Rapid hardening problem in secant piles

[arawinda]

In our site, in which still secant pile construction in progress, we experienced concrete had been hardened rapidly (in less than initial setting time) in several piles along the boundary closer to sea. This pile line is about 120m from sea.

Could you please state possible reasons for this and how to solve it?

Please see map attached.

Thanks.

 

[hokie66]

I doubt the location along that one wall had the effect of premature hardening. Most likely concrete of the wrong mix design was used. Maybe they used the male pile mix instead of the weaker female pile mix.

 

[Ron]

Agree with hokie66...this is a mix design issue.....likely poor quality control by supplier.

hey hokie66....hope SLTA doesn't see this!

 

[arawinda]

But we tried with three different suppliers. at least one pile concreted from each supplier resulted in premature hardening.

 

[Ron]

arawindo...did you specify the mix design? Did you specify any controls on the concrete and its delivery? Did you specify field controls on the concrete? Did you check the soil conditions to see if they might affect the concrete?

 

[hokie66]

Ron, I think she already knows that I resist political correctness.

 

[arawinda]

Ron,

We are in the process of analyzing chemical in water and soil. Will come back soon once receipt of results.

BTW, what is SLTA?

 

[Ron]

Pay particular attention to chlorides and sulfates. Though neither should affect accelerated curing, the chemistry of cement/concrete is complex and various reactions can occur

 

[arawinda]

Hey friends,

Its me came with new problem.

Due to a mistake of rig operator, a set of 4 casings was fallen back into borehole.

Can you please suggest any suitable method to extract them out.

Top of casing set is at around 7-8 meters below the ground level.

This trouble is now becoming a real headache

 

[dik]

a caution... if both sulphates and chlorides are present, use a flyash type 10 and not a sulphate resistant cement. Sulphate resistant cement is contraindicated for chloride resistance.

How large a diameter is the borehole? >30"? Can someone go down a hole?

Dik