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November 2002-April 2009Excavating Hierakonpolis
The fort
Lowered ground level and holes in the wall cause the bricks to fall away, destabilizing the monument.
Major losses of historic fabric have occurred as bricks sheer away. The west wall of the Fort.
The northwest corner. All the corners of the structure have failed or are failing.
An ancient mud brick
The ancient bricks of the Fort have stood up well considering, but the straw in them has been eaten away making them weaker against the elements.
Now that the water table is permanently higher, the cutting down of the rich flood plain soils to make bricks and make irrigation easier has brought saline water to the surface, poisoning the soil for use.
Settling the soils in glass jars allows us to quickly assess the sand and silt composition. On the right, a jar with soil from an ancient brick, the organic inclusions have turned the water brown; beside it a sample of the ancient mortar which was made of the same materials with less organics. On the left a natural soil sample is being tested.
Left, Bill Remsen mixes up a batch of mud for strength testing. Right, rolling damp clay to test for strength and elasticity.
Making bricks.
Our local workmen were more than willing to share their knowledge and expertise in brick making.
Making brick batches for future tests after curing
All photos courtesy of the Hierakonpolis Expedition. Click on images for larger versions.

Fixing the Fort: Week 1

Conservation of the Enclosure of Khasekhemwy, Hierakonpolis, Egypt

by Renée Friedman

The focus of archaeological interest in the early twentieth century, the enclosure or Fort of Khasekhemwy has been abused and neglected from a conservation standpoint. This amazing monument is currently experiencing accelerated deterioration, and immediate action is required to preserve the architectural and historic elements of the ancient structure and its construction features.

The Fort currently suffers from two interrelated problems:

First, archaeological investigations within the structure in 1906 and outside of the walls in 1934 resulted in the lowering of the ground level by up to 2 meters, exposing the foundations, which are being deteriorated by wind erosion, destabilizing the walls, which, although 5 m thick at their base, were built in accretion faces (essentially in vertical layers), thus portions of wall have sheared away. Major loss of historic fabric has occurred because of this type of exposure.

Second, breaches in the wall and foundations have been created in a variety of ways since the construction of the monument. These include: excavation for earlier burials beneath the walls, holes made by treasure hunters, brick mining, and burrowing by animals. These gaps become eroded and unstable leading to dangerously unprotected overhanging segments of upper wall which may collapse at any time.

[image] [image]
At the southeast corner, as at many places, the ground level has been lowered by earlier archaeological activity, exposing the foundations to erosion. Right, archival photograph from Lansing's expedition in 1934 showing excavation of a burial at the southeast corner.
[image] [image]
Left, hole made by treasure hunter in 2000, photographed in 2002. Wind and rain have also taken their toll on the monument. RIght, interior of the west wall.

In early February 2002, Conor Power, a registered professional engineer, made a brief examination of the structure. Power is a structural consultant for the USAID-sponsored project conserving the mud-brick funerary enclosure of Khasekhemwy at Abydos, a structure of similar age with several similar conservation issues. He identified more than two dozen points of weakness in the Fort at Hierakonpolis and prioritized them as to severity. Areas of particular danger exist along the still intact and full-standing west wall of the monument, the entrance/gateway area and at each of the corners.

In November 2004 we invited Conor and his colleague Bill Remsen, a preservation architect also working on the Abydos enclosure, to have another look at the Fort and give us some practical advice on how we might start to fix some of its problems. On hand to soak up the information was Richard Jaeschke, a conservator and long-time veteran of Hierakonpolis. Way back in 1983 he prepared the very first condition report ever made on the Fort--an important paper for documenting the changes that have occurred over this short period of time. Also present, to provide his practical viewpoint, was annual team member Joe Majer, who works in construction in the "real world."

After an intensive examination of the monument, our consultants' recommendations for stabilizing the Fort included the incremental repair of dangerously undercut foundations with compacted soil, the local rebuilding of gaps and corbelled areas of the wall with mud bricks and the leveling, compacting and grading of the ground surface around all of the walls to prevent further erosion and deterioration of the foundations. All this is easier said than done, however, as aside from the logistical issues (the more time one spends in the Fort, the bigger it seems to get, and it is not small to begin with!) there are both technical and ethical issues as Richard Jaeschke explains.

[image] [image] [image] Left, consulation with Conor Power in this Fort with Richard, Joe, and Renée (see larger image). Center, Richard Jaeschke, conservator. Right, Joe Majer, long-time veteran of the Hierakonpolis Expedition

The Conservation and Reconstruction of the Mud-Brick Enclosure at Hierakonpolis

by Richard Jaeschke

Perhaps the first step in the reconstruction of anything is choosing the proper materials. Consideration needs to be taken as to the mechanical properties of the proposed substance. Is it strong enough? Will it shrink or distort with time? Is it too strong? If so, this could result in preferential degradation of the adjacent original material. And there is another no less important issue: it should look pleasing. It should not be too obvious, but one should still be able to differentiate between original material and any new additions.

With these considerations in mind we have decided to use mud brick to conserve the mud-brick enclosure at Hierakonpolis. It seems obvious. Yet with so many fallen bricks around, and some that look pretty darn good even after nearly 5,000 years, it may beg the question: "why don't you just put the original ones back?"

First, consider that each old brick is an artifact in itself. It contributes a testimony to the history of the Enclosure as a whole object--even the fact that it has fallen away. An important point in conservation is that we are not trying to rebuild the monument. The purpose of stabilization in the context of conservation is to present and preserve just what is there. Filling a gap may be necessary to prevent further collapse or erosion, but should not be an attempt at adding anything beyond that. To put an original brick back would obscure the history of the brick itself. To do that would mean the monument is no longer the way the ancients made it. It has become a hybrid object, part ancient and part modern, with no way to tell them apart. Regardless of the methods used to mark the distinction (a border of potsherds, colored mortar, etc.), in the future it might be impossible to tell the difference between the old and the newly replaced, and people studying the monument could make some terrible mistakes and come to entirely the wrong conclusions with regard to construction techniques, building sequences, and more. For example, some bricks being in a random sequence would compromise data for changes in brick composition through time. Subtle changes in size could go undetected. Original sequences of stacking could be lost. People want to know that what they are seeing is just the way it was made in ancient times.

[image] Southwest corner. In a case like this you cannot put the original bricks back where each individual one actually came from. In fact, we do not really know how the corners were built as none survive intact. Thus replacement using original material would confuse the integrity of the monument.

Thus, by filling the gaps with easily identified new bricks there is no confusion. The ancient parts are just the way the Egyptians built it 5,000 years ago and remain viable for scientific and historical research, while the structure is stable, we hope, for another 5,000 years.

Stabilizing with new bricks allows the maintenance of the original shape of the Enclosure. It gives the necessary structural support without compromising the scientific or historical integrity of the original feature. The new stabilization need not look too obvious. It is considered appropriate in conservation circles that the object looks complete from a short distance away. It is only upon closer inspection that the difference is seen. Various methods can be used to make the new materials identifiable.

One obvious way to help differentiate new bricks from the original ones is the use of a brick stamp. Every new brick will be stamped with the logo: HK 2005. Another even longer term method is to make new bricks that differ from the originals. Although the original bricks were made with a recipe that has withstood the test of time, there are a number of good reasons for making bricks in a different way.

First, the ancient bricks were made with organic additions--either straw or more likely cow dung, which promotes faster drying time and adds strength as a binder without increasing weight. Similar bricks are made today in Egypt. However, the use of organic material, whether it is straw chaff or dung containing straw will attract insect infestation. Indeed the straw used in the original bricks has been almost completely eaten away, leaving the bricks full of small holes and now much weakened.

Second, the ancients probably used mud from the cultivated floodplain. The use of this rich gray mud for brick making is now forbidden by the Egyptian Government as a result of the building of the Aswan Dam and the cessation of the renewing Nile inundations. Now that water table is kept high by the dam, the removal of large amounts of field earth allows the salts to rise to the surface, poisoning the precious agricultural resource that kept Egypt great for millennia.

[image] Modern brick makers probably use the same recipe as the ancients.

So we are faced with the prospect of making bricks without straw from a soil source outside the cultivated zone. To find the ingredients for the best brick under these circumstances one must test the available materials. This, as our consultants Bill and Conor demonstrated, is where the fun begins. First, it is necessary to determine the sand and silt composition of the original bricks. At some point in the future it will be interesting to know the composition more accurately, but for our purposes a quick and dirty visual test will do: Take fragment of brick. Put in glass jar with water and shake. Let component parts settle overnight. A stratigraphy of the heavier and lighter sediments should appear. As expected, the ancient bricks turned out to be silty with organic additives and little sand. Next we obtained samples of clay from different natural deposits and tested them to discover their composition in the same way.

In the Hierakonpolis region we are both fortunate and cursed that the ancient Nile of a million years ago was to the west of us and has over the ages traveled gradually eastward, depositing rich Nile silt as it moved. Thus the low desert in the region is not a sandy desert, but a silty one. While this provides us with numerous potential resources for our brick making, it also means that the desert is a perfect zone for land reclamation. Just add water and fertility is assured. As a result, the archaeological site of Hierakonpolis is now surrounded on four sides by ambitious land reclamation schemes and pressures at the edges of the site are extreme. We are grateful to the Egyptian Supreme Council for Antiquities for their constant vigilance concerning this issue and the steps they have taken to protect the site.

Having identified several potential soil sources, we tested their composition and found them to be mainly silty with little sand. Thus, sand would need to be procured that was not too fine but not too course to act as a strengthener. Color was also a consideration. So an expedition to a nearby sand mine was organized and a variety of types were selected for testing. With all these materials now on hand, it was then time to create some recipes. Various percentages of soil to sand were prepared at the expense of the kitchen measuring supplies and then our consultants demonstrated a field method for testing the mechanical properties. Although to the casual observer it may look like making mud cigars, it actually did serve a purpose! The mud mixes were rolled out to 15cm long cigars to test for elasticity and lifted to determine strength (the ability to carry their own weight). In the end, we determined that some recipes were indeed better than others. But the proof is really in the pudding.

The next step was actually making some bricks. A brick form was created with the dimensions of 26cm by 12.5cm by 8.5cm, an average taken from many measurements of original bricks.

Although our first attempts were a little shakey, after taking advantage of some local advice, which was happily supplied (in quantities), we made a number of bricks with three different sand compositions which we will leave to cure (dry) for a month and then test for suitability before the real work begins.

Clearly, the job of fixing the Fort will be big one, but we are pleased to report that step by step progress is being made. It is estimated that over 100,000 bricks will be needed to stabilize the west wall alone, so stay tuned for more moments in mud. Meanwhile, as we waiting for the mud bricks to dry, there are many other ways we having been helping to save the Fort...and we have made some surprising discoveries along the way.

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