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Cutting the over-use of materials in construction

First publishedin Aggregates Business Europe
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New software claimed to stop the ‘over-engineering’ of buildings. Liam McLoughlin reports.

More efficient use of building materials could cut the cost of construction projects by up to 2%, a scientific research team has found. The researchers at Cambridge University are developing software to cut over-use of materials such as cement, concrete and steel in buildings construction.

Industry codes require a minimum size for ensuring the safety of the reinforced concrete, steel or wood beams to be used in various structures but, according to research project leader Dr. Cyrille Dunant, engineers always go beyond what is required.

“The code requires the exact amount of material for the building to stand, plus a margin of safety, which is typically about 20-30% depending on the specification you are looking at,” he says.

He adds that this means a typical building can well withstand the loads it is expected to be subjected to, which are always overstated, and on top of that an extra margin of safety is often included to make it a further 30 to 50% stronger. “This has knock-on effects in that the whole building is much heavier than it needs to be,” he says.

Dr. Dunant, who has a PhD in material science on the topic of concrete durability, has been working in the field of material efficiency in construction since the start of 2016.

He says there are two parts to his team’s research. One is in convincing the engineers that they did in fact over-design their buildings.  “At the beginning of the research there was a surprising resistance to the notion that this was happening,” he says. “They say of course we design things perfectly, but in terms of pure efficiency this is not the case. I think now this is an accepted idea that there is widespread over-design.”

The second, and perhaps more interesting branch of the research, is into the design itself. For example, is a beam necessary in the first place? Is there an overall arrangement to the building that is better, and is the material chosen, whether steel or concrete, the right one for this type of building?

Because there are so many options when planning a building construction, Dr. Dunant says it is not possible for the average human being to explore them all and pick the right one.

“We are trying to design new software which would allow listing all the options and listing the one which would be optimal for a particular type of building. This would help the designers start on the right foot in developing a more efficient building,” he says.

He adds that the research will have cost-savings benefits for the construction industry. Dr. Dunant says the costs of building projects are very variable but that architect fees and the façade can account for a large percentage of about 10-25% each (although some projects don’t employ architects).

The frame of the building can account for about 8% of the total cost of the project, and materials costs are about half that at about 4% of the total cost. The Cambridge research project estimates that half these materials shouldn’t be there – equivalent to 2% of the cost.

“Construction is an industry that has very small margins, and 2% is more than some engineering firms will get out of the project, so a bit of extra time being spent on design and a bit less on materials will be better for everyone,” Dr. Dunant says.

When planning the design of a new building, an engineer will usually first work out three or four likely options, do some basic calculation and then submit one of the options for the tender. This represents perhaps two weeks of preliminary work, and there is no guarantee they will get the contract.

The software is designed to greatly reduce the time spent choosing the options. “In five minutes a designer would have the essential parameters for the optimal design options,” says Dr. Dunant.

In addition to engineers, he says there could also be benefits for major buildings materials manufacturers. An option could be added to the software to describe what the optimal concrete mix would be for a particular type of building design. This would potentially help companies move from a bulk production model to a more tailored, higher value model.

Dr. Dunant adds that companies offering such tailored mixes could increase their revenue as it would improve both their use of materials and the quality of the building.

Although the research is being conducted by a UK-based team, he says it will be applicable elsewhere. The regulations and norms used in the UK are a variant of EU regulations, and with very tiny modifications the same software would probably be applicable almost immediately in Europe. The US has a completely different set of building regulations that would need a re-programme for the software.

The researchers are collaborating with the construction industry and in the first phase of the project, three engineers were working part-time on the research. They hope to get UK government funding for a second phase to examine the whole question of how the software would be used in the workflow of an engineering company. In particular how can it be used to interact with architects, and what is a good commercial strategy for it from the point of view of the design company using the software?

The Cambridge team has also just completed a project on mapping the material flows of cement in the UK from production to final use, and the implications of this for material efficiency. This is more fundamental research and allows them to estimate how much of the material could effectively be saved if constructions were optimised.

Asked for a response to the researchers’ claims about over-use of materials in buildings construction, the Concrete Centre (part of industry body the UK Minerals Products Association) said in a statement: “There are design codes for concrete and steel that will dictate minimum sizes for structural elements. However, there are systems that encourage and enable less materials to be used.”

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