Resumen

ROBLES-CAMACHO, Jasinto et al. Efficiency of Pumice (P-HU) as a capillary moisture absorber for the safeguarding of documentary collections. Ing. invest. y tecnol. [online]. 2022, vol.23, n.4, e1953.  Epub 01-Mayo-2023. ISSN 2594-0732.  https://doi.org/10.22201/fi.25940732e.2022.23.4.032.

The city of Morelia is the capital of the state of Michoacán de Ocampo (Mexico) and its historic center has a declaration of zone of historical monuments, published on December 19, 1990. On 12 December 1991 it was registered as a World Heritage Site by the United Nations Educational, Scientific and Cultural Organization (UNESCO). Among the characteristics of its historic center stands out the uniformity of pink ignimbrite rock, used as a construction material and ashlars. However, the problem of humidity due to capillary ascent considerably affects the buildings of the Historic Center through two main factors: 1) the porosity of the rock, which averages ~10 μm and has a connectivity of the order of 80 % and, 2) shallow water tables with a high rate of recharge accentuated during the rainy period (May to June). Among the characteristics of this important colonial city, there is the common protection of documentary collections and libraries both public and private. One of them is the archive of the Section of Historical Monuments of the Centro INAH Michoacán, integrated for more than four decades, which systematically concentrates the construction data and interventions in buildings from the sixteenth to the nineteenth century throughout the state. This collection occupies a specific space on the ground floor of the building known as the Palacio Federal de Morelia, where the humidity due to capillary ascent is intense. To try to minimize or disappear the humidity that put this important collection at risk, a methodology was applied with natural materials, where the use of pumice stone made the process of safeguarding the collection efficient. After a series of tests, it was observed that the P-HU pumice stone shows values of real density (ρr) in the range of rhyolitic composition rocks, however, its apparent density (ρb) is in a range < 1g/cm3, less than the density of water and directly related to its high porosity. Likewise, the interconnectivity between pores is 70 %, where it is highlighted that the water dynamics of the pumice stone is related and bounded only by the porosity accessible to water. Based on the overall results, water properties are closely linked to the distribution, size and interconnection of pumice pores. In practice, the material in question is highly efficient and allows it to be projected as a reliable option for moisture capture in spaces where, in particular, books or documents of cultural or historical value are protected; without it being the only application of this material with a chance of success.

Palabras llave : Humidity by capillary ascent; documentary collection; pumice; porosity; ignimbrite.