Concrete budget very slim

[Boby]

Hello,

I do not know if this question is appropriate for this forum, but here it is.

Would you know of a cheap concrete placing system apart from concrete pumps, buckets or conveyors for this kind of work. We have a tight budget and have to cast a local foundation to reinforce a retaining wall. The problem is that the pour is only accessible from the top of the retaining wall (road). The vertical distance to the pour is 14m or so. The concrete volume to go in the pour is about 400m3 and concreting time has to be minimised.

Any suggestions?

Thanks

Boby

[webmaster]

Hello Boby,

Suggestion, try with a self modified chute for example!

The concrete pour seems too big to be handled by crane and bucket, it would probably take you more than 24 hours with a standard bucket of 1m3 to get it poured.
A mobile pump with 30m3/hr output could do the job in say 15 hours to be practical. Two pumps would be better but than more mixing trucks would be needed and your budget might explode.
Conveyors are expensive and not practical for a single poor.

I guess the quickest way to handle this major poor would be to use a 12m chute held by a crane and directly supplied by mixing trucks. Standards do not allow free fall of concrete over such height as you know due to segregation of concrete. The chute should therefore be inclined (near to vertical if not enough place available) and you should put a feature at the end of the chute to dissipate the energy. The best dissipation at chute end is to incorporate a peace of chute which is creating an effect like on a ski jump, i.e. flip bucket. This bottom peace should be welded to the previous peace but do not over do the angle (i.e. for the jumping effect) as you would then only end up in blocking the concrete at the chute end. You therefore have to control the concrete quality and a more plasticised mix design would be helpful to minimise segregation or chute sliding problems. If the proper number of mixing trucks are available, this pour could be concreted in say 7 to 8 hours.

If you cannot fabricate (12m long pipe could do the job for example) or get a chute for this pour and alternatively do not want to use more than one mobile pump, than I guess you will have to prepare for a long 15 hours continuous pour with one single pump. To prevent such long pour, you could of course have a construction joint to split the pour in two smaller pours if agreed so by your engineers.

I hope above reflections on the matters are of any help.

[Boby]

Thanks for the chute idea! I have proposed this to the Project Manager and he decided to go for it, as we are having 20' old steel pipes in our stock which could do the job.

Great forum!

Boby

[webmaster]

A link to this query is placed in the "Work preparation and methods" forum.