Arris: The term ”arris” commonly refers to the sharp edge or corner of a paving unit. It emphasises the point where two surfaces meet, which may be 90 degrees, pencil round or a chamfered edge for example.

Admixtures: Admixtures in mortar are substances that are added to the mixture in order to modify its properties and enhance its overall performance. These additives can improve various characteristics of the mortar, such as workability, strength and durability. Some common examples of admixtures used in mortar include: 

1. Plasticisers: These additives enhance the workability of the mortar by increasing its flow without the need for additional water.
2. Retarders: These substances slow down the setting time of the mortar, which can be useful when extended working time is required.
3. Accelerators: Alternatively, accelerators speed up the setting time of the mortar, making them beneficial when working in cold weather conditions or when faster construction is desired.
4. Air-Entraining Agents: These agent introduce microscopic air bubbles into the mortar, which can enhance its freeze-thaw resistance and workability. (Note the use of washing up liquid is not recommended as it can dramatically weaken a mortar mix due to excess/overly large air bubbles.)

Bedding Mortar: A mixture of 1 part cement to 4 parts sharp sand/crushed rock.

Bedding Layer: A layer of sharp sand or crushed rock screeded levels and falls to accommodate a surface course of block pavers.

Biaxal Mesh: A biaxal mesh is designed with reinforcement in two directions, providing strength both longitudinally and transversely to an unbound base or sub-base. 

Bonding Mortar: A cementitious slurry applied to the back of paving slabs to bond them to the bedding mortar.

Bound Base: A structural concrete slab, to lay paving slabs on.

California Bearing Ratio: California Bearing Ratio (CBR) is a measure of soil strength for pavement design, indicating the relative load bearing capacity.

Crushed Rock: Crushed rock, is a type of crushed stone aggregate commonly used in construction for creating a strong and durable base for roads, driveways, and other surfaces. It is typically made by crushing and screening granite or similar hard rocks.

Clay Pavers: Clay pavers are durable, natural paving units made from clay, frequently made in the Netherlands and Belgium as well as the UK.

Cropped Sides: Paving units that have been split or cropped as opposed to sawn.

Delamination: Delamination in paving refers to the separation or splitting of layers within a paving slab, often found with slate. Most commonly caused by water infiltration and freeze-thaw cycles.

Debonding: Debonding in paving refers to a paving slab separating from the mortar bed.

Edge Beam: A sufficiently cured concrete foundation, with bedding mortar applied to the surface to receive kerbs and similar edging products.

False Joint: A false joint that may be cut into the surface of a paving unit, no deeper than 5mm, so as to maintain a pattern within a paving scheme.

Fettling: The act of dressing the edges of stone that has been subjected to sawing along its edge. This is to provide a ‘natural’ appearance and help reduce problems with water ingress causing delamination. Various tools may be used including mechanical grinders with a ‘buffing’ wheel, or hand tools such as pitchers and comb hammers.

Fines: Particles of crushed rock sized 4mm and below.

Flag: A paving unit made from stone, larger than a sett. The term ‘flagging’ is used in some parts of the country when referring to laying larger stone units.

Geotextile Membrane:  A geotextile or geosynthetic membrane is a permeable fabric material. Non-woven membranes are recommended for paving works as they allow water to pass through, unlike woven membranes.

Improvement Layer: A layer of aggregate material, often recycled 6f2, laid over the subgrade to help improve structural strength.

Intermediate Pin: Where a string line is requires further support to prevent sagging, an intermediate steel pin is required. Sometimes referred to as a ‘tingle’ or ‘tinkle’.

Igneous Rock: Igneous rock is formed from molten magma or lava, undergoing solidification. Examples include granite and basalt. 

Joints: The gape in-between two paving units. 

Jointing Material: Often referred to as grout or pointing, which is a material that fills the joints in between paving units. 

Kerbs: A kerb is an individual concrete or natural stone unit, used either on its own or in combination with other units, with the purpose of separating surfaces that are at the same level or different levels. It serves to provide physical or visual separation, delineation, or containment between these surfaces.

Laser Level: A laser level is a tool or device that emits a visible laser bean onto a surface, serving as a reference line for levelling or aligning purposes in construction or surveying. By projecting a straight and easily visible line, it helps ensure accurate measurements, alignment, and horizontal or vertical levelling across various applications. 

Movement Joint: A movement joint in concrete, also known as an expansion joint, accommodates the natural expansion and contraction of the material due to temperature changes, preventing cracks and ensuring structural integrity.

MOT Type 1: Crushed rock, generally ranging in particle size from 40mm to dust sized particles.

MOT Type 3: Crushed rock, generally ranging in particle size from 40mm down but with reduced fine particles, to give a permeable unbound base material.

Metamorphic: Metamorphic rock forms from existing rocks undergoing intense heat and pressure. Examples include marble and slate.

Nibs: Are generally found on concrete block pavers designed to provide a uniform gap, into which kiln dried sand may be brushed to seal the joint.

Pavement: A paved area subject to pedestrian and/or vehicular traffic is commonly referred to as a ‘traffic area’.

Paving Stone: Stone paving slab (see Flag also).

Proprietary Bedding Mortar: High performance bedding mortar, often with polymer enhanced strength that meets BS7533 standards.

Race: Fresh foundation for laying kerbs upon.

Regulating Layer: A regulating layer is a variable-thickness layer applied to an existing surface, often a construction slab base, before construction, adjusting the shape/surface level and ensuring a suitable foundation for subsequent paving.

Riser: Vertical element of a step.

Riven (or Rived) Surfaces: A riven paving slab refers to a type of natural stone or concrete slab that has a texture and uneven surface caused by splitting the stone along its natural bed.

Sawn Paving: A sawn paving slab or sett that has been cut on each side resulting in smooth surfaces to all six sides.

Sedimentary Rock: Sedimentary rock formed from sedimentation and compression of particles. Examples include limestone, sandstone.

(Six) 6F2: 6F2 recycled aggregate is a construction material that is frequently utilised as a capping layer or fill material in a wide range of construction projects. It is produced by recycling construction and demolition waste, such as concrete, bricks, and other inert materials. The term “6F2” relates to the grading specification for the particle sizes contained within the aggregate. This grading requirement ensures that the recycled aggregate meets specific standards and can be effectively utilized in construction applications. By using 6F2 recycled aggregate, construction projects can benefit from sustainable practices by reusing materials and minimising the need for new resources.

Sharp Sand: Sharp sand is a coarse-grained sand used in construction for mixing with concrete and mortar due to its gritty texture. Recommended for paving laying operations.

Slurry Grout: Slurry Grouts are cementitious, pourable grout used for filling and jointing paving units or tiles.

Site Batched Mortar: Mortar mixed on-site, most commonly for bedding mortar.

Sub-Base: Layer of material, often MOT type 1, laid above the subgrade or capping (if used).

Sub-Grade: The subgrade is usually the level where the topsoil has been removed. It is then compacted using layers of base, sub-base and capping material to form the foundations of a paving project.

Tread: The horizontal part of a step where you place your foot. 

Unbound Pavement: Often referred to as flexible base/sub-base. An unbound base in paving refers to a layer of aggregates, such as MOT type 1 and sharp sand that is compacted, but lacks a binding agent such as cement. Most commonly used in block paving. 

Water Table: The water table is the level at which the ground is saturated with water. It marks the boundary between the unsaturated zone below the ground surface.

Zip Level Altimeter: A Zip Level is a digital, high-precision levelling and measuring tool. It uses a pressurised system to establish a reference plane, providing accurate elevation measurements in construction and surveying.

There will be many more ‘Paving Terms’ in use around the country, to describe techniques, materials and their uses.