concrete, ph concerns

[Guy]

I am breaking down ornamental walls in my garden at the moment. The stone is 'gritstone' and has often been mortared together or laid on to concrete bases. I plan to use the stones to wall the pond. With ph in mind do I have to concern myself with thoroughly chipping off all the cement based products from the stones?

 

[Meyer Jordan]

How old are these walls?

 

[Guy]

on asking neighbours I believe none would be younger than 10yrs

 

[Mucky_Waters]

I am breaking down ornamental walls in my garden at the moment. The stone is 'gritstone' and has often been mortared together or laid on to concrete bases. I plan to use the stones to wall the pond. With ph in mind do I have to concern myself with thoroughly chipping off all the cement based products from the stones?

Not sure what you mean by "using the stones to wall the pond" but I will assume you already have an existing pond and you plan to add the stones somehow.
I know that some people have PH concerns about putting concrete blocks in their ponds, but you know,,,, many ponds are made of concrete and they have no issues at all..
If you pour neutral PH water into a freshly poured concrete pond it may raise the PH of the water a little, maybe as high as 9. But it won't take long for the concrete to cure and loose it's ability to affect the PH of the water. Drain the pond and do the same thing a week later and it would probably only raise the PH to 8. Drain it and do it again in a week and 7.5, A week after that and it probably won't effect the PH at all.
Those rocks with the little bit of old concrete on them probably won't effect the PH at all, and even if it did (but it won't), providing you did it slowly (don't dump them using a loader), it won't harm your fish. Assuming that's what you are worried about?

 

[Meyer Jordan]

I agree with Randy for the most part. One thing that needs to be taken into consideration is the present pH of your pond. If it is already high, ~8.0, the old concrete/mortar will likely not really affect anything that much, but if the pH is closer to neutral, 7.0, some effect may be noticed unless, as Randy says, the rock is added gradually to the existing pond. The pH level should be monitored during the entire process. Any change over 0.5 during a 24 hour period may induce stress in your fish.

 

[Marshall]

My pond has a concrete bottom and does not cause me any problems but I did use hydraulic cement which contrary to what you would think should be more likely to cause problems but as I said it doesn't

 

[Meyer Jordan]

My pond has a concrete bottom and does not cause me any problems but I did use hydraulic cement which contrary to what you would think should be more likely to cause problems but as I said it doesn't

Is that bare concrete or did you apply a sealant or waterproof coating? And what is the pH of this pond?

 

[Marshall]

Is that bare concrete or did you apply a sealant or waterproof coating? And what is the pH of this pond?

The bottom is bare and is untreated because it is dense enough to not need a float coating. The ph is 7.0

 

[Marshall]

Is that bare concrete or did you apply a sealant or waterproof coating? And what is the pH of this pond?

Also it is technically cement and not concrete.

 

[Meyer Jordan]

Also it is technically cement and not concrete.

It becomes concrete if an aggregate is used.
This is a moot point in that it is unlikely that Hydraulic cement was used in the construction of these walls. Non-hydraulic cement and, especially, mortar have a tendency to lose structure when continuously exposed to constantly wet conditions, hence some possible initial leaching into the pond water. The older the concrete/mortar before being exposed the higher the possibility of leaching.
Should not cause any long term harm, but could induce a pH spike stressing the existent fish population.

 

[Mucky_Waters]

Actually it is very likely that Hydraulic cement was used in the construction of those walls. Hydraulic cements such as Portland are most commonly used in outdoor concrete or mortar applications (eg, sidewalks, rock walls, foundations, Stucco, pools or cisterns, etc). It uses water in their curing process, and the concrete product it becomes is very water resistant, though not necessarily water proof. How water proof the final product becomes depends a lot on what it is mixed with and in what ratios.
Non-hydraulic cement is used more commonly inside in plaster and drywall products, and it relies on carbon dioxide in the air (not water) to cure and the final product doesn't become water resistant.

 

[Meyer Jordan]

Actually it is very likely that Hydraulic cement was used in the construction of those walls. Hydraulic cements such as Portland are most commonly used in outdoor concrete or mortar applications (eg, sidewalks, rock walls, foundations, Stucco, pools or cisterns, etc). It uses water in their curing process, and the concrete product it becomes is very water resistant, though not necessarily water proof. How water proof the final product becomes depends a lot on what it is mixed with and in what ratios.
Non-hydraulic cement is used more commonly inside in plaster and drywall products, and it relies on carbon dioxide in the air (not water) to cure and the final product doesn't become water resistant.

I concede that hydraulic cement could have been use in these walls. There are many garden/landscape walls in my area that were definitely not constructed using hydraulic cement. Over the years the mortar/cement has suffered major disintegration.
Again, this is a moot point as the nature of the original cement/mortar used to construct the walls mentioned in this thread is unknown. Monitoring the pH level as these rocks are added is just the prudent course of action.

 

[Marshall]

Actually it is very likely that Hydraulic cement was used in the construction of those walls. Hydraulic cements such as Portland are most commonly used in outdoor concrete or mortar applications (eg, sidewalks, rock walls, foundations, Stucco, pools or cisterns, etc). It uses water in their curing process, and the concrete product it becomes is very water resistant, though not necessarily water proof. How water proof the final product becomes depends a lot on what it is mixed with and in what ratios.
Non-hydraulic cement is used more commonly inside in plaster and drywall products, and it relies on carbon dioxide in the air (not water) to cure and the final product doesn't become water resistant.

Actually hydraulic cement does not cure by water as normal concrete does...I know msounds weird but hydraulic cement is designed so thatr it cures underwater. You are misinterpreting the meaning of hydraulic vs say "wet"

 

[Mucky_Waters]

Actually hydraulic cement does not cure by water as normal concrete does...I know msounds weird but hydraulic cement is designed so thatr it cures underwater. You are misinterpreting the meaning of hydraulic vs say "wet"

LOL
I'm not misinterpreting anything, I speak from experience. My business deals with the application of cement and I've worked with it practically every day for the last 25+ years. You tend to understand a few thing about the stuff after a while.
If there is any such thing as "normal cement" in would have to be Portland cement which is basically hydraulic cement, and I assure you it will harden underwater.
Please don't take this the wrong way, I really don't mean to be rude or condescending, but I can tell you don't really understand what you are talking about. Please do a bit of reading and research on the subject. https://www.google.ca/?gfe_rd=cr&ei...ff&q=hydraulic+cement+vs+non-hydraulic+cement
If you order a batch of cement in a cement truck to pour a side walk or pour a foundation, or go buy a bag cement at the hardware store, they will give you hydraulic cement. "Cement that needs water to cure", and basically that's all that hydraulic cement means, as opposed to cement that absorbs CO2 out of the air to cure, which definitely would not be classified as "normal cement" anymore.

 

[Marshall]

LOL
I'm not misinterpreting anything, I speak from experience. My business deals with the application of cement and I've worked with it practically every day for the last 25+ years. You tend to understand a few thing about the stuff after a while.
If there is any such thing as "normal cement" in would have to be Portland cement which is basically hydraulic cement, and I assure you it will harden underwater.
Please don't take this the wrong way, I really don't mean to be rude or condescending, but I can tell you don't really understand what you are talking about. Please do a bit of reading and research on the subject. https://www.google.ca/?gfe_rd=cr&ei...ff&q=hydraulic+cement+vs+non-hydraulic+cement
If you order a batch of cement in a cement truck to pour a side walk or pour a foundation, or go buy a bag cement at the hardware store, they will give you hydraulic cement. "Cement that needs water to cure", and basically that's all that hydraulic cement means, as opposed to cement that absorbs CO2 out of the air to cure, which definitely would not be classified as "normal cement" anymore.

Condescending ? You just told me I know nothing about something I do 5 days a week... lol the irony