What Is Hardcore and What Is It Used For?June 20, 2013
Hardcore is the term used to describe the mass of solid, not easily degraded materials of low absorbency that is employed in creating a base for heavy load-bearing stone and concrete floors. This includes outdoor areas such as driveways or garage floors. It is made up of large aggregates: materials such as construction waste, for example, tiles, quarry waste, other crushed rock and gravel. Clean, graded concrete rubble can be used provided that it does not contain any gypsum as this can cause thaumasite to develop around any limestone in the mix and this can degrade concrete.
Although the materials need to be essentially hard, they will be compressed before the upper layer is added, so if bricks are used, they must be capable of being crushed into relatively small pieces so that the hard materials are close together under compression, as large gaps will, almost literally, undermine its supportive quality.
What is hardcore used for?
A hardcore bed provides an essential part of a strong foundation for building work; when well-compacted it gives a base in which the builder can have confidence when infilling the upper layers. This is an invaluable commodity when it is necessary to raise the level of a floor. It also forms one of the lower layers of road construction, presenting an economical, supportive, and hardwearing option which ensures adequate drainage for the site; essential for the continued integrity of any surface which is subject to great loads and stresses over a protracted amount of time.
Although the pressure is considerably less in pedestrianised areas, it is used in the construction of pavements as well, as the sheer weight of the paving slabs themselves, in conjunction with foot-traffic and the effects of bad weather can cause rapid deterioration of the level plane. In the event of there being no suitable road access, it can be used to create an area to support the weight of construction traffic in safety.
What kind of hardcore do I need?
The importance of using high quality hardcore cannot be overestimated; a number of serious problems can develop if the materials are not of a suitable standard, or if the process is not carried out with meticulous care. It is important that any materials chosen are chemically inert to ensure it is safe for purpose. For example in the case of the reaction between gypsum and limestone which can cause instability. A chemical reaction within the bed can seriously undermine its stability, endangering the construction. Similarly, some substances react when they come into contact with water; colliery spoil may contain soluble sulphate which can infiltrate and disintegrate cement if it combines with water.
The shape and size of aggregates used can affect the ability of the site to drain adequately. For example, if large irregular pieces of rubble have been used, they may not enable the capillary action via which the moisture rises, causing it to pool either at the bottom or in pockets throughout the under-floor. And should this water freeze and expand it will cause cracks and undermine the stability of the structure as a whole regardless of what material is placed on top of it.
It is also important that an appropriate thickness is used depending on the type of job, expected load and probable stresses. If it is not deep enough it will neither support the load, nor provide adequate drainage which will inevitably lead to cracking and/or subsidence.
For peace of mind, it is essential to use good materials, to follow regulations relating to purpose and to ensure that the job is overseen by appropriately qualified individuals. The best way to achieve this is to contact a professional hardcore supplier. One such supplier is Danjo Skips based in Croydon & Sutton. Danjo Skips operate throughout South East London and with over 10 years of experience you can be sure you are employing a professional and expert hardcore supply service. Get in touch today via our online form or call us 020 3124 1697 for an obligation free quote.