Our deepest condolences go to all those who have lost loved ones. The scale of this grief is beyond words, and there are no adequate expressions of comfort. All aid organisations have come together as one, continuing their work under the most difficult of conditions with extraordinary dedication. May they be supported in every way possible.
The loss we are bearing is immense. Yet it must be said clearly: the cause is not the earthquake alone. A significant part of the reason so many buildings failed is that they were not built to withstand it. Two materials form the structural backbone of any building: concrete and steel reinforcement. In this article, I want to draw attention to a specific and serious vulnerability in how concrete quality is currently monitored and how that vulnerability can be, and is being, exploited.
How Can the System Be Exploited?
Until a few years ago, independent private concrete testing laboratories were in operation. Concrete would be poured on site, and laboratories contracted by the building control authority would take samples for testing. A more robust system was subsequently introduced, under which samples are fitted with microchips and monitored centrally by the Ministry. However, this change caused most of the private laboratories to close, as the new costs made their operations unviable. Some regulatory adjustment may have followed since then, but to the best of my knowledge, the majority of those laboratories had already shut down.
The chip-based tracking system has provided a degree of assurance for concrete samples. But this is precisely where the real problem begins.
I have observed a clear deterioration in concrete quality compared to what was being delivered in earlier years. Rising costs may well mean that genuinely high-quality concrete is no longer being supplied at all. When concrete is delivered, samples taken from the mixer trucks are tracked by chip. In many cases, the seven-day strength test results come back below the required threshold. The site is not halted. The twenty-eight-day results then arrive, and they too fall short. Finally, core samples are extracted directly from the structure, and the results suddenly show the required strength.
I do not accept this as credible. The reason is straightforward: by day twenty-eight, concrete has already achieved approximately 99% of its final strength. If samples from the same pour produced low results at seven and twenty-eight days, it is not plausible that a core extracted from the hardened structure would show anomalously high strength. The tracking of core samples is not carried out with sufficient rigour, and it is entirely possible that a different core is being tested in place of the one that should have been. Nobody can verify this with certainty. Furthermore, concrete reaches 99% of its design strength by day twenty-eight; a result that falls short at that stage should not suddenly recover.
| Age | Percentage of Design Strength |
|---|---|
| 1 day | 16% |
| 3 days | 40% |
| 7 days | 65% |
| 14 days | 90% |
| 28 days | 99% |
The Core Sample Problem
Whilst concrete samples can be tracked through the chip system, there is currently no equivalent system for tracking core samples. Their integrity is left entirely to the discretion of the testing laboratory. The location from which a core is to be extracted is marked on a plan, photographed, and entered into the Ministry's system. But if a different core is subsequently broken and tested in its place, there is no mechanism to detect or prevent this. Who would know, and how?
What Must Be Done
The authorities who introduced the chip tracking system have a responsibility to investigate the pattern of low concrete test results with the utmost rigour. Is insufficient cement being used? Is there another cause? A dedicated working group should be established to examine this seriously.
We must also ask whether the laboratories testing core samples are genuinely breaking the correct ones, and we must put measures in place that make it unnecessary to ask that question at all.
In my view, the solution is clear. These laboratories should, where necessary, operate as officially accredited public institutions rather than private ones. The inspection unit responsible for overseeing concrete suppliers, which I have written about previously, should work alongside such a body as an integrated system.