Building with bricks

Firstly, what is Brickforce?

Brickforce is a British brand consisting of two main parallel wires joined by in-line welded cross wires. Main wires are manufactured to a flattened profile to simplify location into the mortar joint without steel build-up problems at lap positions corners/junctions or when used in conjunction with wall ties.

There are various other materials that can be used for brick reinforcement, e.g. Mild steel reinforcing rods and expanded metal. These products and others suitable as brick reinforcement are obtainable in rolls of varying lengths and widths, from your local hardware shop or builder supplies merchants.

Why use masonry reinforcement?

Masonry has excellent compessive qualities and the majority of buildings constructed using this material last for many years with little maintenance. However, masonry has no significant tensile strength and movement caused by substrata changes, moisture or thermal effects can cause cracking.

The use of masonry reinforcement is a very simple and cost-effective way of greatly enhancing the strength and durability of masonry construction by providing both structural and crack control benefits.

It ties the wall together thus providing stability. Over unsupported openings like windows ,doors etc., Brickforce strengthens the wall. If you are building on unstable ground (i.e. there is movement in the ground) it is always good practice to use brick force thus ensuring a very stable wall.

Various types of alternative masonry reinforcement products are also available including mesh and wire.

Well-made clay bricks should never require wetting before laying except (rarely) under extremely hot and windy conditions.

Pressed or extruded bricks of low porosity should never be wetted prior to bricklaying as they naturally have a significantly reduced water uptake (and almost zero with a Class A engineering brick) that, if wetted, would result in the brick retaining a thin film of water on all its surfaces and this would cause it to ‘swim’ on the bedding mortar; and that invariably leads to it both sliding out of face line and sinking out of level. If this happens adjust the water content of the mortar so that it is used as stiff as possible.

Clay bricks purchased from non-accredited sources could have unacceptably high porosity and water absorption rates and might need to be soaked on site with water before being used.

With highly porous bricks there is a danger that they might rapidly absorb moisture from the bedding mortar (particularly in warm weather) causing it to stiffen quickly. This would result in it losing the all-important characteristic of plasticity that would inhibit correct and accurate positioning to line and face-plane and the provision of a secure bedding, leading to poor adhesion with attendant negative consequences on aspects of compressive and flexural strengths of the overall walling. 

How much water do I need on older or porous bricks?

The amount of water required to sufficiently dampen the bricks and reduce their absorbency to a level ideal for bricklaying comes with experience, but a brick that has been sufficiently dampened should not leave the hand wet when held.

There is a big difference between a brick that is ‘soaked’ and one that is ‘saturated’. A brick that has been soaked has a high percentage of moisture content, but retains sufficient available pore space to still provide the all-essential water uptake, or suction, necessary for it to be properly bedded into, and adhering onto, the fresh bedding mortar. A brick that has been saturated, however, has had all available pore space filled with water. In such a case there is no longer an ability for water uptake, with seriously reduced adhesion, or suction, so the brick ‘floats’ on the mortar; and it can even begin to shed its excess moisture into the bedding mortar that can result in it leaking out of the joint and staining the facework immediately below.

With some new bricks, a further possible problem is that saturation can liberate any integral soluble salts into solution resulting in disfiguring efflorescence (white salts)  crystallising on the face of the bricks.

Are you planning a major project? Our user friendly guide "Bricklaying made Easy" is available at Builders Warehouse, or from the CBA for just R150.

Preparation

• Plan site layout e.g. position of building, material stores, access etc.
• Store and protect all materials to minimise saturation and contamination.
• Control the wetting of bricks in hot, windy weather.
• Do not lay surface saturated bricks.
• Set out at ground level to locate all openings before commencing bricklaying.
• Lay out dry and minimise broken bonds.
• Prepare and take care of gauge rods - they are important quality control equipment.
• Work all levels from one datum.

Protection of brickwork

The best treatment is to prevent it from getting dirty in the first place - so protect the wall as work progresses from mortar droppings. After the first course of bricks has been laid - protect the base of the wall by laying sand, straw, sawdust or plastic sheeting along the ground. This minimises mud splashes and damage from mortar droppings.

As clay brickwork should be kept dry as possible during construction, cover the walls at the end of each day's work and during rain in order to keep brickwork free from mortar stains.

At the end of each working day clean the toe boards closest to the wall and turn the boards back to prevent rainfall from splashing mortar and dirt onto the brickwork.

Process & Techniques

• Mix small batches of mortar to suit building rate and 20 minute initial set timing.
• Bed all DPC's on fresh mortar
• Blend face bricks from a number of packs to minimise colour bonding.
• Plumb, level and square brickwork
• Fill all mortar joints solidly to minimise water penetration.
• Clean mortar dropping from cavities regularly

• Class III: Lightly stressed (e.g. single storey) bearing walls where exposure  to dampness  is  not severe but check NBR and NHBRC.

Cementitious Materials

CEM 1 32.5 (ordinary Portland cement) and CEM 11/A (S,V or W) 32.5 (Portland cement 15) may be used in mortar.

It is not advisable to use CEM 111/A 32.5 (PBFC), unless the mortar sands are good quality.  Mortar  with common cement lacks plasticity, may bleed, and will be harsh to work with. This deficiency may be overcome by using masonry cement. The use of lime in the mortar mix is beneficial  but is difficult to obtain. Masonry cements are readily available.

When sealed in airtight drums, cement remains the same in strength for up to 3 years. When packed in sacks, even under good conditions, deterioration in the strength of the cement will occur, with a prolonged shelf life, for example: 20% loss after 3 months, a 30% loss after 6 months and a 40% loss after 1 year. The arrangements for storing or stocking cement should be such that batches are used in the same order in which they were received. First in - first out.

Sand

Sand for mortar should comply with SABS 1090 and be well graded from 5mm downwards.  Sand should be evenly graded and should not contain an excess of dust or other fine material. The use of fine sands, that are more or less uniform in particle size, may contribute  to workability, but frequently leads to excessive shrinkage and cracking of the joints. Sands containing high percentage of clay, tend to give a conveniently plastic mix, but also leads to undue shrinkage.

Lime

Lime used in mortar is hydrated lime (commercial bedding lime) and not quicklime or agricultural lime. Lime give the best results when used with coarse sands. Lime with clayey sands can make the mortar over-cohesive and difficult to use. Lime should not be used with masonry cement.

The use of limes added to cement mortars is recommended as the improved workability and water retentively will lead to superior brick to mortar adhesion, with improved resistance of the brickwork to rain penetration.