Page 15 - W M Donald Newsletter - Edition Thirteen

SUMMER 2022
15
The pandemic exacerbated existing availability and price issues relating to steel reinforcing mesh.
Prompted by discussions with Ewan and the team at W M Donald, I started to look at the potential of using fibres entrained in the self- compacting concrete as an alternative to mesh. The National House Building Council (NHBC) does not approve polypropylene fibres in ground bearing slab applications, so my focus has been on steel fibres.
I have worked on this project with Adfil, steel fibres supplier, for eighteen months. I believe we will have BBA accreditation in place by end August 2022. The accreditation would allow us to supply steel fibres within our self- compacting concrete in lieu of mesh where requested by the customer.
To allay any concerns of housebuilders, Adfil takes each house design and calculates the exact dosage of steel fibres needed to match the performance specifications of the traditional mesh alternative. This is backed up by PI (Professional Indemnity) insurance.
Innovation inevitably requires change, and some will change faster than others. I do believe, however, that over time steel fibres will become ever more commonplace in both domestic and commercial construction practice.
Ellen O’Neill
ellen.oneill@breedongroup.com
Further Innovations in concrete technology
Steel fibres in self-compacting concrete will soon be available to engineers and designers. Here are some more concrete innovations that may, or may not, be used by W M Donald over the coming years:
Translucent concrete (Heidelberg Cement)
Uses translucent fabric cast layer by layer into fine-grained concrete. Allows light, shadows and colours to project through the concrete. Other ‘translucent’ options include the use of acrylic rods and optical fibres.
Mars Regolith – concrete from mars! (NASA)
Regolith is defined as a blanket of unconsolidated, loose, diverse deposits covering solid rock. Mars regolith consists mainly of silicon dioxide and ferric oxide. NASA scientists have used data from equipment that has landed on Mars to recreate Mars regolith using a mixture of Earth minerals. This has then been used to trial new building materials, including Mars regolith concrete.
Bendable concrete (University of Michigan)
Bendable concrete uses tiny steel fibres, accounting for around 2% of its volume. Visually the same as standard concrete, bendable concrete is 40% lighter in weight and, amazingly, 500 times more resistant to cracking!
Bio-receptive concrete (University College London)
Magnesium phosphate is combined with concrete in a variety of geometries to promote the growth of mosses, lichen and algae. These plants create, effectively, a green wall that produces oxygen and absorbs carbon dioxide and other contaminants.
Living concrete (University of Colorado)
Concrete made from bacteria; synechoccus
to be precise. An advantage of the bacterial approach is that if they aren’t dehydrated entirely they continue to grow. One ‘brick’ can potentially create eight with additional sand and nutrient solution.
Thermal insulation using lightweight concrete
The addition of expanded glass to produce lightweight concrete with strong thermal insulation properties.
Low-cost conductive concrete (Lancaster University)
Cement mixture using fly ash (a waste material from coal-fired power stations) and an alkaline solution to produce concrete that can conduct electricity. This could be an alternative to other smart concretes that use expensive materials such as graphene.
Carrot cement (Lancaster University)
By combining ordinary cement with nano- platelets from waste carrots from the food processing industry, scientists have created a cement that is 80% stronger and more resistant to cracking. It also uses less cement than traditional mixes.