Chapter Seven Test Methods Details and Results




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Chapter Seven – Test Methods Details and Results ::

Elizabeth I. Louden :: Department of Archaeology :: University of York ::



Section III

Chapter Seven

Test Method Details and Result Summaries


Unexpected results are the rule rather than the exception.
PLAUTUS (TITUS MACCIUS PLAUTUS)
Roman dramatist
(254 BC - 184 BC)

Introduction


This chapter presents analysis for all test results relative to the previously identified five species chosen for accelerated weathering test evaluations. As mentioned in Chapter Six throughout the discussion of testing procedures, the term sample refers to the small piece of wood collected from an individual historic ranch building. The term specimen refers to a block of wood used for a testing procedure. A general summary begins the chapter with a discussion of each test in subsequent sections. The test reactions of the five species provided a basis to analyse data for Chapter Eight. It should be clarified here that the intention of these tests was to study accelerated weathering reactions of specimens representing a particular species, and each test required a different set of wood block specimens. Since separate specimens were used for each test, test reactions on a particular specimen cannot be followed from one test to the next. However, the species results are traced throughout the tests. During all tests, except during exposure to high temperatures for the Constant Dry Weight and the Freeze/Thaw, specimens were kept sealed in plastic airtight containers to eliminate evaporation loss and prevent re-absorption of air moisture. Polyethylene bag characteristics of porosity were researched and discussed in Chapter Eight.

Overall Test Method Details and Results Summary


The data from the first series of five tests quantified the basic characteristics of the Pinus echinata (AHP), Thuja plicata (CDR), Pinus palustris (LLYP), Prosopis glandulosa (MSQ) and Cupressus arizonica (SCY), and second series of tests presented data to evaluate regional weathering phenomena relative to the deterioration mechanisms in these selected wood species. The acronyms AHP, CDR, LLYP, MSQ and SCY were used extensively throughout the following graphs, tables and discussions since these acronyms provided the test labelling nomenclature for individual specimens. Test results from the wood specimens and regional climate conditions were compared for deterioration rates. For the reader’s reference, the following chart summarizes the Latin species names, the common names and the research acronyms.


Latin Name

Common Names

Test Acronyms

Pinus echinata

Shortleaf Pine, Southern Yellow Pine

AHP

Thuja plicata

Western Red Cedar

CDR

Pinus palustris

Longleaf Pine, Southern Longleaf Yellow Pine

LLYP

Prosopis glandulosa

Mesquite, Honey Mesquite

MSQ

Cupressus arizonica

American Southern Cypress

SCY

Table 7-01. Reference table showing each species Latin name, its common name, and the test reference acronym used in this study.

As previously described in Chapter Six, under the sub-section entitled Specimen Sources, the Shortleaf Yellow Pine (Pinus echinata, AHP), the Longleaf Yellow Pine (Pinus palustris, LLYP) and American Southern Cypress (Cupressus arizonica, SCY) were believed to be from old growth forest while the Western Red Cedar (Thuja plicata, CDR) and the Mesquite (Prosopis glandulosa, MSQ) came from recently harvested sources. (See Chapter Six) The Pinus echinata, Pinus echinata and Cupressus arizonica specimens were expected to demonstrate decay resistant characteristics common for old growth woods (Ridout 2000, Weaver 1993, Fielden 1982). The Thuja plicata, from kiln-dried samples, and the Prosopis glandulosa, non-kiln dried samples, offered interesting counter-point data as present-day harvested specimens. (See General Specimens Characteristics Appendices Forms P – Q) Sample database forms are included in Appendix M and display the individual characteristics, weights and test statistics.


Test results discussion:

The following sections discussed general test results, but reserved analysis for Chapter Eight. The basic sampling strategy remained the same for all tests. As previously discussed in Chapter 6, there were ten sets of blocks prepared, and each test used a random selection of fifteen test blocks from each species set. The following sections detailed the general baseline information and standard test protocol used in conservation studies. The first section of the evaluations expands upon the background specimens data necessary for both control information and for formula computations. The region specific tests provided data to compare with contextual and climatic factors such as photodegradation relative to actual hours of sunshine, mechanical and wind erosion relative to the sandblasting tests, and chemical weathering from acidic and ammonia exposures in animal excrement tests. Each sub-section was organized with “Method Details” and “Results Summary” followed by a section that described the “Types of Information Produced” from each test procedure. In most cases, summary charts also helped to present the raw data.

Section I. General Baseline Information

I.1 General Species information covering average/means for mass, relative density, pH, moisture content, cross-sections and species identification data results.

Mass

Method Details and Results Summary

Observations were recorded for all test specimens to provide a basis of comparisons.
Types of Information Produced

The average mass for specimen blocks in each species was summarized in the following chart along with the average volumetric specimens block for each species (Figure 7-01). The Pinus palustris blocks used in the test protocols were three times the volumetric size of the Thuja plicata test specimens on average; the Prosopis glandulosa and Cupressus arizonica were closely equivalent in volumetric measurements. Pinus palustris blocks were nearest to the median volume. As previously mentioned, the size variation between specimens block series was a function of available materials. For each species within the study, 150 uniform cubes were prepared.

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