Use for bio waste?

[smithw Senior Member Find all posts View Profile Close smithw]

just saw a doco on concrete, and the builder put 20l of his "secret concrete conditioner" into the truck just before the pour. He slipped up though and said that "glycerine" makes the mix more slippery so it flows better into the forms sets more quickly and gives a better surface finish. There was a shot showing him pour what looks like biodiesel glycerine into the mixer. Do you think that is what his secret concrete conditioner is?

[Captaincademan Senior Member Find all posts View Profile Close Captaincademan]

Re: Use for bio waste?

Sound like a twist on plasticisers that brickies use in mortar. Most plasticisers are very similar to a good strong detergent. The plasticiser helps the ‘workability’ of the mix.

As as for what it does for strength in curing though, I would not be using it in structural concrete. Probably ok for footpaths and the like.

[smithw Senior Member Find all posts View Profile Close smithw]

Re: Use for bio waste?

He was using it on a building, one of those god awful architecture designed concrete lego box McMansions.

[Dr Mark Senior Member Find all posts View Profile Close Dr Mark]

Re: Use for bio waste?

just saw a doco on concrete, and the builder put 20l of his "secret concrete conditioner" into the truck just before the pour. He slipped up though and said that "glycerine" makes the mix more slippery so it flows better into the forms sets more quickly and gives a better surface finish. There was a shot showing him pour what looks like biodiesel glycerine into the mixer. Do you think that is what his secret concrete conditioner is?

Bit hard to see how 20L in a truckload would make any difference

[Qwarla Senior Member Find all posts View Profile Close Qwarla]

Re: Use for bio waste?

Bit hard to see how 20L in a truckload would make any difference

You really think so?

Well try this next time you get to doing some concreting done. Chuck a 2 kg bag of sugar into the back of the truck and get them to give it a real got mixing. You should have lost of extra time to spread the concrete.

[Dr Mark Senior Member Find all posts View Profile Close Dr Mark]

Re: Use for bio waste?

You really think so?

Well try this next time you get to doing some concreting done. Chuck a 2 kg bag of sugar into the back of the truck and get them to give it a real got mixing. You should have lost of extra time to spread the concrete.

Sorry I don't understand the point you're making.

[smithw Senior Member Find all posts View Profile Close smithw]

Re: Use for bio waste?

I don't know how much he put in the back of the truck, the Doco showed him pouring a 20L container in for about 2 seconds but it could have been a diffent amount, they didn't say. He could of put 10 of them in, and edited it out, becuase it not that interesting watch someone pour stuff into the mixer.

[Dr Mark Senior Member Find all posts View Profile Close Dr Mark]

Re: Use for bio waste?

I don't know how much he put in the back of the truck, the Doco showed him pouring a 20L container in for about 2 seconds but it could have been a diffent amount, they didn't say. He could of put 10 of them in, and edited it out, becuase it not that interesting watch someone pour stuff into the mixer.

Yes, could be. Well of course the glycerol would be highly alkaline, the same as the cement, so it'd probably blend in pretty well

[Captaincademan Senior Member Find all posts View Profile Close Captaincademan]

Re: Use for bio waste?

I work for a builder. A commercial high rise builder. I am their design manager.

Trust me, if you are going to expect any sort of strength out of any concrete batch, its mix must be exacting.

Mortar that brickies use cures very soft, with very little structural integrity. It has a very low compression strength compared to structural concrete blends. It works as it 'pads' out the forces that the irregular shaped bricks provide.

accordingly, mortar mixes are pretty forgiving to the introduction of admixtures, hence the plasticiser.

However, structural concrete mixes are not. Qwarla's point about a small amount of sugar completely ruining an entire 8m3 of concrete is absolutely correct. the old heads that cart concrete and care for their builder usually have a bottle of fanta or coke in the cab, kept there just incase the builder is running behind or the batching plant sent the trucks too close together. a concrete brew is only able to placed if it is within 90 mins of being batched. if the trucks have to wait, just occasionally a driver will squirt some soft drink into the mix to stop it going off.

There are many factors in concrete design, not just strength. Resistance to carbonation, overall alkalinity, rate of cure, compressive strength at 7, 14, 28 days, resistance to surface stress etc etc the list goes on.

If you ask me, (and I have not seen the doco) i would be very surprised if the bloke knew what he was doing. very highly recommended to any one reading this, only put Sand, Aggregate and Portland cement in your concrete, and ofcourse reinforcing (the steel kind not bicycle frames, tin cans and corrugated steel roofing off cuts). Nothing else.

[Qwarla Senior Member Find all posts View Profile Close Qwarla]

Re: Use for bio waste?

Sorry I don't understand the point you're making.

The point is 2 kg of sugar in a 6 cubic metre truck load of concrete is enough to stop it from setting. So if you think 20 litres of byproduct would have no effect, then maybe you need to rethink it.