Published on 8/5/2018
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Concreting horror stories
Bad workmanship, mistakes, poor planning and an unregulated concrete market all contribute to concreting horror stories
Not all concreting projects go to plan. Often it can be due to poor workmanship, a problem exacerbated by the lack of regulation in the concreting industry. Lets have a closer look at how and why concrete pours can end poorly, and check in with some industry participants to hear their concreting horror stories.
Poor quality workmanship in an unregulated environment
In many countries there are no requirements for concreters to be registered with a body, association or governement entity. In fact, there is no government body to register with. This is a major problem in our industry. It is the number one contributor to the high number of horror stories we hear about.
The term ‘you get what you pay for’ is never more true than when applied to the trade of domestic concrete. The price of a job varies from concreter to concreter for a few reasons. The quality of the finish, materials used and method of preparation varies greatly from concreter to concreter. You would be shocked to know the variance in concreters’ experience, skill, materials they use. Concreters cutting back on materials right is an industry wide problenm to the detriment of many concreting customers. There is no requirement for a concreter to meet a set standard of finish set by law, as domestic concrete is not a regulated industry. Work practices vary from terrible to fair to very good, and as a result. More often than not there are simply not enough crew on hand to pour and place the concrete you require and perform your job to satisfaction.
Common mistakes made by concreting contractors
The quality of workmanship can have other detrimental effects.
Some common mistakes are :
- inadequate cover of reinforcement steel. Inadequate cover can lower steel’s resistance to corrosion. This is a very common problem;
- incomplete consolidation. Concrete is usually consolidated with a mechanical vibrator. Concrete being placed in forms should be placed in layers, with each layer being vibrated when it is placed. Placing too much concrete at any one area at a time, or failing to vibrate concrete adequately can result in incomplete consolidation, causing a honeycomb pattern;
Honeycombing due to poor consolidation
- creating cold joints. Cold joints are created when concrete is poured against concrete that has already hardened to some degree. This condition results in a weakened bond between the existing and the newly poured concrete;
A cold joint in concrete
- finishing the surface too soon. Troweling while the bleed water is still on the surface forces water back into the surface layer of the concrete. This increases the water-to-cement ratio and results in a concrete surface that is overly porous and of substandard durability; and
- improper curing methods or lack of curing. Improper curing can encourage cracking and reduce strength development.
Source : Nachi.org
Lets check in with some self confessed concreting horror stories from concreters and contractors at contractortalk.com
Early 80s....8 foot foundation wall with snap ties and cats heads.....Lumber supply truck shows up with first story frame.....Driver tries a single dogged drop......Banded lumber slides off wrong, slides down the bank and crashes into my freshly poured wall.
Believe it or not....no movement but a load of busted up lumber.
About 15 years ago I watched another builder pouring a big stepped house foundation. one of his young guys was in the stuff up to his knees wearing training shoes. I warned him to get out quick, wash down and get to the hospital, he just laughed and said it would be fine. Anyways, SIX weeks in hospital with second degree burns obviously wasn't fine.
Dont give me problems, give me solutions.
We where pumping a 100 CY+ foundation wall 14' deep using Doka gang forms with a high slump Super P mix one of the she bolts holding the end form to the previously pored wall snap lost about 30 Cy of concrete what a mess.
Years ago when I was part owner of a foundation repair/piling company we did a job where we had to lift the house and support it while we removed the foundation walls (they were toast - obviously poured using a small mixer over many days) form and repour a new foundation. We were pressed for time and found a guy that was willing to come down and set the forms for us on a Saturday (with our help).
He showed up two hours late and almost fell out of his truck when he opened the door (was up all night drinking). Because of our tight schedule we decided to use him anyway. Got it formed on Saturday and concrete came on Monday. Things were going great until we got to one of the corners (the forms blew out). So there's me and my brother with our butts against the excavated soil pushing with all our might with our legs to keep the plywood from totally falling away and trying to save whatever concrete we could. Funny thing is our other partner went for a coffee run and we were stuck holding the forms with our feet for about 15 minutes (talk about lactid acid build up - was like doing 300 squats with 300 lbs). When our partner showed up he quickly cut some lumber and made some braces to go from the forms to the excavated soil. The concrete truck had enough left over to top off what we had lost and after curing the corner bowed out badly but it was all under grade anyways (ugly but nobody would ever see it)...
This was an owner builder neighbor.
The driver pulls up to the job and the lady backs him up to a basement window. The lady tells him 5" slump and that her husband said to pour it in when he was ready. The driver mixes it up and the dumps in a couple of yards. Then stops and looks for some activity in the hole. He asks the lady if anyone was down there? She said her husband went to town and would be back in an hour or so. The driver whistled over to our crew and asked if we could help. We didn't have any tools or enough know how for that but we were able to knock and spread the pile around and convince her that she just couldn't leave a big pile of mud in the basement. She finally sent the truck back and papa came home a couple of hours later. This was before cell phones.
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Tags: bad workmanship cold joint concreting project honeycomb concrete horror stories poor formwork
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