Difficult sites and issues with vibrations are now a thing of the past thanks to an innovative product called Expando – it’s a non-explosive demolition agent, suitable for difficult sites where vibrations and noise are an issue and those with a high concentration of rock, or for confined spaces. Expando is your difficult construction site solution.
Expando, owned by local Australian company, No Blast, was used to excavate a site in Linley Point, NSW, that became one of Sydney’s largest and most innovative homes.
Terrible terrain and a huge amount of rock
The development began with the demolition of two neighbouring waterfront homes that were situated on a steep precipice of rock descending to the waterline at the southern point of the bay. The terrain the houses were built on and the sheer size of the development meant the removal of a momentous amount of rock. Excavation was set to take 15 weeks before it was cleared, levelled and ready for phase two.
So with a project of this magnitude, where do you start? Stephen Johnson, owner of SJ Constructions, who has taken on the planning, design and development of the home, begins: ‘For the first few weeks we went about the dig in the traditional way using an excavator but the noise and vibrations from the continuous thump of the excavator was affecting neighbouring properties so we stopped the dig and went about finding a less intrusive excavation method.’
Finding the solution
‘When water freezes, it expands – that’s why when water that collects in road cracks turns to ice in winter it enlarges those crevices into gaping potholes. I knew there had to be a man-made solution out there that behaved in a similar way so I started a Google search and found a non-explosive expansive mortar called ‘Expando’ from a local Australian supplier.’
‘The owner of Expando, John Rothwell, delivered the first load and demonstrated how to use it. It’s idiot proof really, easy to mix, non toxic so there’s no license requirement for careful handling and no OH&S issues.’
‘Because of the enormous scale of the project we wanted to make sure we had the best and most cost effective technique before we commenced, so we began experimenting with the size and spacing of the holes before we were satisfied we had the best method down pat.’
‘We started by drilling the holes and then we filled them at different times of the day so the rock cracked in sequence. We filled the holes at the face of the rock in the morning and worked our way backward. The face cracks and falls, then the next level back goes and so on. We then used an excavator once a day for final removal offsite; this reduced the impact noise and vibrations had on the neighbours and allowed us to continue working on the dig throughout the day.’
‘We used 20 kgs of Expando per seven 1.6 metre holes, 38 millimeters in diameter – that’s 2.3 cubic metres of rock removed per 20 kg box.’
This case study is a great example of why Expando is your difficult construction site solution.