Abstract
Additions of dredged marine sediments and oyster shell powder (OS) as cement substitute materials in mortars are examined by several techniques. The sediments have high water and chloride contents and calcite, quartz, illite and kaolinite as principal minerals. The OS powders are entirely composed of calcium carbonate and traces of other impurities. Four mixtures of treated sediments and OS powders at 650 °C and 850 °C are added to Portland cement at 8%, 16% and 33% by weight. The hydration of composite pastes is followed by calorimetric tests, the porosity accessible to water, the bulk density, the permeability to gas, the compressive strength and the accelerated carbonation resistance are measured. In general, the increase of addition amounts reduced the performance of mortars. However, a reduction of gas permeability was observed when the addition was up to 33%. Around 16% of addition, the compressive strength and carbonation resistance were improved.
Highlights
RESUMEN: Morteros de cemento basado en sedimentos marinos y polvo de concha de ostra
It is observed that the addition of moderate amounts of fly ash and OS powder as sand substituent in mortars improve workability, porosity, compressive strength and durability and reduce the absorption rate of mortars [9]
It is generally accepted that the early hydration of Portland cement can be divided into five periods on the basis of the evolution of heat curves [18]. (I): The initial period is the first peak which appeared in the first minutes produced by the dissolution of the cement. (II): The induction period between the first and the second peak corresponds to the saturation of the mixing water by soluble ions
Summary
RESUMEN: Morteros de cemento basado en sedimentos marinos y polvo de concha de ostra. Waste recycling has become a key issue in the science of building materials Among these wastes, there are the dredged marine sediments that are available in large quantities. Replacing up to 33% of the sand by treated sediments improves the Young’s modulus, the compressive strengths and the apparent gas permeability compared to normal mortars [6]. It is noted that the oyster shell powders (OS) consist entirely of calcium carbonate with few impurities [8, 9]. When these powders are introduced in the concrete, workability decreases with the degree of substitution. Two different sediments are selected; sediment noted “L” from the trap Lyvet on the Rance river and sediment “M” from the bay of Mont Saint Michel (MSM) which both are in the west of France
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