reduce compresive strength of concrete

Hi

it depends on the compositions of waste water. for instance if there is chlorine or sulfate the problem is different. most of the time Corrosion of the concrete and consequently the reinforcement bars are progressive and results are very disastrous. 

regards

 water between sub-base and pavement can cause pumping and then void and punch-out; chlorine (used to melt snow) can cause corrosion. some factors may endanger the interface between rebar and concrete and lend to debond.  debonding will make rebar useless and there will be  wider crack width and smaller crack space.

it deteriorate and corrode the reinforcement bars and reduce the bonding strength between concrete and RF bars.

Increases the humidity and then affected rebar rust and cause the collapse.

We can study this phenomenon using radar GPR

the corrosion impacts  are in relevance with the composition (quality -strength)  of new concrete (or condition of matured concrete) mainly

Hello Ahmed,

It all depends on the composition of the waste water. 

For example, some studies have shown that using waste wash water had not adverse effects on the concrete, and in fact it improved some properties:

http://umpir.ump.edu.my/2400/1/SAKILA_SABRIANI_ANK__EH_CHAN.PDF

The same thing could be said about stone slurry water. However, oil water had adverse negative effects. See this publication for more:

http://www.academia.edu/19679211/Effect_of_Waste_Water_Type_on_Concrete_Properties

For these reasons, it is important to know the kind of waste water being used.

Best wishes