1.1 ,This test method covers the determination of length change of mortar bars immersed in a sulfate solution. Mortar bars made using mortar described in Test Method C109/C109M are cured until they attain a compressive strength of 20.0 ±, 1.0 MPa [3000 ±, 150 psi], as measured using cubes made of the same mortar, before the bars are immersed.