ASR Issues for reused concrete

[Okiryu]

Hi,

We will be demolishing some walls and would like to reuse the crushed concrete as base course for rigid pavements.

The concern is about Alkali-Silica reaction (ASR) that may affect the new pavement. What are your thoughts about this?

Is any guidelines that specify the allowable amount of alkali-silica in concrete, so it can be reused? What is the test that normally is conducted for checking this?

Thanks for your help.

 

[Ron]

If ASR issues did not show in the wall prior to demolition, it is not likely that you will have an issue afterward. There are several things you can do to test for ASR including mortar bar expansion tests and petrography. Also you can use fly ash in the concrete mix to reduce the alkali in the cementitious material.

 

[Okiryu]

Ron, good point about existing conditions of the walls...also, do you know where can I get guidelines to determine thresholds for ASR? Perhaps ACI?...

 

[Ron]

Okiryu....I'm not sure that ASR thresholds have been established. Usually when we find the potential, we try to mitigate without regard to the level. Since it is a localized reaction, it is hard to quantify.

 

[mbullism]

You might try these for background on tests and recommendations...

ACI 221.1R(98?) State of the art report on Alkali-Aggregate Reactivity (ASR and ACR)

ACI 232.2R(96?) Use of fly ash in concrete

ACI 233R(03?) Slag cement in concrete and mortar

 

[Okiryu]

Thanks! All the above is very good info! I was able to find the ACI reports. will take a look at them...