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/307 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. ~N~ct(: .. so ·;:'l'" ,; .... .. ". .:::i: ., " ;; " .. ' : :!: ! i::; '" ". . !!'! " i .. ... :ii; :H: i n::.. :J: '!\ • ·r, 1;!, : I ' 1 .j 4-0 ·. ~':J:j.~t~:r::·,· -···:'""'."'""'rc"" . !:::: .. ; . . . "J " -· ~.J: t ;h. l . 30 I i " j t ·:-_.! -· -· , I ..·! ii i.l ·: l ,. ; l 'J -. :.--:'"~ I I IOk L l j .! L~:n;;: ~·-!itt :::.~· .. r.:~~j~~~~~~~~~=;~;:l.u:;~~:trti::t;.T,~P·..;jr:~·,~:!,IT~~~~tJ1f~~j~~··~~~ :1:. :: ,, 'i 1 '!·r I :~ '; :-7.:.;-t~:. 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