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Highlights • There is much interest in CO 2 sequestration using carbonate minerals. • Calcium and magnesium carbonation is an effective method for permanent CO 2 storage. • Olivine is highly suited to CO 2 sequestration due to its relatively high solubility. • Olivine is widely available, being one of the most abundant minerals in the earth. • Olivine mined for CO 2 sequestration could be used as an aggregate material. • Olivine aggregate is effective in increasing strength in non-hydraulic lime mortars. • Mortars containing olivine increase CO 2 absorption compared to traditional mortars. Abstract This paper presents the first investigation into the use of olivine as an aggregate material for calcium lime mortars. Lime binders provide many advantages when compared to cement binders such as higher vapour permeability and the ability to accommodate movement. They are undergoing a resurgence in their use in the conservation of historic buildings and in combination with environmentally friendly natural materials where these attributes are particularly important. Their ability to mitigate against global warming through the sequestration of CO 2 by carbonation is a further advantage which will bring impact. The equilibrium reaction products between non-hydraulic lime and olivine were calculated using the thermodynamic software GEMS3 Selektor. Experimental mortar mixes were modelled with varying ratios of quartz sand aggregate and olivine sand aggregate. The software predicted phase assemblage at equilibrium comprising calcite, dolomite, magnesite and quartz, with mass percentages depending on the ratio of quartz to olivine. The mortars morphological, chemical and mechanical properties were evaluated using Scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA) and compressive strength testing. Significantly, this study has shown that the use of olivine based aggregates in finely divided form can enhance carbonation, and hence the CO 2 absorption capacity of these mortars. Dolomite formed within the mortar from the reaction of olivine aggregate with lime and carbon dioxide in the presence of moisture is attributed to the superior mechanical properties observed increasing from 0.5 to 2.5 MPa. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the stabilization of soil using olivine and the application of novel techniques utilizing alkaline activation and carbonation. A rigorous study addressed the effect of carbon dioxide pressure and alkali concentration (10-M sodium hydroxide soil additions from 5 to 20%) between 7 and 90 days. Microstructural and compositional changes were evaluated using microscopic, spectroscopic, and diffraction techniques. Results demonstrate the advantages of using olivine in the presence of NaOH and the associated increases in soil shear strength of up to 40% over 90 days. Samples subjected to carbonation for a further 7 days led to additional increases in soil strength of up to 60%. Microstructural investigations before and after carbonation attributed the strength development to the formation of Mg(OH)2, hydrated magnesium carbonates, and M─S─H, A─S─H gel phases. The impact of this work is far reaching and provides a new soil stabilization approach. Key advantages include significant improvements in soil strength with a lower carbon footprint compared with lime or cement stabilization. [ABSTRACT FROM AUTHOR]