Trabalho apresentado em International conference: construction, energy, environment & sustainability, 12-15 outubro, Coimbra, PortugalN/

Ludovico-Marques, Marco

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MONITORING DEGRADATION PATTERNS OF SANDSTONE MONUMENTS AFTER CONSOLIDATION TREATMENTSMarco Ludovico-Marques INCITE/IPS/ESTBCEES 2021 INTERNATIONAL CONFERENCECONSTRUCTION, ENERGY, ENVIRONMENT & SUSTAINBILITYGT1 –Session 1 -Construction Materials and TechnologiesINTRODUCTION• A major role is played by scientificconservation in a sustainablecultural heritage preservation.• Environmental value of suitableconservation actions.• Contribution to the creation of asustainable habitat.40th IAHS WORLD CONGRESS ON HOUSINGSUSTAINBLE HOUSING CONSTRUCTION  TS 11 –Sustainable Rehabilitation with Emerging Materials and Systems40thIAHS WORLD CONGRESS ON HOUSINGSUSTAINBLE HOUSING CONSTRUCTIONTS 11 –Sustainable Rehabilitation of Buildings using  Emerging  Materials and SystemsCEES 2021 INTERNATIONAL CONFERENCECONSTRUCTION, ENERGY, ENVIRONMENT & SUSTAINBILITYGT1 –Session 1 -Construction Materials and TechnologiesSt. Leonard's Medieval ChurchINTRODUCTIONCEES 2021 INTERNATIONAL CONFERENCECONSTRUCTION, ENERGY, ENVIRONMENT & SUSTAINBILITYGT1 –Session 1 -Construction Materials and TechnologiesDEGRADATION PATTERNS ON THE SANDSTONE FAÇADES OF ST. LEONARD’S CHURCH40th IAHS WORLD CONGRESS ON HOUSINGSUSTAINBLE HOUSING CONSTRUCTIONTS 11 –Sustainable Rehabilitation with Emerging Materials and Systems40thIAHS WORLD CONGRESS ON HOUSINGSUSTAINBLE HOUSING CONSTRUCTIONTS 11 –Sustainable Rehabilitation of Buildings using  Emerging  Materials and SystemsFive types of stone deterioration patterns (ICOMOS-ICSglossary):Crack & deformationDetachmentFeatures induced by material lossDiscoloration & deposit and biological colonization.• Sandstones use is common in traditional buildings in westregion of Portugal, (Peniche and Lourinhã).• Deterioration due to material loss (honeycomb weathering) isthe worst pattern of stone degradation on St. Leonard'schurch, due to sea vicinity.• Discoloration & deposits features such as efflorescences,are not visible in monuments facades. However chloridespredominate over sulphates as found in dissolution watersof tiny sandstones samples.• Detachment of scales visible in the vaults of St. Leonard’schurch façades.• The biological colonization has been found in superficialextent. Black fungi were located close to the zones exposedto water movement and lichens were visible on north andsouth façades linked to blistering and detachmentforms of degradation.STONE DEGRADATION PATTERNS ON BUILT HERITAGE OF ATOUGUIA DA BALEIA VILLAGEEXPERIMENTAL RESULTS• Four typologies of sandstones (A, B, C, M).• The varieties C and M have about 20-25% carbonates and 40-51% quartz.(Lithic arkose with carbonate cement (Folk, 1974))• Similarity to the stones in the monuments (aesthetic,mineralogical composition, texture and structure) wasconsidered in order to collect samples from stone masonrywalls near to the built heritage.• 5cm-long cubic specimens• Open porosity range: 3.6% (A) - 12.7% (C) and 18.5%(M)40thIAHS WORLD CONGRESS ON HOUSINGSUSTAINBLE HOUSING CONSTRUCTIONTS 11 –Sustainable Rehabilitation of Buildings using  Emerging  Materials and SystemsCONSOLIDATING PRODUCTS . Tegovakon V (TG) and Redur 420 (R). Commercially available with reasonable costs.. TGManufacturer: GoldschmidtSingle componentBefore application: unit weight of 0.95±0.02 g/cm3 at 25ºC.After application: dry residue of 34% after evaporationof solvents at 20ºC and 60% of RH.. RManufacturer: PromasilSingle component.Before application: unit weight of 0.83±0.02 g/cm3.After application: dry residue of 17% after evaporationof solvents at 20ºC and 60% of RH.(Treatment of stones were carried out in a laboratoryenvironment and in the monument )EXPERIMENTAL RESULTSCONSOLIDATION PROCEDURES. Applications by immersion and/or  capillarity over all stone mass (Ludovico-Marques, 2008). . Drying at room temperature and RH of Laboratory. . A dry residue after evaporation of solvents during 8 weeks, ofaround: 40% of TG and 17-25% of R.. Karsten pipe method was used to apply R on a sandstone block at right side of south portal below the vault (an absorption of 1.1 kg/m2 per application).EXPERIMENTAL RESULTS05100 500 1000 1500Moisture content (%)C47.2R, C78.1R, C87.2RC85.2TG, C60.1TG, C79.1TGC47.2,78.1,60.1,85.2,79.1t (h)EXPERIMENTAL RESULTSPHYSICAL BEHAVIOUR (DI)NORMAL 29/88 (1991) and RILEM (1980) NORMAL 29/88 (1991) and RILEM (1980) VarietyDrying IndexAverage ± SD (CV %)C 0.17 ± 0.01 (5.88)EXPERIMENTAL RESULTSConsolidatingproductDrying IndexAverage ± SD (CV %)TG 0.29 ± 0.01 (3.45)R 0.25 ± 0.01 (4.00)Major increase71% on TG47% on RPHYSICAL BEHAVIOUR (DI)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationEXPERIMENTAL RESULTSPHYSICAL BEHAVIOUR (DI)0123456789100 500 1000 1500t (h)Moisture content (%)M103,106,104,105,107,108M47R, M57R, M53R, M61R, M51R, M64R05100 500 1000 1500Moisture content (%)M27TG, M42TG, M23TG, M26TG, M29TG, M6TGt (h)M103,106,104,105,107,108NORMAL 29/88 (1991) and RILEM (1980) VarietyDrying IndexAverage ± SD (CV %)M 0.10 ± 0.01 (9.80)EXPERIMENTAL RESULTSConsolidatingproductDrying IndexAverage ± SD (CV %)TG0.12 ± 0.01 (8.33)R 0.11 ± 0.01 (9.09)Minor increase20% on TG10% on RPHYSICAL BEHAVIOUR (DI)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationEXPERIMENTAL RESULTSPHYSICAL BEHAVIOUR (k)0123456789100 1 2 30123456789100 20 40 60 80 100 120 140 160 180)h(t)s(t)mkg( SmΔ2CP4CPp14CP 14C47.2RC60.1TGC78.1RC79.1TGCP1CP12CPp1RILEM (1980) VarietyWater absorption coefficient, k (kg/m2/√h)Average ± SD (CV %)C 7.9 ± 0.9 (11.4)EXPERIMENTAL RESULTSConsolidatingproductWater absorption coefficient, k (kg/m2/√h)TG 5.8R 4.5Decrease27% on TG43% on RPHYSICAL BEHAVIOUR (k)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationEXPERIMENTAL RESULTSPHYSICAL BEHAVIOUR (k)RILEM (1980) VarietyWater absorption coefficient, k (kg/m2/√h)Average ± SD (CV %)M 24 ± 0.9 (11.4)EXPERIMENTAL RESULTSConsolidatingproductWater absorption coefficient, k (kg/m2/√h)TG 12.6± 1.0 (8.2)R 20.9± 1.8 (8.8)Decrease48% on TG13% on RPHYSICAL BEHAVIOUR (k)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationVarietyσc (MPa) Average ± SD (CV %)C 57.5 ± 4.9 (8.5)EXPERIMENTAL RESULTSConsolidatingproductσc (MPa) Average ± SD (CV %)TG 72.2 ± 5.5 (7.6)R 63.2 ± 2.9 (4.6)Increase26% on TG10% on RMECHANICAL BEHAVIOUR (UCS)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationVarietyσc (MPa) Average ± SD (CV %)M 57.5 ± 4.9 (8.5)EXPERIMENTAL RESULTSConsolidatingproductσc (MPa) Average ± SD (CV %)TG 48.1 ± 2.3 (4.8)R 35.9 ± 1.4 (4.0)Increment56% on TG21% on RMECHANICAL BEHAVIOUR (UCS)41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building Rehabilitation• Salt crystallization-dissolution ageing tests were carriedout in an automatic ageing chamber prototype (Mtypology).EXPERIMENTAL RESULTS41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationRILEM V.1a, b, V.2 (1980) and EN 12370, replacingsodium sulphate solutions by sodium chloride solutions.• The variation of mass loss ratio is lower on treatedspecimens with R than on treated specimens with TG,ranging between a mean value of 3% after 70 salt cycleson R to 3% - 15% after 60 salt cycles on TG. The variationof mass loss ratio is even lower on R than on non-treatedspecimens (mean value of 8%).• TG treated specimens had an average UCS reduction ofcirca 75% after 60 cycles of accelerated saltcrystallization, in comparison with sandstone specimenstreated with R that had a minor reduction of about 18% at70th cycle. Non treated specimens decreased the meancompressive strength values of about 56%.EXPERIMENTAL RESULTS41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationPHYSICAL BEHAVIOUR (k)Salt crystallization-dissolution ageing tests on R (70 cycles)EXPERIMENTAL RESULTS41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building Rehabilitation(RILEM V.1a, b, V.2 (1980) and EN 12370)EXPERIMENTAL RESULTSConsolidatingproductWater absorption coefficient, k (kg/m2/√h)R 22.0± 2.1 (2.7)Increment of mean value of k about 5%PHYSICAL BEHAVIOUR (k) ON R AFTER 70 CYCLESOF SALT AGEING41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building RehabilitationTypology MEXPERIMENTAL RESULTS41thIAHS WORLD CONGRESS ON HOUSINGSUSTAINABILITYAND INNOVATION FOR THE FUTUREOS –Experimental Research on Building Rehabilitation• Better performance of R in comparison to TG treatments assessed by means of durability and harmfulness tests (Ludovico-Marques 2008, 2014, 2016). • Then, R was applied by Karsten pipe method on a selected sandstone block of C variety at right side of south portal below the vault.Easiness for applying stone consolidation treatments on its smooth surface, but more difficulty to apply than a block of M variety due to the lower value of porosity.EXPERIMENTAL RESULTSMECHANICAL BEHAVIOUR (Drilling Strength)d (MPa)012340 5 10 15 20 25d (mm)IgIV - m1.2 MPa1.4 MPa1.7 MPa 1.8 MPaIgIV - R2d (MPa)012340 5 10 15 20 25d (mm)IgIV - NTm1.4 MPa2.0 MPaIgIV - R11.4 MPa1.2 MPaMean values increased from 1.2 – 1.4 MPa onC sandstone to 1.7 – 2.0 MPa on R applications (up to 40%).Drilling depths reached up to 20 mm.Impregnation thickness higher than 15 mm.WEATHERING AFTER 14 YEARS OF TREATMENT• Visual inspectionassessment by Karsten tube                      & water absorption under low pressure coefficientBefore treatment 14 years after treatmentCoefficient of absorption of the area of non-treated block (NTM) is a value of 6 kg/m2/√h, i.e. between mean values of 7.9 kg/m2/√h on non-treated specimens and 4.5 kg/m2/√h on R, being closer of R value than non-treated specimens value.  As R value of coefficient of absorption corresponds to higher water repellency characteristics, than non-treated specimens value, a closer value to the former means less similarity to the hydric properties of the stone-substrate.Larger differences of these properties could jeopardize the durability of the treatment for being responsible for more severe damages than the slight weathering evolution of C sandstone block.WEATHERING AFTER 14 YEARS OF TREATMENTWEATHERING AFTER 14 YEARS OF TREATMENTIn TMR the water absorption coefficient increases from 6 to 10.7 kg/m2/√h. The latter value is higher than the recorded range of 6 to 9 kg/m2/√h obtained in sandstone specimens and in the monument.DISCUSSIONWheeler (2005) reported that the levels of decay of the treated zones with the alkoxyalkysilane Brethane generally took 4-8 up to more than 15 years to reach the same extent of non-treated zones. The reduction of water absorption values to the corresponding values before ageing of treatments took between around 10 years to almost 21 years. Butlin et al (1995) presented detailed records of the application of the alkoxyalkysilane Brethane on sandstones building stones of 6 sites and treated buildings, mostly castles and abbeys. Its effectiveness was lower after 8 to 16 years regarding decay almost in all sites and the water absorption has increased.DISCUSSIONWheeler (2005) stated an important finding: a stone could be preserved when water repellence is not due to the increment of water absorption. The consolidated area of the selected block of St. Leonard’s church is still well-preserved, as visible in Figure, in spite of the higher value of water absorption.WEATHERING AFTER 14 YEARS OF TREATMENTConclusions• An experimental programme was carried out on sandstones of C and M varieties of St. Leonard’s church of in order to select the ethyl silicate application with better performance. Minor harmful characteristics and a better durability assessed by salt crystallization artificial ageing tests were obtained on R applications.• A sandstone block of C variety was selected on the monument to apply the treatment and monitoring the weathering evolution through visual inspection and assessment of coefficient of water absorption under low pressure. • A recent visual survey revealed a better surface, regarding visible degradation patterns  after 14 years of the treatment occurrence.Conclusions• The consolidated zone of the treated block reveals a higher value of the coefficient of water absorption under low pressure after 14 years than the non-treated zone in the beginning of the study. This result agrees with the data reported by several authors about the performance of sandstones circa 5-10 to 20 years after Brethaneapplications. • The treated zone of the selected block of the monument is well-preserved in spite of the significant increment of the value of water absorption under low pressure.Thank Youfor Your Patience!MONITORING DEGRADATION PATTERNS OF SANDSTONE MONUMENTS AFTER CONSOLIDATION TREATMENTS

Monitoring degradation patterns of sandstone monuments after consolidation treatments

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Monitoring degradation patterns of sandstone monuments after consolidation treatments

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