+ All Categories
Home > Documents > REPAIR MORTARS FOR THE CONSERVATION OF...

REPAIR MORTARS FOR THE CONSERVATION OF...

Date post: 19-May-2018
Category:
Upload: hathuy
View: 216 times
Download: 2 times
Share this document with a friend
24
International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26 th - 28 th January 2005 242 REPAIR MORTARS FOR THE CONSERVATION OF CULTURAL HERITAGE: A MULTILAYER RENDER SYSTEM WITH MASS WATER-REPELLING TO BE APPLIED IN FACINGS WITH HIGH MOISTURE AND SALTS M. P. Luxán 1 , F. Dorrego 1 , J. Dorrego 2 1 Institute c.c. E. Torroja (CSIC), Madrid, Spain 2 Azrael Sistemas, S.L., Madrid, Spain Abstract The use of new homogeneous highly water-repellent mortars has favored the design of new render and plaster systems, compatible with most of the surfaces on which they are used (lime, gypsum, cement, stone, brick …), in restoration and new construction. The non-salt transporting designed system with very high vapor transmission is applicable in the case of surfaces having a high moisture and salt content according to the case studies in the EU COMPASS Project. This system is based on the application of two layers of mortar, both homogenously treated to be made water-repellent and colored in bulk (render/plaster-set) with high performance under the harshest of conditions. Other previous treatments of consolidation and water-repellent may also optionally be applied. This system has proven itself to be both useful and versatile in more than 300 historic buildings and new constructions completed in 2004 and 2005. 1. Introduction Moisture-related problems of all types are quite common to all structures (1). Moisture has been an as yet to be fully solved, year-round problem which has had a bearing on the preservation of mortars from the discovery of gypsum to lime. Moisture also poses an additional problem: When water migrates through a facing, it dissolves and transports salts as it moves along. Afterward, when this moisture evaporates, the salts crystallize inside the face or on its surface, with the negative impacts that this may involve as regards to the structure’s integrity and preservation. Actions against water in the construction field start by preventing its effects. Thus, rising damp is combated by means of perimetral ventilation trenches, static ventilation systems, bulk wall waterproofing treatments, waterproof sheeting cutoffs, which have been used to date with varying degrees of success. Doing away with filtering water or rainwater entails other problems which are also hard-to-solve in many cases.
Transcript
Page 1: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

242

REPAIR MORTARS FOR THE CONSERVATION OF CULTURAL HERITAGE: A MULTILAYER RENDER SYSTEM WITH MASS WATER-REPELLING TO BE APPLIED IN FACINGS WITH HIGH MOISTURE AND SALTS M. P. Luxán1, F. Dorrego1, J. Dorrego2 1 Institute c.c. E. Torroja (CSIC), Madrid, Spain 2 Azrael Sistemas, S.L., Madrid, Spain Abstract The use of new homogeneous highly water-repellent mortars has favored the design of new render and plaster systems, compatible with most of the surfaces on which they are used (lime, gypsum, cement, stone, brick …), in restoration and new construction. The non-salt transporting designed system with very high vapor transmission is applicable in the case of surfaces having a high moisture and salt content according to the case studies in the EU COMPASS Project. This system is based on the application of two layers of mortar, both homogenously treated to be made water-repellent and colored in bulk (render/plaster-set) with high performance under the harshest of conditions. Other previous treatments of consolidation and water-repellent may also optionally be applied. This system has proven itself to be both useful and versatile in more than 300 historic buildings and new constructions completed in 2004 and 2005. 1. Introduction Moisture-related problems of all types are quite common to all structures (1). Moisture has been an as yet to be fully solved, year-round problem which has had a bearing on the preservation of mortars from the discovery of gypsum to lime. Moisture also poses an additional problem: When water migrates through a facing, it dissolves and transports salts as it moves along. Afterward, when this moisture evaporates, the salts crystallize inside the face or on its surface, with the negative impacts that this may involve as regards to the structure’s integrity and preservation. Actions against water in the construction field start by preventing its effects. Thus, rising damp is combated by means of perimetral ventilation trenches, static ventilation systems, bulk wall waterproofing treatments, waterproof sheeting cutoffs, which have been used to date with varying degrees of success. Doing away with filtering water or rainwater entails other problems which are also hard-to-solve in many cases.

Page 2: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

243

Moisture in facings comprises a major hindrance with regard to the application of any type of render, given that good adherence to the substrate cannot be assured and detachments may therefore occur. The render mortars per se are also affected by this same moisture and by the salts transported thereby. Thus, when applied to a damp facing, traditional lime and gypsum mortars entail well-known problems. - If lime mortar has high moisture content, it hardens very slowly, and calcium hydroxide may migrate toward the surface, the hydroxide proper forming surface deposits and bloom which, on coming in contact with the air, crystallizes in the form of calcium carbonate. - In gypsum mortar, calcium sulphate also dissolves and migrates to the surface, where it crystallizes. - Cement or lime-cement mortars involve very similar problems: portlandite migration and calcium carbonate forming on the surface. Alkaline cement compounds may also migrate, causing surface efflorescence. The solution would theoretically seem simple. All that would be needed would be to design a high-performance, fast-bonding, hard-surfaced, mass water-repellent mortar of the suitable strengths which would be smooth-flowing for easy application and highly long-lasting. Apart from the above, moisture-damaged facing surfaces are not usually in the best condition for applying mortar, previous treatments often being necessary for improving the applicability and adherence-related conditions of the substrate. And if these mortars are to be used in restoring or refurbishing Historical buildings, they must be compatible with the different types of mortars which have been used throughout the course of history. The aspects previously taken into consideration have led to a complete render system having been designed and prepared to be used on damp and/or salt-laden facings. 2. Render and Plaster System In the research conducted, a render and plaster system which may be used on highly damp facings with salt migration has been designed and prepared. The designed system summarizes in:

- Consolidating treatment. - Water-repelling treatment.

Page 3: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

244

- Base mortar. - Render/Plaster mortar.

All of the specially-designed treatments and mortars comprise a system for finishing facings in both restoration as well as new construction, involving some optimum properties as regards the moisture and salt transport problem-related results achieved. This system was given an Award honorable mention in the “Premios de la Edificación Escuela de la Edificación 2004”. Logically, the initial treatments are optional, and the render-set system may generally be used as finishing mortars in Restoration and new construction in most cases, when no major degrees of moisture are involved. 2.1 Consolidating Treatment Moisture-damaged facing surfaces are usually not well-bonded and often show very little coherence, entailing disintegration-related problems. The system designed entails a starting application of a new consolidant, inorganic polysilicate. The inorganic polysilicate is supplied in water solution, is highly-penetrating and highly durable, providing clear-cut advantages over organic consolidants:

- Being supplied in water solution, making it totally compatible with the damp substrate.

- Not forming any crystallization areas. - Providing excellent penetrability. - Not giving rise to any flammable by-products. - Not giving rise to any salts subject to migration. - Very high degree of moisture conduction.

This treatment considerably improves the substrate to which the mortar is to be applied and makes improved applicability and adherence possible. 2.2 Water-repellent Treatment The system designed includes a water-soluble polysiloxane water-repellent treatment being applied over the consolidation treatment, not waterproofing (2). This water-repellent is used dissolved in water and provides for a high degree of penetrability. This treatment provides several advantages over conventional water-repellents dissolved in organic solvents:

- High penetrability. - Totally compatible with the wet surface on which to be applied, as being

dissolved in water.

Page 4: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

245

- Zero areas of accumulation. - Possibility of graduating the degree of water repellency.

The water-repellent treatment creates an added barrier in cases of a very high degree of moisture and forms an excellent substrate for applying mortar. 2.3 Base Mortar The base mortar designed for use in this system is a mass water-repellent, lime-cement mortar with high lime content. The prepared powered mortar, ready to use by simple adding water has some innovative characteristics:

- Full mass water repellency by means of natural additives, adapting from the systems used by the Romans and other ancient cultures.

- Balanced rheology and perfect workability. - High-performance adherence to the substrate. - Compressive and flexural bond strength suited to its use. - May be applied either manually or mechanically. - Balanced shrinkage. - No cracking, even when applied in very thick layers (up to 10 cm). - Reinforcing fibers may be added.

These characteristics make it ideal for use for leveling and serving as the substrate for the finishing rendering (render mortar). 2.4 Render/Plaster Mortar The render mortar has been designed as a mass water-repellent lime mortar. The mortar has been prepared in powder form, ready to use by adding water. This mortar is of the following characteristics:

- Mass water repellency using natural additives. - Excellent workability. - Optimized rheology and high-performance adherence to the substrate. - Flexural bond and compressive strengths suited to its use. - May be applied either manually or mechanically. - Allows for any type of finish and coloring added into mix. - May be applied in thickness of up to 1.5-2 cm without any cracking.

3. System Component Property Study The mortars comprising this system have been studied extensively in the laboratory, and the system has been applied under the harshest of conditions for the purpose of testing its

Page 5: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

246

properties. The treatments applied in the system have been previously studied and individually evaluated.

- Inorganic polysilicate of well-studied properties and providing excellent results and a high degree of penetratability when used on wet substrates has been used as consolidant.

- The water-soluble compound used as water-repellent is an industrial product of know features and well-studied properties.

- The base mortar has been designed as a new mass water-repellent, lime-cement mortar of ideal properties as regards its ability to withstand moisture and salts. It is supplied in powder form, to which only water need be added for its mixing.

- The render/plaster mortar has been designed as a new mass water-repellent lime mortar. It is supplied in powder form, to which only water need be added for its mixing. This mortar shows an excellent ability to withstand moisture and salt transport.

3.1 Base and Render Mortars. Composition. Physical-mechanical

Properties So as to be able to draw a comparison between the results of the base and render mortars and to actually study their water-proofing, a comparison has been made between these mortars and identical, non-water-repellent mortars. The study thus includes:

- Water-repellent lime-cement base mortar: MH - Water-repellent lime render mortar: CH - Non-water-repellent lime-cement base mortar: M - Non-water-repellent lime render mortar: C

The base and render mortars were designed and studied as a result of Spain’s contribution to the EU COMPASS Project (3). The M and C mortars differed from the MH and CH mortars solely in that they contain no water-proofing. Therefore, with the exception of the water-proofing, they must be quite similar with regard to their properties. The results of the study of the physical and mechanical properties of the two mortars as a whole are provided in following: Bulk Density and Flow Table As was to be expected, the water/binder ratio, the apparent density when fresh (UNE 83814) and the flow table (UNE 83811) were tremendously similar for both the water-repellent and non-water-repellent mortars.

Page 6: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

247

Table 1: Fresh mortars test

Mortar Type Proportion (binder /

aggregate)

Water (mL)

Water/BinderRatio

Bulk Density (Kg/m3)

Flow Table (mm)

Standard 346 0.7 2020 158 M 394 0.8 1900 167 Lime /

Cement MH

2/1/9 390 0.8 1830 162

Standard 470 1.0 1860 155 C 494 1.1 1810 160 Lime

CH 1/3

486 1.1 1780 161 Mechanical Strength The flexural and compressive strength results at 28 days (UNE-EN 196-1) are provided jointly for the MH and CH mortars. The values found are typical for the lime-cement and lime mortars currently used as facing render-set finishing mortars. Table 2: Mechanical strength

Mortar Flexural Strength (N/mm2)

Compressive Strength (N/mm2)

M 1.2 5.8

MH 1.2 5.6

C 0.5 2.7

CH 0.7 3.8

Bulk Dry Density The water-repellent MH and CH mortars show a density somewhat below the non-water-repellent mortars, which means a slightly higher performance in their application (~10% volume increase). Table 3: Bulk density of the hardened mortars (dry). (UNE 83-820-94)

Mortar Type Bulk Density (Kg/m3) M 1670 Lime/Cement MH 1750 C 1480 Lime CH 1530

Page 7: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

248

Vapor Transmission In the water vapor transmission test (RILEM 25-PEM test II.2) (4), the water-repellent mortars, that is, the lime-cement (MH) and the lime (CH) perform better than the corresponding non-water-repellent (M and C) mortars. In both cases, the vapor transmission is higher in the water-repellent mortars than in the corresponding non-water-repellent mortars, as is shown on the graph. This is of major importance, given that, in general, commercial water-repellent mortars undergo a major decrease in vapor transmission, as much as 40-60% in some cases, compared to the non-water-repellent mortars. A 20% decrease (indicated by the lower dash line in figure 1) is established, in theory, as being acceptable. Good vapor transmission is highly important for mortars which are to be used on damp facings. The high degree of permeability of the mortars studied allows the moisture in the facing to evaporate and to flow through the mortars. This makes it possible to continually rid the facing of moisture and to keep the salts inside the wall from migrating to the exterior, thus prevent the problems this would involve.

Vapor Transmission

0

1

2

3

4

5

6

0 24 48 72 96 120

t (h)

Evap

orat

ed M

ass

(g)

MHCHMCMinimum Limit

Figure 1. Vapor transmission test (RILEM 25-PEM test II.2) Low-Pressure Water Absorption The study was conducted following the RILEM 25-PEM test II.4 recommendations (Karsten pipe) (4). The comparative absorption figures (Figs. 2a and 2b) for the mortars tested reveal the water repellency of the MH and CH mortars. The water absorption for

Page 8: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

249

the water-repellent MH mortar is over 60 times less than that of the non-water-repellent M mortar. In the case of the water-repellent lime mortar (CH), the absorption is 110 times less. The mortars are nevertheless not waterproofed. They are highly water-repellent, but do absorb a very small degree of water. This fact involves these mortars being resistant to rainwater even in strong winds, as is described in the RILEM Test employed.

Karsten PipeLime/Cement 2:1 Mortar

05

10

1520

253035

40

0 30 60 90 120 150 180 210

t (min)

V (m

L) M HM

Karsten PipeLime Mortar

05

101520253035404550

0 30 60 90 120 150 180 210

t (min)

V (m

L) CHC

Figure 2. Karsten pipe (RILEM 25-PEM test II.4).

a

b

Page 9: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

250

Water Absorption The water-repellent MH and CH mortars were found to have a low degree of absorption as a result of Test II.6 set out in the RILEM 25-PEM recommendations (4). The absorption of the MH mortar is 5 times less than the M mortar (Fig. 3a), and the lime mortar (CH) is thirty times less than the non-water-repellent mortar (Fig. 3b). The mortars therefore show a very low degree of absorption in keeping with their high degree of water repellency.

Water Absorption CoefficientLime/Cement 2:1 Mortar

0

5

10

15

20

0 25 50 75 100 125

t (s0,5)

m (k

g/m

2 )

MHM

Water Absorption Coefficient

Lime Mortar

0

5

10

15

20

0 25 50 75 100 125

t (s0,5)

m (k

g/m

2 ) CHC

Figure 3. Water absorption coefficient (WAC) (RILEM 25-PEM test II.6)

a

b

Page 10: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

251

Surface Hardness The surface hardness (Shore C) of the water-repellent lime and lime-cement mortars was measured. Both mortars showed a major degree of hardness. The hardness of the mortars, in conjunction with their mechanical strength properties, make them ideal for being applied as base (MH) and render (CH), in keeping with the principle of applying a less resistant mortar on top of a stronger one. Table 4: Shore C hardness

Mortar 28 days 90 days

M 71 84

MH 75 90

C 58 71

CH 60 74

3.2 Base and Render/Plaster Mortars: Substrate (brick)-Mortars Tests

in the Evaluation of their Water Repellency and Salt Resistance The properties evaluated would lead to predict good performance with regard to the salts in the lime-cement and mass water-repellent lime mortar. A laboratory test was thus designed for a quick evaluation of water-repellent and non-water-repellent mortars. As part of the tests conducted in the European Project COMPASS (3), the water-repellent and non-water-repellent lime-cement and lime mortars were studied, their water repellency and their resistance to salt transport and crystallization having been evaluated. The water-repellent and non-water-repellent lime and lime-cement mortars were applied to solid ceramic bricks. The bricks and the mortars applied to them were treated by water absorption with a 10% NaCl solution and a 10% Na2SO4 solution throughout a twenty-four hour period and then dried throughout a forty-eight hour period, in each cycle.

Page 11: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

252

The damage was assessed following 5, 8 and 10 cycles. Both the damage found as well as the salts retained inside each brick-mortar is stated in the Table provided below. Table 5: Plaster/Render mortars, water and salt resistance test results

Damage Damage Damage Salt Cryst. (g) Shore C H2O 5 cycles 8 cycles 10 cycles 10 cycles 10 cycles C o o o NA 78 CH o o o NA 74 M o o o NA 70 MH o o o NA 86 Damage Damage Damage Salt Cryst. (g) Shore C NaCl 5 cycles 8 cycles 10 cycles 10 cycles 10 cycles C # # # # # # # # # # # # # # 242 0 CH # # # # # # # # 188 0 M # # # # # # 243 66 MH o o # 169 87 Damage Damage Damage Salt Cryst. (g) Shore C Na2SO4 5 cycles 8 cycles 10 cycles 10 cycles 10 cycles

C # # # # # # # # # # 238 0 CH # # # # # # # # # 193 0 M # # # # # # # # 251 69 MH o # # # 217 79 DAMAGE o None # Very low # # Low T: 24 - 27ºC # # # Medium R.H.: 35 - 42% # # # # High # # # # # Very high

Page 12: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

253

The mass water-repellent lime-cement mortar was the one found to have shown the best performance in the test. These tests afforded the possibility of evaluating the additives used and of optimizing the additives which have been used in the design of the mortars employed (MH and CH) in the system discussed herein. 4. System Study and Evaluation: Actual Case Employing the System 4.1 Employing the System The studies conducted in the laboratory and the prior experience led to rounding out the design of the base and render system useable on facings entailing a high degree of moisture and salt migration (5).

Figure 4. Domed room at “Nuestra Señora de Valverde” Hermitage (Madrid)

Cement floor

Page 13: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

254

A truly difficult case was selected for employing the system in a true life situation. In the rehabilitation being carried out by the City Housing Authority on the former “Nuestra Señora de Valverde” Hermitage (Fuencarral, Madrid) (6), a domed room located below the level of the surrounding floor and with a cistern nearby, with lime mortar-grouted brickwork and lime mortar-grouted stone walls was selected (Fig. 4). One of the side walls was found to be extremely damp. There were two focal points of moisture, one coming from the left-hand area, up to a height of 2-2.5 m, the other entailing moisture ascending from the floor, which occurred following the flooring having been laid on concrete throughout the entire room. After sandblasting all of the old gypsum plaster off the wall, the condition of the moisture in the walls of this room in the spring of 2004, following a great deal of rainfall in the area, was one of tremendous moisture. The grouting was highly eroded, and the bricks were visibly crumbling. The render system was applied to the facing in the following stages (Fig. 5):

- Application of the consolidating treatment - Application of water-repellent treatment - Application of base mortar - Application of render mortar.

The consolidant was brushed on, the product having been used in a 17% water solution, a total of 150-200 mL/m2 having been used in all. A 4% solution water-repellent treatment was used, having been applied using a low-pressure spray, a total of 120-150 mL/m2 having been used in all. Throughout the entire area selected, which takes in one brick dome area part and another stone and mortar facing part, the mass water-repellent, lime-cement mortar was applied in thickness of up to 10 cm. The plaster mortar was applied in the right-hand half of the area being worked on, in a thickness of 5-6 mm. The mortars were applied using specialized technicians (Rescalfa, S.L.). These applications were spaced 24 hours apart.

Page 14: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

255

Figure 5. Render and plaster system application

The temperature reading was 12-14ºC and the relative humidity reading, 63-66% on the days the mortars were applied. These temperature and relative humidity ranges remained unchanged throughout at least the six days immediately following the application, which increased the mortar drying problems. Temperatures of 5-9ºC were measured on the wall to which the mortar had been applied, the dew point thus having been reached throughout the entire day on the surface to which the mortar was applied, water thus settling on the wall all day and all night. The water saturation situation remained stable for 6-7 days, gradually lowering over the following 10-15 days. The rising temperatures at the beginning of the summer improved the hydrometric situation, and the mortars began their drying and hardening process. Sixty days immediately following the application, samples were taken for test check and analysis purposes.

1. Consolidation treatment 2. Water repellent treatment

3. Base mortar Lime/Cement Mortar with water

repellent additive in mass

4. Plaster mortar Lime Mortar with water repellent

additive in mass

Page 15: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

256

4.2 System Evaluation Infrared Thermography Moisture Evaluation The infrared thermography technique has been employed for evaluating the condition of the facing and detecting moisture on the surface to which the system is to be applied, as well as in the study of the conditions of the facing after the system has been applied (7). A full evaluation was made of the entire facing using this technique, locating the areas having a greater or lesser degree of moisture, and the discontinuities caused by water moving on its interior (Fig. 6). Facing condition prior to the application

Figure 6. Facing condition prior to application In the thermographs taken, no rising damp was found to exist in the facing. The moisture found came from the back of the wall, being located mainly starting as of the brickwork up to a height of some 2 meters, thus having made it possible to choose this area due to its conditions for applying the system. Facing condition following the application of the system At the lower area some major rising damp was found from the floor level upward, covering the entire facing. In the render system, the whole is homogeneous, there being no discontinuities due to variations in the moisture content, the system functioning, in other words, as a single unit, and not in spots. In the infrared thermographic analysis (Fig. 7), it was found that:

- The amount of moisture retained is low. - The water is evaporating from the system surface.

Without moisture

Application zone

Highest moisture

Page 16: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

257

Figure 7. Facing condition following the application of the system In the upper area, above where the system was applied, moisture from the back of the wall was found to be building up, this being a condition which had already been detected prior to applying the system (Fig. 7). Moisture. Hygroscopicity and Salts The evaluation of the condition of the facing before and after the render system being applied was carried out following the guidelines of the aforementioned European Project COMPASS (3), one of the objectives of which is that of proposing a methodology for the analysis of renders on facings containing salts and moisture. This methodology consists of ascertaining the hygroscopic moisture content (HMC) (8) and moisture of the facing by means of determining both contents in samples taken at different heights and, in each one thereof, at different depths. By means of the plotting of the values found, the existence of moisture in the facing and the origins thereof (from the floor, exterior, etc.) can be evaluated, in addition to setting out a ratio regarding the hygroscopicity behavior, the salt content and the location thereof in the facing in accordance with the profile obtained. In the case of the study of the facing of the domed room at the “Nuestra Señora de Valverde” Hermitage, an analysis of the facing has been made before and after the application of the render system by taking samples at the following heights: Table 6: Samples taken at the “Nuestra Señora de Valverde” Hermitage

Height (m) Wall Zone Zone of the Mortar-System

Application 2.1 brickwall/mortar 1.9 brickwall/mortar X 1.7 brickwall/mortar X 1.2 rough stone/mortar X 1.0 rough stone/mortar 0.5 rough stone/mortar

Without moisture:

Drying

High moisture

Page 17: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

258

Three samples were taken at each one of the heights, within the following depth ranges, 1-5 cm, 5-10 cm and 10-15 cm. Following the application of the render system, these same depths and heights were employed for taking the samples from the facing, samples additionally having been taken of the base and render mortars. Moisture and hygroscopicity behavior before applying the system The facing showed very high moisture content. Values of 15-30% were found at all heights, and the samples taken were practically saturated with moisture. No significant differences were found between the upper and lower areas. The analysis of the data indicates that the moisture comes from the back of the facing. This data confirms the infrared thermography study conducted for the entire facing as a whole (Fig. 8).

Moisture ContentBefore Application

0,3

0,6

0,9

1,2

1,5

1,8

2,1

0 5 10 15 20 25 30 35 40

Moisture Content (% kg/kg)

Hei

ght (

m)

0 - 5 cm

5 - 10 cm

10 - 15 cm

Figure 8. Moisture content (MC) before application The hygroscopicity behavior profiles show low values in the lower area (stone/mortar). In the brickwork area, the values increase toward the exterior, being lower inside the wall (10-15 cm) and higher on the wall surface (0-5 cm). It is in the areas showing the greatest hygroscopicity behavior (heights 1.2, 1.7 and 1.9 m) that the system has been applied (Fig. 9).

Page 18: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

259

Hygroscopicity Moisture Content (HMC) Before Application

0

0,5

1

1,5

2

0 5 10 15 20 25 30Hygroscopicity Moisture Content

(HMC) (% kg/kg))

Hei

ght (

m) 0 - 5 cm

5 - 10 cm

10 - 15 cm

Figure 9. Hygroscopicity moisture content (HMC) before application Moisture and hygroscopicity behavior after applying the system In the moisture content tests, the rising damp in the lowest areas (heights 0.5 and 1 m) is patent due to the domed room having been paved in cement, thus preventing water from evaporating from the ground and causing it to move up through the wall. In the area where the system was applied (heights 1.2, 1.7 and 1.9 m), the moisture content is below 8%, as well as at the height of 2.1 m above the render. This value contrasts with the high moisture contents of around 15-30% found before the application. Special mention must be made of the fact that the moisture content has dropped to a great extent in the area where the system was applied, thus confirming that this system allows the water contained in the wall to evaporate. The moisture contained in the wall is found to progressively decrease from the back of the wall toward the surface. The mortars also show moisture, decreasing from the base to the render (no waterproof), and are allowing the wall to breathe (Fig. 10).

Page 19: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

260

Moisture Content After application

0

0,5

1

1,5

2

0 2 4 6 8 10 12 14

Moisture Content (% kg/kg)

Hei

ght (

m)

PlasterBase0 - 5 cm5 - 10 cm10 - 15 cm

Figure 10. Moisture content (MC) after application As regard to the hygroscopicity behavior, the values found decrease on the order of 40-50% following the application, dropping to minimum values at 1.7 m, the central part of the area where the mortars were applied. Above the system applied, there is no increase in the hygroscopicity behavior, to the contrary a decrease in hygroscopicity behavior having been found at 2.1 m. This fact can be related to the system applied not inducing an increase in salts above the area where applied (Fig. 11).

Hygroscopicity Moisture Content (HMC)After application

0

0,5

1

1,5

2

0 5 10 15 20 25

Hygroscopicity Moisture Content (HMC)(% kg/kg)

Hei

ght (

m) Base

Plaster0 - 5 cm5 - 10 cm10 - 15 cm

Figure 11. Hygroscopicity moisture content (HMC) after application

Page 20: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

261

Salts The facing salts have been identified in samples taken at different depths (0.5, 5-10 and 10-15 cm) and at two heights (1.9 m and 1.2 m), corresponding to each one of the building materials, that is, respectively brickwork and stone/mortar (Fig. 12).

D100abc

1.2 m height rough stone/mortar

KN100

Q100

KS100

CC100

T100

a: 0-5 cm b: 5-10 cm c: 10-15 cm

KN100

Q100

CC100 D100

T100

KS100

1.9 m height brickwall/mortar

a: 0-5 cm b: 5-10 cm c: 10-15 cm

abc

Figure 12. Identification and composition of salts (X-ray diffraction)

Page 21: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

262

There is a great similarity between the X-ray difractograms taken both in the stone as well as the brickwork area. However, the peaks are sharper at the height of 1.2 m than at 1.9 m, thus indicating a greater salt content in the area around the lower level. Potassium sulphate (KS - K2SO4), sodium sulphate (T - Thenardite - Na2SO4) and potassium nitrate (KN - KNO3) (9); and compounds from the mortars: calcite (Cc - CaCO3), quartz (Q - SiO2), dolomite (D - CaMg(CO3)2) and clayey minerals had been identified by X-ray diffraction. The different intensities of the salts have been plotted individually, thus revealing that the highest concentration of alkaline sulphates (KS and T) are found at a height of 1.2 m and in the lowest-lying area (10-15 cm), while the at the height of 1.9 m the greatest concentration of these salts is located on the surface (0-5 cm). Special mention must also be made of the fact that the proportion of lime, now carbonated and identified as calcite (Cc), is greater in the surface areas (0-5 cm) than on the interior (Fig. 13).

Proportion of the alkaline salts and calcite (X-ray diffractograms)

0

500

1000

1500

2000

2500

3000

3500

KS T1 Cc KN

Compounds

Cou

nts

(XR

D)

1.2 m / 0-5 cm

1.2 m / 5-10 cm

1.2 m / 10-15cm

1.9 m / 0-5 cm

1.9 m / 5-10 cm

1.9 m / 10-15 cm

Figure 13. Proportion of alkaline salts and calcite

Page 22: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

263

5. Conclusions The mass water-repellent mortar render system applicable to facing having a high moisture and salt content is, as a whole (consolidation + water-repellent treatment + base mortar + render mortar) of the following characteristics:

- High water repellency and high vapor permeability, higher than that of the corresponding non-water-repellent mortars, allowing the moisture to be eliminated from the facing by means of this system. However, even with the high degree to which this system is water-repellent, it is not waterproof. The water repellency has been done in mass and not on the surface, thus preventing the system from losing its water-repellent properties due to impacts on the mortars entailing the falling away of material. The evaporation of moisture from the facing has been proven by means of infrared thermography over the entire surface where the system was applied and has been confirmed in a timely manner in samples taken at different heights and depths.

- Prevents the inflow of rainwater (on exteriors) even with strong winds.

- Prevents salt transport by moisture from the inside to the surface of the

facing.

- Good bonding even on damp substrates with flawed surfaces (pulverulence, crumbling, etc.).

- The surface water-repellent (water-soluble polysiloxane) used as a

treatment prior to the application of the mortars aids in creating front-line barrier shielding the system from moisture from the facing.

- The base mortar (mass water-repellent lime-cement) allows for application

up to 10 cm in thickness in one single coat, without any cracking or detachments.

- The render mortar (water-repellent lime, bulk colored) can be applied in

thicknesses of up to 2 cm without any cracking.

- Both of these mortars (base and render) possess physical and mechanical properties appropriate for the application, and the water-absorption characteristics are proof of its high degree of mass water repellency.

Page 23: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

264

- This system has been designed for the most difficult cases of facing moisture and salt transport.

- This system may be applied to curved facings without any problems of

cracking with excellent results.

- The base and render mortars may be applied together, or either one by itself. The previous treatments may also not be applied in those cases in which they are not necessary.

- The designed mortars have already been applied in 2004 and 2005,

individually and together, as base – render/plaster, in over 300 restoration, rehabilitation and new constructions with optimum results in their features and performance, both on interiors and exteriors. One example is the restoration of the Middle-age Roman bridge “Puentecillas” (Palencia); and in Madrid, such as the buildings located at Belén No. 1, Claudio Coello No. 32, Díaz Zorita No. 8, Cruz No. 9 and Ortega y Gasset No. 5 and No. 52.

- Due to their efficient mass water repellency, these mortars may be used in

any restoration and rehabilitation as they are compatible with any type of mortar dating from any era, given that they neither interact with these earlier mortars nor give rise to salt migration.

6. Acknowledgements The authors would like to thank: Fundación Escuela de la Edificación – Colegio Oficial de Aparejadores y Arquitectos de Madrid the Award of Investigation 2004. The research has been partially supported by EU-COMPASS (CE-EVK4-2001-00047) and CICYT Research Project BIA2004-04506. The designed mortars used have been prepared and manufactured by Hidrobinder, S.L. 7. References 1. Delgado Rodrigues, J. and Diaz Gonçalvez, T., ‘Sais solúveis nas construções

históricas. Introdução e relato sumário’ in ‘Sais solúveis em Argamassas de Edifícios Antigos: Danos, processos e soluções’, Proceedings of an International Seminário, Lisboa, Fevereiro 2005 (LNEC, Lisbon, in press).

2. Dorrego, F., Carrera, F. and Luxán, M. P. ‘Investigations on Roman amphorae sealing systems’, Materials and Structures RILEM, 37 (369) (2004) 369-374.

3. EU Research Project COMPASS ‘COMpatibility of Plasters And renders with Salt loaded Substrates in historic buildings’ (EVK-CT-2001-00047). htpp://www.compass-salt.org and Newsletters 1, 2, 3 and 4.

Page 24: REPAIR MORTARS FOR THE CONSERVATION OF ...demo.webdefy.com/.../uploads/2016/10/pro067-023.pdfInternational RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands,

International RILEM Workshop on Repair Mortars for Historic Masonry Delft, The Netherlands, 26th - 28th January 2005

265

4. RILEM TC - 25-PEM, ‘Recommended tests to measure the deterioration of stone and to assess the effectiveness of treatment methods’, Materials and Structures RILEM, 75 (13) (1980) 175-253.

5. Dorrego, F., Luxán, M. P. and Collaro G. de Lourenço, B., ‘Argamasas Históricas. Sistemas de Restauración de Argamasas de Enfoscado y Revoco. Las Fachadas del Pavilhão Mourisco’, in ‘II Caminhos da Arquitetura em Manguinhos: Patrimônio e Técnicas de Conservação’, Proceedings of an International Workshop, Rio de Janeiro, May 2005 (Fiocruz, Brasil, in press).

6. Dorrego, F., Fernández, V., Luxán, M. P. de and Vicente, B., ‘El conjunto histórico de nuestra Señora de Valverde (Madrid)’, en ‘La Conservación del Patrimonio en un entorno sostenible’ Ed. IETcc-CSIC. Luxán, M. P., Dorrego, F. and Aymat, C. Eds. (Madrid, 2004) 55 – 57.

7. Dorrego, J. F., Luxán, M. P. and Dorrego, F., ‘Damage detection and localization of reinforcement elements in historic buildings with infrared thermography’, in 'Advances in Concrete Structure’ Proceedings of an International Conference ICACS 2003, Xuzhou, China, September 2003, Y. Yuan, S. P. Shah and H. Lü, Eds. (RILEM Publications S.A.R.L., 2003), 1, 567-574.

8. ‘HMC method’. EC Contract EV5V-CT94-0515 ‘Evaluation of the performance of surface treatments for the conservation of historic brick masonry’, Research Report n. 7, van Hees, R.P.J. Ed., 1998, 80-82.

9. Doehne, E., ‘Salt weathering: a selective review’, in 'Natural Stone. Weathering Phenomena. Conservation Strategies and Case Studies’, Siegesmund, S., Weiss, T. and Vollbrecht, A. Eds. (Geological Society, London, Special Publications, 2002) 205, 51-64.


Recommended