assessing the cleaning methods on the...

E.M. Perez-Monserrat1, M.J. Varas1,2, R. Fort1, M. Alvarez de Buergo1,

1 Institute of Economic Geology (CSIC – UCM), Madrid (Spain)2 School of Geological Sciences, Complutense University of Madrid (Spain)

ASSESSING THE CLEANING METHODS ON THE LIMESTONE FAÇADES IN THE FORMERLY WORKERS HOSPITAL OF MADRID, SPAIN

Assessing the cleaning methods on the limestone façades in the Formerly Workers Hospital of Madrid, Spain

1. INTRODUCTION 1. INTRODUCTION

2. AIMS AND METHODOLOGY 2. AIMS AND METHODOLOGY

3. RESULTS3. RESULTS

4. CONCLUSIONS4. CONCLUSIONS


1. INTRODUCTION (a)1. INTRODUCTION (a)

Designed by Antonio Palacios in the Nothern enlargement of Madrid.

Constructed between 1909-1916.

The building and its surrounding wall are mostly built with limestone masonry (Colmenar stone).

Abandoned at the beginning 70´s.

The Government of Madrid purchased the property and commissioned its restoration (1984 – 1986).


1. INTRODUCTION (b)1. INTRODUCTION (b)

70´s 1986

Works restorationWorks restoration 1984 1984 -- 19861986

One of the most important tasks was the stone façades cleaning

and the application of conservation treatments.


2006

2006

Main decay formsMain decay forms

Soiling processes

Black crusts

Principal soiling causesPrincipal soiling causes

Urban environmentFaçades design

Rusticated finishing ashlarsPassage of time

WallWall

1. INTRODUCTION (c)1. INTRODUCTION (c)


2. AIMS AND METHODOLOGY (a)2. AIMS AND METHODOLOGY (a)

To assess the most effective and suitable stone cleaning method.To assess the most effective and suitable stone cleaning method.

1. Alkaline gels

NaOH KOH

3. Glass microspheresblasting

1:4 ratio (w:µsp)

50-100 µm 60 kg/cm2

2. Pressured hot water jet

60 kg/cm2 60ºC

4. Latex-based product

10% EDTA Ammonia


2. AIMS AND METHODOLOGY (a)2. AIMS AND METHODOLOGY (a)


1. Alkaline gels

NaOH KOH

2. Pressured hot water jet

60 kg/cm2 60ºC

3. Glass microspheresblasting

1:4 ratio (w:µsp)

50-100 µm 60 kg/cm2

4. Latex-based product

10% EDTA Ammonia


2. AIMS AND METHODOLOGY (b)2. AIMS AND METHODOLOGY (b)


Effective assessmentEffective assessment

Limestone chromatic parameters before and after its cleaning

Global index of colour changecompared to the building

rainwashed limestone

∆E* = (∆L*2 + ∆a*2 + ∆b*2)½

SpectrophotometrySpectrophotometry

-a* +a*

+b*

-b*

Suitability assessmentSuitability assessment

Ion chromatographyIon chromatography

Alteration products formation

SEMSEM

Stone superficial changes


NaOH Water MicrospheresKOHLatex

Natural washedstone

LatexNaOH Water MicrospheresKOH

Natural washedstone

3. RESULTS (a)3. RESULTS (a)

Before cleaning

After cleaning

Latex pill off


3. RESULTS (b)3. RESULTS (b) Effective assessment: limestone chromatic parameters before and after its cleaning

∆∆EE **Rainwashed stone

Before 29.41

After 8.438.43

Before 38.46

After 11.6111.61

Before 33.05

After 13.7413.74

Before 34.5134.51

After 30.7430.74

Before 35.78

After 27.7927.79

Latex

Water

Microspheres

KOH

NaOH

White and yellow indices increase of the cleaned stones with respect to the rainwashed limestone.

0

5

10

15

20

25

-15 -10 -5 0 5

∆YI

∆ WI

NaOH

KOH

Microspheres

Water

Latex

Global index of colour change∆E* = (∆L*2 + ∆a*2 + ∆b*2)½

Compared to the limestone washed by rain


3. RESULTS (c)3. RESULTS (c) Suitability assessment: alteration products formation

ANIONSANIONS CATIONSCATIONS

Chloride Nitrate Sulphate Sodium Potassium Calcium

Rainwashed stone 46.64 119.15 101.79 12.61 4.18 8.64

NaOH 22.51 70.70 50.41 26.62 5.45 21.38

KOH 29.45 59.44 65.94 25.91 26.35 16.65

Microspheres 17.11 1.91 35.58 23.47 3.92 13.73

Artificial rain water cationic and anionic contents over natural washed stone, and limestones tested with the three most effective methods (mg/l).

Lixiviated water chemistry analysis

Anionic content Cationic content


3. RESULTS (d)3. RESULTS (d) Suitability assessment: stone superficial texture changes

NaOH

Cross section

Area analysis

Surface section



KOH

Area analysis

Surface section

Cross section



Microspheres

Cross section

Area analysis

Surface section


4. CONCLUSIONS (a)4. CONCLUSIONS (a)

Alkaline gels Pressured hot water jet Glass microspheres blasting Latex-based product

∆E* - ∆YI - ∆WI

NaOH KOH Glass microspheres blasting

Alteration products

NaOH Glass microspheres blasting

NaOH

Superficial texture changes

Glass microspheres blastingwith lower pressure


4. CONCLUSIONS (b)4. CONCLUSIONS (b)

2006 2007

2006 2007


4. CONCLUSIONS (c)4. CONCLUSIONS (c)

2006


4. CONCLUSIONS (d)4. CONCLUSIONS (d)

FUTURE?FUTURE?

Façades cleaning as part of thebuilding maintenance

Preventive maintenance


Thank you very much for your attention

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