Chemical Characterization of Historical Brickwork of the Church Convento in Pagsanjan, Laguna

Abstract

This study reports the chemical composition of historical brickworks from Franciscanbuilt church complexes in the Philippines. An old brick sample from the Spanish colonial period church convento at Pagsanjan, Laguna was characterized by atomic absorption spectroscopy (AAS), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Conventional hot plate aqua regia (1:3 HNO3:HCl, v/v) digestion method was employed to extract iron, calcium, and magnesium from the brick sample. The combined AAS and EDX results yielded a percentage composition of iron ranging from 5.48 to 6.62%, calcium ranging from 1.50 to 3.72%, while magnesium ranges from 0.083 to 0.12%, respectively. These amounts were compared to a similar AAS and EDX study made on a historical brick sample from Ilocos Norte. The presence of possible pores on the brick's microstructure was confirmed by SEM. Minerals consisting of hematite, kaolinite, illite, quartz, and calcite were present in the sample, as well as trace amounts of other minerals based on IR peak intensities. Upon heating to about 800⁰C using TGA, the loss of bound water from the sample's internal surface structure and the decomposition of brick minerals and carbonates are evident.

Asian Building Techniques for Colonial Manila: Reviewing the Concept of Cultural Hybridity

“…The formation of post ring minerals speci cally hematite (Fe 2 O 3 ) and magnetite (Fe 3 O 4 ) were established based on the bands at 536 cm -1 and 579 cm -1 , respectively. All the bands observed in the FTIR spectrum agrees well with the characteristic absorption patterns for old clay brick materials in the Philippines [40].…”

“…Besides having similar Si-O stretching vibrations with quartz, clay minerals are identi ed based on the characteristic OH stretching modes ranging from 3400 to 3750 cm -1 [39,40], as shown from the broad peak centered at 3440 cm -1 . Natural clays are usually composed of different clay minerals with minor structural differences hence, it absorbs together and appearing as a broad peak in the spectrum.…”

Characterization of Mortar from Church Ruins in Barangay Budiao, Daraga, Albay

“…As the temperature was increased to 900 o C, weight loss measurement of the historical mortar sample is established to acquire information about the sample's binder matrix. It is shown by the thermograph in figure 4 its continuous weight loss and its significant peaks between 740 o C and around 850 o C. This particular drop in the sample's mass pertains to a characteristic peak of decomposition of calcium carbonate, with its release of CO 2 [6] . The significant drop of sample's mass between 200 o C and around 590 o C is attributed to the evaporation of water which is chemically bounded to hydraulic compounds, and the decrease in weight above 590 o C is due to the loss of CO 2 [7].…”

CALCIUM CONTENT OF LIME MORTARS FROM 19th CENTURY CHURCH RUINS IN THE PHILIPPINES USING VOLUMETRIC ANALYSIS

“…Furthermore, the broad peak at 1419 cm -1 is attributed to the C-O asymmetric stretching (ʋ3) of CaCO 3 . The most intense absorption bands of silicon dioxide are centered at 1082 cm -1 assigned to the asymmetric stretching mode of Si-O-Si, 795 cm -1 which is the symmetric stretching mode of Si-O-Si and the bending vibrations of Si-O-Si centered at 463 cm -1 , respectively [20,21]. Based on the IR spectrum in Figure 4, the binder fractions from both mortar samples have absorption peaks that are very similar with the bands of calcium carbonate.…”