Kochi: In what could be a major setback to the Army Welfare Housing Organisation (AWHO), a study conducted by the Indian Institute of Science (IISc), Bangalore has expressed doubts over its plan to retrofit the Chander Kunj Army Towers (CKAT) at Silversand Islands, Vyttila, a residential complex built for retired and serving army officers which is in severe distress.
A team from the Department of Civil Engineering, IISc, which conducted a structural assessment of the buildings has concluded that it cannot recommend retrofitting as an option. The structures of towers B abnd C need to be demolished to avoid any casualties in the future, the report prepared by Professor J M Chandra Kishen states.
The IISc conducted the study based on an order by the Kerala High Court. The court ordered the study by the premier institute after a section of flat owners challenged the AWHO’s move to retrofit the residential towers as per the plan prepared by Bureau Veritas, a private firm engaged by the organisation. The IISc has submitted the report to the High Court. The court will be considering the case after Onam vacation.
The IISc report states that retrofitting can provide only a cosmetic make-up and the root cause of the problem will continue to be present even after the works.
“Retrofitting cannot be a solution to solve the major problem especially in a residential complex of this size. The main reason is that the cause of the problem which is the presence of chlorides in concrete causing corrosion cannot be removed. In the presence of chlorides in concrete the rate of corrosion of steel would increase leading to quenching of reinforcement and snapping. This may lead to higher levels of deterioration in the structure. By retrofitting we are only pushing the problem to only a certain extent, maybe 10-15 years. The sacrificial anodes which are used during retrofitting have a certain life of 10-15 years. These need to be replaced within their life span. If the rate of corrosion is very high, then they need to be replaced much sooner. The replacement process brings us back to the current situation -- retrofitting by chipping the cover concrete and replacement of the anodic devices,” the report reads.
The study has also expressed doubts over the quality of concrete used in the foundation.
The report states that the extent of retrofitting as spelt out in the BV report appears to be highly infeasible in terms of cost and time.
The estimated cost of retrofitting is about Rs 86 crore, according to the BV report. According to the IISc study, it may increase up to 25%. The IISc study says that there are many items that are underestimated in the BV report.
The IISc study pegs the estimated cost of new construction of similar nature at Rs 150 crore. “The cost of new construction is less than twice the cost of retrofitting. The life of the new structure would be significantly higher than the retrofitted one,” the report states.
The IISc findings go in tune with the conclusions of some earlier expert studies. A report prepared by Radhakrishna G Pillai, a professor of Civil Engineering at IIT-Madras and a team from Mar Athanasius College, Kothamangalam had recommended evacuation from the buildings in distress earlier. The AWHO has repeatedly rejected the findings of the purported IIT report, calling it unauthorised.
Later, a joint report submitted by engineers from various government departments also made similar observations and recommended evacuation.
Signs of poor construction started appearing in the 29-storey residential buildings soon after they were handed over to the owners in 2018.
