Sublime Cement Electrochemical Portland Replacement

Sublime Systems is a cement company based in Somerville, Massachusetts that replaces the kiln in cement making with an electrochemical process. It targets the emissions of ordinary Portland cement, which come from burning fuels and decomposing limestone, and is backed by Holcim, CRH, Siam Cement Group and Suffolk Construction.

Its process works like a refinery for rocks: electricity, not heat, breaks down low-value calcium silicate rocks or industrial wastes at ambient temperature into reactive calcium (Sublime Lime) and silicates, which are blended into Sublime Cement. The cement meets ASTM C1157 for hydraulic cement and replaces Portland cement in concrete with similar mix designs, admixtures and equipment. Non-cementitious co-products can be sold to steel, ceramics and pigment markets. It is produced at a 250 tonnes per year pilot plant, with commercial plants in development. Customers are concrete producers, contractors, data centre and building owners.

• Kiln-free electrochemistry: electricity drives reactions at ambient temperature instead of burning fuel.
• Flexible feedstocks: uses abundant calcium silicate rocks or industrial wastes rather than limestone.
• ASTM C1157 compliance: meets the performance specification for hydraulic cement in third-party tests.
• Durability profile: better resistance to alkali-silica reaction, chloride permeability and sulfate attack than Portland cement.
• Drop-in use: compatible with existing mix designs, admixtures and concrete equipment.
• Co-products: high-purity minerals such as Sublime Lime for steel, ceramics and pigments.

Data centre developers in Vietnam can pilot ultra-low-carbon cement for slabs and foundations to meet hyperscaler sustainability requirements. Cement producers could partner to license or co-develop electrochemical plants using local silicate rocks or slag. Marine and wastewater projects can benefit from its chloride and sulfate resistance.

A screening life cycle assessment by Climate Earth validated a path to a 90% reduction in cement's global warming potential. Third-party tests show much better resistance to alkali-silica reaction and chloride permeability than Portland cement, with better sulfate and shrinkage performance. The process offers a path to 30% to 40% energy savings. It works with existing ready-mix batching, pumping and finishing practice.

Technology companies building data centres are seeking low-carbon cement to cut the embodied emissions of their facilities, and major cement groups are investing in kiln-free processes. In Southeast Asia, regional cement leaders such as Siam Cement Group back such technologies, and Vietnam's export-oriented cement industry faces carbon border pressure and growing data centre construction.

Headquartered at 28 Park Street, Somerville, Massachusetts, USA, with a 250 tonnes per year pilot facility. Financial backers include Holcim, CRH, Siam Cement Group and Suffolk Construction. Co-founder Leah Ellis was named a Forbes Sustainability Leader in 2025, and the company appeared on the Boston Globe Tech Power Players 2025 list.