Anti-clay agent: how it works with high-mud aggregate

Crushed sand and recycled aggregate often carry clay fines. Montmorillonite-type clay can adsorb several times its own weight of PCE superplasticizer, so the same dosage gives a different slump every day. Adding more PCE is expensive and brings slump and strength instability.

What an anti-clay agent does

Anti-clay agents are small cationic or amphoteric molecules that adsorb onto clay surfaces first, blocking the sites where PCE would otherwise be consumed. The PCE stays in the water phase where it belongs, and your dosage becomes stable again.

Diagnosing the problem

• Slump changes sharply when the sand pile changes.
• Admixture demand climbs while water demand looks normal.
• Fresh concrete looks sticky; 28-day strength drifts low.

A simple methylene-blue or sand-equivalent test on the fines confirms the clay level before you change the mix.

Dosing notes

Anti-clay agent is usually added as a separate stream or pre-blended into the PCE. Start at the dosage in the data sheet, verify with a 30-minute slump test on the worst sand you actually receive, and adjust only after confirming the clay level is stable.

See our anti-clay agent for typical solid content, dosage and packaging. Free samples with COA are available for a lab trial.