazil have had an impact beyond those companies’ own sector.

Demolition has suffered a big blow as well, with the market falling in the past two years.

“Without the big construction companies developing new projects, demolition companies have to look for other smaller industries, smaller,” according to Fabio Bruno, owner of the Brazilian construction business that bears his name.

Fabio Bruno is among the major companies in the country’s demolition industry, and one of its major innovators.

“I could not say that we are the first, but certainly we are among those who have the greatest knowledge and experience,” said Fabio.

Reinforced concrete
That experience was reflected in one of the company’s latest projects, in May, when the company was responsible for demolishing the Olivério Kraemer building in Rio de Janeiro.

A reinforced seven-floor concrete structure with masonry almost 26 metres (85 ft) high, its demolition was made more complicated by the proximity of the Albert Schweitzer hospital only 40 metres (130 ft) away. Conventional demolition would have taken a long time and involved moving patients, so the company suggested an implosion.

“We have performed other complex projects in Brazil before, so we were able to convince everyone that this would be the best option. However, to proceed with it would mean we had to overcome several challenges.

With the patients remaining in the hospital while the implosion took place, it was important that they were not scared by the noise, and also that dust from the implosion did not get into the projects.

A newly built dining room and an electrical substation – which could not be turned off – were also close to the implosion site, and 1,200 people within a 150-metre (492 ft) radius had to be evacuated.

The implosion was timed for 6.30 on a Sunday morning.

Work began with dismantling the inside and outside walls of the first three floors, along with the disabling of concrete stairs and lift shafts. The company drilled the pillars for the placement of explosives and prepared a fire plan.

This was sent to its partner at Applied Science International (ASI), the company in charge of simulating implosions for Fabio Bruno.

Overall, the implosion would need 47.5 kg of explosives in more than 500 holes.

Electronic fuse
The solution for minimising the damage to the environment, including the hospital, was the use of an electronic fusse to reduce air displacement and vibration.

This allowed each drill to be detonated at a specific time without using a detonator cord or exposed fuse. The demolition team also had the idea of lessening the contrast between the silence before the implosion and the noise during it by playing Beethoven’s Ninth Symphony for 20 minutes beforehand and then turning up the volume while the explosions were taking place.

“To protect the structures of the dining room and the substation, we used a metal coating and two water suppressors,” said Fabio.

“We also used an 80 x 40 metre (262 x 131 ft) screen next to the hospital to stop any dust that might pass through both the coating and the suppressors.

“After the implosion, we could prove that the dust did not reach the screen, which was completely clean.”

To measure the vibrations of the service location three seismographs are used. One in the Fabio Bruno offices, 13 m (42 ft) from the implosion with 6.05 mm sec; a second in access corridor to the hospital, 15 m (49 ft) from the implosion and 1.44 mm/sec; and the third in the substation of the building, 12 m (39 ft) and 5.73 mm/sec.

The surrounding area was reopened to pedestrians and cars at 7.20am.

Full service provider
In Chile, family owned company Flesan has, in a 30-year history, grown and diversified to become a full service provider including demolition, earthmoving, civil engineering and construction.
Executive director Emilio Salgado estimated that the company has been responsible for almost 95% of buildings demolition in the country.

The company, which has also operated in Peru for the past decade, turns over around US$170 million, of which $120 million is in Chile. Demolition accounts for 25% of Chilean turnover and 35% of that in Peru. According to Emilio, the Chilean market has become much more professional in recent years, encourage the company to diversify and invest in new technologies.

As a result of attending international trade fairs, it is now equipped with cutting plates, wire cutters, milling machines and shears.

“Incorporating technology is what sets us apart from our competitors,” said Emilio.

Among these innovations, he highlighted a Caterpillar hydraulic arm with a range of 26 metres (85 ft), which has enabled the company to demolish structures such as 10-storey buildings and silos.

“Due to the great Chilean earthquake [of February 2010] several structures collapsed, and there was a lot of work at that time,” he continued.

Today, Flesan is in the process of acquiring a similar arm for digging.

Examples of the company’s demolitions include the cinemas at Las Condes, Astor and Santa Lucia.

But the stand out is probably the demolition of the 5,000 sq m (16,400 sq ft)Diego Portales building in Santiago after it burned down.

The project was described as a “a huge metal structure collapsed on all slabs, with great engineering work and structural and lift calculations.”

It took two months.

Chile has no standard method of urban demolition using explosives.

While Flesan imploded the large structures in the projects it has worked on, demolishing homes is still done manually with chisels, hammers and similar equipment.

In any event, implosions are not always the best option for demolition in Chile.

“Because it is a seismic country, there is a lot of reinforced concrete,” said Emilio.

“Using explosives is not always cost-effective in the time available.”

This article is taken from the July-August 2016 issue of Demolition & Recycling International. To see the full article, including extra images, or to register to receive the magazine on a regular basis, please visit www.khl.com/subscriptions