Hydroseeding causing concrete damage? 1

[TehMightyEngineer]

We've had a few of our customers recently contact us about precast steps having spalling occur on precast steps following hydroseeding operations adjacent to the steps. This is the first I've ever heard of this being an issue.

Is there anything in the hydroseeding process that can harm concrete?

Only thing I could think of is the hydroseeding spray being slightly acidic but I would think it would hardly be acidic enough to harm the concrete.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[jayrod12]

I've seen this stuff applied on boatloads of boulevards around here and haven't noticed an issue with the adjacent curbs or sidewalks. Seems odd considering your concrete is likely of higher quality than what is used around here for sidewalks.

 

[TehMightyEngineer]

A few additional details, hydroseeding was applied months ago, areas that hydroseeding contacted concrete damaged the mortar for the brick finish and caused "pitting" of the concrete lower step.

As best we can tell it was indeed the hydroseeding causing this but I can't find anything in typical hydroseeding brands or MSDS sheets that could cause this. Best guess is some sort of sulfate in, or created by, that specific hydroseeding brand or the water used. Nothing else seems to fit the timeline or damage caused.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[btrueblood]

TME,

from this

http://www.cement.org/docs/default-...causes-of-concrete-deterioration.pdf?sfvrsn=4

on page 6 it states "The chlorides and nitrates of ammonium, magnesium, aluminum, and iron all cause concrete deterioration, with those of ammonium producing the most damage."

Most fertilizers that get mixed into hydroseeding solutions are nitrates in some form, and ammonium nitrate is quite common I think.

 

[TehMightyEngineer]

Interesting, I'll see if we can confirm that ammonium nitrate was used.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[SlideRuleEra]

Agree with btrueblood, ammonium nitrate fertilizer.

A minor family connection there. In the early 1930's (Great Depression) my father had just finished engineering school. Was lucky to get a job as an operator in high-tech industry - one of the first large scale chemical plants to extract nitrogen from air (atmospheric nitrogen) to manufacture ammonium nitrate fertilizer. This Haber Process has revolutionized fertilizer production, which in turn has dramatically increased agricultural crop yield.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[Ron]

Agree....ammonium nitrate is likely culprit.