Rich limestone deposits helped the Lehigh Valley become a focal point of portland cement 100 years ago; scientific prestige, venture capital and climate
Rich limestone deposits helped the Lehigh Valley become a focal point of portland cement 100 years ago; scientific prestige, venture capital and climate change concerns might make an urban institution a few hundred miles north of eastern Pennsyvlania this century’s successor as a center of aggregate-binding advancement.
Massachusetts Institute of Technology, Cambridge, and its Department of Civil and Environmental Engineering have become catalysts for developing and promoting alternatives to ASTM C150 product. Faculty, alumni and industry partners envision compounds whose chemistry or production offers a net reduction in carbon dioxide emissions compared to conventional portland cement milling. Prevalence of the greenhouse gas in calcining and kiln phases has put concrete’s key ingredient high on climate-change believers’ radar.
A proposed aggregate-binding agent that reportedly imparts higher strength characteristics in concrete, and whose production might yield half the CO2 emissions of portland cement, earned its developers a $100,000 business start-up grant. MIT Sloan School of Management Masters of Business Administration candidate Natanel Barookhian and MIT Civil and Environmental Engineering doctoral candidate Rouzbeh Shasavari, founders of C-Crete Technologies, took the top prize in the school’s annual Entrepreneurship Competition, announced in May. They bested five other finalists from a pool of 200-plus entries in the MIT Entrepreneurs Club- and Sloan New Ventures Association-sponsored program.
The world has been looking for simple, scalable solutions to reduce the global carbon footprint, notes Barookhian. C-Crete Technologies [has] developed a method for tackling this issue by targeting production of cement, one of the most widely used materials on earth, while improving all of its core properties. We believe our technology will make a significant impact on the world.
C-Crete is based on nanotechnology, where chemists alter molecular structure to improve or change a compound’s performance. MIT Civil and Environmental Engineering staff observed nanotechnology application to portland cement in mid-2009. In a report to the National Academies of Science, Professor Franz Josef-Ulm explained that nano-scale study of calcium silicate hydrate, a key compound of a green or hardened concrete matrix, indicated potential for formulating significantly higher performance structures than derived from current practice.
Professor Ulm followed the report by helping Portland Cement Association and RMC Research and Education Foundation launch the MIT Concrete Sustainability Hub last fall. While acting as interim director (note Renowned chemist sidebar, page 17), he has overseen a charter Hub project, Liquid Stone, where investigators aim to leverage nanotechnology to manipulate cement’s molecular structure toward a greener concrete. That work appears to run in tandem to the graduate students’ C-Crete endeavor.
LONDON EMISSIONS FALLING
Weeks prior to the C-Crete Entrepreneurship Prize announcement, the MIT Technology Review ranked a magnesium oxide cement among 2010 Top 10 Emerging Technologies. Milled from minerals for which proven global reserves Û including magnesium silicate-bearing serpentine, talc and olivene, located up and down the U.S. East Coast Û reportedly exceed 10 trillion tons, Novacem has the potential to absorb as much as 220 lbs of CO2 gas per ton, proponents contend. A working formulation of what developers dub carbon-negative cement was devised by Nikolaos Vlasopoulos, chief scientist at London-based Novacem Ltd.
Novacem is refining the product to achieve mechanical performance equal to that of portland cement Û a goal Vlasopoulos asserts is attainable within one year. A pilot plant has been built in Novacem’s laboratories to be followed by a semi-commercial facility. Licensing of the first volume-output plants is anticipated in 2014-15, when production and use of the cement will be licensed on a nonexclusive basis worldwide. Company officials project that at 500,000 tons’ output, a magnesium silicate cement mill can be competitive with a portland cement operation.
Vlasopoulos formulated the binding agent as a graduate student at London’s Imperial College, where lab work led to investigating magnesium oxide and portland cement combinations. Adding water to magnesium compounds exclusively, he observed a solid-setting cement that did not rely on carbon-rich limestone. As it hardened, atmospheric CO2 reacted with the magnesium to make carbonates that strengthened the matrix while trapping the gas.
Novacem’s technology is based on magnesium silicates rather than limestone (calcium carbonate) as used in traditional portland cement. The company converts magnesium silicates into magnesium oxide using a low-carbon, low-temperature process, finishing the Novacem powder with special mineral additives.
Novacem Ltd. has enlisted as industrial partners Laing O’Rourke, a major U.K. contractor, and Rio Tinto Minerals, a leading global mining and exploration company. Among venture capitalists backing the company are Royal Society Enterprise Fund, Imperial Innovations, and London Technology Fund.
As MIT-recognized ventures take shape, another university-centered project involving nanotechnology and reduced-carbon powder production has been launched in Denmark under the National Advanced Technology Foundation. The undertaking is a collaboration between FLSmidth, global leader in cement plant equipment; Aalborg Portland, the country’s lone powder producer; Interdisciplinary Nanoscience Center at Aarhus University (iNANO), offering expertise in thermal dynamics and nano-scale studies of cement; and, Department of Energy Technology at Aalborg University, which has developed model descriptions of process plants. Research will focus on new types of reactive supplementary cementitious materials and related process technology for large-scale production. Technology is being developed for sale to the global market and will be centered around the manufacture of SCM materials based on locally available raw materials.
Notes Aarhus Professor Flemming Besenbacher, iNANO’s contribution will be in the form of advanced analyses that will help us understand the structures formed in cement during the various process stages. This understanding will enable us to design and create materials that have the desired properties.
In North America, nanotechnology-derived product has reached commercialization in concrete agents, including recently introduced admixtures such as Chryso’s Fluid Optima 256, a high-range water reducer with extended slump retention and high early-strength capabilties; and, BASF Admixtures’ Rheo-Tec family of workability retaining agents. Both products are promoted for slump-retention capability of 60 minutes or longer.