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Documentation and Evaluation of the Conditions of the Ninth Century B.C.E. Mosaic from Gordion, Turkey, and Recommendations for its Conservation and Treatment
Elizabeth Tiffin Thompson

In 1956 a unique and nearly complete mosaic pavement was discovered within a megaron building at the archaeological site of Gordion, Turkey.  Dating to the ninth century BCE, it remains one of the earliest mosaic pavements to be discovered.  Its exceptional artistic quality and outstanding condition revealed intricate geometric and abstracted patterns composed of red, white, and dark blue pebbles that distinguished it from other known mosaics of the time.  In 1963 Turkish conservators lifted approximately half of the mosaic and backed the lifted sections using reinforced concrete.  Despite efforts to preserve the mosaic’s exquisite motifs, the reinforced panels weathered in outdoor storage for years before their installation in the Gordion Museum in the 1980s.  Pebble loss from storage and a thin cementitious grout applied over the panels during installation contribute to the now disfiguring display of the pavement; consequently, it remains little known, uninterpreted, and poorly presented.  In response, this thesis attempts to (1) construct a written history of the pavement from available documentation, (2) identify and analyze the conditions that have and are affecting its condition and preservation, (3) critique comparable projects that can provide guidance on future work on the mosaic, and (4) propose a phased schedule that can be used to facilitate the conservation of the mosaic pavement in the years to come.


The Early Phrygian Gate at Gordion, Turkey: An Investigation of Dry Stone Masonry in Seismic Regions and Recommendations for Stabilization
Meredith Keller

The archaeological site at Gordion, Turkey is located in a region of high seismic activity, which threatens the standing masonry structures—particularly the dry laid limestone gate—of the ancient Phrygian capital. First excavated in the 1950s, the citadel gate is composed of an ashlar limestone veneer encasing a rubble core and, for nearly 3,000 years, served as the foundational support for a later gate building. Sixty years of exposure to the harsh Anatolian climate and the additional load from later structures have produced extensive cracking, spalling, open joints and bulging. Over the past few decades, concrete capping and grout injections have been implemented at the site as reactive measures to inhibit water ingress and prevent further bulging; however, a more diagnostic approach is necessary to respond to ongoing displacement and possible collapse, which may result from future seismic activity. This research synthesizes existing knowledge of the behavior of masonry during seismic events, properties of dry stone structures, and site-specific characteristics—such as existing conditions, climate, soil properties, construction techniques, and past interventions—as a basis to construct recommendations for future monitoring and stabilization efforts.


Soft Capping of Archaeological Masonry Walls
Alex Lim
Archaeological sites account for a large percentage of the world’s cultural heritage, and they rank among the most at risk from natural and human threats.  The protection of exposed masonry walls and other architectural features depends ultimately on control of moisture, temperature fluctuations, and movement.  Exposed compound walls traditionally have been protected by hard cappings of lime, cement, and modified soil mortars.  However, hard capping has been found to be inadequate in addressing the long-term management of moisture ingress and thermal movement that will continue to stress and damage masonry walls.  Instead of protecting the wall as initially designed, hard capping can actually accelerate deterioration over time.  Moreover, such approaches to stabilization and display have been challenged by culturally affiliated groups (e.g., Native American tribes) as to their insensitivity to the environment.  In order to counter such problems posed by hard capping, a procedure called 'soft capping' has been introduced in recent years at several archaeological sites in England, Turkey and elsewhere.  Soft capping replaces hard caps with vegetation planted on top of layers of soil, gravel, and geo­synthetics.  The idea is to prevent water penetration and to reduce thermal fluctuations by taking advantage of plants' abilities to utilize the water and provide a protective barrier on the wall top.  The concept is very similar to green roof technology that has gained increased popularity in recent years.  This thesis presents laboratory and field-based research conducted on the performance characteristics of soft capping for the exposed masonry walls at Mesa Verde National Park, Colorado.  Wall movement, moisture and temperature as well as environmental conditions were monitored to evaluate the effects of hard and soft-capping on the test walls.

Assessment of the grout used for the structural stabilization of the Early Phrygian Citadel Gate at Gordion, Turkey
Kelly H. Wong
Injection grouting for the stabilization of historic masonry structures using traditional hydraulic lime-based mixtures has become increasingly popular in the architectural conservation and civil engineering communities in the past thirty years. Between 2001 and 2005, the Early Phrygian Citadel Gate, an unreinforced masonry structure at the Iron Age archaeological site of Gordion, underwent a structural consolidation program by injection grouting using a hydraulic lime and brick dust mixture, to resist seismic activity in the area. The research presented in this thesis includes an overview of hydraulic lime and crushed brick grouts used in the stabilization of other historic unreinforced masonry structures, the laboratory testing program of three hydraulic lime and brick dust grout formulations conducted in 2006 at the University of Pennsylvania Architectural Conservation Laboratory, and a discussion of test results as it applies to the future stabilization of the Early Phrygian Gate and other historic unreinforced masonry structures in seismically active zones.
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