Precast concrete is preformed concrete using moulds to create a finished product.
There are two main types. Wetcast Concrete & dry cast concrete.
Wetcast concrete generally regarded as the superior process in the drainage industry, as it is typically stronger, less pouress or actually sealed, so no general liquids permiate through the walls.
Drycast is typically formed under pressure and usually has voids throughout, that will let water penertrate through if continually exposed to it.
This allows for quicker installation time no need to form up and waiting for concrete to cure.
A cover is a solid lid designed to restrict water from passing through it.
A grate is a grid type design which allows water to pass through it.
Durham's have over 50 years' experience in providing long life products with a proven performance.
Stainless steel is a steel alloy with a minimum of 10.5% chromium content by mass. There are two common grades of stainless steel used in the drainage industry. Grade 304 & 316. Grade 316 is the higher (more resistant) grade.
Stainless steel does not readily corrode, rust or stain with water as ordinary steel does. However it is not fully stain-proof in low oxygen, high-salinity or poor air-ciculation environments.
There are 2 common termonoligies for load ratings: Class Rating & "Duty"
Class Load Ratings are specific load classifications under standards, such as AS3996-2006 & BS/EN: 124 - 1994. "Duties" (Light, Medium, Heavy & Extra Heavy) are more ambiguous and are open to interpretation. These usually do not have "specific" load ratings.
Australian Standards has 7 load classes. A (lightest) to G (Heaviest)
From AS3996-2006 (Please reference the full standard for more details)
Class A: Areas (including footways) accessible only to pedestrians and pedal cyclists and closed to other traffic). Nominal Wheel load of 330kg's - Ultimate Limit State Design Load 10kN.
Class B: Areas (including footways anf light tractor paths) accerssible to vehicles (excluding commercial vehicles) or livestock. Nominal Wheel Load of 2670kg's - Ultimate Limit State Design Load 80kN.
Class C: Malls and areas open to slow moving commercial vehicles. Nominal Wheel Load of 5000kg's - Ultimate Limit State Design Load 150kN.
Class D: Carriageways of raods and areas open to commercial vehicles. Nominal Wheel Load 8000kg's - Ultimate Limit State Design Load 210kN.
Class E: General docks and aircraft pavements. Nominal Wheel Load of 13700kg's - Ultimate Limit State Design Load 400kN.
Class F: Docks and aircraft pavements subject to high wheel loads. Nominal Wheel Load of 20000kg's - Ultimate Limit State Design Load 600kN.
Class G: Docks and aircraft pavements subject to very hight wheel loads. Nominal Wheel Load of 30000kg's - Ultimate Limit State Design Load 900kN.
*NB: A force of 10kn approximtely equal to the weight of 1 tonne.
"Duties" are commonly refered to the following loadings (but not by all suppliers):
Light Duty: Pedestrian Areas only
Medium Duty: Light vehicles (cars)
Heavy Duty: Commercial Vehicles (cars & light trucks)
Extra Heavy Duty: Heavy Vehicles (Trucks & commercial vehicles)
DURHAM precast concrete products can be a quicker, easier and cheaper option than cast on site items. Durham precast products are of a high quality and continuous consistancy.
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