Most Commercial & Industrial Construction projects in Perth Western Australia utilise concrete in their construction in one form or another. Whether it be in the footings, ground slabs, wall, columns or suspended slabs.
All concrete used in commercial and industrial construction projects will be specified by an engineer as being suitable for the intended purpose. Concrete is specified by its Mpa (Mega Pascal) rating, being the strength it will achieve on average at 28 days after pouring.
Generally higher strength (Mpa rated) concrete is used in more critical installations or where additional strength is required by the design and lower strength concrete is used in less critical parts of the works.
Cast in situ (meaning poured in place) footings are generally used for commercial and industrial projects. These may comprise strip footings or pad footings depending on the application. Footings concrete is specified according to the loadbearing capacity of the footing on account of the engineers design.
Ground slabs are usually pouted in situ over a layer of plastic which acts as a vapour membrane to avoid damp under the floor slab penetrating the slab from underneath. This plastic layer also prevents contamination of the bottom layer of the concrete on pouring.
Floor slab thickness and Mpa rating will be determined by the engineer or building designer based on the expected conditions the floor will be subject to during its working life.
The higher Mpa rating specified for the floor concrete the better the abrasion and impact resistance however as the Mpa rating increases additional consideration needs to be given to shrinkage as this tends to increase as the strength rating (and cement content) increases.
The typical minimum thickness for a floor slab in Perth, Western Australia is 125mm thick given that this is the minimum thickness permitted for propping of concrete panels given under the National Code of Practice for Precast, Tilt Up & Concrete Elements.
Such floors are usually designed for use in pneumatic rubber wheeled vehicles (forklifts) with a maximum wheel load of 3.5T or racking installation bearing of up to 3.5T on a single racking leg. Thicker floors and higher strength concrete are usually specified where duty and load conditions require additional strength or long-term abrasion resistance.
Concrete is a versatile material for constructing walls of commercial and industrial developments. It has an inherent fire rating, is stable and durable and resists impact damage within reason. It can also be economical to build compared to other construction methods.
We have covered tilt up panel (link) and precast panel (link) construction on separate pages so won’t cover that again here. The concrete in concrete panels needs to achieve its minimum design strength prior to lifting. To minimise the curing time between casting and lifting specifiers often specify a higher Mpa rating to ensure that the concrete in the concrete wall panels reaches its design strength at the time of lifting.
Concrete can also be poured in situ (cast in place) inside shutters or forms, or inside of blockwork to form concrete walls in certain situations. Concrete in these instances will generally be specified for its nominated load bearing or specified fire rating application.
Concrete is often used as a substitute for lightweight construction in floors above ground level and suspended slabs. In these cases, the engineer will specify a formwork system, concrete grade and reinforcing to allow for the necessary load bearing capacity and spanning distance as well as any other required performance parameters.
There are several different formwork systems from traditional timber form boards, to prefabricated sacrificial steel formwork systems or even waffle pod slabs. Often a suspended slab will have a beams or columns incorporated to provide additional load bearing support, to reduce or minimise the overall slab thickness and cost on account of larger spans.
Another form of suspended slab is a composite slab comprising pre-cast concrete elements and a toppling slab poured over as the finished surface. One such product is called a Delta Core Panel slab which comprises lengths of precast concrete panel units with hollow cores and pre tensioned steel cable reinforcing.
The unique design of these precast units allows for longer spanning distances than traditional floor slabs with lower cost and reduced project duration timeframes compared to projects where formwork is required to be installed and then back propped due to curing times for suspended slab concrete.
As a second-generation family business, Mapel Building has been designing and constructing commercial and industrial buildings in Perth, Western Australia for over 25 years.