Comb polymers as blocking additives for swelling clays

A method for inerting a swellable clay and/or for reducing or inhibiting adverse effects of swellable clays on the effectiveness of dispersants in mineral binder compositions, comprising adding a comb polymer to a mineral binder composition,

• wherein the comb polymer comprises:
• at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups,
• optionally at least one anionic monomer unit MA,
• optionally, at least one non-ionic monomer unit M3,
• wherein the comb polymer, with respect to a total number of monomer units present in the comb polymer, comprises:
• 98-100 mol-%, of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1,
• 0 mol-%, of a cationic monomer unit MC,
• 0-1 mol-%, of the at least one anionic monomer unit MA, and
• 0-1 mol-%, of the at least one non-ionic monomer unit M3, and
• wherein the side chain-bearing monomer unit M1 includes a structure of formula I
• wherein
• R1, and R2, in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
• R3, in each case independently, is H, an alkyl group having 1 to 5 carbon atoms, or a group with formula
• m and m″=0, 1 or 2,
• p and p″=0,
• X and X″, in each case independently, is —O— or —NH—,
• R4 and R4″ is a group of the formula -[AO]n—Ra
• where A is a C2- to C4-alkylene, Ra is H, a C1- to C20-alkyl group, -cycloalkyl group or -alkylaryl group,
• and n=2-250.