Concrete strength classes

M7.5 lean concrete

A lean fill mix, a step up from M5. Used for levelling and mass filling where strength is not a concern.

Mix ratio

1 : 4 : 8

Cement : Sand : Aggregate

Proportions & strength

Designation	M7.5
Ratio (by volume)	1 : 4 : 8
Cement	1 part
Sand	4 parts
Aggregate	8 parts
Typical compressive strength	1,090 psi · 7.5 MPa
Typical use	Blinding, mass fill, non-structural pads.

Planning reference. Strengths are typical values for a well-made mix at 28 days, not a guaranteed design strength. Structural work must follow your local building code and a qualified engineer's mix design.

Where M7.5 is used

A lean fill mix, a step up from M5. Used for levelling and mass filling where strength is not a concern.

Nominal mixes like this are proportioned by volume on site and suit general and domestic work. Anything structural — reinforced, load-bearing or engineered — should use a design mix proportioned by weight from tested materials.

Need quantities? The volume calculators give the cubic yards, cubic metres and bag counts for the pour this mix goes into.

Same family

Other concrete strength classes

M51 : 5 : 10Blinding / levelling course under footings.M101 : 3 : 6Levelling courses, path bedding, kerb backing.M151 : 2 : 4Paths, patios, shed and light slab bases.M201 : 1.5 : 3Driveways, footings, reinforced slabs (light).M251 : 1 : 2Reinforced footings, columns, structural slabs.M30Design mixStructural columns, beams, suspended slabs.