The Features and Benefits of Concrete
Concrete is one of the oldest and most widely used construction materials in the world and possesses many unique qualities that benefit the owner, developer and designer. Due to its versatility, aesthetic appeal, cost-effectiveness and availability, concrete is changing the face of southern Africa's landscape. Increasingly, cutting-edge architects and engineers are making concrete their material of choice.
For the Owner, concrete offers both aesthetic appeal and cost effectiveness. Its strength, durability and natural thermal mass result in buildings that require low maintenance, offer high durability and have high operating energy efficiency.
For the Developer, concrete offers a competitive building solution based on first cost, long term economic benefits, energy efficiency, lower maintenance, and overall operating costs, as well as opportunities for future reuse should the occupancy of the building change.
For the Designer, concrete offers a dramatic range of colours, finishes and unlimited design possibilities, difficult to match in other materials. At the same time, a structure is created that provides superior environmental and energy performance.
Designs that take advantage of the thermal mass and structural integrity of concrete have resulted in many award-winning projects throughout the world. For the Country, concrete is a low impact, environmental material and is the cornerstone of building construction and infrastructure that can put our society on the road to a sustainable future.
Design Flexibility - concrete can be moulded into any shape by using appropriate formwork. This capability can be used to provide tailor-made design solutions to specific problems and also aesthetically pleasing finishes which often eliminate the need for further fixings, e.g. false ceilings.
Due to its valued load-bearing properties, concrete allows for longer floor spans with fewer columns to plan around. This offers flexibility in architectural layout and even more usable space. Increasingly, concrete is setting the standard for space planning and utility infrastructure.
Thin concrete floor structures facilitate the use of raised floor systems. Raised floors are ideal for Intelligent Building Construction where the wiring is run in the space below. Where flexibility and increased wiring are common demands in new construction, concrete fits the bill. Concrete is readily available from many locations across southern Africa. A concrete structure can be well underway before final plans are complete. Earlier start-up means better cash flow for owners and developers. As requests for changes are not uncommon in any construction project, the design flexibility of concrete allows the contractor to accommodate design changes after the construction process has begun.
Specification Variety - concrete can be manufactured to an enormous range of specifications to suit a wide variety of applications. This can be achieved by using different mix designs or by the addition of different materials.
A major advantage of concrete construction for engineered structures is the material’s properties of density and mass. Lateral stiffness, or resistance to horizontal movement, make concrete the product of choice when constructing in areas where high winds or seismic conditions are considerations. This lateral stiffness also means that occupants of concrete towers are less able to experience building motion.
Durability - concrete is one of the most durable materials on earth. Well designed, well placed concrete offers exceptional durability and long life in any structure. Concrete structures built over 100 years ago (even some as long as the Roman times) are still in active service today. Such extended life span conserves resources by reducing maintenance and the need for reconstruction.
Aesthetic Appeal - the aesthetic potential of concrete can be exploited through a variety of finishes. Exposed aggregate, and off-shutter, are two broad categories of decorative surface finishes. These techniques, combined with coloured aggregates, imagination and various other methods, form the basis of the aesthetic expression in concrete structures.
With concrete cladding panels, a great range of finishes and textures are available. Precast panels are extremely durable, weather resistant, offer superior air tightness, increased sound attenuation and thermal properties and are inherently fire resistant. Concrete cladding permits fast enclosure of the structure, allowing other trades to start sooner, cutting construction time, and reducing wall thickness to maximize rentable space.
As natural stone becomes inaccessible or the cost prohibitive, concrete is a natural alternative for recreating traditional finishes in a cost effective way. Besides being widely available and less expensive than quarried stone, cement-based cultured stone is easier to match and install. This makes it popular even in places where quantities of quarried stone are available.
Limited only by one’s imagination, the breadth of colours and textured finishes available in concrete today is amazing. Mixing and matching colours and textures provides a spectrum of design possibilities.
Energy Efficiency - the majority of concrete is produced locally, minimizing fuel requirements for handling and transportation. Once in place, concrete offers significant energy savings over the lifetime of the structure. The energy efficiency of a structure is a major consideration in the life cycle cost analysis. Concrete construction minimizes the overall building height. This shortens vertical runs of mechanical and electrical systems and reduces the exterior surface area to be enclosed and insulated.
The mass of a concrete structure makes it a significant thermal reservoir with the ability to store large amounts of energy. In the heating months, concrete walls and floors absorb the interior heat during the day, then radiate warmth back into the space at night. The same principle holds true for cooling. This thermal inertia allows concrete to help maintain a relatively steady interior temperature. By storing and releasing the energy needed for heating or cooling, concrete delivers year-round energy-efficient buildings reducing peak energy demands and the size of HVAC equipment required.
Sound Insulation - containing sound within the walls of a structure is critical in today’s highly competitive environment. Should tenant requirements include sound transmission control, the natural mass of concrete floor and wall systems provides both acoustical resistance and vibration control.
Fire Resistance - concrete is almost unique in being an inexpensive, readily available building material which is intrinsically fire resistant, needing no additional application of fire protection, and at the same time having structural and aesthetic qualities.
Light Reflectance - the light colour of concrete provides a safer environment and also enables lighting requirements to be reduced, both internally and externally.
Faster Construction - concrete provides faster construction which means reduced carrying costs and faster revenue generation. This facilitates more timely pay back of financing charges and faster revenue generation for the developer/owner.
Cost Effectiveness - due to its longevity and ease of construction, concrete is often the most economical choice for engineered structures. Load-bearing concrete exterior walls serve not only to enclose the buildings, but to carry roof and wind loads – eliminating the need to erect separate cladding and structural systems.
Shallower floor systems are an important structural advantage of concrete. On average, the construction of concrete buildings will allow one additional floor to be created for each 10 stories of traditional building height, resulting in more rentable space for buildings of similar size. When faced with height restrictions, concrete construction is a key consideration and could represent initial construction cost savings and additional income generation.
Precast/prestressed concrete can help reduce construction time and on-site labour costs by taking advantage of pre-fabrication of standard and custom structure segments. Advanced construction techniques such as “flying formwork systems”, increase the speed of floor construction. As a concrete frame progresses upward, workers on the completed floors below can proceed with interior partitions, exterior finishing, electrical, mechanical and plumbing systems.
Re-Use - concrete is an inert material that is easily recyclable. Old concrete that has reached the end of its service life can be reused as aggregate for new concrete mixtures. The addition of industrial by-products such as fly ash, silica fume and blast furnace slag enhance the various performance properties of concrete, whilst incorporating waste materials that would otherwise be deposited in landfills.
CONCRETE – CAN YOU AFFORD TO BE WITHOUT IT
The Institute offers a free advisory service for general concrete technology queries. A consultancy service focused on concrete and related issues is offered, including on-site investigation, trouble shooting and reporting. The technical team is available for consultation on construction sites anywhere in Southern Africa.