“This concrete failed to reach even half of what is required. That is a catastrophe. It means collapse,” the labour department’s occupational health and safety manager Phumudzo Maphaha said.
He heads a three-man commission investigating the collapse.
The weak concrete was used in the portion that collapsed on November 19 last year, killing two people and injuring 29.
It failed to achieve the required strength of 30 megapascals (MPa) after 28 days of curing.
“The concrete could not even reach one third of what was required,” Maphaha said.
He was speaking during testimony of Roderick Raw, the Durban laboratory manager for Contest, a company which tested the concrete at the mall while it was under construction.
Maphaha asked why Raw’s laboratory had not raised the alarm over the test results.
Raw said the results would be sent to the builders, Gralio Precast (Pty) Ltd, and he assumed the person receiving them would take action.
He said Gralio never queried the test results.
Gralio mixed the concrete on site. Raw said he did not believe anything was wrong with the cement used, Lucky Cement.
He said concrete could be weak because insufficient cement was used, or too much water was added.
Raw said from the date Gralio contracted Contest in June 2013 there were substantial variances in the strength of the concrete.
“These results are different from anything that I have experienced,” Raw said.
The concrete was tested at three days, seven days, and 28 days.
According to the design by the structural engineer Andre Ballack all concrete had to have a strength of 30Mpa after 28 days.
Bruce Zinn from Mega Pile, the company responsible for installing the piling that would have supported the mall, said during the construction he became aware that the load which some of piling would have to carry had been increased.
He said he had informed the engineers of his concerns.
One of the piles had a diameter insufficient to carry the weight of the structure, he said.
Earlier on Wednesday, the inquiry was told that Gralio was fined twice for failing to submit building plans and continuing construction despite being served with notices to stop.
Lungiswa Cemane, a law enforcement officer with the eThekwini metro municipality, told the inquiry that she visited the site on May 8 last year and told the foreman that the construction was illegal.
“We showed him the contravention notice and told him to stop building.”
She said a fine was issued to a site foreman for R2500 — R1000 for failing to comply with a notice to cease building and R1500 for building without approved plans.
She waited for the workers to leave, but when she returned the next day, found them back on the site.
She then issued another site foreman, Rajan Haripersad, another fine of R2500 and waited for the workers to leave. The fine issued to Haripersad was subsequently paid.
Building continued and she referred the matter to the eThekwini metro municipality’s legal department. She visited the site several times and took photographs which she submitted to the municipality’s legal department.
She sent a letter from the city’s legal department to the developers.
The commission is expected to prepare a report of its findings and formulate recommendations. These would be handed to the labour minister and National Prosecuting Authority for consideration.
The inquiry continues on Thursday.