Earth-Lime Mortars

York 2019 Nigel Copsey Traditional mortars and their primary historic uses:

Earth mortars – clay-bearing sub-soil, improved or otherwise with sand and well- tempered. Typically 12% clay, high volume of silt and of fine texture. Masonry construction, plastering, daubing, floors (with additives).

Earth-lime mortars, typically 10% lime to a clay (and silt) bearing sub-soil:

Masonry construction, especially of stone buildings across the UK until around 1800; base- coat plasters. Always pointed with lime rich mortar and finished internally with lime rich or pure lime, haired finish coat and limewash.

Hot mixed air or feebly hydraulic lime mortars: general building with stone and brick; repointing; plastering (except top coat); external renders. Feebly hydraulic in water works local to their sources, with and without pozzolanic addition.

Putty lime, slaked with minimum volumes of water and sieved:

Used on its own as a mortar for gauged brickwork, very fine stone ashlar, fine plaster finish coats. Very rarely as a binder before 20thC, when it was gauged with cement or gypsum. Used on its own for plasters and pointing over earth and earth-lime mortars. Or with minimal limestone or marble addition and usually haired.

Hot mixed moderately or eminently hydraulic lime mortars, either artificial (air quicklime and pozzolan) or NHL (typically blue lias in England and Wales, locally and then more widely after railways)

Underground or underwater works – docks, quays, sea-walls.

Only use for which NHL preferred (during 19thC): Concrete footings and floors.

Some above-ground construction late 19thC or where only locally available quicklime. Some gauging of hot mixed air lime mortars with NHL. Immediately displaced by cement-lime mortars for general use. And by portland cement for concretes

Natural Cement (after 1796). Waterworks, cast mouldings, fortifications (mostly as a gauge for hot mixed common mortars), external renders, some repointing over earlier mortars.

New Malton, North Yorkshire, 1728, John Settrington. Vernacular and sustainable

Earth mortars and plasters the norm in Thornton Dale, as across Vale of Pickering and upon North York Moors. California and Hall Farms, 1787. Same stone mason, probably.

From The City and Country Purchaser, Richard Neve 1726. Neve lived in Sussex and his examples are mainly from the SE of England. Lome: A sort of reddish earth, us’d in Buildings (when temper’d with Mud Gelly, straw and Water) for Plaistering of Walls in ordinary Houses. White Mortar: this is used in plaistering of Walls and Ceilings, that are first plaister’d with Lome and is made of Ox or Cow-hair, well-mixed and tempered with Lime and Water (without any Sand). The common Allowance in making this kind of Mortar is one Bushel of Hair to six Bushels of Lime. Valencia. 17thC Merchant’s house

Tonge Hall, Middleton in Rochdale;16thC 224 quarters of (quick)lime, price per quarter, including carriage 20d. £17 13s 4d And for 42 quarters of (quick)lime at 19d per quarter And for 23 quarters of quicklime, at 18d per quarter.

And for 312 loads of sand, 2d per load And for red earth with sand for making mortar

ACCOUNTS OF ALL SOULS COLLEGE, OXFORD 15THC

John Pygot for walling le Yatehouse of the Manor 10d Thomas Harpur hewing and ‘stauryng’ the same 4/- 6 cartloads of earth for the same 18d 1 quarter of lime (calcet) 8/- 3 cartloads of sand ZBA 11/8/1/7 Mich 1432-33 BEDALE NORTH YORKS

To Thomas Clapham constructing and daubing the wall of said house To John Cartere of Harnby for 2600 slatstonis for roofing said house …To Wm Symondeson for 7 quarters of burnt lime for the said walls To John Hamswey carrying lime from Ffrtheby to said house To same for digging, laying and carrying 13 cartloads of calay for said house To same for 3 cartloads of sand. ZBA 11/8/1/10 Mich 1442-43

Calvados Region, Normandy

Rasumi et al (2014) India. average 10% lime addition = 1 Mpa

Eires et al (2013) Portugal. 4% quicklime addition gave TWICE the compressive strength as when no lime added:

4% quicklime addition gave 25% MORE Mpa than same volume of Portland cement.

In accelerated erosion tests, quicklime stabilised earth was the most durable. quicklime stabilised earth absorbed 33% LESS water by capillarity than with either hydrated lime or cement, reduced erosion and no reduction in vapour permeability and gave ‘better mechanical resistance’ in both dry and in saturated conditions. rammed earth, Bhutan... Images: Nagshto Dorji Mileto, Vegas, Cristini, Garcia Soriano 2014 Any stone to be smeared with a mortar of clay should be cut square, but most importantly it must be dry; the bricks most suited to this are fired ones, or even better, unfired ones that have been well dried out. A wall of unfired brick is very healthy for those who live within…ALBERTI 1460 But though burning of Bricks be necessary for building of Houses, &c. yet a Wall or House may be made with un-burned Bricks; for which end, 1. Let your Earth be high and well temper'd, smooth and well moulded, as already hinted, and this done in the hottest Season; then dry'd and turn'd after the manner of Brick-making; only it must be longer exposed to the Sun and Elements, till they become hard and tough, and then use them after this manner: Take Loam or a Brick-earth, and mixing therewith some good Lime, temper them very high till they become tough, smooth and glewy; let the Wall of your House be one Brick or one and an half thick, and your unburnt Bricks being laid in this well-temper'd Mortar, they will cement and become one hard and solid Body, as if the whole were but one entire Brick or Stone:

When you have raised your Wall 4 or 5 Foot high from the Foundation, let it dry 2 or 3 Days before you proceed further; then build thereon 4 or 5 Foot more, making the like Pause as before, and so proceeding till the Wall is finished: Afterwards temper some of the same Earth the Wall was made of, with a little more Lime that was used for the Wall, which you must be sure to temper very well, and with this Mortar plaister all your Wall well on the other side, which will keep off the Weather; and if you would have it more beautiful, it's only putting more Lime to it and less Loam; and when this is dry, you may colour and paint it, with Red, Blue, or any other colour that you like best. Worlidge & Bailey 1726

Busby Hall, North Yorkshire. John Carr Architect 1765 Romanesque Tower of St John the Baptist, Whitton, North Lincolnshire, reputedly built on the site of a Roman Temple. Earth-lime mortars. Lime pointing mainly lost. STILL THERE, STILL PLUMB. To Lawrence Hunne for carieng 1 bote (boat) of Stones 2s To Thomas Skorye for 2 doss of earthe 3s [‘doss’ is an unknown measure, the author thinks a small amount, which seems most unlikely, as it costs 3 times the price of a quarter of sand] Paid for 1 quarter of sand 1s To Alise Jory for bearinge 1 quarter of sande, 1 quarter of Lyme ashes and 1 quarter Lyme 1s 6d PLYMOUTH SHAMBLES AND GUILDHALL 1606-1607

An account of the expence of building the Oasthouse at Hole Farm 1736 Paid the Sawyer’s bill 6-8-4 Paid the Carpenter’s bill 10-6-0 Paid the Mason’s bill 6-1-9 Paid for deales and carriage 3-3-6 Paid for nails, hooks & rides 2-14-3 Paid for bricks and tiles 8-17-0 Paid for 5 load of Lime 3-0-0 Paid for a Bushel of Tarris 0-5-0 Paid for carrying Loam & sand Paid for drawing Timber 1-19-0 For 13 tun of timber also 19-10-0 Allowed for the Rearing 0-15-0 East Sussex Archives. ACC 8648/3/25/5

Remnant vault, Malton Priory site lime mortar to ribs, earth to less structural in-fill (left and below) Crambe St Michael’s. Tower 14thC. Earth bedding mortars throughout.

1675 General accounts Fitzwilliam Misc Vol 50. Building of new stable 1674, SETCHY NORFOLK

October 10 paid Tho: Handly Mason for worke at Tho: Wilsons House Paid for brick for the same worke Paid for a load of clay for the same worke Paid for a load of sand for the same worke

…21 paid Gurton for 2 load of Clay carrying for Sam: Barker’s house in Westwinch… August 9th paid Wm Grasby the Mortarman for 6 daies worke

1693 paid (Edwd Seyton) what he paid John Sutton in full for digging mortar for himself and ye other men… paid Goodman Shaw for 4 loades of Sutton stone Coins paid Seyton and he paid Bradery wife for digging Mortar by the Loade- 33 loads

Circa 1725 warehouses, Malton. Earth mortar bedded calcareous sandstone Earth floor survives within. When they are to make a new barne floore, they grave it all over, and then rake it all over with hey rakes or iron waine rakes till the mowles be indifferent small; then they bringe water in seas and in greate tubes or hogsheads on sleddes and water it till it bee as soft as morter, or almost as a puddle; then lette it lye a fortnight, till the water bee settled in that it beginner to waxe harde again, and then beate it downe smooth with broad flatte peeces of wood. When a floore is decayed , that there are holes worne, they usually leade as many coupe loades of red clay, or else clottes from the faugh field, as will serve, but they must not leade theire clottes from such places where the clay is not mixed with sands; and then when it commeth, theire manner is for one to stand will a mell and breake the clottes small, another hath a showle and showleth the mowles into the hole, the third and all the rest have rammers for ramming and beating the earth down into the hole….then they water it, and lette it lye three or foure dayes to mawme, for if they shoulde ram it presently it would cleam to the beater: we use to digge and leade clay for our barne from John Bonwickes hill.

Henry Best, East Yorkshire 1641 Earth plastering, Bhutan. Note plaster at liquid limit and use of float to apply.

All Bhutan Images: Nagshto Dorji

Castelgate. …William Plumpton for carriage of 25 loads of lime, sand and other things…And Robert Canmsmyth…for le betyng of one kiln of plaster…And for 2000 turf for firing the plaster kiln in the aforesaid messuage…And to a labourer for betyng plaster in the same messuage…And paid to William Walker for dobyng…And paid for earth, litter, dobyng and water…And to William Plumpton for carriage of forty loads of lime, sand and other things…And to William Bouland, limeman, for five mele of lime…And paid to William None for carriage earth and tiles…

Paid for carriage of seventeen seams of lute for doubyng…including 4d paid for straw bought for mixing with the same…And for wages for working and doubing…And paid to William Gayle for carriage of fifteen seams of sand to various tenements this year….

And paid to Thomas Plumpton for leading sabulum (sand) for twenty seams of earth and (daubing)… and paid to a man of Clifton for five cart-loads for daubing of a new house there and paid to John Pereson for daubing and leccyng of the said parclose in the aula there…And paid…for daubing the same new house by agreement made in gross. And paid to the same Thomas for working there three days receiving 4d in the day…And paid to William West for carriage of six loads of lyme for pergettyng of the same house…

YORK BRIDGEMASTERS ACCOUNTS 15THC (STELL 2010)

Balscote, near Banbury. Iron-rich limestone, earth mortars Cadgewith, Lizard, earth mortared serpentine

Carting of 13 loads of stone and sand 1 load of sand cartage of 15 loads of clay and sand 16 sacks of lime at 6d each 3 sacks of same saw bought for sawing stone 2 sieves bought to sift sand Osiers for the Lodge, straw for the same 36 hurdles (cladis) for the scaffolding 13 sacks of lime. SHERBORNE ALMSHOUSES 1440-1444

January 5th 1737. Agreed with Robt Owram & Richard Smith to do all the Daubing &

Plaistering work that is necessary to be done at Widow Rowntree’s House & to have three pence a yard, they finding, mortar, lime & hair, and twelve shillings per thousand for laying on the tiles & pointing. As witness our own hands, Richard Smith, Robert Owram. ,ALTON AGENTS MEMO BOOK

1st July 1748. Agreed with Percival Luccock for himself and (sic) behalf of James Luccock, his partner to build a wall to Fenton and Robinson’s yard adjoining Water Lane 7 foot high with the coping at 5s per rood and to do it with old stone in the yard. They are to have two chaldern of lime allowed to mix with the mortar which is to be taken fresh out of the kiln, and Mr Turner to see it measured. Witness my hand, Percival Luccock.

York House, Malton, North Yorkshire York House Interior, modern paints removed.

Earth-lime plaster, York House Malton. 1 quicklime: 3.1 clay-bearing subsoil.

York House, W elevation. Early 17thC blocking of window to form fireplace. Earth plaster with lime mortar finish coat over Ð evidence that same system was applied externally in the past. The blocking ‘beefed up’ with stone 18thC, hence this rarely surviving evidence.

Asturias, NW Spain Earth mortar to wall-face, Malton, as well as remnant limewashes. Rather than rake back and repoint with lime mortar – limewash to be preferred

Swallow Head Farm, Fylingdales. Earth bedding mortar Pointed with soft, hot- mixed lime mortar, laid over full earth bedding

Mud and Stud, Lincolnshire and (kind of) in Jamestown, Virginia (left and below left). Limewashed earth renders over. Repair and conservation of mud and stud, Rob Ley.

Minke building, Kew Gardens (right) Dawn Chapman 2012 Log walls with earth chinking (with quicklime?) and renders, Cold Lake, NE Alberta, Canada. Original timber cladding lost. Earth renders under timber cladding. Earth first floor construction. Alberta, Canada; Ukrainian settler house.

St Hilda’s, Ellerburn. Anglo- Scandanavian. Earth-lime building mortars

1. The Plasticity Index (or degree of plasticity of the soil) decreases sharply – as much as three- or more fold. 2. The Plastic Limit generally increases and the Liquid Limit decreases. (The difference between these two values is the Plasticity Index). 3. The soil binder (clay and fine silt sizes) content decreases substantially because of the agglomerating effect of lime. 4. The lineal shrinkage and swell drop markedly. Fine-grained clays without lime have greatest volume change in wetting and drying cycles as evidence of their instability. 5.Lime and water accelerate the disintegration (breaking up) of clay clods during the pulverisation construction step, resulting in coarser, more friable soils that can be manipulated more readily, thereby expediting construction. 6. Unconfined compressive strength increases considerably – in varying amounts, but as much as forty-fold. 7. Load-bearing values, as measured by California Bearing Ratio (CBR) and triaxial tests, increase substantially from two to ten times 8. In swampy areas or with soils exceeding optimum moisture content, lime facilitates drying the soil by increasing both the plastic limit and optimum moisture content of the soil. This expedites construction under wet conditions. 9.A lime-stabilized subbase or base forms a water-resistant barrier by impeding the penetration of both surface and capillary moisture. Exposed but compacted lime-stabilized clay layers shed water readily during rains, thereby minimizing construction delays. This factor also provides some degree of protection against disruptive frost heaving. BOYNTON 1980

% calcium carbonate in basecoat plaster samples, the sources of which will be both added lime and limestone or calcareous sandstone aggregates. Testing and graphs R. Allen

Typical ingredients, though straw the least typical in Yorkshire.

Hay Straw Quicklime from kiln Clay bearing subsoil CaO IT IS ESSENTIAL FOR COMPATIBILITY AND DURABILITY WITH EARTH AND EARTH-LIME BUILT FABRIC THAT THE MORTARS USED OVER ARE HIGH IN FREE LIME AND HIGH IN CAPILLARITY. EARTH-LIME MORTARS ARE DOMINATED BY INTERCONNECTED PORES OF BETWEEN 0.8 AND 1 MICRON (PAVIA 2016), AS ARE NON-HYDRAULIC LIME MORTARS, ENSURING OPTIMAL CAPILLARITY. Modern mortars and sick buildings

c.15% porosity c.50% porosity ineffective ineffective

Historic Lime Mortar (Balvenie Castle) Porosity = 35% NHL 3.5 Porosity = 28% 0.3 0.3

0.25 0.25

0.2 0.2

0.15 0.15

0.1 0.1 Intrusion Volume (mL/g) (mL/g) Volume Intrusion Intrusion Volume (mL/g) (mL/g) Volume Intrusion 0.05 0.05

0 0 1000000 100000 10000 1000 100 10 1 1000000 100000 10000 1000 100 10 1 Pore Diameter (nm) Pore Diameter (nm)

BLF Hot-Mixed Lime Mortars, Coventry LimeHistoric mortar andlime sacrificial and NHL weathering:… Spot the how it works DAVID WIGGINS 2016. CURTINS difference! An earthen House Martin’s nest, York House.

Objectives- To practice To study To educate and inform To train To encourage ongoing and habitual use www.maltonbuildingsgroup.com www.HotMixedMortars.com www.ebuki.co