Quality control of precast elements and real-time monitoring of concreting using innovative
methodology
R. Narasimhan
Engineering Manager - CMPC
Transportation Infrastructure IC
L&T Construction
narasimhan@lntecc.com
Enabling structures engineer (CMPC), with 11 years
of experience in Construction methods. He has
experience in managing large infrastructure projects
of roads and elevated corridors. He is currently
managing the construction methods planning and
design of enabling structures for Dwaraka
Expressway and Tallah ROB
Abstract
Accelerated bridge construction techniques have now become a part of infrastructure industry wherein project
commissioning to completion is under stringent time limitation amidst other physical constraints at project
sites. Therefore, innovative design approaches and construction techniques are the key factors in deciding the
success rate of a project. In this context, precast construction plays a pivotal role in speeding up the construction
process. Many factors influence the quality of precast works such as compaction, workability, placing
temperature etc. Despite all the efforts, not all the precast elements meet the standards as expected by the client.
Few of the common defects include honey combing, formation of voids in precast segments due to poor
compaction, cracks due to shrinkage and creep etc. This paper deals with formation of voids in precast
segments and innovative testing methods to ensure the integrity of precast elements. Prevalent methods for
testing of precast elements include Ultrasonic pulse velocity test, rebound hammer test, cover meter test etc.
However, all these tests can be performed only after the formwork is removed and concrete has attained
minimum strength to perform the test. Due to this drawback there is huge cost incurred by contractors to do
the repair works in casting yard such as pressure grouting using epoxy or other high strength grouts. The
current study focusses on performing real-time monitoring of concrete pour when the concrete is still in
workable state and the formwork is intact. By monitoring the concrete pour using sophisticated digital tools,
any voids that are formed due to poor compaction can be rectified instantly and thus repair works on precast
elements can be drastically reduced. Studies suggest that 2% of the project cost is wiped off only due to poor
quality of precast works in infrastructure sector. Thus, this innovative method of quality control by real-time
monitoring of concreting during precast works could be a major breakthrough in project cost control.
Keywords: Precast construction, NDT testing, project cost control, concrete defects
Sensitivity: LNT Construction Internal Use