Dry density–moisture relationship (MDD and OMC) in GeotechOS Lab

This course teaches you to do a dry density–moisture relationship test in GeotechOS Lab. You book in the test, screen the sample and choose the mould. You prepare and cure the portions, and compact enough points on each side of the optimum. Then you check the maximum dry density (MDD) and optimum moisture content (OMC). After review, the result goes on the report, and the CBR and field density tests use it.

What you learn

• What the MDD and OMC are, why they matter, and the stages of the test.
• How the oversize decides the mould, and how Lab checks it.
• How to record the curing, compact and type each point, and what Lab needs before it gives a result.
• How Lab fits the curve and finds the MDD and OMC, and what to check before you submit.
• How the result is reported and used, and what changes for the TfNSW methods.

Who this course is for

Laboratory technicians who do compaction tests in GeotechOS Lab, and the reviewers and approvers who check them. Know the test at the bench before you start. The course teaches Lab, not the method.

Take this course before the Soaked CBR course: a CBR is built on the MDD.

What you need

• A free GeotechOS account.
• Your laboratory's licensed copies of AS 1289.5.1.1 and 5.2.1, and the TfNSW methods it runs. The course gives clause numbers, never the standards' text, tables or limits.

How it works

Ask to join. Our team checks with you and your laboratory, then enrols you. Each module has short lessons and a quiz of four questions. Pass every quiz and read every lesson to get your certificate.

Questions

Does Lab draw the air voids lines?

Not yet. Lab draws the points and the fitted curve, with the peak marked. The reviewer judges the wet side of the curve.

How many points can I enter?

Up to eight. The method decides the fewest, and Lab tells you when the optimum is not straddled.