[There should be a set of navigation buttons here, but your browser does notsupport inline frames or is currently configured not to display framesYou can still use the text-based navigation facility on the Site Map page, though.] On This Page. • • • • • • • • • • • • • • • • • • • • • Related Pages • • • • • • • • • • • • • • • • • Introduction All concrete, once placed, will contract slightly during the curing process; this is the primary cause of small surface cracks that appear during the curing process.

When set, concrete will expand and/or contract slightly with ambient temperature. It is therefore advisable to incorporate some form of movement joint within larger slabs, particularly those 6m x 6m in plan or larger. Any concrete structure that is going to require numerous movement joints, is best designed by a civil or structural engineer. Movement joints are also useful when laying concrete within an area bounded by walls or buildings, or when an object such as a manhole cover has to be incorporated within the slab, as they allow the concrete to expand and/or contract without transferring pressure onto the other structures, causing cracks within the concrete slab, or the wall, MH cover, etc. Spacing The usual recommendation is for some form of movement joint to be created in a non-reinforced slab at a separation of approximately 30 times the slab thickness.

So, for a 100mm thick slab, there should be some for of joint every 100m × 30 = 3000mm = every 3.0-3.6m and, in a 150mm slab, 150 × 30 = 4500mm = 4.5-5.4m. Naturally, there is some leeway with these calculations, and joints can be positioned to coincide with band courses or to be 'centred' within a slab for aesthetic reasons. Types of Joint Different joints are used for differing purposes: Expansion joints - allow expansion AND contraction of a concrete slab without generating potentially damaging forces within the slab itself or the surrounding structures. Expansion joints are usually a complete 'gap' between adjacent bays, ie, there is a definite break in the concrete and any reinforcing steel that may be present. Where adjacent bays are 'tied' together by means of dowel bars, these dowels are sleeved in one of the bays to allow expansion to take place without generating stresses within the slab. Contraction joints - also known as 'shrinkage joints', this type of joint allows only for contraction or shrinkage of the slab, as can be anticipated during the curing process. 1 Hole Washer Board Game Dimensions.

Crack control joints - as some wit once remarked, 'There are only two types of concrete; that which has cracked, and that which is about to crack.' Crack control joints are a partially-formed contraction joint that aims to ensure that when the concrete does crack, it cracks in a predictable manner at a precise location.

Construction joints Although this type of joint is not a true movement joint, it is a commonly formed joint in concrete construction and so is included here for completeness. Construction joints can be horizontal or vertical and are formed when placement of the concrete is interrupted for some reason. Dungeon Siege 2 V2.3 Patch there.

Crack Inducers and Void Formers. Base Crack Inducer. Standard Serial Over Bluetooth Link Driver. The top section is easily removed after the concrete has cured, leaving a sealant void of 25 mm deep x 10 mm. Info on jointless concrete slabs. Jointless slabs- Reducing. Induces narrow cracks on a 1-meter-square grid by positioning crack inducer tubes on the. The two part PVC crack inducer and groove former induces a controlled crack in continuously laid concrete. Its hollow, braced section makes it strong enough to be. The crack inducer should be between ¼ and 1/3 of the slab depth and eliminates the need for a base crack inducer in slabs. Crack Inducer Top. Concrete, the.