Secretive1,000 Years Lasting Concrete From Ancient Romans Could Reduce Climate Change

Calendar February 8, 2023 | Posted by admin

Rome's Pantheon stands defiant 2,000 years after it was built, its marble floors sheltered under the world’s largest unreinforced concrete dome. For decades, researchers have probed samples from Roman concrete structures—tombs, breakwaters, aqueducts, and wharves—to find out why these ancient buildings endure when modern concrete may crumble after only a few decades.

In a recent study, scientists have got closer to the answer—and their findings could reverberate long into the future. Not only is Roman concrete exponentially more durable than modern concrete, but it can also repair itself. Creating a modern equivalent that lasts longer than existing materials could reduce climate emissions and become a key component of resilient infrastructure, like seawalls. Currently, concrete is second only to water as the world’s most consumed material, and making it accounts for about 7 percent of global emissions.

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New Concrete Incorporates And Reduces Carbon Dioxide Emissions

Calendar March 3, 2020 | Posted by admin

Concrete surrounds us in our cities and stretches across the land in a vast network of highways. It’s so ubiquitous that most of us take it for granted, but many aren’t aware that concrete’s key ingredient, ordinary portland cement, is a major producer of greenhouse gases. Each year, manufacturers produce around 5 billion tons of portland cement — the gray powder that mixes with water to form the “glue” that holds concrete together. That’s nearly three-quarters of a ton for every person on Earth. For every ton of cement produced, the process creates approximately a ton of carbon dioxide, all of which accounts for roughly 7 percent of the world’s carbon dioxide emissions. And with demand increasing every year — especially in the developing world, which uses much more portland cement than the U.S. does — scientists are determined to lessen the growing environmental impact of portland cement production.

One of those scientists is Gaurav Sant of the California NanoSystems Institute at UCLA, who recently completed research that could eventually lead to methods of cement production that give off no carbon dioxide, the gas that composes 82 percent of greenhouse gases. Sant, an associate professor of civil and environmental engineering and UCLA’s Edward K. and Linda L. Rice professor of materials science, found that carbon dioxide released during cement manufacture could be captured and reused.

For every ton of cement produced, the process creates approximately a ton of carbon dioxide, all of which accounts for roughly 7 percent of the world’s carbon dioxide emissions.

“The reason we have been able to sustain global development has been our ability to produce portland cement at the volumes we have, and we will need to continue to do so,” Sant said. “But the carbon dioxide released into the atmosphere creates significant environmental stress. So it raises the question of whether we can reuse that carbon dioxide to produce a building material.”

During cement manufacturing, there are two steps responsible for carbon emissions. One is calcination, when limestone, the raw material most used to produce cement, is heated to about 750 degrees Celsius. That process separates limestone into a corrosive, unstable solid — calcium oxide, or lime — and carbon dioxide gas. When lime is combined with water, a process called slaking, it forms a more stable compound called calcium hydroxide.

And the major compound in portland cement is tricalcium silicate, which hardens like stone when it is combined with water. Tricalcium silicate is produced by combining lime with siliceous sand and heating the mixture to 1,500 degrees Celsius. Of the total carbon dioxide emitted in cement manufacturing, 65 percent is released when the limestone is calcined and 35 percent is given off by the fuel burned to heat the tricalcium silicate compound.

But Sant and his team showed that the carbon dioxide given off during calcination can be captured and recombined with calcium hydroxide to recreate limestone — creating a cycle in which no carbon dioxide is released into the air. In addition, about 50 percent less heat is needed throughout the production cycle, since no additional heat is required to ensure the formation of tricalcium silicate.

The study is published in the journal Industrial and Engineering Chemistry Research.

Source: https://newsroom.ucla.edu/

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Wooden Skyscrapers

Calendar July 9, 2019 | Posted by admin

Recent innovations in engineered timber have laid the foundations for the world’s first wooden skyscrapers to appear within a decade, a feat that is not only achievable—according to the Centre for Natural Material Innovation—but one they hope will beckon in an era of sustainable wooden cities, helping reverse historic emissions from the construction industry.

The research team based at the Faculty of Architecture of Cambridge University (UK), is interdisciplinary, composed of architects, biochemists, chemists, mathematicians and engineers, who specialise in plant-based material, including cross-laminated timber, arguably the first major structural innovation since the advent of reinforced concrete, 150 years ago.

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“Until cross-laminated timber, there was simply no building material to challenge steel or reinforced concrete. To construct cities and indeed skyscrapers, we just had to accept the good and the bad of existing materials“, said Principal Investigator Dr Michael Ramage.

“Concrete is about five times heavier than timber, which means more expense for foundations and transport; it’s resource-intensive, and contributes to tremendous carbon dioxide emissions. After water, concrete is the most consumed material by humanity. But now we have an alternative, and it’s plant-based,” he added.

The team envisage trees supplanting concrete as the predominant building material for cities, with buildings sown like seeds and cities harvested as crops, a way of simultaneously addressing climate change and global housing shortages.

Dr Ramage explained: “In England alone, we need to build 340,000 new homes each year over the next 12 years to accommodate our population. Concrete is unsustainable. Timber, however, is the only building material we can grow, and that actually reduces carbon dioxide. Every tonne of timber expunges 1.8 tonnes of carbon dioxide from the atmosphere. Doing the calculations, if all new English homes were constructed from timber, we could capture and offset the carbon footprints of around 850,000 people for 10 years.

“The sustainable forests of Europe take just 7 seconds to grow the volume of timber required for a 3 bedroom apartment, and 4 hours to grow a 300 metre supertall skyscraper. Canada’s sustainable forests alone yield enough timber to house a billion people in perpetuity, with forested trees replenishing faster than their eventual occupants.”

Various teams around the world are hoping to produce the tallest wooden skyscraper, however the team from Cambridge is confident they’ll be the first, having done holistic work on three proposals for timber skyscrapers in London, Chicago, and the Hague, all of which are set to be showcased to the public at the Royal Society’s Summer Science Exhibition 2019, freely open to the public from July 1–7.

Source: https://www.cam.ac.uk/

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Timber Cities And Algorithmically Designed Structures

Calendar May 23, 2019 | Posted by admin

Design Computation Lab is a new research laboratory at The Bartlett School of Architecture, University College London  (UCL) developing design methods for the utilization of computational technologies in architectural design, fabrication and assembly. Design Computation Lab has cross-faculty partnerships in the The Institute for Digital Innovation in the Built Environment, UCL and The School of Construction + Project Management, UCL.

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In a recent installation, Real Virtuality, Gilles Retsin Architecture and the Design Computation Lab proved that timber could indeed become the material of the 21st century by using augmented reality to fabricate algorithmically designed structures with LEGO-like timber blocks.

Construction relies heavily on cement, the production of which is responsible for approximately 8 percent of global carbon dioxide emissions. Architect Gilles Retsin suggests that we should look into timber for an alternative.
Sustainable cities can’t rely on concrete. Let’s try algorithmically designed timber buildings.

Source: https://designcomputationlab.org/
AND
https://mashable.com/

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How To Produce Entire Homes With A 3D Printer

Calendar March 25, 2019 | Posted by admin

If you’re looking for a 3D printer that can fit comfortably on the side of your desk and bust out small home-printed objects, then Danish company Cobod International’s new 3D printer definitely isn’t for you. Roughly the size of a small barn, the BOD2 is the world’s largest 3D printer designed for construction purposes. It is capable of printing entire buildings up to 40 feet wide, 90 feet long and 30 feet tall. In other words, if you’re only looking to print out a DIY fidget spinner, you’re going to want to search elsewhere.

“Our second-generation 3D construction printer, BOD2, is special in the way that it has a modular frame which gives the opportunity for our customers to choose the size of printer that fits their specific purpose,” said Asger Dath, communications manager for Cobod, “Furthermore, it is currently the fastest-printing construction printer on the market. With the tangential controlled print head, together with our customizable nozzle system, our customers are able to print different wall surfaces, especially very smooth wall surfaces.”

The printer functions in a very similar way  to a standard FDM (fused filament fabrication) printer. It is fed with concrete, which is then extruded using a motor in the print head. This concrete material is fed into the printer as a dry mix, prior to being mixed by a pump and then traveling through a tube to the print head to be expelled.

“We decided to develop the BOD2 after we found a great interest from the construction industry after we 3D printed the first building in Europe,” Dath said. “The many requests we got had all different purposes and therefore the sizes differed a great deal. [This] led to the idea of developing a modular construction printer that could meet the needs of all the requested sizes, instead of developing a printer in one or two sizes.”

The BOD2 printer was recently purchased by the construction company Elite for Construction & Development Co., with the express purpose of creating 3D printed private homes in Saudi Arabia. This is going to be a big job. In all, Saudi Arabia aims to build 1.5 million private houses over the next decade. While not all of those will necessarily be 3D printed, a tool such as this could certainly help save on both time and money.

Source: https://cobod.com/
AND
https://www.digitaltrends.com/

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How To Make Concrete Leaner, Greener, Stronger And More Elastic

Calendar September 27, 2018 | Posted by admin

Rice University scientists have developed micron-sized calcium silicate spheres that could lead to stronger and greener concrete, the world’s most-used synthetic material. To Rice materials scientist Rouzbeh Shahsavari and graduate student Sung Hoon Hwang, the spheres represent building blocks that can be made at low cost and promise to mitigate the energy-intensive techniques now used to make cement, the most common binder in concrete.

The researchers formed the spheres in a solution around nanoscale seeds of a common detergent-like surfactant. The spheres can be prompted to self-assemble into solids that are stronger, harder, more elastic and more durable than ubiquitous Portland cement.

Packed, micron-scale calcium silicate spheres developed at Rice University are a promising material that could lead to stronger and more environmentally friendly concrete

“Cement doesn’t have the nicest structure,” said Shahsavari, an assistant professor of materials science and nanoengineering. “Cement particles are amorphous and disorganized, which makes it a bit vulnerable to cracks. But with this material, we know what our limits are and we can channel polymers or other materials in between the spheres to control the structure from bottom to top and predict more accurately how it could fracture.”

He said the spheres are suitable for bone-tissue engineering, insulation, ceramic and composite applications as well as cement.

Source: https://news.rice.edu/

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