64743 2025 eng 1 9 494 article Elsevier Ltd. 1 -- -- -- This paper deals with the study of different lime-based repair mortars for the conservation of sandstone objects in the context of monument preservation. New types of lightweight aggregates, which were manufactured from masonry rubble, were used to develop these repair mortars. This allows for recycling of construction and demolition waste while helping to conserve natural resources. As part of this work, the mortars were comprehensively characterised in terms of their chemical, physical, mechanical and hygric properties, such as bulk density, pore structure, strength, water absorption, shrinkage and carbonation. All mortars are lightweight mortars with bulk densities of about 1300 kg/m³. They achieve high porosities of around 50 %. At the same time, the mortars exhibit sufficient compressive strengths ranging from 1.8 to 11.3 MPa. The compressive strength depends on the degree of carbonation of the mortars and increases with sample age. The analysis of the pore structure shows that the mortars mainly contain macropores. The large number of capillary pores, with sizes ranging from 0.1 to 1000 μm, results in a good water absorption behaviour. The evaluation of the results proves that the repair mortars are compatible with Cotta sandstone. Construction and Building Materials 0950-0618 10.1016/j.conbuildmat.2025.143378 urn:nbn:de:kobv:b43-647431 true journal-article https://www.elsevier.com/tdm/userlicense/1.0/ crossref PersonAuthorFirstName_1,PersonAuthorLastName_1,PersonAuthorIdentifierOrcid_1,PersonAuthorFirstName_2,PersonAuthorLastName_2,PersonAuthorFirstName_3,PersonAuthorLastName_3,PersonAuthorFirstName_4,PersonAuthorLastName_4,PersonAuthorFirstName_5,PersonAuthorLastName_5,PersonAuthorIdentifierOrcid_5,PublisherName,TitleMain_1,Language,TitleParent_1,ArticleNumber,Volume,PublishedYear,IdentifierIssn,Enrichmentlocal_crossrefLicence doi-import 19.11.2025 false true Creative Commons - CC BY - Namensnennung 4.0 International Constanze Müller Julia Seher Nicole Pniok Bianca Dreisow Katrin Rübner eng uncontrolled Repair mortar eng uncontrolled Lime mortar eng uncontrolled Lightweight aggregates eng uncontrolled Sandstone eng uncontrolled Stone conservation eng uncontrolled Recycling Ingenieurbau 7 Bauwerkssicherheit 7.4 Baustofftechnologie Infrastruktur Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Green Intelligent Building Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/64743/Mueller_Seher_Pniok_Dreisow_Ruebner_Const. Build. Mat._494_2025.pdf