It Shouldn’t Crack Like That, Should It?
By Pat Gurrie
(latest updates are at the foot of the article)
My answer is always NO! That is in response to a question I have been asked a number of times in the last 20 days in relation to the concrete pathway we recently had laid.
The concrete was poured on 18th October, which in Caroline Springs was a day of 21o C, no rainfall and moderate winds – almost perfect conditions. Three truck loads of charcoal coloured concrete were delivered, being two 7m3 loads followed by one 6m3 delivery. With 6 concreters on the job from 6am, the work was completed by 1pm. I checked it just after that and it was just damp to the touch but very solid. I checked it again when I came to Line Dancing that night and my hand was clean indicating that the surface dampness had gone (exactly what was expected).
Overnight there were a few light showers which all helped to initially slow the curing of the concrete. Next morning (Saturday), I arrived about 9am to lightly hose down the concrete to maintain a slow curing rate but found some fine hairline cracks in the main pathway opposite the middle Church window. With interest piqued, I looked for more and was aghast to find more fine cracks the closer I got to the car park. But wait there’s more! Turning towards the back of the Presbytery, I was confronted by a cob web of cracks from the corner to where the garden starts.
After consultation with the concreter, who was on-site cleaning up and recovering timber, a representative of the concrete supplier was contacted and called in. “A classic case of plastic shrinkage” was proffered by him which was quickly rejected by the concreter and myself with “Never seen that before” based upon 30+ years of full time concreting behind the professional and my 40+ years of part-time concrete experience gained from my full-time professional concreter father. I know that neither of us are mushrooms so we “should not be left in the dark and covered with….”
Photographs were taken and supplied to the representative and daily inspections have continued with another assessment undertaken on Thursday 24th October which indicated that most cracks were more prominent, wider and deeper than a week before and many new ones had emerged. More photographs were taken.
There has been some communication with the concrete supplier on both a semi-official basis and at grass roots level and a number of paths (pardon the pun) have been investigated on possible future processes available to the parish.
Two representatives of the concrete supplier inspected the concrete on Wednesday 30th at 9.30am and we then waited on a report.
The major problem that we have is that in order to cut the concrete to provide the blocks and also to cut expansion joints in the cob webbed piece of concrete, we need to use a highspeed concrete saw. Even in the hands of the cutting professionals we have engaged, the saw when it is in the proximity and parallel to one of these cracks or even when traversing across a crack, will attack the surface of the concrete to the extent that the surface will become severely chipped and even small chucks being ejected from it. The surface of the concrete would end up looking like the lunar landscape without the dust.
We are completely satisfied with the preparation and workmanship of our concreter as he and his team have poured many concrete paths and driveways in the parish over the last 8-10 years without a moment of concern at any time. The quality of their workmanship can be seen in this project as the white concrete laid on Monday 14th at the end of the 2.4m wide coloured path and the paver base laid on Tuesday 15th adjacent to the coloured concrete near the disabled parking are without blemish.
On 7th November, we received the report from the concrete supplier through the concretor. It referred to a phenomenon called “plastic shrinkage cracking” – once again a completely foreign and unknown term to the parish team. It also came to conclusions that we totally disagree with.
We have a lot of highly qualified trades people in the parish and plenty of others who are prepared to offer an opinion AND NOT ONE OF THEM think this concrete is acceptable. The only ones who seem to think it is excusable are the concrete supplier representatives.
We want this issue to be resolved expediently and with as little fuss and inconvenience as possible. But if that does not come to pass, we have options and strategies to go forward.
Update 20th November - After 12 days, there has not been any response from the concrete supplier or Cement Australia to our communications to them following their report on 7th November.
The parish has engaged an NATA accredited laboratory to investigate and analyse the concrete and provide a preliminary report.
On 19th November, a Sharp & Howells representative spent time on site, looking at the concrete, obtaining information, taking photographs and video and undertaking initial tests. All that information and data will now be examined and an initial report provided. That report will determine the next steps to be undertaken.
The parish has liaised with the Archdiocese Property Services and been advised that we have followed the correct dispute process so far.
This explanation will be updated as further details come to hand.