Non-Traditional Cement and Concrete

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Authors: Vincent Meyer, Nick de Cristofaro, Jason Bryant, Sada Sahu
Abstract: Solidia Cement is a non-hydraulic binder that is produced in existing cement kilns using the same raw material as Portland cement (PC). The key difference is that the Solidia binder is produced using less limestone and at lower kiln burning temperatures. This translates into reduced CO2 emissions during cement manufacturing (30% reduction). The Solidia concrete solution consists in a mix between the binder, aggregates, sand, water that is reacted with CO2 to form a durable matrix. The curing process captures up to 300 kg of CO2 per ton of cement used. Together, the Solidia cement and concrete reduce the CO2 footprint by down to 70% when compared to conventional cement and concrete products.The advantages to precasters are multiple also:- Full strength in concrete parts achieved within 24 hours thus allowing just-in-time manufacturing and a significant reduction in inventory cost.- Concrete waste from forming process is almost eliminated and equipment cleanup time is significantly reduced because the concrete does not harden until it is exposed to CO2.- The final precast products present better aesthetics than PC-based concretes (no efflorescence, better pigmentation, and better color grading).The first industrial demonstrations (cement production and precast applications) were achieved and confirm the CO2 and energy savings announced.
Authors: Ildiko Merta, Ana Mladenovič, Janez Turk, Aljoša Šajna, Alenka Mauko Pranjić
Abstract: Three cementitious composites containing different natural fibres (flax, hemp and sea-grass) were evaluated from an environmental perspective by means of Life Cycle Assessment (LCA) method applying the cradle-to-gate approach. The environmental impact of these composites was compared to that of cementitious composites reinforced with conventional synthetic polyacrilonitrile (PAN) fibres. The functional unit was the production of one cubic meter of cementitious composites ready-for-use. The results show that generally the environmental footprint of composite with synthetic fibres is bigger than the footprint of the composites with added natural fibres. Exceptions may only be the impacts on eutrophication and freshwater aquatic ecotoxicity, which are significantly affected by cultivation of crops. Flax and hemp cultivation is associated with emissions to soil and water. For this reason, the composite mixture with flax fibres has a significantly greater impact on eutrophication and freshwater aquatic ecotoxicity than the composite mixture with synthetic fibres. A cementitious composite mixture with sea-grass shows the lowest impacts in all impact categories. The entire life cycle of the studied composites was not included in this research since the life cycle of natural fibre composites is not straightforward and is highly dependent on the durability of the fibres within the matrix.

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