Concrete strength classes

M15 nominal concrete

The classic 1:2:4 general-purpose mix. Fine for domestic paths, patios and non-structural slabs on well-prepared ground.

Mix ratio

1 : 2 : 4

Cement : Sand : Aggregate

Proportions & strength

Designation	M15
Ratio (by volume)	1 : 2 : 4
Cement	1 part
Sand	2 parts
Aggregate	4 parts
Typical compressive strength	2,175 psi · 15 MPa
Typical use	Paths, patios, shed and light slab bases.

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 M15 is used

The classic 1:2:4 general-purpose mix. Fine for domestic paths, patios and non-structural slabs on well-prepared ground.

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.

Applications

Jobs that use M15

Concrete mix for a patioConcrete mix Concrete mix for a fence postConcrete mix Concrete mix for a shed baseConcrete mix

Same family

Other concrete strength classes

M51 : 5 : 10Blinding / levelling course under footings.M7.51 : 4 : 8Blinding, mass fill, non-structural pads.M101 : 3 : 6Levelling courses, path bedding, kerb backing.M201 : 1.5 : 3Driveways, footings, reinforced slabs (light).M251 : 1 : 2Reinforced footings, columns, structural slabs.M30Design mixStructural columns, beams, suspended slabs.