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Lime mortar on Masonry Locks


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Coal Canal - pondering repointing at Combe Hay locks - 

 

Would a masonry lock have pointing in the conventional sense? and if so what with, lime mortar?

 

And how many ways are there of getting lime mortar wrong?

 

I've invited the work party manager to join the forum, so soon it won't be me with these burblings! :) 

 

Thanks all

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The properties of lime mortar depend upon where the lime was obtained. Limestone is not a uniform substance, and its properties vary from quarry to quarry. Rennie's notebooks, held by the National Library of Scotland, give such properties for a number of quarries, often those near to where Rennie was working. Some limestones create hydraulic limes, capable of hardening when water is present. The following are notes I wrote ten years ago regarding hydraulic lime. I suspect there is still much to learn about lime mortars.

 

The use of naturally-occurring hydraulic lime was well established by the eighteenth century. With regard to Eastern Europe, the English engineer, Captain Perry, worked on canals in Russia around 1700, and had previously learnt about hydraulic lime from Dutch engineers. Later, the Dutchman Devollant was in charge of engineering in Russia where he was also involved in canal construction. One problem with researching lime during this period is that terminology is very inexact. It is sometimes difficult to decide what is natural hydraulic lime and what is manufactured.

 

The development of manufactured Portland type cements, capable of hardening in wet conditions, took place over many years. Joseph Moxon noted that lime heated up with the addition of water in 1678. The first scientific investigations were probably undertaken by John Smeaton, during his construction of Eddystone lighthouse in the 1750s/60s, and he continued experimenting with calcining mixtures of lime and clay into the 1790s. In 1796, James Parker had patented a type of hydraulic cement, with similar ideas developing in France post-1800. It was there that Vicat undertook further experiments from 1812, and he published his results in 1818. It was in France in the period up to 1824, that many others followed Vicat's work, such as Descotils, Dumas, Petot, St Leger, Sgauzin, Charlesville and Berthier. Hydraulic lime was well-known, and used extensively in the construction of the Canal Saint Martin and the Canal Saint Maur in Paris in the late 1820s. Also, in 1824, Joseph Aspdin, from Leeds, England, patented his artificial lime which he called Portland Cement. It was used by I K Brunel to staunch a breach during the construction of the Thames Tunnel in 1828.

 

The research into manufactured hydraulic lime centred around the mixing of suitable clay with lime, and then to calcine and crush the resulting mixture, as can be seen from the Augustowski Canal paper. Joseph Aspdin's British Patent specifies:

 

My method of making a cement or artificial stone for stuccoing buildings, waterworks, cisterns, or any other purpose to which it may be applicable (and which I call Portland cement) is as follows:- I take a specific quantity of limestone, such as that generally used for making or repairing roads, and I take it from the roads after it is reduced to a puddle or powder; but if I cannot procure a sufficient quantity of the above from the roads, I obtain the limestone itself, and I cause the puddle or powder, or the limestone, as the case may be, to be calcined. I then take a specific quantity of argillaceous earth or clay, and mix them with water to a state approaching impalpability, either by manual labour or machinery. After this proceeding I put the above mixture into a slip pan for evaporation, either by heat of the sun or by submitting it to the action of fire or steam conveyed in flues or pipe under or near the pan till the water is entirely evaporated. Then I brake the said mixture into suitable lumps and calcine them in a furnace similar to a lime kiln till the carbonic acid is entirely expelled. The mixture so calcined is to be ground, beat, or rolled to a fine powder, and is then in a fit state for making cement or artificial stone. This powder is to be mixed with a sufficient quantity of water to bring it into the consistency of mortar, and thus applied to the purposes wanted.

In witness whereof, I, the said Joseph Aspdin, have hereunto set my hand seal, this Fifteenth day of December, in the year of our Lord One thousand eight hundred and twenty-four.

 

The basic idea does seem similar to what happened in Poland. However, it did take some time for Aspdin's cement to become established. Initially based in Yorkshire, the business only really took off after his son, William, built a new plant in Kent in 1842, where a large part of the English industry is still based. William subsequently worked in Germany from 1853.

 

Because of the extensive research into hydraulic lime undertaken in France, it is interesting to note the French influence on the construction of the Augustowski Canal. For example, General Malletski was a French military engineer who had settled in the Duchy of Warsaw and became the Director of the Engineering Corps, and Henry Rossman had served in the French army. There was also considerable French influence on Russian engineering training at that time. Four French engineers had been in Russia during the Napoleonic Wars, and had settled there afterwards. Augustin de Béthancourt became Inspector General of Engineers around 1818, and took over the main engineering administration in 1819. With French engineers in senior posts in both Poland and Russia, it would be unlikely that they did not keep abreast of the latest French developments and publications, and would have read Vicat's book.

 

With regard to similar structures erected at the same time, I have not found any further details regarding the Saint Martin and Saint Maur Canals other than a brief mention of the extensive use of hydraulic cement during their construction. There are two contemporary books: Description du canal de Saint Denis and Saint Martin, R E de Villiers, 1826, and Nouvelles observations sur le canal Saint Martin, Pierre Girard, 1821, but I have not been able to see copies. There is also an article in the Ponts et Chausées of 1832 by Beaudemoulin, Béton dans les fondations d'écluses, which may throw further light on the subject. Further details regarding history can be found in: The Cement Industry 1796-1914, A J Francis, ISBN 0715373862. 

 

A chronology for hydraulic lime/cement, 1750-1850.

1753, Semple uses a concrete for the foundations of a bridge over the Liffey, Dublin.

1756, Smeaton uses hydraulic lime for the construction of Eddystone lighthouse.

1793, Smeaton publishes papers on his hydraulic lime experiments.

1796, James Parker patents his process for making hydraulic cement in England.

1818, Vicat published his book on lime.

1818, Maurice St.Leger patents his process for making hydraulic lime in America.

1818, Dr John, of Berlin, publishes memoir on hydraulic lime.

c1820, used for constructing Toulon harbour.

1822, Berthier publishes analysis of different limestones.

1822, Raucourt publishes experiments on limestones in St Petersburg.

1822, used on the construction of the Erie Canal, America.

1824, Vicat completes the first concrete bridge at Souillac, France.

1824, used on the construction of the Saint Martin and Saint Maur Canal, Paris.

1824, Joseph Aspdin patents his process for hydraulic lime in England.

1825, Hassenfratz publishes memoir on mortar.

1828, Brunel uses hydraulic lime to repair the Thames Tunnel.

1850s, used extensively on the London sewerage system.

 

The Eddystone lighthouse was probably the most influential structure to use hydraulic lime in the early period. Smeaton is regarded as the first professional civil engineer, and he published his work widely. Vicat's bridge over the Dordogne at Souillac is still standing, and as such is another important marker in the development of hydraulic lime and cement. There is probably little left of any historic use of hydraulic lime on the Erie Canal as it has been completely rebuilt, and the same is probably correct for the Canal Saint Martin. The Thames Tunnel still survives, but is not accessible to the public. There are certainly more structures from this period which used hydraulic lime, but they are probably difficult to identify. The success of hydraulic lime was still in doubt, and many engineers continued to use more traditional methods with mortars.

 

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If the masonry was originally bedded in mortar then it will need to be repointed from time to time.  Lime mortar of some variety is probably most suitable, but take advice from a stone mason (not the special handshake sort).  The constitution of the "right" mortar is likely to be affected by the type and condition of the stone.   If it is actually immersed hydraulic cement may be needed.

 

There are many more ways of getting it wrong than of getting it right.

 

If the structure is listed you will also need to talk to the heritage chap, but you know about that, and the pitfalls associated.

N

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I am always amazed that CRT are sometimes happy to use red engineering bricks to repair a lock built with black engineering bricks but still insist on using lime mortar for heritage reasons.

 

I reckon that if you use lime mortar then mix a bit of proper cement in to make it stronger and stickier, but still just a little softer than the surrounding bricks.

My only experience of this is building a brick shed in my back garden (with my 7 year old daughter doing quite a bit of the bricklaying). When the estate agent came to value the house he explained to me that the shed was almost certainly converted from an original pig stye ?

 

..............Dave

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Lime mortar was used from a supply source that was cost sensitive.  Newspapers often record the movement of lime, or limestone, in the early nineteenth century by canal boat. Whether the canal builders had a particular concern to source the best qualities of hydraulic lime, is an issue for further discussion. The use of bricks or stone masonry is another related fact. Talking about blue, red or yellow bricks is a matter of canal development. It seems some engineers preferred  to use stone, and John Rennie Senior seems to fit that category, but local stone was not always available. Hence brick making by hand in temporary kilns and lime mortar. Not all was done to the best standard. Pilkington working in the Birmingham & Fazeley  at Curdworth and Fazeley had a poor record in that regard.

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  • 1 month later...

When I bought my first house over 40 years ago, I went through most of the books on building practice in my local public library. They all said that the eminently hydralic lime that had formerly seen extensive use, was no longer commercially available: all the economically- workable deposits had been exhausted, leaving only semi-hydraulic and  non-hydraulic limes. For hydraulic mortar you had to use portland cement, or a portland plus lime mixture. 

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