Concrete refers to specially created (artificial) stone building materials. It consists of water, a binder (most often cement) and fillers of various sizes. Concrete is one of the most widely used building materials in the world. It is the material of choice for most new major roads, buildings, bridges and many other structures because of its durability and relative ease of use. Technology does not stand still, scientific teams are conducting new research with the material presented, as a result of their work there are new developments.

Concrete from wood: reality or myth?

Previously, wood was one of the most common building materials, but today it has been replaced by concrete mixes. The active development of technology made it possible to combine the two types of materials, creating a combined mixture of wood and concrete.

Swiss national program “Resource Wood” (NRP 66) focuses on the creation of a unique mixture. Swiss researchers have succeeded in developing a radical approach to combining wood and concrete: they are making a durable concrete mix that is 50 percent wood. The high wood content in the concrete mixture contributed to the good thermal insulation of the material without compromising the fire resistance.

The main difference between the described mixture and classic concrete is the replacement of gravel and sand with fine wood.

Creating floating concrete

“They weigh no more than half of what conventional concrete weighs – the lightest of them even float!” says the research organizer. In addition, once dismantled, the materials can be reused, as fuel for heat and electricity. Despite the fire safety requirements, the building material can also be incinerated together with other waste materials.

The results of the stress tests confirmed that the new wood-based concrete is suitable for the production of slabs and wall panels, and can be used as a load-bearing material in construction. The forthcoming studies are required to find out in which areas it is better to apply a certain type of wood-concrete composite and effective methods of its production. According to Daya Zwicky (organizer), the level of knowledge required for widespread application is still too limited.

Revolutionary Graphene Concrete

Revolutionary concrete made of grapheneGraphene is a modification of carbon, which has recently been actively gaining popularity. Experts from the University of Exeter have developed a pioneering technique using nano-engineering to introduce graphene into the classic production of concrete mixtures. The unique technology made it possible to create durable, environmentally friendly, and strong concrete. In addition, water resistance increased several times. Testing of the produced material proved full compliance with the British and European construction standards.

It is important to note that the new concentrate, reinforced with graphene, significantly reduced the carbon footprint of traditional methods of production of concrete, making it more sustainable and environmentally friendly. At the same time carbon emissions were significantly reduced (by 446kg / t), and the amount of materials needed to create concrete was reduced by 50 percent. Most scientists are confident that the new methodology will make it possible to introduce new nano-materials into concrete, thus modernizing the global construction industry.

Finding environmentally friendly ways to build is a step toward reducing carbon emissions worldwide and a way to protect the environment. It is an important investment in creating a progressive construction industry of the future.

Coal ash in concrete

Coal ash in concreteGaining an accurate moisture content inside concrete is difficult because the powder and aggregates form a dense cementitious matrix, which creates difficulties for moisture movement once it begins to dry. In addition, special atmospheric conditions are required for drying. If the outside of the concrete dries out before the inside has cured, it can lead to a weaker product structure.

Farnham’s lab wanted to develop an aggregate product that had optimal characteristics for mixing, strength and porosity, and to find a way to make it from a lot of waste.

Coal ash is a byproduct of coal-fired power plants that is produced by burning coal. Every year, hundreds of tons of ash are sent to landfills. Researchers at Drexel University believe they have found a use for the powdery residue. They believe the ash can make concrete more durable and crack-free.

Calcium silicate in concrete

Calcium silicate microspheres have been developed by scientists at Rice University. The invention is proven to help produce stronger and more environmentally friendly concrete, with improved mechanical properties (strength, hardness, elasticity and durability) than Portland cement, the most common binder used in concrete. The spheres range in size from 100 to 500 nanometers in diameter. Their use promises to reduce the energy intensity of cement production (one of the most common binders in concrete). Shahsavardi says the spheres are suitable for bone tissue engineering, insulation, ceramics and composite applications, as well as cement.

According to Shahsavardi, an increase in cement strength will contribute:

• Reduced weight of concrete.
• Lower material consumption.
• Reduced energy consumption during concrete production.
• Reduced carbon emissions during the production process.

The scientist said that particle size and shape generally have a significant impact on the mechanical properties and durability of bulk materials such as concrete.

Concrete from recycled tires

UBC engineers have developed a more resilient type of concrete using recycled tires. The substance can be used for concrete structures such as buildings, roads, dams and bridges. At the same time, the amount of waste in landfills would be significantly reduced.

Researchers experimented with different proportions of recycled tire fibers and other materials used in concrete – cement, sand and water – before finding the ideal mixture. It contains 0.35 percent tire fibers. Asphalt roads with crumbled tire fibers already exist in the U.S., Germany, Spain, Brazil and China. The presence of these particles has been shown to improve the resiliency of concrete and extend its service life.

Tire concrete test results

Laboratory tests confirmed that fiber concrete reduces cracking by more than 90 percent compared to the classic mixture. This is due to polymer fibers that overlap cracks as they form, helping to protect the structure and extend its life.

“Most worn-out tires are destined for landfill. Adding fiber to concrete can reduce the carbon footprint of the tire industry and also reduce emissions in the construction industry, since cement production is a significant source of greenhouse gas emissions,” said Bantia, who is UBC’s scientific director.

The new concrete was used to line the steps in front of the McMillan Building on the UBC campus. Banthia’s team is monitoring its condition with sensors embedded in the concrete, observing the development of stresses, cracks and other factors. At this point, the observation results confirm the results of laboratory tests and indicate a significant reduction in cracking.

How do I avoid concrete cracking from sulfuric acid?

Sulfuric acid concrete failure atmospheric and chemical effects on concrete pavement are detrimental to its condition. Concrete deterioration from sulfuric acid can be avoided by finding ways to prevent its precursor gas from adsorbing into concrete. In his research, Matthew Lasich found that protecting concrete infrastructure from corrosive effects would require a pretreatment that targets the adsorption sites in cement hydrate where most hydrogen sulfide molecules attach. However, this approach can be difficult because of their widespread occurrence.

The porous structure makes concrete vulnerable to natural gas adsorption. In their study, the authors conduct a nanoscale analysis based on Monte Carlo simulations to simulate the migration of gas molecules into the cement hydrate structure. Their simulations suggest that a certain combination of molecule size and surface area is required for good absorption of cement hydrate.

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