Concrete fails the test in Chembur, raises larger concerns

On Thursday night, though, residents of Nitu Mandke Marg and Maharshi Dayanand Saraswati Marg in Chembur were pleased to see two trucks that had pulled up with RMC being sent back by additional municipal commissioner (projects), Abhijit Bangar

MUMBAI: Residents of two Chembur streets being concretised are assured of quality concrete, thanks to a spot inspection by civic officials on Thursday night. But the action raises more concerns than it allays – if the concrete meant to pave these two streets was found to be below par and had to be replaced, what of the hundreds of streets already paved?

Concrete fails the test in Chembur, raises larger concerns

The spot inspection in Chembur comes amid a variety of complaints from Mumbaiites regarding the mammoth road concretisation drive launched in 2023. The Brihanmumbai Municipal Corporation (BMC) launched the initiative in January 2023, issuing tenders worth ₹6,080 crore for 397km of road concretisation. Around 324km of roads in the eastern and western suburbs will be concretised in Phase 1 and 377km in Phase 2, with a deadline of May 31, 2025.

Across both phases, around 1,100km of roads will be excavated, rebuilt and paved with ready-mix concrete (RMC). Among the complaints from dismayed citizens are substandard paving of newly concretised streets.

On Thursday night, though, residents of Nitu Mandke Marg and Maharshi Dayanand Saraswati Marg in Chembur were pleased to see two trucks that had pulled up with RMC being sent back by additional municipal commissioner (projects), Abhijit Bangar. The concrete they had brought failed the slump test, which measures the consistency of concrete by assessing its workability, cement content and water content. The test is conducted using a cast, which is first filled with concrete. When the cast is removed five to ten seconds later, the concrete should have set. Concrete that doesn’t, or ‘slumps’, fails the test.

The slump test at Chembur revealed that the concrete transported from a ready-mix plant at Turbhe had a higher slump than it should have. It was sent back after consultation with experts from the Indian Institute of Technology (IIT)-Bombay, which is consulting with the BMC on the city’s road concretisation drive.

Bangar has issued a notice to the contractor and has asked the Quality Monitoring Agency (QMA), a private agency, to provide a clarification on the discrepancies in the concrete mix. To ensure the best results, the BMC has mandated that the slump test be conducted by the QMA at both the ready-mix plant and the work site.

“The problem appears to be related to the RMC plant. It seems to have occurred during the batching process, with the particular batch from the RMC plant showing poor quality concrete. This could be due to an unfavorable water-cement ratio. While this observation does not suggest that the contractor is responsible for similar issues at multiple locations, it is something that must be taken seriously. We need to ensure action is taken to create deterrence and encourage vigilance in the future,” said Bangar.

Considering the 30 to 90-minute transportation time from the RMC plant to the work site, he suggested that contractors prepare three different concrete mix designs. “The mix selected should depend on the estimated travel time, which can be determined using tools such as Google Maps. This strategy will help maintain the quality of concrete throughout the transportation process.” He has instructed civic officials to issue a circular detailing these measures.

Bangar reiterated municipal commissioner Bhushan Gagrani’s directive that engineers, including secondary engineers and assistant engineers, be present at work sites during night shifts. This will ensure their active participation in technical testing and oversight.

During the inspection on Thursday, Bangar inspected a road constructed using the ‘pre-cast’ method in the Godrej premises at Vikhroli. He proposed exploring the feasibility of using this construction method experimentally for future road work. He directed that discussions be held with IIT-Bombay to assess the possibility of implementing this technique.