news & events: news

LCA Research Brief - May 2013
Initial Cost Uncertainty in LCCA

Using historical bid data to characterize uncertainty in initial costs for LCCAs will help improve the accuracy of probabilistic LCCAs. Some of the cost variation can be explained by understanding the implication of bid quantity, but the amount of variation that can be explained can vary significantly from state to state for similar bid items. Future work will explore including other factors that could impact initial costs. more >>

Research Profile Letter – April 2013

Clinker Grindability: Microstructure Matters

This multi-scale investigation of fracture properties with the microscratch test highlights the importance of microstructure in clinker grindability. This original approach also provides a means for investigating the effects of microstructural characteristics (e.g. crystal size, porosity, belite clustering) on the grindability of clinkers. more >>

LCA Research Brief - April 2013
PVI Mechanistic Model Refined

The refined PVI model can be used to obtain the deflection in any direction (including the direction perpendicular to the motion) and allows us also to study effect of tire shape and multi wheels on an axel on IFC. The improved model can be used in LCAs to understand the contribution of deflection-based PVI to life cycle impact. more >>

LCA Research Brief - March 2013
Quantitative Assesment of Resilience in Residential Building Envelope Systems

The intent of our research is to help designers and builders quantify the physical resilience of residential structures as a portion of the overall systems concept of resilience. Comparing this performance against costs will inform decision-making and facilitate communica-tion of the cost and performance trade-offs of alterna-tive designs. more >>

Research Profile Letter – March 2013

Predicting C-S-H aging

This is the first time that rigidity theory has been applied to such a complex material. Importing glass science tools to C-S-H brings new ideas to predict the effect of composition on cement aging. The use of the predicted optimal compositions of cement could lead to more durable concrete. More generally, this highlights the fact that increasing the amount of silica in cement is another means for producing green sustainable concrete. more >>

LCA Research Brief - February 2013
Deterioration Induced Roughness in the US Network

Pavement material and structural design directly influence pavement performance and its deterioration rate. Pavements with slower deterioration rates require fewer maintenance activities to meet agency IRI guidelines and will have lower environmental impacts within the pavement lifecycle. Analysis of PVI roughness, its progression, and its impacts at a national level can guide design and policy for sustainability of the US roadway network. more >>

LCA Research Brief - January 2013
Survey of LCA Tools for Residential Buildings

Through surveys, focus groups, and exploration of existing tools we are identifying the most effective ways to integrate environmental performance metrics into the design and decision making processes. Robust, streamlined residential building LCA tools would help decision makers, builders, and architects to make holistic decisions that integrate environmental impact of all phases of the building’s life cycle. Revised brief April 11, 2013. more >>

Research Profile Letter – February 2013

Nucleation Seeding of Alkali Activated Paste

This study examines the rate controlling step that leads to a better understanding of how to use supplementary cementitious materials such as slag and fly ash to produce more sustainable mixes. more >>

Research Profile Letter – January 2013

Properties of Polymorphs of Belite

This research provides new information about polymorphs of belite obtained by atomic scale modeling. Results of impurity defects, which vary reactivity for γ-C2S and β-C2S polymorph, can be used to control reactivity of belite. Information on surface energetics of polymorphs with impurities can shed also light on grinding processes. more >>

LCA Research Brief - December 2012
The State of LCA for Residential Buildings

In order for LCA to be scaled to fit the building sector, a method is needed to calculate life cycle impacts under diverse conditions, while fully accounting for uncertainty. Policymakers, engineers, and architects need an LCA method that can be used to ensure that sustainable buildings are being designed to meet long-term energy savings standards while also reaching today’s GHG reduction goals. Ongoing research in the CSHub seeks to address these needs. more >>

Research Profile Letter – December 2012

Mesoscale Modeling of Sorption Hysteresis

The model quantitatively predicts sorption hysteresis in hardened cement paste. By answering the basic question, “Where is the water?” it paves the way for bottom-up descriptions of diverse phenomena, such as shrinkage, creep and corrosion. The model can also be used to predict sorption/desorption isotherms and infer microstructural information. more >>

LCA Research Brief - November 2012

Key Drivers of Uncertainty in Pavement LCA

This research presents a sensitivity analysis to quantify the level of contribution of different factors in the life cycle assessment of pavements under uncertainty. The results of this approach can be used to identify the elements to focus on to improve the characterization of pavement environmental impact. In addition, it can shed light on the areas that can change the outcomes of a comparative assessment and the associated decisions. more >>

Research Profile Letter – November 2012

When fracture stems from the atoms

We propose a new approach to study fracture properties by molecular simulation valid for both brittle and ductile materials. This research highlights the possibility to understand and engineer the fracture resistance starting from the smallest scale. For instance, it suggests that a binder-mineral interface with high ductility and a significant stiffness contrast may improve significantly the fracture resistance of concrete. more >>

LCA Research Brief - October 2012

Forecasting Prices with Limited Data

Characterizing the price behavior of inputs for concrete and asphalt is a major step towards identifying an appropriate price model in the absence of significant historical data. Current work is validating whether such a price model would have, on average, led a decision-maker to the “better” pavement selection. more >>

Research Profile Letter – October 2012

Energy Management: City Texture Matters

The novel approach leverages Statistical Physics to describe the complexity of cities in terms of molecular structures. This provides city planners and developers with innovative texture information, which can be used for effective energy management, including heating, ventilation and air conditioning of buildings in the scale of neighborhood and cities. more >>

LCA Research Brief - August 2012

Optimizing Passive Thermal Mass

The research aims to identify relationships that optimize passive thermal mass performance while maximizing energy efficiency. These have implications on the design of wall and floor systems, from both a manufacturing, construction, and design point of view. more >>

Research Profile Letter – August 2012

Induction Period in Alite Hydration

This research provides new information about the mechanisms that control the decrease in reactivity of alite during the induction period. This information can only be obtained by detailed atomic scale modeling, which provides an important piece of a complex puzzle, and brings us closer to a complete mechanistic description of the hydration process. more >>

Research Profile Letter – July 2012

C-S-H Texture From Sorption Isotherms

This unique bottom-up approach developed by the CSHub combines information from atomistic and colloidal simulations with the coarse-grained lattice-gas model allowing validation of the cement model structure at a larger length scale. This facilitates the first composite model of C-S-H at mesoscale, guiding the development of cement microstructures with desired mechanical properties. more >>

LCA Research Brief - July 2012

Potential Roadway Network Savings and PVI

Analyses of the impact of PVI on vehicle fuel consumption for different roadway functional systems demonstrate the impact of pavement design and management on vehicle fuel consumption. Such analyses can provide direction for future investments in maintenance, rehabilitation, and reconstruction of the pavement network to reduce its impact on PVI. more >>

Research Profile Letter – June 2012

Validating Effects of Cement Paste Composition on Mechanics

We validate the computational prediction that Ca/Si ~ 1 creates significantly stiffer and harder C-S-H than in OPC pastes, with direct consequences for concrete performance and environmental footprint. This work shows that this Ca/Si is accessible in current, commercially available processing routes and products. more >>

LCA Research Brief - June 2012

Comparative Pavement LCAs With Uncertainty

This research provides a probabilistic model for comparative life cycle environmental assessment of pavements in the presence of uncertainty and variation. Making use of this model (while accounting for correlation between designs) under a variety of scenarios enables decision-makers to choose a pavement with an associated degree of confidence. Corrected brief Nov 15, 2012. more >>

Research Profile Letter – May 2012

Visualizing Hydration Products

These experiments provide direct access to the kinetics associated with hydration mechanisms. Different parameters such as initial clinker composition and initial concentrations of calcium, silica or H+ ions (pH) within the solution can be compared quantitatively to models under development for clinker dissolution and cement setting. more >>

Research Profile Letter – April 2012

Crystallinity of Cement Clinkers: Application of Rietveld Refinement

Using the Rietveld method, we provide evidence that the presence of non-quantified material is significant in the studied samples of industrial clinker. This material likely affects grindability and reactivity, and our strategy allows one to quantify systematically its content, which has the potential to permit more complete characterization and therefore better estimates of performance and grindability. more >>

LCA Research Brief - May 2012

Quantifying Passive Thermal Mass

This research aims at identifying strategies for using concrete construction systems in homes to maximize energy efficiency. It has implications for how asnd where different wall systems are used to maximize energy savings using passive thermal mass. The findings equally apply to multi-family and commercial buildings which are the focus of ongoing research. more >>

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 >>

*Image courtasy of Link

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 »