The ministry of Science and Technology through the Synchrotron Light Research Institute (Public Organization) has successfully researched on the decay of household walls, leading to concrete quality improvement as a preventive measure to future decay.

Household wall decay at first glance seems quite harmless, but if neglected by the owner may result in structural damage of the house in the future.  Dr. Yingyos Poo-aporn, SLRI Beamline Scientist , principal researcher for “Synchrotron light and household wall decay,” said that his research began from observing his own home which was only 2 – 3 years old.  He noticed that some parts of the wall were decaying, so he brought the problem areas to be analyzed by synchrotron light through x-ray photoemission spectroscopy as well as x-ray absorption spectroscopy, to discover the components of the concrete problem spots, as well as their elemental and compound composition.

Analysis revealed that the decayed concrete had sulfur (S) in the form of sulfate (SO42).  If concrete or cement comes in contact with sulfate compounds, it will decay, expand, crack, and eventually compromise the structure. Further analysis realized that the sulfates discovered may have originated in the transformation of pyrite (FeS2), found in sand everywhere, as sand is the principal component of cement in house construction.

How do we solve this problem?  Initially, upon discovering decaying walls, the sulfate infected area should be excised.  An easy rule of observation is that the problem cement will have darker color.  Once excised, the area should be coated with new cement.  If the problem area is not excised completely before the new cement is coated, the decay can still occur and will grow further in depth.  “Subsequent research is to find the source of this type of sand, as to avoid using this sand in cement for construction, which will stem the problem of cement decay of household walls in the future,” concluded Dr. Yingyos.

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