UNDP/MYA/86/019 M Y A N M A R

Assignment Report Conservation of Cultural Serial No. RACAP/PROAP/92/3 ,_, .» 4 0 . . .

Heritage at Selected

Sites in Myanmar For internal use only : not for general distribution

Conservation of Historic Brick Masonry in Pagan, Myanmar

by J.C. Yarmola

UNITED NATIONS EDUCATIONAL, UNITED NATIONS SCIENTIFIC AND CULTURAL DEVELOPMENT ORGANIZATION P R O G R A M M E

Bangkok 1992

UNDP/MYA/86/019 M Y A N M A R

Assignment Report Serial No. RACAP/PROAP/92/3

Conservation of Cultural

Heritage at Selected

Sites in Myanmar

For internal use only: not for general distribution

Conservation of Historic Brick Masonry

in Pagan, Myanmar

by J. C. Yarmola

United Nations Educational,

Scientific and Cultural

Organization

United Nations

Development

Programme

Bangkok 1992

UNDP/MYA/86/019 Assignment Report (Yarmola)

RACAP/PROAP/9 Bangkok, 9 September 1992

Note: This report reflects the views of the author and not necessarily those of UNESCO.

CONTENTS

Page

Foreword

General Comments on the Masonry Works 1

Definition of Missions 1

Methodology v.s. Improvisation 1

Necessity of a Field Laboratory 1

Basic Knowledge that the Staff Should Remember 3

Mon Gu Temple 6

Modus Operandi 12

Conclusion 13

Appendix 14

Foreword

The mission described in this report is the fourth mission undertaken by the consultant to advise on the conservation of historic brick masonry in Pagan, Myanmar.

The consultant stayed in Pagan from 21 December 1991 to 10 January 1992. A few activities were done as follows:

1) Meetings were held with Myanmar officials, including U. Than Maung, Director General of Archaeology, Yangon. Other meetings with the members of the team of foreign consultants, Pierre Pichard, International coordinator, M. Manhart, UNESCO officer from Paris, and Myanmar field staff in Pagan.

2) Lectures in the office of the Department of Archaeology in Pagan were given to the staff from the Department of Archaeology and the Construction Corporation.

3) Visits to several structures where works are being carried out, generally brick structures, but also stone conservation in Nampaya and timber in Taungbi village.

A) The border between the field of reinforcement and strengthening for better seismic resistance and repair or/and restoration cannot be definite - therefore Professor Gavrilovic and the consultant worked together very often as they did in 1987.

I. GENERAL COMMENT ON THE MASONRY WORKS

1. The consultant's personal impression is that there is a significant improvement in the masonry works compared to what was done prior to the early eighties. But the criteria to choose the structures to be restored is not clear.

2. Classification will be improved now that the complete inventory exists and that the decision to build a master plan is taken. But "What should be the master plan?" is one of the main questions.

II. DEFINITION OF MISSIONS

3. Definition of missions is necessary as well as the means to carry out missions. Needs of material and man power should be clearly pointed out for the best working conditions.

4. It might be wrong but the consultant feels that a confusion about a job description; MAINTENANCE, STRENGTHENING, REPAIR, RESTORATION, exists among the staff of the Department of Archaeology and the Construction Corporation.

III. METHODOLOGY V.S. IMPROVISATION

5. This is the consultant's main recommendation. For every project, multidisciplinary approach will give the best results: a project is a synthesis of all the data collected after a complete detailed analysis of all symptoms that have to be observed and an objective appreciation of the stage of decay.

6. By the term methodology, the consultant also means technically sound appreciation; objective versus subjective appreciation. Instead of saying "this mortar is good", we should say "the bearing capacity of the mortar obtained with a mix composed as follow is of so many kilograms per square centimetre - after one week, three weeks, six weeks."... "The color of the mortar matches the general color of the facings"

IV. NECESSITY OF A FIELD LABORATORY

7. In any masonry characteristics of mortars must be weaker than that of stones or bricks: crushing strength, shear strength, water absorbtion, etc. This is why we need a simple but efficient field laboratory to carry out these tests systematically.

8. Laboratory What do we need for a laboratory? Mould for samples, made of planks or sheets of metal, that must be standardized in size so that one can compare identical samples of several mixes. Precise balance. It can be a simple one. It should cover a range from 0.5 gramme to 10,000 grammes (10kg). Press with dynamometric gauge. Humidity (or moisture) tester. Chemical reactive to soluble salt.

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9. Drafting Equipment Civil Engineers and assistants need such common tools as a

blue print table, files, cardboard tube to keep plans drawn on tracing paper, files for negatives and photographs taken systematically for the record.

10. Special Equipment for Better Bricks The bricks used for repair should have the same size and

quality as the bricks used to build the structure. The modern bricks used are too different from the ancient ones and I recommend that an equipment should be provided to obtain proper bricks: a mixer, that can be run by animals, or electric power and a good hydraulic press - strong mould, made of wood and steel frame, for instance, special thermometer to appreciate the heat of burning. For the best repair and restoration of brick structures in Pagan, the Archaeological Department should be able to make its own bricks adapted to each temple or monastery.

11. Conservation of Historic Brick Masonry in Pagan consists in maintenance, strengthening, repairing, and restoration.

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V. BASIC KNOWLEDGE THAT THE STAFF SHOULD REMEMBER

12. Soil Every soil can carry certain weight of load, depending on what you want to build on it. Damp condition can change the allowable bearing soil pressure; when sandy with cubic repartition of grains, or when of a clayish nature "the swelling pressure". Clay is a colloid which is subject to variation due to dampness.

13. Foundations Every load is carried by soil; the figure of stress or diagram is drawn;

as a rectangular constant value? Theoretical as a bulb, depending on the nature of the soil. as a diagram including the non-vertical pressures.

14. Vertical is an ideal No structure carries a real vertical stress on the soil. Wind pressure, arch pressure, and flexible beam bring a horizontal stress on supports.

Several types of non-symmetrical foundation or of too close ones bring an excessive pressure on soil. Any structure including beams or vaults exercises an horizontal pressure that is combined with vertical loads.

a) Beams - When loaded, any beam bends. Therefore, contraction of upper fiber and extension of lower one brings a horizontal pressure on bearing points.

b) Arches - The very simple expression of what is so called a "truss" in carpentry or an "arch" in masonry is the condition of equilibrium of two bricks: unless the friction in A & C is sufficient, this cannot stand.

This is the basic concept of arch pressure.

T I E BEAM

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16

15. As most historic brick structures in Pagan Archaeological Area are vaulted structures, the problem of arch pressure must be considered. If combined with seismological stress, arch pressure may cause collapse due to:

a) insufficient resistance of vertical support to horizontal stress (shearing capacity)

b) change of bearing capacities of soil foundation - not uniformly loaded.

Arch pressure is a function of load. Dampness increases the weight of structures and therefore increases the compression stress on vault, walls, foundation, soil - a change of arch pressure brings a change on horizontal stress, i.e. shearing efforts.

Catenary arch is considered as the closest to perfect repartition of compression.

The key word for conservation is maintenance "keep the monuments dry"

a) Dampness increases the weight, therefore it also increases the horizontal stress (arch & vault pressure)

b) Dampness lowers the friction of elements of any kind of masonry. One can say "it lubricates the elements" and makes the structure fragile. This "lubrication" is high with mud or/and clay mortar, (pore pressure).

c) Dampness also washes out inner mortar of the core of walls. The consequence is a higher stress on the facings especially when the core and the facings are of different quality of masonry.

d) Dampness spoils mural paintings when carrying dissolved chemical salt, (evaporation)

e) Dampness brings failure to stucco carved motives, (evaporation)

17. Dampness comes mostly from roofs and terraces, crack in vaults or walls, capillarity through foundations, and sometimes due to condensation of vapour on a cold surface.

18. One can say that dampness is the cause of many decays: mechanical, chemical, and biological.

5

19. Since an important staff needs to inspect and maintain so many structures, motor bicycle will be helpful for this task.

20. To keep the monuments dry, water drainage must be checked at least once a year and weep holes must be kept clean.

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CATENART PROFILE OF THE VAULT -PORCH OF MON GU TEMPLE

6

VI. MON GU TEMPLE

21. In Old Burma - early Pagan, by Gordon H. Luce, New York, 1970, Mon Gu Temple, West of TAUNGBI village brick tank, now recorded as temple 2013/1309, is described in a complete manner.

This photograph of the southern facade (probably prior to 1961, plate 156) shows a big vertical crack on the wall that has been repaired prior to the earthquake in 1975.

The consultant was told that last repairs were carried out ten years ago in 1981.

Ancient cracks are not stabilized and it is not certain if any new ones occurred.

Telltales, mortar patches, or plaster pads, dated should be applied on cracks.

A programme of works on this interesting structure is to be carried out in 1992 - 1993.

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Mon Gu Temple Dec. 1991

7

Level 1

Level 2

Level 3

Entrance facade, East wall Of the porch. Note the inadequate repair of the gate, the buttresses and the bases of the angles. Better toothing of adequate bricks and grouting of cavities, coloured mortar are necessary.

South wall, the cracks repaired in 1981 are not stabilised. Note the settlement on the roof.

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22. During many centuries, the level of the ground around the temple was raised by about four feet (1.20m):

23. For better look, a ditch was dug around the temple, but the water is not drained away and during monsoon season heavy rain raises dampness. This ditch should be completed by real drainage ditch, eastward and westward.

24. The level of the ditch is not proper: the ancient pavement at the base of the walls is still in situ, about half a foot (0.15m) below. This pavement is made of two layers of flat bricks, 8cm thick, 21cm wide, 38cm long - These bricks are not toothing the bricks of the wall. It is not a footing of the foundation - The foundation level is about 0.53cm below the level of the pavement.

25. Do vertical cracks of the south and the west wall go down to the foundations? Two trial boring proved that the cracks did not affect the foundations. Underpinning does not seem to be necessary - except under the repaired corners.

26. In fact, the cracks that affect the peripheral walls, the vaults and the central pillars are due to two reasons:

a) Central pillar: crushing of the "jacket" i.e. the lining of the faces that is harder than the core of loose bricks and mud mortar.

b) The strengthening of the core of the pillars should be carried out by grouting and insertion of steel bars.

27

.SOUTHERN P A C 4 © E - 3o]3

Poor restoration of the gate: whitish mortar, toothing of modern and ancient bricks is not possible. The crack between modern and ancient masonry should be filled with hydraulic grout.

28. The cracks do not affect the foundations - ancient pavement was found, about one foot below actual ditch around the temple.

29. Correct drainage of this ditch must be carried out to avoid dampness of the base of the walls.

- ^

LEVEL 1 « ^ ^

LEVEL 2

LEVEL 3

R I G H T : Poor toothing, poor looking repointing and crack not filled with liquid mortar

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MOHG GU TEMPLE 20L3/1309.mHE.fcS.WG>rn«*-CON\PRX//IOM C R A C K / : -

11

30. Peripheral walls were pushed outward by arch pressure, and longitudinal cracks appeared in the vaults.

31. Two actions should be considered to strengthen the structure:

a) Tie beams: peripheral tie beams as high as possible: two sets of reinforcing bears between the level of higher and lower window and one at the level of the cornice, by boring and grouting.

b) Another peripheral R.C. tie beam, flexible. Two should be inserted at the bottom of the roof combined with efficient grouting of this mass of masonry, and repair R. C. of the vault.

32. Mechanical anchor (R.C.) of the tie beam, and the mass of the Sikara, inserted in the sloped roof.

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33. Shoring

a) Temporary tie rods can be used to absorb arch pressure during conformation work on an anchor or on a vault.

b) Buttresses can be combined with ties or with truss or alone.

34. This choice depends on the work to be carried out on the vault: temporary structure is necessary to absorb horizontal component of arch pressure -

a) 1 on the edge bearing of the vault

b) 2 on to maintain the voussoirs in position when repairing the vault.

35. Repairing a vault - trusses, adjusted to the shape of the intrados will carry a continuous cylinder made of purlins. The truss is to be adjusted to some kind of a shoring (I beam on masonry or tubes) with jacks.

36. Then the voussoirs can be taken off from the extrados and the cracks repaired. This repair is to be carried out carefully, with good adjustment of voussoirs.

37. Mortar should be hydraulic lime mortar with sulky (Myanmar name for brick powder).

38. The design of the shoring is a responsibility of the Civil Engineer.

39. When drilling a vaulted structure with pneumatic rotary percussion drill, remember that this tool develops vibrations. Accidents may occur just due to vibrations or/and to resonance.

13

40. On Mon Gu Temple (2013) as the crack in the vaults are important on both directions, longitudinal and transversal, we should use planking on trusses in every corridor and 2 buttresses on each N. W and S walls, when placing the tie beams, grouting, and repairing the roof and the vault. (See sketches attached) Except for tie beams, do not use cement, but use hydraulic lime.

41. Porch of Mon Gu Temple Vaulted with a catenary arch vault, the weakest arch

pressure one can imagine, the porch is in good condition except the poor repair of the gate and the angles of the bases of the walls.

42. Gate to be completely rebuilt after archaeological research of the door sill level. Bricks should be of proper dimensions, arch of good toothing and filled with wet hydraulic lime.

Note: Check the former architectural design of the gate in Luce's plan and section - Are there any other photos in the archives?

VIII. CONCLUSION

43. Restoration and conservation work on brick masonry of ancient structures is more a matter of practical application than a matter of theory.

44. The actual staff in Pagan know enough about theory. They will remember that they have to keep the monuments dry. This main recommendation concerns foundations as well as terraces and cracks. Weep holes and so on.

45. As for the cracks, they should first be deeply grouted, and a pinning can be done too, but always have a good toothing of the bricks.

46. During my stay, December 1991 - January 1992, I discovered that people in Pagan, the very people who carry out the field work, had not received any of my reports. If they have no record of my recommendations, part of the benefit of my mission is lost.

47. Practical training is very important - I suggest that, if I can return to Pagan, in December 1992 - January 1993, it would be good to spend one month on Mon Gu Temple, for this small temple is a good illustration of every point we have to work on, both theoretically and practically.

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APPENDIX 1

Lectures on 24 and 30 December were attended by; DAW TIN AYE, Head, Civil Engineer U KYAW SEIN, Assistant Engineer U THAUNG MYING, Assistant Engineer U KYIN ZAW, Assistant Engineer U AUNG KYAING, Assistant research officer U SOE SOE LIN, Conservation assistant U AUNG SINT, Head of the masons U BA HAN, U MYO NYUNT AUNG, Conservation assitant U KYAW LWIN 00, Conservation mural paintings U YIN HTWE

Field works visited: GAW DAW PA LIN, by U Kyaw Sein - R.C Tie beam THA BYIN NYU, by U Khin Saw. R.C. Tie beam LAY MYAT HNAR, by U Thaung Mying. brick work SIN PYU SHIN, by U Hla Nyunt - Complex - brick KYAUK SA GA GYI pagoda by U Aung Sint MINGALAZEDI pagoda by U Ba Han maintenance DAH MA YAN GYI pagoda by U Soe See Lin maintenance CITY HALL by U Myo Nyunt Aung - pointing NAMPAYA Temple in MINKABA (Sandstone) MONG GU Temple in Taungbi village and some others...