The development of new, sustainable, low-CO2 construction materials is essential if the global construction industry is to reduce the environmental footprint of its activities, which is incurred particularly through the production of Portland cement. One type of non-Portland cement that is attracting particular attention is based on alkali-aluminosilicate chemistry, including the class of binders that have become known as geopolymers. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint and with the potential for performance advantages over traditional cements in certain niche applications. This review discusses the synthesis of alkali-activated binders from blast furnace slag, calcined clay (metakaolin), and fly ash, including analysis of the chemical reaction mechanisms and binder phase assemblages that control the early-age and hardened properties of these materials, in particular initial setting and long-term durability. Perspectives fo...

Geopolymers and Related Alkali-Activated Materials

Over the past two decades, nuclear magnetic resonance (NMR) has emerged as one of the three principal analytical techniques used in metabolomics (the other two being gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography coupled with single-stage mass spectrometry (LC-MS)). The relative ease of sample preparation, the ability to quantify metabolite levels, the high level of experimental reproducibility, and the inherently nondestructive nature of NMR spectroscopy have made it the preferred platform for long-term or large-scale clinical metabolomic studies. These advantages, however, are often outweighed by the fact that most other analytical techniques, including both LC-MS and GC-MS, are inherently more sensitive than NMR, with lower limits of detection typically being 10 to 100 times better. This review is intended to introduce readers to the field of NMR-based metabolomics and to highlight both the advantages and disadvantages of NMR spectroscopy for metabolomic studies. It will also explore some of the unique strengths of NMR-based metabolomics, particularly with regard to isotope selection/detection, mixture deconvolution via 2D spectroscopy, automation, and the ability to noninvasively analyze native tissue specimens. Finally, this review will highlight a number of emerging NMR techniques and technologies that are being used to strengthen its utility and overcome its inherent limitations in metabolomic applications.

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NMR Spectroscopy for Metabolomics Research.

Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have evolved as the most common techniques in metabolomics studies, and each brings its own advantages and limitations. Unlike MS spectrometry, NMR spectroscopy is quantitative and does not require extra steps for sample preparation, such as separation or derivatization. Although the sensitivity of NMR spectroscopy has increased enormously and improvements continue to emerge steadily, this remains a weak point for NMR compared with MS. MS-based metabolomics provides an excellent approach that can offer a combined sensitivity and selectivity platform for metabolomics research. Moreover, different MS approaches such as different ionization techniques and mass analyzer technology can be used in order to increase the number of metabolites that can be detected. In this chapter, the advantages, limitations, strengths, and weaknesses of NMR and MS as tools applicable to metabolomics research are highlighted.

The strengths and weaknesses of NMR spectroscopy and mass spectrometry with particular focus on metabolomics research.

Fresh and hardened properties of seawater-mixed concrete

Cement is the ubiquitous material upon which modern civilisation is built, providing long-term strength, impermeability and durability for housing and infrastructure. The fundamental chemical interactions which control the structure and performance of cements have been the subject of intense research for decades, but the complex, crystallographically disordered nature of the key phases which form in hardened cements has raised difficulty in obtaining detailed information about local structure, reaction mechanisms and kinetics. Solid-state nuclear magnetic resonance (SS NMR)spectroscopy can resolve key atomic structural details within these materials and has emerged as a crucial tool in characterising cement structure and properties. This review provides a comprehensive overview of the application of multinuclear SS NMR spectroscopy to understand composition–structure–property relationships in cements. This includes anhydrous and hydrated phases in Portland cement, calcium aluminate cements, calcium sulfoaluminate cements, magnesia-based cements, alkali-activated and geopolymer cements and synthetic model systems. Advanced and multidimensional experiments probe 1 H, 13 C, 17 O, 19 F, 23 Na, 25 Mg, 27 Al, 29 Si, 31 P, 33 S, 35 Cl, 39 K and 43 Ca nuclei, to study atomic structure, phase evolution, nanostructural development, reaction mechanisms and kinetics. Thus, the mechanisms controlling the physical properties of cements can now be resolved and understood at an unprecedented and essential level of detail.

Solid-state nuclear magnetic resonance spectroscopy of cements

This research was supported by Award No. KUS-l1-004021, from King Abdullah University of Science and Technology (KAUST). Data were acquired at beamlines 12.2.2 and 12.3.2 at the Advanced Light Source at the Lawrence Berkeley Laboratories, supported by the Director of the Office of Science, Department of Energy, under Contract No. DE-AC02-05CH11231, and the Advanced Nanofabrication Imaging and Characterization Laboratories at King Abdullah University of Science and Technology. We thank CTG Italcementi researchers and staff, especially B. Zanga, in Bergamo, Italy; G. Vola at Cimprogetti S.p.A., Dalmine, Italy; S. Clark at the 12.2.2 beamline; and N. Tamura at the 12.3.2 beamline; and the ROMACONS drilling program: J. P. Oleson, C. Brandon, R. Hohlfelder. T. Teague, D. Hernandez, C. Hargis, I. A. Delaney, and B. Black provided research support. We thank J. G. Moore, M. Sintubin, G. Sposito, P.-A. Itty, and J. Kirz for critical discussions, and three anonymous reviewers whose comments improved the manuscript.

Sejungrosie Chae

Papers

Material and Elastic Properties of Al-Tobermorite in Ancient Roman Seawater Concrete