Design and implementation of alkali activated cement for sustainable development

Alexander J. Moseson

doi:10.17918/etd-3680

Herein, progress is presented on the design and implementation of technology for sustainable development in general and international development in particular. Necessarily interdisciplinary, the work draws upon the tools and techniques of Mechanical, Materials, and Civil Engineering; and History & Politics. The work was conducted along two paths, the first being the theory and methodology of sustainable development. A flexible design and dissemination framework was developed, Technology Seeding, defined as: development by the transfer and participatory adaptation of appropriate proven conceptual designs. The methodology was developed in part through two case studies which implemented, respectively, wood-turning lathes in Tanzania and upland rice planters in Thailand. The second path is the design and investigation of alkali-activated cements (AACs) for practical use. Those developed herein, for US markets, comprise ground granulated blast furnace slag, soda ash (sodium carbonate), and up to 68 wt.% granular limestone. Mixture Design of Experiment (DOE) was utilized to guide empirical and theoretical analysis of performance (e.g. compressive strength), economic & ecological aspects (e.g. cost, CO₂ production, energy consumption), and chemistry (e.g. Rietveld analysis of x-ray diffractograms). Models were derived to understand the impact of mix design on performance and for optimization. Successful formulations are hydraulic and cure at room temperature, with strengths as high as 41 MPa at 3 days and 65 MPa at 28 days. Some of these formulations, compared to OPC, are competitive in performance, reduce cost by up to 40%, and reduce both CO₂ production and energy consumption by up to 97%. Major chemical products include calcium silicate hydrates / calcium aluminum silicate hydrates (C-(A)-S-H), gaylussite, and calcite (both newly formed and remaining from limestone). Calcite/dolomite and C-(A)-S-H both contribute to strength. A fraction of the limestone is consumed and becomes part of the C-(A)-S-H, with an average CaO/SiO₂ ratio of 1.4. A six month term as a Visiting Scholar at the Indian Institute of Technology (IIT) in Mumbai, India built upon both paths. Several AACs that use local materials and techniques and pass local standards were rapidly developed, and the potential positively assessed for these AACs to be used to empower slum dwellers.

Design and implementation of alkali activated cement for sustainable development

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Design and implementation of alkali activated cement for sustainable development

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