True-zero emissions cement gets ASTM approval

Sublime Systems' cement receives ASTM C1157 designation, signaling a potential shift toward sustainability in the construction industry.
Rizwan Choudhury
Cement blocks.
Cement blocks.

Source: Sublime Systems 

Sublime Systems, a company that offers a low-carbon alternative to conventional cement, has achieved a major milestone in its quest to transform the global construction industry. The company’s innovative product, Sublime Cement, has received the ASTM C1157 designation, which is a key standard for performance-based hydraulic cement. This standard specifies rigorous criteria for various properties of cement, such as strength development, durability, and low shrinkage and cracking. The attainment of this standard signifies a crucial change in the acceptance of low-carbon solutions in the construction sector, enabling Sublime Cement to be widely used in accordance with U.S. and international building codes.

Addressing a major climate crisis issue

As per Sublime System’s press release, cement production currently accounts for a staggering 8% of global CO2 emissions. These emissions are a result of the traditional process that uses fossil-fuel-fired kilns to break down limestone into lime. Sublime Systems, however, introduces an innovative electrochemical approach, bypassing the need for these kilns and functioning entirely on renewable electricity. Unlike existing 'net-zero' solutions that rely on carbon offsets, Sublime's process is 'true-zero', requiring no additional carbon capture infrastructure.

According to Leah Ellis, PhD, Co-Founder and CEO of Sublime Systems, "Our aim is to make a profound and lasting impact on global CO2 emissions. The ASTM C1157 designation is a validation of our efforts to integrate low-carbon innovation into quality construction materials." She also stressed the need for performance-based standards, like ASTM C1157, that focus on solving key issues such as safety and carbon avoidance.

To earn this coveted designation, Sublime Systems underwent a series of tests conducted by a Cement and Concrete Reference Laboratory-certified third party. Not only did Sublime Cemen meet the stringent ASTM C1157 General Use performance requirements, but it also exceeded many samples of Ordinary Portland Cement (OPC) in terms of ultimate strength and durability. This suggests a longer life cycle for the final products, making Sublime's offering an attractive alternative for the industry.

The process

To simplify it, as Sublime Systems explains on their website, making cement today typically consumes a lot of energy and emits a significant amount of pollution. Roughly half of this pollution comes from burning fossil fuels to heat an oven, known as a kiln, to extremely high temperatures. The other half is generated by a chemical reaction that occurs within the limestone, a core ingredient in traditional cement, inside this hot kiln.

True-zero emissions cement gets ASTM approval
Syblime System process.

Sublime's technology eliminates both of these sources of pollution. The company employs a specialized electrical process capable of creating cement from certain types of rocks and industrial waste without releasing any harmful emissions or requiring the use of fossil fuels.

Sublime's machine, known as an electrolyzer, has two main components. The first component extracts calcium from specific minerals, leaving behind another substance called silicate. The second component creates an environment where calcium turns into a solid substance known as lime. This lime and silicate are then mixed at low temperatures to produce the final product, sublime cement.

Future infrastructure and global impact

It is worth noting that approximately 70% of the infrastructure required to accommodate the world's growing urban population by 2050 has yet to be built. Given this, the low-carbon approach championed by Sublime becomes crucial in balancing the global need for infrastructure with the pressing need to reduce emissions.

Jim Carreira, technical director at Boston Sand and Gravel, noted, "Sublime's ASTM C1157 compliance increases industry confidence in making a shift towards substantially decarbonized material without compromising on performance."

Sublime Systems is already in conversations with an extensive ecosystem of potential buyers, including ready-mix concrete suppliers, architects, engineers, and government agencies. With its first field pours planned for the last quarter of 2023 and its inaugural commercial plant set to be commissioned in 2025, the company is gearing up to make a seismic impact on sustainable construction globally.

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