Utrjevanje odstopajočih plasti ometov stenske poslikave z nekonstrukcijskim injektiranjem : doktorska disertacija

Padovnik, Andreja (avtor), Bokan-Bosiljkov, Violeta (mentor)

V doktorski disertaciji se ukvarjamo z razvojem kompatibilnih injekcijskih mešanic z apnenim vezivom, namenjenih utrjevanju odstopajočih plasti ometov stenskih slik z nekonstrukcijskim injektiranjem. Podlaga za razvoj injekcijskih mešanic je pregled slovenske in tuje prakse utrjevanja odstopajočih plasti historičnih ometov, katerega rezultat so natančno definirane zahteve za lastnosti injekcijskih mešanic, ki morajo biti kompatibilne s historičnimi ometi v kemijskem, fizikalnem in mehanskem vidiku. Istočasno moramo zagotoviti tudi dobro obdelavnost teh mešanic v svežem stanju, ki jo vrednotimo s pomočjo lastnosti, kot so pretočnost, injektabilnost, zadrževanje vode, čim manjše plastično krčenje, stabilnost itd. Razvoj injekcijskih mešanic je potekal v več fazah. V okviru preliminarnih raziskav je bilo zasnovanih 9 različnih mešanic, kot kriterij za izbiro sestav za nadaljnje raziskave (17 mešanic) pa je bila izbrana prostorninska stabilnost mešanice. Injekcijske mešanice so na osnovi mineralnega veziva in polnila (hidratiziranega apna in kalcitne moke), ultralahkega polnila (zmanjšanje teže mešanice), pucolanskega dodatka tufa (izboljšanje mehanskih lastnosti) in kemičnih dodatkov (PCE in PPh superplastifikator) za zmanjšanje količine vode. Kot prvi ukrep za povečanje prostorninske stabilnosti mešanic je bilo izbrano manjšanje razmerja vezivo : polnilo. Drugi ukrep je bil uporaba superplastifikatorja za zmanjšanje potrebne količine vode za zahtevano obdelavnost. Raziskave mešanic so razdeljene v več sklopov z izključevanjem mešanic s slabšimi lastnostmi (ne dosegajo kriterijev). V okviru raziskovalnega dela so bili razviti posebni modeli – modeli z zračnimi žepi in sendviči, ki simulirajo sklope odstopajočih plasti ometov in omogočajo dodatne raziskave nekaterih ključnih lastnosti, kot je sprijemna trdnost. Uporabljene standardizirane metode smo modificirali in prilagodili za testiranje nekonstrukcijskih injekcijskih mešanic. Kot mešanici z najbolj optimalno kombinacijo ključnih lastnosti sta se izkazali mešanici L1 S3 PCE in L1 S2B1 PCE. Mešanici imata dobro prostorninsko stabilnost z minimalnim krčenjem, dobro sposobnost zadrževanja vode, injektabilnost v stolpcu iz suhega ali predhodno navlaženega drobljenega ometa. Mehanske in fizikalne lastnosti so v okviru tistih pri historičnih ometih, z dobro oprijemljivostjo v primeru 2 mm visokih zračnih žepov. Pri preiskavah pospešenega staranja se je pokazalo, da je mešanica L1 S2B1 PCE obstojnejša ob različnih klimatskih vplivih, v kombinaciji z destilirano vodo ali raztopino NaCl. Zato je bila mešanica L1 S2B1 PCE izbrana za stabilizacijo odstopajočih plasti ometov izbrane stenske slike.

• Jezik: Slovenski jezik
• Ključne besede: grajeno okolje, gradbeništvo, disertacije, stavbna dediščina, stenske slike, injekcijske mešanice, utrjevanje, nekonstrukcijsko injektiranje
• Vrsta gradiva: Doktorsko delo/naloga
• Tipologija: 2.08 - Doktorska disertacija
• Organizacija: FGG - Fakulteta za gradbeništvo in geodezijo
• Kraj izida: Ljubljana
• Založnik: [A. Padovnik]
• Leto izida: 2016
• Št. strani: XXX, 218 str., XXVI str. pril.
• PID: 20.500.12556/RUL-82789
• UDK: 691.5:699.8:(043)
• COBISS.SI-ID: 7476577
• Datum objave v RUL: 03.06.2016

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Consolidation of detached plaster layers of mural paintings with non-structural grouting : doctoral thesis

Izvleček

In this doctoral thesis the development of compatible injection grouts based on hydrated lime for non-structural consolidation of detached plaster layers of decorative architectural surfaces (mural paintings) is studied. A review of Slovenian and international conservation practices of re-attachment interventions of historical plaster layers is given, which has resulted in well-defined requirements for injection grouts that must be compatible with historical renderings in the chemical, physical and mechanical aspects. At the same time, the injection grouts had to assure good working properties in the fresh state, evaluated according properties such as fluidity, injectability, water retention, minimal shrinkage, stability, etc. Injection grouts were developed in several phases. In the framework of preliminary research 9 different injection grouts were designed. Volume stability of the injection grouts was selected as a criterion for the selection of compositions used for further researches (17 injection grouts). Injection grouts were designed based on mineral binder and filler (hydrated lime and inert limestone filler), ultra light filler (for weight reduction), tuff as puccolan additive (to increase the mechanical properties) and chemical admixture (PCE and PPh superplasticizers) to reduce the water content. The first selected measure to increase the volumetric stability of grout mixtures was the decrease of the binder to filler ratio. The second measure was the use of superplasticizer to reduce the water content for the required workability. Furthermore, the research of grout mixtures was divided into several steps by eliminating the mixtures with poor properties (not reaching the requirements). In the framework of the research work, special models have been developed – models with air pockets and sandwiches simulating the detached plaster layers and allowing additional research of significant properties, such as adhesive strength. The grout mixtures were tested following the modified standard tests specially adapted for non-structural grouts. Grout mixtures L1 S3 PCE and L1 S2B1 PCE have proved to possess the most optimal combinations of key properties. Both mixtures have good volumetric stability with minimal shrinkage, and good water retention and injectability with dry and pre–wetted crushed lime mortar columns. Their mechanical and physical properties are within the range of historical plasters and provide good adhesion in the case of 2 mm high air pockets. Moreover, accelerated ageing showed that mixture L1 S2B1 PCE is more durable under various climatic influences in combination with distilled water or NaCl. Therefore, mixture L1 S2B1 PCE was selected for stabilizing the detached plaster layers of the selected mural painting.

• Ključne besede: building environment, civil engineering, thesis, architectural heritage, soimural paintings, injection grouts, consolidation, non-structural grouting