A new study has found that environmentally friendly cement made using waste ash is significantly stronger than its conventional peers.
Researchers from the Niels Bohr Institute at the University of Copenhagen have used sophisticated technical analysis to prove that cement made using the agricultural waste from sugar production can outperform conventional cement in terms of durability and resilience while also requiring less energy and generating less pollution during the manufacturing process.
The production of sugar using sugar cane generates large amounts of fibre waste which can be employed as a bio-fuel. This use of fibre waste for fuel in turn produces large amounts of ash.
In many countries with large-scale sugar cane industries, such as Cuba and Brazil, this ash, which would otherwise be disposed of as a waste product, is often added to cement mixtures as a strengthening ingredient.
Experts in nanophysics at the Niels Bohr Institute have used advanced technical analysis to determine that what would initially appear to be a quaint folk practice of local construction industries actually yields significant improvements in the strength of cement.
“I have been studying cement using quasi-elastic neutron scattering for several years and researchers from Brazil asked whether I wanted to analyze samples of cement mixed with waste products in the form of sugar cane ash,” said nanophysics researcher Heloisa Bordallo.
Bordallo received a variety of cement samples from Brazil which contained differing amounts of the ash waste from sugar production. The inner structure of these samples was analyzed at the ISIS facility in the UK, using an IRIS instrument which bombarded them with neutrons.
“The quality and strength of cement is directly related to how much of the water is chemically bonded. The more the water can move around, the worse it is for the strength and durability,” said Bordallo.
Neutron scattering can determine how much water moves within samples, as their movements are sensed by detectors when they hit the hydrogen atoms of water molecules.
Experiments conducted using neutron scattering determined that cement containing approximately 20 per cent ash was stronger and more durable, as water bound to the ash moves around much less.
The strength of differing types of cement is dependent upon the time frame of usage, however. Ordinary cement is usually stronger than ash cement during the first few months of setting, but ash cement emerges as the winner in the long run, surpassing ordinary cement in strength for periods greater than a year.
Ash cement is also far more environmentally friendly than standard cement, the production of which entails the usage of considerable amounts of energy and generates large amounts of carbon dioxide due to its high temperature requirements.
“Cement production accounts for five per cent of global CO2 emissions. If you replace 20 per cent of the content with ash, you are saving both CO2 emissions and raw materials, are you use 20 percent less by utilizing a waste product like ash,” Bordallo said.
Bordallo also pointed out that firm scientific evidence of the advantages of ash cement could serve as a huge boost to its global usage.
“The cement industry is huge and if they are to adopt a new idea, they need to have proof it works,” she said. “Using quasi-elastic neutron scattering we have now studied cement mixed with ash and shown what is happening and why it is stronger.”