Brookhaven Scientists Develop Eco-friendly Sulfur Polymer Technology that Replaces Concrete

SulfCrete in association with the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, have developed a distinct and inexpensive construction material - sulfur polymer having a lower carbon footprint than present concrete materials.

Concrete production is one of the key applications that contribute to the rise in carbon footprint across the world. In terms of greenhouse gas emissions, the concrete production stands between the energy required to heat limestone and the release of carbon dioxide while producing cement, accounting for nearly 5 to 10% of all emissions.

The technology developed in the Brookhaven Lab has been licensed by the SulfCrete. The SulfCrete's product that constitutes sulfur polymer in the place of cement will remain greener by over 90% when compared to the existing concrete. Conventional cement needs to be set and cured over time with the addition of water and through a chemical hydration reaction. Unlike this, sulfur polymer is simply melted, mixed with aggregate and cured until achieving 90% strength in few hours after cooling to room temperatures.

Paul Kalb, a Brookhaven scientist has been investigating sulfur polymer and its applications for several years. Based on the positive results achieved, he hopes that the product can be scaled up for commercialization as it offers several benefits over other traditional construction materials.

“Concrete is very porous. Water can move in and out of it very easily. This new material reduces permeability and is also extremely strong," he said.

Studies on sulfur polymer applications have been carried out in Brookhaven Lab for several years. The U.S. Bureau of Mines (USBM) discovered the material in early 1970s to make benefits out of waste sulfur. Although elemental sulfur is unique as a byproduct, it can be subjected to phase transitions that minimize physical stability following melting and re-solidification.

However, USBM researchers have discovered that the addition of expensive organic materials such as dicyclopentadiene can suppress these phase transitions. The high cost has not favored widespread use, except for certain niche applications.

Kalb stated that the potential benefits of sulfur polymer were identified 30 years back while improving the methods of encapsulating radioactive waste. The technique involved simply mixing the waste with cement until the formation of a solid that can be buried. This method posed several issues associated with the Portland cement limitations including chemical interactions with the waste that influences cement hydration.

Following this, Kalb's team started to focus on thermoplastic materials such as sulfur polymer alternative in order to increase waste compatibility and minimize leachability. Brookhaven Lab owns the patent for the sulfur polymer solidification process. The process was then tailored to suit hazardous waste treatment applications such as mercury using physical encapsulation and chemical stabilization processes. Brookhaven patented another process - Sulfur Polymer Stabilization/Solidification (SPSS) technique which was licensed by a gold mining company for mining applications.

After this, Kalb assisted environmental remediation project while working on a DOE initiative in Kazakhstan, which involved the use of SPSS in treating mercury waste with high toxicity. There, Kalb’s team worked on cleaning up the waste mercury from a chemical factory. During the project, they observed large stockpiles of sulfur coming from the emerging local oil and gas industry.

The team came up with a plan to minimize the cost of construction material using sulfur, in order to provide a more viable alternative to concrete. They made the sulfur to react with other inexpensive organic materials such as oil refinery waste, and achieved desirable results. Following this, they started the ongoing process of patenting this technology.

After some years, Brookhaven Lab researchers started to experiment with these sulfur polymers and set up an independent laboratory to conduct performance tests.

“The results of these initial performance tests were very positive. The normal strength of Portland cement mortar is about 20 to 23 megapascals (MPa). The average strength of our sulfur polymer mortar test samples was more than three times that, over 60 MPa. The material also had other desired properties, as its permeability was very low, “ Kalb said.

William Biamonte, SulfCrete CEO and co-founder who had been worked on the cool-roof technologies development projects, recently contacted Brookhaven’s Office of Technology Transfer and Partnerships (OTCP) for licensing the available carbon emissions reducing technologies. He came to know about Lab’s sulfur concrete through OTCP.

“I was unaware that concrete production is the third-worst source of environmental pollution in the world. “With cool roofs taking off across the world, there is also a secondary and more important concept called cool paving. I saw a technology that could lower carbon emissions, upcycle waste materials to a much greater value, use zero water, and be used as a heat island mitigation,” he said.

Biamonte and his partners started SulfCrete with support from Stony Brook University’s Sensor CAT program, the National Science Foundation, the Long Island Emerging Technology Fund and Accelerate Long Island. The company signed the contract with Stony Brook and Brookhaven for further testing and development of the product.

“There are concrete manufacturers all over the world looking for a low-impact material with a longer life cycle than conventional Portland concrete. SulfCrete is a low-impact, low-carbon technology that’s impervious to salt water, chemicals, and acid attacks. I think this is going to be a technology breakthrough, ” Biamonte said.

Biamonte also believes that the interest towards climate change concerns could result to new customers.

“The world has changed dramatically. From Manhattan hit with hurricanes to Bangladesh, where there are so many floods that the ground is too salinized to grow crops there anymore. Everything that’s been built of steel and concrete is being compromised by the salt water— including piers, pilings, and bulkheads. So, making the world more adaptable to our changing climate is an important consideration for our future, “ he said.