The job
Buildcorp is building a new apartment tower on Elizabeth Street in the Sydney CBD. As the structure and services came together, the job needed a concrete care crew for a lot of detailed work: coring for services, repairs to the concrete in the plant rooms, and new reinforced concrete hobs along balcony and slab edges on the upper levels.
Perfect Concrete Care has been on the job for Buildcorp since March 2026, starting with scanning and coring and moving on to the remediation and hob work from July. The work is still going, so this page covers it as at September 2026.
What the work involves
- Concrete scanning before coring, locating reinforcement, post tensioned cables and services in the slabs
- Core drilling through walls, slabs and upstands for services, including groups of cores through plant room walls, drilled wet with the slurry on a wet vac
- Drilling dowel holes into the existing slab edges and fixing new dowels and bars
- Breaking out slab edges to the reinforcement, then tying in new bars, setting straight and curved formwork and forming new reinforced concrete hobs
- Concrete repairs in the plant rooms: exposing and treating rusted reinforcement with a zinc rich primer, patching holes, and skin coating the walls
- Grinding and preparing surfaces ahead of the waterproofing, and removing old fixings and brackets from walls
What makes it hard
The upper level work sits inside the scaffold on a tower in the middle of the city. Every bag of repair mortar, every length of formwork and every tool comes up through the building, and the work has to fit around the other trades on each floor.
The hobs follow the building, not a straight line. Many of them run on a curve along the balcony edge, so the formwork has to be bent and set to the line, and the new bars have to land inside the finished hob with the right cover. Weather matters too: rain on an open balcony slab stops the pour and changes the day.
How it is done
Before any coring, the slab or wall is scanned and every position is marked. Cores are drilled wet with the slurry vacuumed as the crew goes. For the hobs, the slab edge is broken out to sound concrete and reinforcement, dowels are drilled and fixed, new bars are tied in, and the formwork is set to the line, straight or curved. The concrete is placed, finished and cured, then the forms come off.
In the plant rooms, damaged areas are cut back square and broken out to sound concrete, any rusted reinforcement is cleaned and primed, and the holes are patched and the walls skin coated so the next trade has a sound, even surface.
Lessons learned on this job
Every job teaches the crew something. These are the ones from Elizabeth Street so far, and we take them onto every remediation and hob job.
What worked
- Scan before you core. Locating the reinforcement, cables and services first meant the cores went in without hitting anything that mattered
- Measure twice before the formwork. Checking the hob measurements on site against the drawings before building forms saved rework on the curves
- Cut repairs square. Saw cutting the edge of every repair area before breaking out gives a clean edge for the patch and a better repair
- Prime the steel straight away. Treating exposed reinforcement as soon as it is cleaned stops new rust before the patch goes on
What is difficult
- Curved hobs. Bending formwork to a curve and keeping the bars in the right place takes more time than a straight run, so the programme needs to allow for it
- Existing bars in the way. Old reinforcement is rarely exactly where the drawings show, so new bars sometimes have to be moved to fit the formwork
- Materials up a city tower. Everything comes up through the building, so deliveries and hoisting have to be planned day by day
- Rain on open balconies. Wet weather stops pours and patching outside, so outside work is best planned with a weather check
Where the job is at
As at September 2026, the scanning and coring is done on the levels released so far, the plant room repairs and skin coats are under way, and new hobs have been formed on the upper levels, with more to follow as Buildcorp releases each area. This page will be updated when our part of the job is finished.
If you have something similar
Builders on new towers and refurbishments need concrete remediation, coring and new hobs done to the drawings, floor by floor. Have a look at our structural remediation, concrete repairs Sydney and concrete core drilling Sydney pages, or get in touch.
Remediation or hobs on your project?
Perfect Concrete Care acknowledges the Aboriginal and Torres Strait Islander people as Traditional Custodians of the country on which we live and work. We pay our respects to the Traditional Custodians and Elders past, present and future, and honour their connection to the land and ongoing contribution to society.