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Construction Quality Alert

1) Concrete poured for a laser screed floor did not set for over 16 hours, causing delays to finishing. 2) The concrete mix design was not properly tested and the admixture was not stirred before use, likely contributing to the delayed setting. 3) The freshly poured concrete was dismantled without consulting experts, even though the concrete had gained strength after setting and delay does not necessarily impact strength.

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Kumar Abhishek
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251 views1 page

Construction Quality Alert

1) Concrete poured for a laser screed floor did not set for over 16 hours, causing delays to finishing. 2) The concrete mix design was not properly tested and the admixture was not stirred before use, likely contributing to the delayed setting. 3) The freshly poured concrete was dismantled without consulting experts, even though the concrete had gained strength after setting and delay does not necessarily impact strength.

Uploaded by

Kumar Abhishek
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Quality Management System

QUALITY ALERT Quality Alert # 21-009 dt. 11/05/2021


Doc No:-01000/JMC/JMCH20R/QA009

Concern: Dismantling of 175mm thick Laser screed flooring as finishing could not be done by Laser screed
Leveller because of delayed setting of concrete
Situation Analysis : Requirement of concrete for laser screed flooring was asked to maintain a steady slump of 130 mm
in first 3 (three) hours (?) and for smooth pumping of concrete, 160-180 mm slump was required. This was asked to
maintain ±2mm precision in floor level. During starting of 1st floor panel in night, lesser slump was observed and to adjust
the slump, re-dosing of PCE based admixture was done. The concrete thus prepared was poured in the floor and it got set
after 16 Hrs. By the time, customers and the specialised agency got panicked and disrupted the finishing of concrete and
asked to dig the freshly poured concrete. Finishing by floater was supposed to be started after 3 hours and before that, it
was to be levelled by laser leveller. Customers asked the contractor to break the floor and redo it. During breaking, it
was found that the concrete was homogeneous and had attained good strength after setting.

Concrete

Concrete not set after 12 hrs was distubed Concrete after setting in 16 hrs

Deviations:
 Design mix not made with sufficient timing to have due testing and checking for limitations. Because of
the time constraints, enough due diligence and limit checking on the mix design not done.
 Admixture not stirred just before starting batching plant and Mix correction done without due diligence.
 Hasty decision for disturbing and digging out concrete for delayed setting without taking expert’s advice.

Learnings:
 For any concrete especially with specific requirements to be inform by vendor in advance and just before
starting of the activity as happened in this case. Requirement analysis shall be done whether it is required
actually or vendor with his own understanding of partial knowledge is asking it.
 Batching plant restarting even after few hours of gap shall be done as per procedure for starting batching
plant. Admixture shall be properly stirred.
 Mostly , delay set does not reduce strength of concrete and in case of unplanned delayed setting of
concrete, concrete should be kept undisturbed.
 Situation Analysis and options shall be explored before concluding any action. Manual finishing could
have been done instead of electric floater finishing in the case.

This alert is published by Corporate Quality Head (email: rupesh.k@jmcprojects.com , Mobile 9428369702) with input
from Mr. Sunit to take a note of this and avoid such situation at Project site.

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