Grouting issues cause of embarrassing crumbling in CBUS's Pantscraper construction project
Multiplex has pinpointed incomplete grouting as having caused crumbling of precast concrete columns at its $1.2 billion Collins Arch project.
The issue halted work at the Collins Street, Melbourne CBD work site of the CBUS project, nicknamed the Pantscaper.
The builder would not say how many columns had been affected or what levels of the 44-level twin-tower project had been affected.
The embarrassed super fund, which provides superannuation and income stream accounts to more than 790,000 members, prides itself as being a leading commercial and residential property developer across the country.
The concerns triggered an investigation by structural engineers.
"In limited locations the liquid grouting solution between the column and the floor slab has been found not to have fully penetrated, leading to minor spalling of the precast column edges," Multiplex said on Wednesday.
"The columns in question have since been remediated in accordance with the engineers’ recommendation and a full audit of all precast structural columns is expected to be complete later today."
The builder said there were no structural problems with the building, the design or the precast columns separating floors.
But is acknowledged that "spalling", or crumbling, of the pillars had occurred where pressure built up because the grouting was not evenly spreading the load of the column above.
RCP was appointed by Cbus Property in 2015 to project manage the redevelopment of 447 Collins Street, Melbourne. The quantity surveyor is Rider Levett Bucknall.
It is understood Cbus Property board members were briefed on the issue after the stopwork gained national attention on the Nine Entertainment website.
The Cbus Property board includes trade union construction boss Dave Noonan who worked as a builder’s labourer, and managed major union sites at several iconic Melbourne landmarks.
Noonan’s qualifications now comprise the RG146 for Superannuation.
Poor grouting was part of the problem at Sydney's troubled Opal Tower, from which residents were evacuated on Christmas Eve.
Along with the poor assembly of beams, there was also insufficient grout – concrete glue made up of water, cement, and sand – at the joints between the hob beams and panels, causing stress in the panels, the Opal investigation found.
Opal Tower also had unique construction challenges.
