{"id":25702,"date":"2026-02-24T10:48:49","date_gmt":"2026-02-24T10:48:49","guid":{"rendered":"https:\/\/www.tobermore.co.uk\/professional\/?p=25702"},"modified":"2026-04-03T15:21:23","modified_gmt":"2026-04-03T14:21:23","slug":"concrete-facing-bricks-what-is-the-best-mortar","status":"publish","type":"post","link":"https:\/\/www.tobermore.co.uk\/professional\/blog\/concrete-facing-bricks-what-is-the-best-mortar\/","title":{"rendered":"What is the best mortar to use for concrete facing bricks?"},"content":{"rendered":"
The best mortar to use for\u00a0<\/span>\u200b<\/span>\u200b<\/span><\/span>concrete facing bricks<\/a>\u00a0has\u00a0the right amount of strength\u00a0required\u00a0to meet a project\u2019s structural and durability performance. The strength of mortar is derived from its constituent parts and is expressed as its compressive strength value measured in Newtons per square mm (N\/mm<\/span>2<\/span>).\u00a0<\/span>\u00a0<\/span><\/p>\n For most applications where concrete facing bricks are used in facing masonry, a mortar that would be expected to achieve a compressive strength of 4 N\/mm<\/span>\u00b2<\/span><\/span><\/span>\u00a0is used. This is known as a mortar with a strength class of M4.<\/span>\u00a0<\/span><\/p>\n As mortar accounts for around 17% of facing bricks built in stretcher bond<\/span>,<\/span>\u00a0it has a large part to play in the structural performance and the durability of the wall.<\/span>\u00a0<\/span><\/p>\n In this blog<\/span>,<\/span>\u00a0we will look at how the composition of mortar affects its properties. Then we will explore which standards should be referenced for recommendations on the use of mortar with concrete facing bricks. Also, we will\u00a0<\/span>consider<\/span>\u00a0the strength requirements of concrete facing bricks and see how they may vary depending upon the conditions to which they, and the chosen mortar, are exposed.<\/span>\u00a0<\/span><\/p>\n A major part of the composition of mortar is sand and about one-third of the volume between the grains of sand is air space. The type of binder used to fill this space affects the mortar’s strength and physical properties. Using one part cement to three parts sand will fill all the spaces between the sand and result in the strongest mix. However, this will also be a coarse mix, have poor workability and\u00a0<\/span>will\u00a0<\/span>be the most brittle mortar once cured.\u00a0<\/span>\u00a0<\/span><\/p>\n The mortar used for facing bricks needs to have good workability, flexibility and adhesion to the concrete facing bricks<\/span>,<\/span>\u00a0and this can be achieved by including additives.<\/span>\u00a0<\/span><\/p>\n Adding lime to a mixture of ordinary Portland cement (OPC) and sand helps to improve the\u00a0<\/span>mortar’s<\/span>\u00a0workability. It also increases its flexibility, so it is better able to withstand movement from ground settlement or thermal expansion and contraction. The OPC is made of at least 95% clinker. This is referred to as a CEM I class of cement.\u00a0<\/span>\u00a0<\/span><\/p>\n Masonry cement<\/span>\u00a0is made using Portland cement blended with supplementary cementitious materials,\u00a0plasticisers\u00a0and air entraining agents. These\u00a0additional\u00a0materials are designed to improve mortar performance in\u00a0a similar way\u00a0to lime<\/span>\u00a0<\/span>and, in some cases<\/span>,<\/span>\u00a0lime itself is one of the additives.\u00a0\u00a0The cement in this case is known as CEM II or a Portland composite cement<\/span>,<\/span>\u00a0showing that it\u00a0contains\u00a0between 65% and 94% of clinker.<\/span>\u00a0<\/span><\/p>\n In both cases, the more lime or masonry cement that is added<\/span>,<\/span>\u00a0the lower the compressive strength of the mortar class. However<\/span>,<\/span>\u00a0the qualities\u00a0required\u00a0to produce a mortar best suited for facing bricks are enhanced, so there is\u00a0balance\u00a0to be found<\/span>.\u00a0<\/span>Advice on this can be obtained from standards.<\/span>\u00a0<\/span><\/p>\n The table below shows the different mortar mixes that would be expected to achieve a compressive strength of 4N\/mm<\/span>\u00b2<\/span><\/span><\/span>\u00a0after 28 days and are suitable for use in environmental conditions classed as moderate.<\/span>\u00a0<\/span><\/p>\nWhat role does the composition of mortar play in its suitability for use with concrete facing bricks?<\/span><\/b>\u00a0<\/span><\/h2>\n
Lime additives to improve mortar performance<\/span><\/b>\u00a0<\/span><\/h2>\n
Masonry cement to improve mortar performance<\/span><\/b>\u00a0<\/span><\/h2>\n