Hydraulic Cement

[Bryan]

Hi Randy:

On occasion I use the product THORO Waterplug to cement rock together and to mount frags. The only problems I have ever encountered is a short lived diatom bloom. This is the list of "ingedients" from the MSDS.

Ingredient Name PORTLAND CEMENT (70-75%)
Ingredient Name SILICA, CRYSTALLINE QUARTZ (25-30%)
Ingredient Name CALCIUM HYDROXIDE (0-5%)
Ingredient Name CALCIUMCARBONATE (0-1%)


While at Home Depot the other day I noticed a product called DAP WaterPlug which is also a hydraulic cement. From the MSDS it has the following. Would you consider the fused calcium aluminate harmful.

01 Hydrated Lime 39445-23-3 1.0-5.0 %
02 Portland cement 65997-15-1 40.0-50.0 %
03 Fused calcium aluminate 65997-16-2 20.0-30.0 %
04 Crystalline silica 14808-60-7 20.0-30.0 %
05 Calcium sulfate 7778-18-9 1.0- 5.0 %


Thanks

[Randy Holmes-Farley]

Diatoms need silica to grow, and your cement (both of them) have a whopping amount of it, although it is hard to tell how much gets released to the water column. Nevertheless it isn't surprising that you get diatoms. If the diatom problem goes away, then the silica isn't a concern.

I do not know if the aluminum gets into the water. However, the Portland Cement also contains alumina, so both have it to some extent.

[Bryan]

Thanks Randy.

[Randy Holmes-Farley]

You're welcome.

Good luck. )