Influence of the organic and mineral additions in the porosity of lime mortars.

The main objective was to determine the effect of additions of cactus mucilage (colloquially called cactus slime which on drying produces weddellite and whewellite crystals, calcium oxalates) and/or volcanic ash in masonry mortars made with lime, on the properties as mechanical resistance to compression, tension and bending, and the physical properties such as porosity which,leachates and capillary absorption. The Fagerhind method was used, on lime mortar specimens according to ASTM standards. Four mortar mixtures were debeloped: with additions and without them, like sample witness. The lime is slaked handcrafted and comes from Piedras de Lumbre Quarry Stone, Zitacuaro, Michoacan, Mexico; the volcanic ash is a mud from Acambaro, Guanajuato, Mexico and the fine aggregate, sand, proceeds from Joyitas Quarry stone in Morelia, Michoacan, Mexico. A correlation of the mechanical properties of the four mortar mixes versus its degree of porosity was made. Porosity and absorption were affected by the mucilage and/or ashes addition increasing the mechanical strength; however this was not the aim of the research, since it is not intended that the mortars were rigid, it was intended that they were capable of absorbing deformations of the natural stone masonry. The addition of mucilage and/or ash, did reduce the percentage of total porosity, the cactus mucilage when dried formed crystals of whewellite and wheddellite which filled in the pores of the mortar matrix, and the ash, mud, as it is an igneous extrusive stone, in crypt crystallite form, it presented puzolan activity forming new minerals filling the matrix pores.