Treating concrete wash water

Mar 29, 2017

With focus on our pollution prevention objectives and our commitment to ISO 140001, we have purchased five of Siltbuster’s RCW (Roadside Concrete Washout) units to ensure that any concrete wash water put back into the ground will not harm the environment.

Why treat concrete wash water?

Water that comes into contact with freshly exposed or poured concrete takes on an alkaline pH due to chemical reactions between the water and free lime particles within the cement. While everyone is familiar with the dangers associated with acids, highly alkaline substances such as concrete wash water can be just as corrosive and if left untreated can cause concrete burns and damage to the surrounding ecosystem.

How it works

  • High pH concrete wash water is discharged from concrete mixer trucks chutes directly into the reception hoppers
  • The aggregate and cement fines are retained in geotextile dewatering bags and allowed to hydrate whilst the water bleeds through into the main storage chamber
  • A battery powered, automated digital pH controller monitors pH levels and automatically doses carbon dioxide to reduce the pH when an alkaline value is detected
  • Once the precipitated fines are left to settle the treated water (with a pH between 6-8) is manually discharged via a control valve and the treated water is then reused on site.