Precast concrete: optimising DfMA and lean construction in civil construction

In some respects, the civil construction sector has led the way in optimising the benefits of two significant methodologies that are only now starting to get more widespread attention in the building and construction space.

Design for Manufacture & Assembly (DfMA) and lean construction can be applied in many forms. Both engage a holistic process, using the supply chain to design and deliver improved efficiency and value adding with minimal waste to maximise customer satisfaction outcomes.

While its methodology might be obvious, DfMA entails more than just designing for manufacture and designing for assembly. It is a system that takes the process of off-site manufacture one step further by identifying the most cost effective material early in a structure’s design, to speed construction and reduce costs.

Similarly, lean construction seeks to minimise waste in all its forms. Waste has been defined as anything in addition to the minimum amount of resources needed to add value to a project. Waste can relate to quality of work, constructability, material management, non-productive time and safety issues.

Both concepts might seem new; in fact, because precast is often specified from a civil project’s outset, the principles of both tools have and are being applied to varying degrees in civil construction.

Role of designer and early engagement of precast critical

Key to the success of both methodologies is the role of the designer throughout the process, who can influence the ability to cut costs, maximise quality and reduce construction time.

From the outset, the designer ensures that structures are designed for off-site prefabrication and all that entails in a way that makes assembly (more commonly referred to by the industry as installation) a quick, easy and safe process – all while minimising waste.

Also critical is early involvement of the precast manufacturer. When the designer engages a precast manufacturer early in a project’s design stages, benefits of both tools are optimised.

The precaster can assist the designer to achieve design solutions that maximise manufacturing and construction costs and there is no need to redesign a project for precast. This can maximise the efficiencies of repetition, transportation, placement of componentry, site access, craneage and scheduling.

The precaster will also be able to inform designers of the myriad possibilities when it comes to shape, colour, texture and finish (if required), thereby giving them the full suite of design options (and their associated costs) up front for consideration.

Notwithstanding the need to involve the precaster early, it is useful for designers to engage with a precaster who is a member of the industry association. It’s been shown that suppliers who are engaged with their industry body are generally more innovative and more aware of latest technologies and methods of manufacture. In the case of precast, designers would be best talking with members of National Precast Concrete Association.

Controlled factory environment delivers many benefits

Being manufactured off-site in purpose-built factories, the inherent benefits of precast concrete deliver both DfMA and lean construction outcomes.

The controlled factory environment in which precast elements are manufactured has its own advantages. Efficient, highly evolved and often automated processes ensure high quality outcomes and safe manufacture can occur while site preparations are underway. Just as there is minimal labour waste during the design phase, there is minimal materials waste throughout manufacturing and construction. Any waste in the factory is recycled, and because exact products are delivered to site, waste on site is also non-existent. Elements can be delivered to site just in time and in the right order, ready for a speedy assembly.

Highly flexible products, precast concrete elements have proved their relevance in the civil space and continue to do so. Pipes, culverts, arches, bridge beams, decks, noise walls, road barriers, tanks, kerb units and sleepers are some of the precast products that are used in myriad applications.

These products are ideally suited for any civil application, whether that be a large or small civil infrastructure project, for example, a highway network, sewer system, water treatment plant or tunnel.

Precast elements deliver both DfMA and lean construction benefits. And they result in a high quality and incredibly durable solution that requires minimal maintenance and that will last for many years.