The Baclayon Church (Bohol) debris of mortar: A geomaterial dimension of Philippine cultural-historical church

Heritage is the totality of tangible and intangible inherited identity in a society. Different churches are tangible ancestral heritage with its unique architectural framework and artistic elegance. Baclayon Church as heritage of one of the earliest historical-cultural structures by the Spanish conquistadores with its unique baroque architectural design. Structural materials include adobe, coral stone, bricks and limestone with organic adhesive additive like eggs, oil and viscous plant extracts. On October 15, 2013 a 7.2 earthquake devastated the province of Bohol with Baclayon as one of the most affected. This research explores the Baclayon Church: the historical cultural testimony and mineralogical components of its mortar. The methodology used is a complementary study on narrative from archival data files and geomaterial characterization of different fragments. From the debris, samples with code BCB1, BCB2 and BCB3 are analyzed for its chemical components using Shimadzu FT-IR and ED-XRF. From this analysis, the major mineralogical hulk is calcite. Based from FT-IR spectra, the adsorption peaks are located in the calcite range point and in complement with the ED-XRF. The greater volume of calcite is 95.139% (BCB2) and 94.190% (BCB3). Aggregate materials like silicates are limited to a minimal proportion. Mineralogical constituents include strontium, silicon, potassium, iron, sulfur, zinc, copper, nickel, lead, phosphorous, magnesium and lutetium. Traces of inorganic barium and lithium as well as organic amine group related to protein compounds are identified using the Shimadzu spectral library as reference. The mineralogical composition indicates that the binder is a hydrated mortar containing lime particles. Lime mortar is a primary material for the conservation of historical-cultural structures which are significant for aeration and water absorption