<p>This exam report has been developed in association with Strangbetong AB, Sweden.</p><p>The natural gravel that is being used as fine aggregate for concrete production today is an ending natural recourse and the Swedish government has decided to strongly reduce the extraction from the year of 2020. The only reasonable replacement is aggregates from crushed rocks but this material has other properties than natural aggregates. The concrete manufacturers now have to learn how to use these new fine aggregates in a cost effective way in order to ensure the quality of their concrete production.</p><p>In this project, crushed aggregates and combination of crushed and natural aggregates have been tested with existing formulas for fresh concrete. The two parameters yield stress and plastic viscosity have been measured which gives a good description of the workability of the fresh concrete. Different methods to make measurements on the dry fine aggregates, has also been tested, to find out if there is any correlations between these parameters and the parameters from the measurement on the fresh concrete.</p>

This exam report has been developed in association with Strangbetong AB, Sweden. The natural gravel that is being used as fine aggregate for concrete production today is an ending natural recourse and the Swedish government has decided to strongly reduce the extraction from the year of 2020. The only reasonable replacement is aggregates from crushed rocks but this material has other properties than natural aggregates. The concrete manufacturers now have to learn how to use these new fine aggregates in a cost effective way in order to ensure the quality of their concrete production. In this project, crushed aggregates and combination of crushed and natural aggregates have been tested with existing formulas for fresh concrete. The two parameters yield stress and plastic viscosity have been measured which gives a good description of the workability of the fresh concrete. Different methods to make measurements on the dry fine aggregates, has also been tested, to find out if there is any correlations between these parameters and the parameters from the measurement on the fresh concrete.

To produce enough food for a growing population, soil remediation is crucial unless more forests are to be cleared to make way for agriculture land. Finely ground rocks have been proposed as a soil amendment for highly weathered soils. In Chontales, Nicaragua most of the forest has been converted to cattle pasture. In fertile soils, crop agriculture is more lucrative per unit of area than cattle grazing, but the low nutrient content of Chontales soils makes it uneconomic. The purpose of the study was to examine whether incorporation of rock dust is a sustainable way to increase the fertility in Chontales and thus can be part of a strategy that encourages farmers to adopt crop agriculture as an alternative to animal husbandry. A field experiment was conducted in which basaltic rock dust and compost was applied to soil for cultivation of common beans. Three sustainability parameters were analyzed and the diffusion potential of the proposed technology was assessed. The experiment failed to confirm the positive result obtained in previous studies on yield in similar soils and no correlation between pest resistance and rock dust applications was found. The failure to produce a confident result on yield was partly due to a leaf hoppers invasion and harm caused by intruding calves into the experiment site. Rock dust was found to be typically free of toxic agents and little environmental damage is associated with the practice, provided that the source of extraction is close to the application site. The relative disadvantage in terms of social prestige and incompatibility with the current cattle oriented production system were found to be the main obstacles for diffusion of the technique in Chontales.