Significant roles of laboratory stress-strain tests of geomaterial for developments in geotechnical engineering research and practice are shown by summarising several recent advances in our understanding and modelling of the following properties of geomaterial: 1) quasi-elastic stress-strain behaviour; 2) rate-dependent stress-strain behaviour due to elasto-viscoplastic properties; and 3) strength and pre-failure stiffness of compacted soil related to field fill compaction control and design values of strength and stiffness. Several related findings obtained from laboratory stress-strain tests are presented and related issues of Geotechnical Engineering practice are discussed.