news & events: news

LCA Research Brief - April 2012

Network, Pavements, and Fuel Consumption

Quantifying the impacts of pavement properties and management strategies on vehicle fuel consumption can provide guidance to pavement design and maintenance schedules while reducing the footprint of these systems. Although the impact of pavement roughness is higher than that of deflection, both are highly important within the environmental analyses of pavement systems, and greatly influence the aggregated vehicle fuel consumption. more >>

Research Profile Letter – March 2012

Aluminum and Sulfate Doped Belite

This research highlights the critical role of aluminum and sulfate doping on the reactivity of belite and indicates that by considering relatively simple chemical techniques, the dissolution and precipitation rates of belite can be significantly increased. more >>

LCA Research Brief - March 2012

Modeling Uncertainty in LCCA

Interfacing this model with the recently developed MEPDG will allow decision makers to fully understand the probabilistic life-cycle cost of alternative designs for a given project. This will allow a decision maker to choose a pavement alternative based on the risk they are willing to accept. more >>

Research Profile Letter – February 2012

Gaining strength by splitting water

Besides giving a more refined description of the C‑S‑H gel atomic structure, we have demonstrated that water speciation has a great effect on the strength properties of C‑S‑H nanoparticles. It is important to note that controlling the speciation of water within the C-S-H model through the Ca/Si ratio and temperature, provides a new degree of freedom from which one can master/improve the strength of the solid C‑S‑H phase. more >>

LCA Research Brief - February 2012

Homes: A Match for Concrete Innovation

This research aims at moving LCA in the design space of architects, engineers and developers, by quantifying the link between energy costs and architectural, materials and construction technology design parameters. This research makes it possible to match specific material solutions with structural tightness levels that need to be implemented in order to enhance the energy efficiency of homes in the United States. more >>

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Research Profile Letter – January 2012

Locking radionuclides in cement

We propose a new approach to investigate environmental and safety issues for the use of cement as a candidate for immobilizing radioactive waste such as strontium. It is based on first-principle statistical physics and allows a quantitative assessment of the impact of locking radionuclides on cement hydrate stability and mechanical properties. more >>

LCA Research Brief - January 2012

Roads: Smoothness Matters, But…

Interfacing modern pavement design tools such as MEPDG with Life Cycle Analysis (LCA) provides pavement engineers with an indispensable tool for a sustainable pavement design that is both structurally and environmentally sound. This research provides a means to moving LCA into the pavement design space. It can contribute to prepare our Nation’s road system for the economic, social and environmental challenges ahead. more >>

Research Profile Letter – December 2011

Holding It Together: C-S-H Cohesion

Our approach shows that cohesion within cement paste decreases with decreasing water content, specifically at RH<20% and 27°C. This loss of cohesion within the binding phase significantly affects the strength and durability of the material. These calculations help to explain reduced strength and creep resistance of concrete in very dry environments, and also provide insight toward damage mechanisms in concrete at high temperatures (e.g., fire environments) even before heat-induced polymerization of silica chains.
more >>

Research Profile Letter – November 2011

Predicting Setting Times Bottom-Up

This model of setting couples hydration kinetics and development of mechanical properties, a combination that allows the prediction of setting times in a bottom-up fashion. Our setting model brings information from atomistic and colloidal simulations to larger length and time scales, suggesting opportunities to link atomic structures of hydration products with engineering properties. more >>

Research Profile Letter – October 2011

Why Wet C-S-H is Weak

These results provide new understanding of how C-S-H structure and properties vary with water content. The proposed mechanisms governing increased stiffness and strength of C-S-H with low water content, particularly the humidity-dependent silica connectivity and resistance to shear deformation, can now be validated experimentally. more >>

Research Profile Letter – September 2011

When Concrete Takes (part of) the Heat

This research highlights the impact of chemical modifications, namely the calcium-to-silicon ratio, on specific heat capacity of C-S-H. It also highlights the power of the bottom-up approach being developed at MIT. Specifically, the derived functional relations between thermal properties and molecular structures provide a molecular baseline for nanoengineering the thermal performance of cement-based materials that will eventually contribute to increasing the energy efficiency of buildings. more >>

Industry Day August 11 - CSHub@MIT

Full Reports

Methods, Impacts, and Opportunities in the Concrete

• Building Life Cycle
• Pavement Life Cycle

Inflation and its Volatility on Construction

Life Cycle Cost Analysis Brief– July 2011

Accounting for Inflation in LCCA

This study examines historical data on real prices of construction materials, and finds that the assumption of constant real costs is seriously inconsistent with historical experience. Ignoring that experience can lead to serious cost overruns. To avoid such overruns, this study suggests the use of material-specific escalation rates that can be easily implemented into the LCCA practice to reflect changes in relative commodity prices. more >>

Paper by CSHub researchers wins Stephen Brunauer Award

A paper by recent CEE graduate Rouzbeh Shahsavari Ph.D. '11, Professors Franz Ulm and Markus Buehler, and senior research scientist Roland Pellenq has been selected by the Cements Division of the American Ceramic Society (ACS) as winner of the 2010 Stephen Brunauer Award. The award is given annually to the authors of the best refereed paper on cements published in the previous year's ACS Bulletin or the Journal of the American Ceramic Society. The winning paper, "First-Principles Study of Elastic Constants and Interlayer Interactions of Complex Hydrated Oxides: Case Study of Tobermorite and Jennite," appeared in the journal in 2009. The award will be presented during the 2011 Advances in Cement Based Materials conference July 24-26 at Vanderbilt University in Nashville, Tenn. more >>

Research Profile Letter – July 2011

ReaxFF Hydration of Clinker Surfaces

This research highlights that the difference in reactivity of alite and belite is inherent to their crystalline structure. This means, from a dissolution kinetics perspective, that a shift from an alite to belite dominated system can be achieved by crystal modifications and surface engineering. The insight thus gained with ReaxFF can enable R&D of clinker phases with higher reaction rates and early strength development. more >>

LCA Research Brief – June 2011

When the Rubber Hits the Road

This research suggests that a mechanistic approach can close the uncertainty gap of Pavement Vehicle Interaction (PVI) in LCA of pavements. Implemented in an LCA environment, the derived functional relations between fuel consumption, structural and material pavement design parameters, provide pavement engineers and decision makers with a design tool to optimize our Nation’s pavement inventory for high performance fuel and GHG efficiency. more >>

Research Profile Letter – June 2011

Setting from Statistical Principles

A new approach to quantitatively model the formation of cement hydration products, including their mechanical properties is proposed based on basic statistical mechanics. With the bottom-up philosophy, the input comes directly from the atomistic composition of solution and precipitates. Captured by cement-specific inter-particle potentials, investigation and control of microstructure and property evolution during setting become possible. more >>

Research Profile Letter – May 2011

Clinker Grinding at Breaking Point

This research highlights that the grinding technology currently in use in the cement industry has significant reserves for substantial energy efficiency improvements. The atomistic approach provides a baseline for the optimization of cement grindability. This optimization will also be most critical for the implementation of lower green-house gas components, such as belite, slag, fly ash and so on. more >>

Research Profile Letter – April 2011

What’s in Your Concrete? (Part 2)

This research combines nanoindentation and multivariate statistics to characterize quantitatively the mechanical response and volume fractions of phases in hardened cement paste. The comparable size of voxels in this mechanical analysis and our chemical characterization provides a formidable tool to relate mechanical performance to cement and concrete chemistry. more >>

Special Research Brief – April 2011

Adopting a Life-Cycle Perspective

The economic and environmental impacts of infrastructure should be evaluated using a life-cycle perspective. The coupling of two methodologies — lifecycle assessment (LCA) for environmental impact and life-cycle cost analysis (LCCA) for economic impacts — provides decision makers with the tools to reach sustainability targets using cost-effective strategies. more >>

Research Profile Letter - March 2011

Clinker: When Impurities Matter

This research highlights the critical role of guest ions on available reactive sites in alite and belite. The novel understanding of the role of impurities on reactivity opens the possibility for designing new doped clinker phases with a higher reaction rate, and hence, earlier strength development. Engineering the reactivity of belitic cements could thus become a reality through an appropriate choice of impurities. more >>

Special Research Brief: LCA - March 2011

Designing for Sustainable Pavements

The use of optimized design thicknesses helps reduce costs and CO2 emissions by minimizing the materials needed to construct a pavement. The economic and environmental benefits are significant and can help transportation agencies reduce their carbon footprint while working within tight budgetary constraints. more >>

Research Profile Letter - February  2011

What’s in Your Concrete? (Part 1)

Concrete is defined by its properties in the hardened state. However, these are known to depend strongly on the chemical make-up created by the tens of chemical hydration reactions that take place when cement clinker phases react to form this cohesive liquid stone. This research combines in situ X-ray spectra and multivariate statistics to characterize quantitatively the chemical signature and volume fraction of phases in hardened cement paste. more >>

Research Profile Letter - January 2011

Toughness Simply by Scratching

Scratching a weaker material with a tougher one is no doubt the most elemental conceptualization of a materials test ever conceived by mankind. This research highlights the relevance of the scratch test for assessing fracture properties of cement-based materials at multiple scales. This research makes it possible to identify reserves in concrete design that could enhance the crack resistance of concrete materials. Moreover, the test can be conducted over a period of time on the same sample that provides a benefit of evaluating the evolution of properties with time. All this makes the scratch test most appealing for innovative concrete applications. more >>

Research Profile Letter - December 2010

C-S-H: Water, Water Everywhere

This research highlights the importance of the water content within C-S-H on the properties of this nanoscale phase. As water content decreases, the stiffness and strength of the individual particles increases. Water content may be varied by environment, or controlled by C-S-H composition. This model can now be extended to predict how chemical composition, temperature, and humidity can affect the density and mechanical behavior of the aggregated C-S-H nanogranular phase that forms the “liquid stone” of concrete. more >>

Life Cycle Assessment- December 2010

Interim Report

Because of the enormous environmental and economic impact of infrastructure in the United States, there is a growing need to better understand the life cycle performance of structures and to investigate methods of reducing their global warming potential (GWP). Over the last year, MIT researchers have created new models to quantify the life cycle carbon emissions from manufacturing to disposal for a variety of structures. The reports are here presented:

• Life Cycle Assessment of Buildings [PDF]
• Life Cycle Assessment of Pavements [PDF]

Research Profile Letter - November 2010

The Hidden Forces of Setting

This research highlights the importance of the
interaction forces between the liquid and solid components of cement hydration (clinker, CH, C-S-H, pore solution etc). The approach holds the promise to become a quantitative bottom-up engineering tool for a science-driven engineering design of the next generation of setting agents including chemical admixtures. more >>

Research Profile Letter - October 2010

Quantum Clinker Engineering

This research highlights the critical role of the crystal structure of alite and belite on the dissolution energetics. This novel understanding of the dissolution chemistry eventually holds the key to designing potential dissolution accelerators and retarders for the activation of lower greenhouse components such as belite so that they can be used in demanding construction schedules. more >>

Special Research Brief – October 2010

Locking Mercury into Concrete

This research suggests that C-S-H can safely host mercury while maintaining full chemical stability and mechanical performance, when less than 2% of calcium sites are exchanged for mercury. To fully recap the benefits of higher strength and durability of concrete with high fly ash concentrations, it may turn out beneficial to limit the mercury content in fly ashes for concrete. more >>

Research Profile Letter - September 2010

Fly Ash is Critical For C-A-S-H

This research highlights the beneficial role of aluminum substituting for calcium on chemical stability and performance of C-A-S-H. It suggests that a high amount of aluminum provided by a larger fly ash concentration than currently in use can enhance properties in a "bottom-up" fashion. more >>

Hamlin Jennings to lead new Concrete Sustainability Hub at MIT

Hamlin Jennings, who is known among academic and industry researchers for his influential work on the fundamental chemistry of cement, will be the inaugural executive director of the Concrete Sustainability Hub (CSH), a research center established last fall at MIT in collaboration with the Portland Cement Association (PCA) and Ready Mixed Concrete (RMC) Research & Education Foundation.

Jennings will leave a tenured faculty position at Northwestern University to lead the CSH, taking up his new responsibilities at MIT beginning July 1, where he will also hold the position of adjunct professor in MIT's Department of Civil and Environmental Engineering, administrative home of the CSH. more »