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REPORT ON RAUNDS MORTAR
VISUAL INSPECTION
All samples submitted for analysis were in a degenerate condition.
contained charcoal fragments or brick.
None apparently
EXPERIMEN'.!' AL
The samples were dried at 110°C to constant weight, 100 g of each sample was
then treated with dilute hydrochloric acid to remove acid-soluble material
(mainly calcium carbonate) and thus reduce the sample to ita insoluble aggregate.
The aggregate was filtered off, thoroughly washed and dried to a constant weight.
It wae then passed through a aeries of sieves and the various quantities retained
noted. In order to enable comparison of the aggregates to be made, the weights
retained were converted into a percentage of the total aggregate weight and plotted
against sieve mesh size. A typical result of this exercise is attached. All
analyses were carried out in duplicate and the mean values used,
Aggregate-size analysis assigned the samples into 5 groups, details of which
are shown in the table.
GROUP
SAMPLE NUMBERS
Al'PROXIMATE MIX
GRAVEL: SAND: LIME
I
II
III
IV
v
*
+
105, 107. 108, 109+ 110, ( 173+)
92, 103, 114, (181 )
104, 106
116, ( 172+)
120, 202-218*, (168+)
Not possible to estimate owing
to degenerate nature of samples
II
II
II
204, 208, 212, 215, 216, 217 unsuitable for analysis
Geological zone possibly associated with aggregate source.
Approximately ~/o of the samples was acid soluble.
The aggregates were composed of rounded to sub-rounded sand and gravel. The samples
all exhibited a fairly dark brown colour indicative of iron staining. The finest
fractions (those passing through the 0.075 mm mesh sieve) showed the same general
colour as the coarser fractions and consequently were not likely part of the
geological make up of the sands and not an additive, such as crushed atone.
A striking feature of the aggregate-size data is the relatively high levels of
fine material in the mortar samples (Group I 14-21%, II 12-1~/o, III 16-18%, IV 2ry/o
and V 2~/o). Such levels are usually detrimental to the strength of the mortar and
can lead to fairly rapid deterioration. The presence of such levels in mortar
tends to reflect inadequate preparation of the sand prior to use. As the
corresponding levels in the pit complexes are 22-24% it would seem that some
preparation of the sand in I, II and III had taken place but not so in IV and V.
However, the presence of such fines in plasters, such as Group II, is acceptable
as such systems are not load bearing; and furthermore it can produce a smoother
finish to the final product.
Only 116 had a substantial amount of coarse (gravel) aggregate (approx 40)6) which
suggests it was b~ter considered as a concrete, possibly a foundation layer, as
opposed to a mortar,
JOHN EVANS
Division of Chemistry
North East London Polytechnic
September 1982
.· -!
'
MAIN PERCENT
GROUP
I
II
III
IV
v
AGGREGATE-BIZE DISTRIBUTION OF SANDS
~
0.075
17.12
12.98
16.87
22.42
22.91
0.075
12.98
14.45
11.97
20.04
14.44
0.125
22.40
26.20
22.58
22.64
18.68
0.250
43.84
44.6.3
46.67
.34.21
42.77
0.500
,3.81
1.80
1.90
0.69
0.67
mm
FOOTNOTE
Although these sands exhibit similar aggregate-size distribution patterns the samples
within any one group fall within 1 or ~~ of each other. It is quite clear that all
are using closely related aggregate sources. It is also interesting to note that
Group II and I are very similar. II being enhanced in fines (excluding.(0.075) as
one would expect for a plaster. III also shows a marked similarity to I and II
but the 0. 250 sieve percentage is very characteristic in both 104 and 106.
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INVESTIGATION OF PIT SAMPLES
168, 172 and 173 have particle size characteristics similar to those of the mortar
systems (see mortar report) and consequently are most probably natural material,
possibly resulting from back filling after gravel/sand extraction. The bulk of
the remaining samples had particle sizes in the range of 0.125 mm and below,
clearly unsuitable for building purposes,
All the samples were investigated by emission spectroscopy. Only 174 and 189
contained any "abnormal" elemento. 114 gave weal< lines for silver, copper and
zinc (?), whilst 189 contained traces of lead, copper and tin, The absence of
slag or crucible fragments, etc, in either sample would seem to rule out metal
working as such and consequently the presence of the metals may owe their origin
to the decomposition of metal artefacts.
Size and emission analysis of 219 and 220 suggested they were natural materials.
J EVANS
Division of Chemistry
North East London Polytechnic
September 1982
REPORT ON POT DEPOSIT FROM RAUNDS (NORTHAN'l'S) AM Nos 800733
The sherds examined had two deposits,white and black. The white material was
mainly calcium carbonate with traces of phosphate. No organic substances were
detected, The calcareous deposit was most probably produced by the percolating
ground water.
The black deposit was examined initially by infrared spectroscopy. The. spectrum
obtained suggested the presence of organic substances, The residue was extracted
with a series ofsolventsof varying polarities and each extract was investigated
by various chromatographic techniques and infrared and ultraviolet spectroscopy.
The results of this investigation showed the presence of beeswax, sucrose, glucose
and tartaric acid. Citric acid was also suspected but not proven. No
triglycerides or proteins were detected.
Examination of the black material with a scanning electron microscope showed no
vegetable matter. No structures apart from the ves,icular nature of the residue
were observed.
The presence of beeswax and sucrose suggests honey in the original system. The
presence of tartaric acid indicates a fer mented system, possibly wine as no
vegetable matter was present. (ie the tartaric acid did not result from the natural
decay sequence of vegetable/fruit matter). The ves#icular nature indicated that
the system had been burned.
It would seem therefore that a wine and honey mixture was burned in the vessel.
Analysis of the surrounding soil and soil within the pot gave no useful results.
J EVANS
Division of Chemistry
North East London Polytechnic