No more than half the clay content should be expansive clays, with the remainder non-expansive illite or kaolinite.
nˈoʊmˌoːɹ ðɐn hˈæf ðə klˈeɪ kˈɑːntɛnt ʃˌʊd biː ɛkspˈænsɪv klˈeɪz, wɪððə ɹᵻmˈeɪndɚ nˈɑːnɛkspˈænsɪv ɪlˈaɪt ɔːɹ kˈeɪəlˌɪnaɪt.