Section 4
Additional Information
As approximately 15% of the visible area of a typical wall is made up of mortar, the choice of mortar colour employed in a project will have a significant impact on the final aesthetic appearance. The colour choice will often be mandated by architects or designers, but otherwise it will always pay
Brick Stretchers
A Guide to Mortar Colours
dividends to choose mortar colour carefully. Whether it’s with coloured ready-mixed mortars or using a bespoke combination of cement and coloured sand, extra attention here will be rewarded with a superior end result.
A Guide to Mortar Mixes Mortar must be carefully gauged in the proportions given in the specification, obtained from the Architect or our Technical Sales Department. Too strong a mix may lead to cracking in the finished brick work elevation, too weak a mix will adversely affect both the strength and durability of the overall brick work elevation.
Consistency of mortar is a key factor to reduce variation in shades between batchs. Accurate measurement volumes of sand, cement and added water and / or plasticisers, along with mixing times (whether mixing by machine or hand) are essential.
Mixes for prescribed masonry mortars and mortar classes Prescribed mortars (traditional proportion of materials by volume)A
Mortar designation
CementB : lime : sand with or without air entrainment
CementB : sand with or without air entrainment
Masonry cementC : sand
Masonry cementD : sand
Mortar class that may be assumed
Suitable for use in environmental condition
(i)
1 : 0 to ¼ : 3
1:3
Not suitable
Not suitable
M12
Severe(S)
(ii)
1 : ½ : 4 to 4½
1 : 3 to 4
1 : 2½ to 3½
1:3
M6
Severe(S)
(iii)
1 : ½ : 4 to 4½
1 : 5 to 6
1 : 4 to 5
1 : 3½ to 4
M4
Moderate(M)
(iv)
1 : ½ : 4 to 4½
1 : 7 to 8
1 : 5½ to 6½
1 : 4½
M2
Passive(P)
Note 1. When the sand portion is given as, for example, 1 : 5 to 6, the lower figure (as highlighted) should be used with sands containing a higher proportion of fines, whilst the higher figure should be used with sands containing a lower proportion of fines.
Guidance note
Brickwork below DPC level Brickwork above DPC level
Note 2. The highlighted mixes are recommended for standard mortars to be used for AG facing brick depending on the exposure condition.
Mortar classes Class
M1
M 2.5
M4
M5
M6
M 10
M 15
M 20
Md
Compressive strength N/mm2
1.0
2.5
4.0
5.0
6.0
10
15
20
d
36 | 37
d is a compressive strength greater than 20 N/mm2 as a multiple of 5 declared by the manufacturer.
