piles without cold joints

[merbas]

does anybody interested in piles (more than 50meters)without cold joint?

 

[drx]

I for one would be curious in knowing how that would be achieved.<br>
<br>
drx

 

[merbas]

you can use two way<br>
1.continously casting method.It requires tower crane and special concrete<br>
2.retarder way. You cast a part of pile then apply a surface retarder product on top of pile. The day after pile is strong enought to de-molding.Open mold and wash the top of the pile with high pressure water and find aggregate very rough then cast next part of pile.<br>
<br>
When you cast high but section is small coloums or piles, after vibration, concrete is settling and you find fine elements such as sand+cement+water mortar on the top. This is the weakest part of this kind of elements.<br>
<br>
Surface redarder is acting as retarder on the top and stop the setting period of mortar.When the day after you wash the surface with water, you remove this weak part of concrete and find rought agregate surface which it is ready to cast next part.<br>
<br>
Surface retarder alternate and cost effective solution, instead of mechanical abbrasion which cause damage the concrete body, because not set enought.

 

[ayfarm]

What I have done before is to drive/drill the closed ended pipe form to required tip/brg, then cast the conc/rebar next.