An Experimental Study on the Effect of Water on Historic Brickwork Masonry

Architectural heritage is deeply threatened by extreme weather events due to ongoing climatic change. Since these phenomena are becoming more and more serious, their effects cannot be neglected when a reliable assessment of a historic masonry structure is required. In this paper, the phenomenon of rising damp was studied, focusing on the influence of water on the unit weight of masonry walls made from fired clay bricks and lime mortar. This study consists of a basic experimental research on the variations in the unit weight of masonry undergoing an ageing treatment, which was simulated through some cycles of capillary water absorption and temperature changes. The experimental study proves that penetrating damp causes an increase in masonry unit weight of more than 20%. This basic result is significant in the structural assessment of historic masonry buildings. Subsequent papers will analyze the interaction with strengths parameters

Assessing the Reliability of Single and Combined Diagnostic Tools for Testing the Mechanical Properties of Historic Masonry Structures

Diagnostics is an important and challenging task of the structural analysis and condition assessment of historic masonry structures. However the interpretation of the results of the measurements, especially for buildings made from brick and stone, is to be more subjective than that for concrete structures. Therefore improvement of the reliability of the used techniques and finding better correlations between the test results and the mechanical properties of masonry has proven to be of great importance. While several diagnostic procedures are commonly used in practice to test mechanical properties of masonry, e.g. Schmidt hammer test, analysis of drilled samples, penetration tests, etc. the results of these methods are considered reliable under laboratory conditions, several additional factors have to be taken into account in case of an in-situ application of these methods, that may largely affect the obtained results and conclusions. The results of the diagnostic procedures therefore need to be interpreted with a view to these environmental factors. The paper focuses on the practical use of several test methods for historic masonries via a real case study. The presented case study attempts to demonstrate benefits from the combined application of Pendulum Schmidt Hammer, moisture meter and scanning electron microscopy

The Evolving Philosophy of Climate Control for Historic House Museums in Subtropical Climates: Recommendations for the Aiken-Rhett House, Charleston, South Carolina

This study was designed to determine the most appropriate type of climate control system for the Aiken-Rhett House (1820-22), a historic house museum located in Charleston, South Carolina. The Aiken-Rhett property is unique in that it has never been restored and the current stewards of the museum have taken a conservation philosophy to the interpretation of the house. This house museum is rare because it is one of the few remaining unrestored antebellum structures in the South. Although grand mansions were never intended to exist in a state of decline, as the Aiken-Rhett does now, the preserved layers of time provide visitors with a sense of place and connect them to the past. Therefore, preserving this house museum and its original nineteenth-century finishes is of great importance to its interpretive value. Because a majority of the house is not climate-controlled, the building and its finishes are subjected to the high heat and humidity of Charleston, accelerating the deterioration of the historic building fabric. The owners of the property, Historic Charleston Foundation, are seeking new ideas for a climate control system to better protect the building and the collections that are exhibited inside. The type of environment that is beneficial for museum collections is not always best for historic buildings. This study aims to find the most appropriate interior climate control system for the building and its finishes, while collections and visitor comfort are treated as secondary priorities. The final recommendations will respect the historic fabric of the Aiken-Rhett House, while also providing economical and sustainable solutions for its continued care

Infrared Thermography as an Alternative Method for the Assessment of Moisture Content Readings in a Porous Brick

Many pre- to late-nineteenth century brick masonry structures encountered by conservation professionals are constructed with hygroscopic, porous brick that has been attacked by the combination of moisture and salt. The presence of these enabling factors of deterioration accelerates damage to a brick. Professionals need an affordable nondestructive tool that does not require extensive calibrations to highlight dangerous levels of moisture in the presence of soluble salts at a macroscopic scale prior to evident material loss. The infrared camera has been proven to display a visual image of moisture anomalies in a brick wall, but quantification requires spot readings with a moisture meter and accurate quantification requires sampling and laboratory testing. This paper investigates whether an infrared camera can be used to quantitatively determine in situ moisture content of a porous brick wall. In achieving this, a testing procedure was developed and performed on thirty-two hand-molded colonial face brick cuboid samples conditioned to four equilibrium moisture contents. The results of this test concluded that infrared thermography can distinguish different levels of moisture content with the thermal images. Secondly, there exists a linear relationship between ∆T surface center point and measured moisture content as well as a similar relationship between ∆T average surface and measured moisture content when room %RH is lower than equilibrium %RH for the sample. The linear relationship of measured moisture content and ∆T may be consulted for determining moisture content readings in different ambient conditions; however, nearly saturated samples require further study

WEATHERING THE STORM: DIAGNOSTIC MONITORING FOR PREVENTIVE CONSERVATION AT SPRUCE TREE HOUSE, MESA VERDE NATIONAL PARK, COLORADO

This paper examines Spruce Tree House, an alcovate site located in Mesa Verde National Park, as a model for monitoring the impacts of the natural environment on the deterioration of a unique collection of archaeological resources. At present, it is the only alcove site in the park that has been fully documented by park service archaeologists. In the past, preservation at Mesa Verde has focused on the minimal remedial stabilization of the prehistoric masonry structures. A comprehensive study of broad deterioration patterns across the alcovate sites in the park and the possible causes of these patterns has never been performed. Identifying common sources of deterioration site-wide has the potential to lead to a comprehensive maintenance plan that could slow deterioration through preventive as well as remedial actions, thereby protecting the resources and decreasing the amount of emergency rehabilitation work needed. Implementation of a monitoring program is the first step in this process, as it allows us to identify patterns and establish causality, leading eventually to non-invasive preventive and protective measures. This paper proposes that the presence of water is the main cause of deterioration at the site. A specific monitoring program has been put forth in order to verify that this is still an active problem at the site. The program includes the use of soil moisture meters, motion activated cameras and at least one weather station to record the external environmental conditions for comparison with occurrences within the alcove

Guidance on the Stand Down, Mothball, and Reactivation of Ground Test Facilities

The development of aerospace and aeronautics products typically requires three distinct types of testing resources across research, development, test, and evaluation: experimental ground testing, computational "testing" and development, and flight testing. Over the last twenty plus years, computational methods have replaced some physical experiments and this trend is continuing. The result is decreased utilization of ground test capabilities and, along with market forces, industry consolidation, and other factors, has resulted in the stand down and oftentimes closure of many ground test facilities. Ground test capabilities are (and very likely will continue to be for many years) required to verify computational results and to provide information for regimes where computational methods remain immature. Ground test capabilities are very costly to build and to maintain, so once constructed and operational it may be desirable to retain access to those capabilities even if not currently needed. One means of doing this while reducing ongoing sustainment costs is to stand down the facility into a "mothball" status - keeping it alive to bring it back when needed. Both NASA and the US Department of Defense have policies to accomplish the mothball of a facility, but with little detail. This paper offers a generic process to follow that can be tailored based on the needs of the owner and the applicable facility