Effects of Organic Additives

Work at the University of Granada found that the addition of nopal juice into lime putty produces a high quality lime putty following lime slaking. The microstructural characteristics of such hydrated lime are similar or superior to those of aged lime putties: high surface area and small particle size, which should affect reactivity and water retention and may lead to easier and faster carbonation. This quality improvement is obtained readily, after slaking in the presence of nopal extract, an important fact to consider for practical, economically feasible conservation interventions. At the GCI, this work was complemented by a study of the short-term effects of both organic and inorganic additives on the rheological and working properties of lime putties, and the long-term effects on the chemical stability of the additives, their effects on curing, and on strength development.

Based upon the results of the nopal study, the University of Granada received a research grant from the European Union to study "The Effects of Organic Additives on the Nanostructure and Colloidal Behavior of Hydrated Lime. Applications in the Design of Mortars for Restoration." The short-term and long-term effect of traditional and modern organic additives on properties of lime putties and mortars were also studied at the GCI.

Reactivity of natural zeolites with lime was studied by Catholic University and the GCI. The importance of physical properties (e.g, surface area) and chemical composition (Si/Al ratio, Si content, etc.) of natural zeolite and their reactivity with lime were determined. The results indicated that the external surface area only influences the short-term reactivity. Their long-term reactivity is mainly related to the Si/Al ratio of zeolites. Zeolites rich in Si react faster than those rich in Al. These results are published as, "Pozzolanic Reactions of Common Natural Zeolites with Lime and Parameters Affecting Their Reactivity" in Cement and Concrete Research, 39(3): 2009, pp. 233-240.

Page updated: October 2007