sulfur yellowing of CMU surface

[camptadma]

In a building still under construction, the ground-face CMU turned yellow over the winter in northeast US. The yellow was identified as sulfur, and is limited to the face of the CMU exposed to the building interior and not found within the CMU. Sulfur is also identified on the surfaces of mortar joints and caulk. Lots of tests done on water, soil, air, cleaners, paints, etc., as sources for the sulfur on site and within the enclosed area.

I was looking for information on the cumulative effects of combustion byproducts, such as exhaust and heaters, on the CMU. Wondering if some series of chemical reactions takes place on the concrete surfaces exposed to combustion gases. The sulfur on the caulk is worth a re-mention.

Any suggestions or recommended sources? Thanks.

 

[TomDupuis15]

The cube moulds of required size (150 mm for nominal size of aggregate not exceeding 38 mm) shall be made in such a manner as to facilitate their separation into two parts. Cube moulds shall be provided with a base plate and they shall be as per IS:10086-1982. The dimensions, tolerance and materials of cube moulds shall be as given in below

S.No. Description Requirements
1 Distance between opposite faces, mm 150 ± 0.2
2 Height of mould, mm 150 ± 0.2
3 Thickness of wall plate, mm 8
4 Angle between adjacent interior faces 90 ± 0.50
and between interior faces and top and
bottom plates of mould.
5 Length of base plate, mm 280
6 Width of base plate, mm 215
7 Thickness of base plate, mm 8
8 Permissible variation in the planeness of base plate, mm 0.03

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