A Grave Affair


After external restoration of Apse at St. James Episcopal Church in Lancaster City, Lancaster, PA
Before external restoration of Apse at St. James Episcopal Church in Lancaster City, Lancaster, PA
Inscription reads: “Ann Caroline Coleman Daughter of Robert and Ann Coleman”

Recently the LimeWorks.us Technical Install Crews completed a project in Lancaster Pennsylvania at St. James Episcopal church, and while we were there we walked among the graves at the rear of the building, reading the placards and faces of several stones. We stumbled upon several graves closest to the church where the Coleman family lay to rest. Judging by the size and number of the graves, we assumed they were of significant importance and most likely wealth. At this time we were told by one of the local masons who had been around during the job that there was a story buried with that of Ann Coleman, daughter of Robert and Ann Coleman. A story that involved our fifteenth president, James Buchanan. And so it begins.

Robert Coleman, Ann’s father, migrated to America in 1764 and ironically, the Coleman residence in Ireland was just about twenty miles from the ancestral homestead of the Buchanans. Robert Coleman would become an iron-master capping his fortune through his marriage to the daughter of the then famous iron-master of Reading, Ann Old. Robert came into possession of several iron properties in southern Lancaster County. After 1800 he served Lancaster greatly through his service as associate judge of the Court of Common Pleas, a trustee of Dickinson College, and a warden of St. James Episcopal Church where he himself would come to be buried. Robert had been acknowledged as one, if not the wealthiest man in Lancaster and perhaps even one of the wealthiest men in the state by around 1819. In being self-made, Robert Coleman became very self-conscious of his wealth and suspicious of those who might be looking to exploit it.

James Buchanan came to Lancaster in 1809, at the same time when Robert Coleman had settled there with his nine children and wife Ann. The Jacobs 600px-Presidents_James_Buchananfamily, another wealthy family in the Lancaster area were James Buchanan’s connection to the young Ann Coleman. Cyrus Jacobs had worked alongside Robert Coleman when they worked for James Old as laborers. Just as Robert had married James Old’s daughter Ann, Cyrus married Old’s other daughter Marguaretta, making the Coleman and Jacobs children first cousins. Cyrus Jacobs had a son who carried his name and would later study law in Buchanan’s office in 1818. One of Jacobs’ daughters, Eliza Jacobs, became the sweetheart of Buchanan’s law partner, Molton C. Rogers around 1818, and around the same time Buchanan began to gain interest in Eliza’s cousin Ann Coleman.

ColemanIn 1819, Ann Coleman had the eyes of Lancaster due to her wealth and social position. Her friends often characterized her as proud, gentle, full of sensibility, lovely in person, tender and affectionate, and intelligent and thoughtful. James Buchanan had built for himself a significant reputation in politics and law around this time, so much so that he was making around $8,000 a year, a fortune in that day. In the summer of 1819, James and Ann got engaged. Serving the typical role of a father, Robert Coleman examined all things James Buchanan. He researched family history, education records, and even the backgrounds of past associates. Robert found instances where he did not approve but unfortunately for Buchanan, he wasn’t perfect, and because of that Robert Coleman was not a man to ease the path for his daughter, although there was no record of hostility against Buchanan from Ann’s father.

Autumn of 1819 became a nightmare to property owners and the lawyers who handled said property. Panic reached its peak in august and James became extremely busy. Not only was James overwhelmed with the case which had ramifications in Philadelphia, which required his presence every so often, but the political scene was also in trouble. The local Federalist party was going to the wayside and as a leading young federalist, Buchanan was needed to remedy the damage. When you think his troubles were over you are wrong, the Missouri question was consuming the nation at the same time, and Buchanan was appointed to a committee to prepare official resolutions to instruct district congressman that would represent the sentiment of voters in Lancaster on the question of slavery in Missouri. To say James Buchanan was busy would be an understatement, and because of his legal and civic responsibilities, Ann Coleman took second place in priorities. Unfortunately for James, his engagement prompted the town’s observation of his every act, exposing him to special scrutiny.

James Buchanan’s final resting place at Woodward Hill Cemetery in Lancaster, PA

James Buchanan’s most favorable traits became an unfair judgement in regards to his persistent ambition to become financially successful and his unfailing good manners. These manners in particular, which to some, seemed to take the form of affability towards young ladies. Gossip swarmed upon these observations and eventually landed on two ideas that would misrepresent Buchanan; Buchanan loved the Coleman fortune, and he did not love Ann Coleman. Ann caught wind of these rumors and so did the whole Coleman household, and her parents did nothing to convince her otherwise. Over time Ann became convinced of the rumors and she wrote James, telling him that his object was her riches rather than regard for herself. Upon reading the letter Buchanan was hurt deeply, especially his pride and self-respect, and because of these same traits he was unable to solve the problem in direct terms. He answered Ann’s note politely, but came to no explanation. Since there was no formal break in their bond, matters still could happily be resolved, although another incident involving false assumptions arose. Buchanan had to go out of town on business and before the trip was over he casually dropped in to see Mrs. William Jenkins, whose husband was one of James’ intimate friends. Mrs. Jenkins’ sister, Miss Grace Hubley informed Ann of James’ visit and she became ridden with jealousy. She penned an angry note and released him from his engagement. James received the note while in the Court House and persons who saw him receive it observed him turning pale upon reading it. Buchanan only saw Ann’s large fortune as an issue if he were to try and persuade her to reconsider her breaking of engagement.

Ann Coleman’s resting place at St. James Episcopal Church in Lancaster City, Lancaster, PA

Ann became low in spirit and was encouraged by her mother to go to Philadelphia to ease her depression. Ann brought along her younger sister Sarah and caught a cold on her way to the city on December 4th. They both stayed with their sister Margaret who lived on Chestnut Street. A series of plays and operas served as a distraction for Ann. Buchanan on the other hand immersed himself in business. He successfully concluded a case on December 6th and was winding up some details, which served as a huge triumph for him, although it most likely paled to rescue his pride from the upset of his marriage plans.

Ann Coleman died on December 9th shortly after midnight. Judge Kittera of Philadelphia who knew the Colemans relived the events in his diary where he mentioned she had been engaged to be married and that some unpleasant misunderstanding occurred. He said that the circumstance was preying on her mind. Kittera also summarized daily happenings including fits of hysteria that later after night turned into strong convulsions which caused Ann’s sisters to send for doctors who though that it would soon end, and it did although her pulse continued to weaken until midnight when she died.

The news did nothing less then drown Lancaster. No one could explain exactly what happened. As for the friends of Ann, they all looked on Buchanan as her murderer and the Colemans felt the same way. When Buchanan received the news he wrote an anguished letter to Mr. Coleman asking for permission to see the corpse and walk as a mourner. His letter never reached the Coleman home, in fact it was refused at the door and returned unopened. In the letter, James wrote that he and Ann had been much abused and the he felt happiness had fled him forever. Ann Coleman’s body arrived in Lancaster on Saturday December 11th, and the next day it was buried in the churchyard of St. James Episcopal Church. At that time the church was under construction and lay half dismantled, described as a symbolic depiction of the life of Ann Coleman and the wreckage it now lay in.  James tried to get back to work but he simply could not do so. Buchanan disappeared for a few days before his return to Lancaster where he prepared himself to start again. He would never marry but would hold onto Ann’s letters throughout his life implying that he never recovered from her tragic death.


This story is an abridged version created from the cumulative research of Dr. Philip Shriver Klein, Head of the History Department of the Pennsylvania State University from “James Buchanan and Ann Coleman”. To read the complete work with complete citations from several sources including George Tichnor Curtis, Franklin Ellis, and E. C. Watmough, visit: https://journals.psu.edu/phj/article/viewFile/22321/22090

Old Stone Basement Foundation FAQ by Randy Ruth

This is part of a series of blog entries that will feature mason, Randy Ruth.

Randy was the former lab technician at LimeWorks.us and received lots of questions on masonry and the use of our materials. We post some of these questions on our blog.  Look for “FAQ” in other titles of our blog.

Q: I have an old stone basement foundation (house was built in 1900) and need to “re-point” or fill in holes in the basement walls. Would your Ecologic mortar work? I am not sure that lime based mortar was used originally; would this still be OK or how can I tell if lime was used?

A: “cement” was not produced in the United States until 1870 in Coplay, PA, only up until around 1910 was Portland cement starting to find its place in society as a masonry binder. Prior to 1910, most mortars used were based on either lime putty, Natural hydraulic quicklime, or natural cement. Regardless of what the exact mix design was used to build your basement foundation, Ecologic™ Mortar would most likely be suitable for repointing your old stone basement foundation walls as it would be sympathetic to the adjacent mortar mix by maintaining good vapor permeability. An easy way to determine if you have a lime based mortar, especially in stone construction, is to break a piece from the wall and visually inspect for any white nodules or specks. The white nodules are an indicator of what is called a “hot lime” mix and commonly found in stonework. Any presence of those nodules or specks suggests a high lime content mortar, and should thus be repaired with a comparable material.

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Phone: 215-536-6706

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Let’s Talk Sand

Our Ecologic™ Mortar uses a sharp well graded proprietary blend, so it’s not just ANY Sand!

The dictionary definition of Sand: weathered particles of rocks, usually high in silica, smaller than gravels and larger than silts, typically between about 0.06 mm to 5 mm. The particles are hard and will not crumble. Sand is used as an aggregate in mortars, plasters and renders as well as a component in concretes. The properties of sand used in a mix have a major effect on its workability, final strength and durability.

The types of sand normally used in building are:

  1. Sharp sand: consists of predominantly sharp angular grains. Clean well graded sharp sand for mortar, render and plaster is selected as the best for the strength and durability it imparts to the finished work. Workability is improved by mixing with fat lime as the binder and allowing this to stand as coarse stuff (not possible with OPC as a binder on its own).
  2. Coarse sand: A sand which is composed of predominantly large and medium sized grains. The higher the proportion of large grains, then the coarser the sand. Coarse sand is used for external renders and mortars to improve durability. Very coarse sands usually require a lime binder, blending with other sands or the addition of a plasticizer to assist workability. Sharp coarse sand is the most durable but the least workable, although suitable for roughcast.
  3. Soft sand: A sand which is composed of predominantly small and rounded grains. It often has a set content, the proportion of which is variable. It feels soft in the hand when squeezed. The smallest rounded particles assist workability but can give rise to cracking and failure in the finished work.
  4. Well-graded sand: A sand with an approximately even particle size distribution. As the smaller particles may fit in between the larger particles, this even distribution reduces the proportion of voids to solids and thus is less demanding on the binder than poorly-graded sand.
  5. Blended sand: A blend of sands of different grain sizes and sharpness to achieve a good particle size distribution. This provides a balance between durability and workability. Used mostly in connection with plaster for backing coats and pointing mortar when the quality of available sand needs to be improved. Sand may be blended by sieving it to adjust the particle size proportions, or by using sands from different sources.

Taken from Ecole d’Avignon/Re’seau Art Nouveau

Click here to read more about the ‘right’ sand for your mortar project.


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Phone: 215-536-6706

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Join LimeWorks.us at the IPTW 2015 in Burlington Vermont

July 22 – 24, 2015 for all the trades under one roof.


LimeWorks.us will be having two Grave Restoration Workshops at IPTW in July in

Burlington, Vermont at the Shelburne Farm on Lake Champlain.

If you register for IPTW, email us a copy of your paid IPTW registration to annie@limeworks.us or admin@limeworks.us, and with this voucher you can purchase a Graveyard Kit for $75.00 plus shipping! (A retail value of $400.)

Click here to learn more about our Graveyard Kit.  Any questions, please call us at 215-536-6706.

A limited number of 10 kits will also be available for sale at IPTW workshops at $100.00 each as an IPTW Vermont program special.  You can take both workshops if you like when you register for IPTW.  Please do not bring your Graveyard Kit with you.  We will be demonstrating using the products in our kit, so save your material for your own work.


Workshop #1

“Conscientious Conservation”

Andy deGruchy leads a workshop working with an historical stone marker of an actual gravesite.  He will discuss the considerations one must make when attempting to conserve such sacred objects.  He will talk about the least invasive (level 2) intervention methodology.  There will be hands on work and a demonstration of our own custom archival software which organizes the setting up of a conservation campaign.

Workshop #2

“Respectful Restoration”

Dan Montgomery will lead a workshop working with an historical stone marker of an actual gravesite. He will discuss the ramifications of restoration when more invasive actions are taken to refurbish a broken marker.  The intervention is a lot like surgery.  He will be using products from our graveyard kit to make those repairs.


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Phone: 215-536-6706

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Restoring Mt. Vernon’s Upper Garden Wall

Mt Vernon's Flower Garden

by Debra Grube and Samantha Horvath

LimeWorks.us is providing a custom blend of our Ecologic™ Mortar for the restoration of Mt. Vernon’s Upper Garden Wall.

Mt. Vernon was built in 1735 by George Washington’s father, Augustine, and George acquired Mount Vernon in 1754.  It began as a one and one-half story farmhouse, and over the next 45 years the building was slowly enlarged to create the wonderful 21-room residence we see today.  Washington personally supervised each renovation, selecting architectural features that expressed his growing status as a Virginian gentleman planter and ultimately as the first President of the United States.

The gardens that surround the mansion, however, were just as important as the living quarters considering they sustained the food supply of the family and all the visitors that flocked to George Washington’s home every year.  Even when the Washingtons were not present at the mansion, Martha Washington made sure the gardens were well tended, to be sure of the supply and abundance of fruits and vegetables upon their return.  The upper garden was transformed into a pleasure garden, occupied by a myriad of beautiful flowers surrounding the remaining vegetable beds. Washington procured the pleasure garden, along with a green house, as an alluring keynote for his guests to admire the beauty and fragrances provided by his lush gardens.

In the attached video you will catch glimpses of the upper garden wall, which is currently being restored using LimeWorks.us’ Ecologic™ Mortar manufactured using St. Astier’s NHL 2 and a custom blend of aggregates and pigments to simulate the coloration of the historic garden wall. Although you will not see the actual mortar in use, these videos below share more about the Upper and Lower Gardens.

The Beautiful Upper Garden at Mt Vernon

The Lower Garden at Mt. Vernon

The information shared here has been taken from the Mt Vernon Website.  Further reading and in depth history and facts of George Washington’s Mt. Vernon, can be found at their site.

Phone: 215-536-6706

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The Stonemason’s Gospel According to Ian Cramb

dsc_0004Lime Explained by Andrew deGruchy (pg. 143)

Limestone, the material calcium carbonate, has never changed from its beginning up to and including now. There have always been two classifications, ‘pure’ and ‘impure.’ Today it is classified as pure (high calcium) and two levels of impure lime based on the magnesium content, Dolomitic and Magnesian.

What has changed over the course of time, especially in more recent years, is how the calcium carbonate stones have been prepared by firing them in the kiln to produce quicklime. There is a most simple way of burning limestone in a vertical kiln using wood for fuel and keeping the temperature between 1650F and 2000F and then cooking it slowly over a few days. This has been done for centuries.  The proof that this method of cooking the stone has extreme merit is evidenced by the very old buildings throughout the world which still stand that utilized this method of preparing lime. ‘Lime’ is what limestone is called when it is cooked and slaked to make a putty that is incorporated into making building mortars, plasters and paints. The technical chemistry was unknown to old lime burners and masons. They just knew what worked and kept using the time-honored methods of preparing the lime.

When burned limestone has water reintroduced to it, called slaking, it then blooms into a beautiful white putty-like material. The volume of putty produced is double that of what was once the condensed rock. This ‘lime putty’ will draw carbon dioxide out of the air for a very very long time and slowly convert back closely to a limestone again. Lime putty has its initial set over a six week period by exposure to air. However it will attract carbon dioxide almost to a point of being completely ‘carbon neutral’ over time in regard to the embodied energy first required to produce the lime.  Through lime’s interconnected pores it even knits minor fissures together by moving about some of the not fully burned ‘free lime’ which creates more surface area to draw in the carbon dioxide.

Early masons knew that some limestone deposits produced limes that set quicker and became harder sooner. So, unlike simple air-setting lime putty, hydraulic limes were used throughout the world and in the United States to build with when the impure raw material had reactive silica or certain clays naturally found in the stone. These impurities were cooked along with the calcium carbonate stone. The term ‘hydraulic’ means to set with water and under water. Portland cement is hydraulic lime. The reason it is overall strongly suggested not to be used for masonry building conservation is that the synthetically added materials used to make Portland cement become intensely hydraulic also make the whole lot detrimental by various degrees of incompatibility with original porous building components. Two of those detrimental characteristics are that Portland cement is brittle and does not accommodate movement and secondly it reacts with sulfates. But a great incompatibility and detriment to historic masonry buildings is the increased densification of mortar that consequently occurs with every increment of additional Portland cement added to make the mortar become very hard. Densification does not allow the building to remain ‘breathable’ through the mortar joints but instead allows water to become held back and sometimes trapped into absorptive inner bedding joints. This phenomenon forces the wetting and drying cycles of the building to occur through the porous historic units and this is what greatly contributes to accelerated deterioration of the irreplaceable bricks and stone used to originally build a building.

In Ian’s first book he used and suggested mortar mixes that I and every other mason has typically used. These mixes gauge-in some Portland cement into high-lime (Type S lime) containing mortars. The reason we all did this is because readily available Type S Hydrated Builder’s Lime and cement were what we had to work with prior to the commercial availability of natural hydraulic limes now sold in the US. If Type S lime was blended with sand alone we discovered it would not hold up to the freeze-thaw cycles in northern climates. Why this occurs when nothing has changed about the limestone itself puts the spotlight on the cooking procedures. Too hot and too fast of a burn can cause the limestone to become ‘dead-burned’ and loose its ‘reactive’ nature which allows it to closely convert back to a hard and durable limestone again. A durable mortar made from reactive lime which maintains vapor permeable pores and has a desired malleable nature to accommodate minor building movement is the best for vertical, above grade work. Pure air- setting limes that remain reactive because they are burned at a low temperature can be obtained in the US too. However, due to the six week set time the cost for building with these limes goes up exponentially. So in this book the mortar mixes are more clearly defined from Ian’s first book as being mixes that use a binder of hydraulic lime but not the hydraulic lime that is Portland cement. I hope this helps you in designing appropriate mortar mixes for certain corresponding applications. It is a labor of love and worth understanding in order to realize the greatest long-term service life which can be obtained for repairing a vintage building and its components. I hope my contribution of this knowledge into what makes one lime better than another brings about a higher degree of excellence in the historic building conservation work you endeavor to do.


Andrew deGruchy


P. S. Ian passed away in 2013 and has left his legacy in print.  You can purchase this Ian Cramb  book from LimeWorks.us at the on-line store.


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Sunday, May 3, 2015
12:00 PM until 4:30 PM
Cost: $5.00
View map
Iron Hill Museum
1355 Old Baltimore Pike
Newark, DE
The Delaware Academy of Science (Iron Hill Museum) is pleased to announce the 2015 Archaeology & Heritage Festival. This event will feature professionals in the fields of Archaeology, History, Mineralogy, and Natural Sciences. Come to the Iron Hill Museum and see the past come alive.

Andy deGruchy from LimeWorks.us will be there demonstrating the slaking of lime  –  join us and learn about the process! 


Andy is also building a kiln on site and continuing the burning of oyster shells he started a few days earlier in another kiln. He is having kids weave some wattle and then after slaking the lime and mixing it with clay and sand, daub up the wattle and demonstrate some plastering circa 1660 in Colonial America and circa 4500 BC worldwide.

The 2015 Archaeology Festival will be held from Noon to 4:30 p.m. on Sunday May 3th on the grounds of the Iron Hill Museum–1355 Old Baltimore Pike.

Admission is $5.

Scouts in uniform are free. Children under 4 years old are free.

Additional Information
Sponsor: Delaware Academy of Science
Phone: 302-368-5703
Contact name: Maureen Zieber

Contact email:
The Museums Website: http://www.ironhill-museum.org
County: New Castle County
Neighborhood: Newark, DE

We make every effort to ensure the accuracy of this information. However, you should always call ahead to confirm this information.

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Types of Masonry Binders

Lime and Cement Cycle

by  Jessica (Focht) Aquiline, MSHP, LimeWorks.us Conservation Specialist

Binders are materials that act as a bonding agent that when mixed with aggregate and water form mortar, which is used to bond various masonry units together playing a structural and decorative role in a building. There are four main binders that have been used throughout masonry history, lime, hydraulic lime, natural cement, and Portland cement, all of which are derived from limestone. Binders affect the physical and chemical properties of the mortar including its strength, how quickly it hardens or sets, and how it reacts with surrounding materials. Below is a brief history of each binder type, the chemical reaction of their production, and their physical properties.


The history of the use of lime in an architectural application dates to the fourth millennium BCE in Anatolia and Palestine where it was used as a medium to paint walls. The earliest surviving known example of lime used as a binder in mortars is found in the Knossos palaces of the Minoan age, around 1700 BCE, were it was applied as a plaster. Lime mortar used as a structural component is not documented prior to the third century BCE in Rome, which coincides with the addition of pozzolanic materials modifying the chemistry of the mortar.1

Lime mortar is derived from limestone, composed primarily of calcium carbonate (CaCO3), which is fired in a kiln at temperatures above 700°C (calcination process), and is slaked with water to produce lime, which is then mixed with sand to make mortar. During calcination the limestone decomposes, losing carbon dioxide and 40% of its weight, producing quicklime (CaO).

CaCO3 ￿ CaO + CO2 (g)

Quicklime is then added to water during the slaking process, resulting in an exothermic reaction which produces calcium hydroxide (Ca(OH)2) known as slaked lime.

CaO + H2O  Ca(OH)2 + heat

This process was traditionally carried out in a pit dug in the ground where the quicklime was left to mature, allowing the calcium hydroxide to break down slowly and thoroughly to achieve the characteristic smoothness, workability and stickiness of fine lime putty.2 Today slaking is preformed by blowing steam over the quicklime resulting in a powder known as hydrated lime.

At this point the slaked lime is combined with sand in a 1:2-3 v/v ratio to produce a lime mortar that can then be used in the laying of masonry units or as a plaster or stucco. Water must be added if hydrated lime powder is used, however, the volume of water should not largely exceed the volume of lime. Lime mortar sets by contact with carbon dioxide that is present in the air through a process known as carbonation, converting back to calcium carbonate.

Ca(OH)2 + CO2  CaCO3 + H2O

Lime mortars are typically classified as air-setting mortars. As the water in the fresh mortar evaporates, air can enter into the now open pores allowing CO2 to react with lime inside the mortar achieving complete hardening. Since lime mortars require CO2 to set and harden there are some limitations as to where they can and cannot be used. They do not harden properly in very damp environments because the water does not leave the pores open for air penetration. They also cannot be used in bulk or in the core of thick walls because carbonation would not occur in a reasonable time allowing the mortar to harden. Unreacted Ca(OH)2 is frequently found in the core of ancient walls.3

There are several benefits to using a lime mortar in a masonry system. They have higher vapor permeability allowing the system to breath, keeping moisture from becoming trapped, and making the system more durable. Lime mortar provides flexibility to the masonry system allowing it to accommodate movements resulting from environmental and structural loading. The low strength of the mortar ensures that any structural movement occurs along the joints between the masonry units, protecting them from cracking and breaking. Lime mortars are also considered to be autogenous or self-healing. Cracks and fissures are healed through a process of dissolution, transport and re-precipitation of calcium compounds, CaCO3 and Ca(OH)2, within the mortar. Water allows calcium bearing compounds to go into solution and then transports them from a binder rich zone to voids and cracks that are present in the mortar. Re-precipitated calcium compounds may then fill thin cracks.4

Hydraulic Lime

A binder is considered hydraulic when it can set and develop strength through a chemical interaction with water. Hydraulic limes are produced from mixtures of limestone with clays, which can occur naturally as in impure limestone (natural hydraulic limes, NHL) or be achieved artificially (hydraulic lime, HL) through the addition of clay and other materials to calcium hydroxide. Impure or clay contaminated limestone contains silica and alumina and often other materials that can provide hydraulicity.5 These impurities form materials similar to those found in Portland cement, such as dicalcium silicate, aluminate and ferric phases. Hydraulic lime mortars are stronger and set faster then lime mortars while still being breathable, allowing moisture to escape the masonry system, and are able to set under water.

The reaction of the silica and alumina of the clay with heat, water and lime are what provide the hydraulic component to the binder. There are two principal types of hydraulic components, alite (tricalcium silicate, C3S) and belite (dicalcium silicate, C2S). Alite is only produced at firing temperatures above 1260°C and is therefore not present in hydraulic lime, where the initial material is burned between 600 and 1200°C. Alite is the main hydraulic component found in Portland cement. Belite forms at temperatures between 900 and 1200°C, which falls within the firing range of limes.6 Analysis has shown that hydraulic lime was used in medieval structures before the modern discovery of the process as a result of clay-rich limestone being fired at adequate temperatures to produce belite, resulting in a natural hydraulic lime.7

Natural hydraulic lime is produced from limestone (calcium carbonate, CC) containing 5-20% clay (marliacous limestone) that when fired at a high temperature (1000-1100°C) results in a silica-lime reaction producing belite or dicalcium silicate (C2S), lime (calcium oxide, C), alumina (A) and carbon dioxide (C).

CC + AS  C2S + C + A + C

Since there is more calcium carbonate present in the limestone than clay, firing produces a sizeable amount of quicklime (CaO). The burnt stone is then slaked with a calculated amount of water breaking it into a powder, as seen in the reaction above.

Hydraulic lime sets initially by the reaction of dicalcium silicate with water (H) at room temperature forming hydrated calcium silicate (CSH) and some free lime (calcium hydroxide, CH).

C2S + H  CSH + CH

As with lime, hydraulic lime also undergoes carbonation. Carbon dioxide from the atmosphere penetrates into the mortar after it has dried transforming the hydrated lime into calcium carbonate and splitting the hydrated calcium silicate into calcium carbonate and amorphous silica (SH).

CSH + CH + C  CC + SH + H

During the hardening process the binder undergoes some shrinkage and the addition of a non-shrinking inert filler, sand, is needed to reduce the shrinkage and improve the binder’s mechanical properties. The typical ratio for hydraulic lime mortar by volume is 1 part hydraulic lime powder to 1 to 3 parts sand to 1/3 to ½ part water.

Natural Cement

During the eighteenth century there were substantial developments in the understanding of cementitious materials, the first since the time of the Romans. In 1796, a patent was granted to Rev. James Parker for his invention of “Roman cement”, natural cement, which was notable for having a rapid set. Many other types of natural cement then began to appear on the market, all with varying characteristics. Natural cements are produced from argillaceous limestone, such as marls and septaria that have a clay content higher then 25%. They are classified as natural because all of the necessary materials needed are already present in the limestone. The limestone is fired in a kiln at the same low temperatures, 1000-1100°C, which are used for firing hydraulic lime. The calcium in the limestone combines with the alumino-silicates in the clay to form hydraulic minerals.8 After firing the calcined rock is ground into a fine powder, unlike lime, natural cement cannot be slaked.

Natural cement is a hydraulic binder with rapid setting due to the production of calcium aluminate hydrates.9 As a binder, natural cement has a high compressive strength compared to lime mortars but is still water vapor permeable. Rapid setting and the hydraulic properties of natural cement made it a popular mortar choice for civil engineering projects as well as general construction during the nineteenth century until the arrival of Portland cement in the mid nineteenth century. The properties of natural cements are a direct result of the amount and composition of the clay present in the limestone.

Portland Cement

Portland cement was patented by Joseph Aspdin in 1827, who claimed that his invention could produce an artificial stone as good as Portland stone. However, his invention was not yet comparable to what is used today. A comparable material to present day cement was produced by I. C. Johnson in 1845 by firing limestone and clay at such high temperatures that the final product was a vitrified mass.10 As kiln technology advanced during the nineteenth century they were able to fire at higher temperatures for longer periods of time allowing for complete vitrification of the silicates present in the clay.

Portland cement is manufactured by firing a mixture of limestone (CC) and clay (AS), around 22%, at high temperatures (1450°C) where almost complete melting occurred, transforming the limestone clay mixture into their hydraulic mineral species, resulting in a clinker after cooling. The clinker is then finely ground into a powder and mixed with up to 5% gypsum, which is required to reduce the speed of setting that starts when the powder is combined with water. Firing of the original product at this temperature results in the production of tricalcium silicate (C3S, alite), dicalcium silicate (C2S, belite, the only active compound in hydraulic lime), tricalcium aluminate (C3A), and calcium alumino-ferrite (C4AF).

CC + AS  C3S + C2S + C3A + C4AF

Water (H) is then added to the products resulting in the formation of hydrated calcium silicate (CSH), hydrated calcium aluminate (CAH) and free lime, calcium hydroxide (CH). This reaction is what causes the cement to harden and gives it its hydraulic properties as well as its high strength.

C3S + C2S + C3A + H  CSH + CAH + CH

As the hardened material ages and undergoes carbonation the free lime converts back into calcium carbonate and converts the hydrated calcium silicate and aluminate into amorphous silica and alumina. Carbonation reaction is very negligible and does not impair the mechanical strength of the cement mortar.


The physical properties of Portland cement are primarily dictated by tricalcium silicate (C3S). C3S is what gives Portland cement its fast hardening time and high strength. During setting C3S will hydrate to produce hydrated calcium silicate (CSH), just as dicalcium silicate (C2S) will, but C3S will produce over three times more calcium hydroxide (CH) then C2S does. The formation of calcium hydroxide begins as soon as water is added to the powdered clinker and will crystallize in the pores of the mortar altering the pore structure.11 This results in a poor void structure within the mortar making it quite dense and reducing the vapor permeability to the point where it is four times less vapor permeable then Natural Hydraulic Lime. Crystallization of calcium hydroxide also alters the elasticity of the mortar, stiffening it, which puts the mortar at higher risk of long-term cracks forming.

The binder is an integral part of a masonry system, bonding the structure together. The type of binder used dictates the physical and chemical properties of the mortar. In a properly engineered masonry system the mortar is meant to be compatible with the masonry units used and to be sacrificial so that the masonry units do not become damaged as a result of the binder that is present in the mortar. Each of the binders discussed provide different properties that are more suitable for specific applications. When choosing a mortar for a masonry project keep in mind the properties of the masonry units that are being used and choose a mortar that will be compatible and in best service to the building.

1 Torraca, Giorgio. Lectures on Materials Science for Architectural Conservation. (Los Angeles: Getty Conservation Institute, 2009). 50.

2 Brocklebank, Ian. Building Limes in Conservation. (Shaftesbury: Donhead, 2012). 23.

3 Torraca. 53.

4 Lubelli, B., T.G. Nijland, and R.P.J. Van Hees. “Self-healing of Lime Based Mortars: Microscopy Observations N Case Studies.” HERON 56.1/2 (2011): 76.

5 Brochleband. 48.

6 Brocklebank. 24.

7 Torraca. 58.

8 Lowry, Richard M. P. “In Defense of Natural Cement: A Critical Examination of the Evolution of Concrete Technology at Fort Totten, New York.” (Thesis. Columbia University, 2013) 6.

9 Brocklebank. 11.

10 Torraca. 61.

11 “Mineralogy of Binders and the Effects of Free Lime Content and Cement Addition in Lime Mortars.” Test and Research for Natural Hydraulic Lime Products from St. Astier UK. (St. Astier, 2006). 8 Nov. 2013. <http://www.stastier.co.uk/nhl/testres/mineralogy.htm>.

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D/2 Biological Cleaner – Winter Special 2015

Safely Cleans Natural Stone/ Masonry/Wood/Canvas/Vinyl

10% Off   Through March 31, 2015

Enter Code:  D2CEM15 at our online store shoplimeworks.us

D2 bottleD 2 GravestoneBirdbath

Stock up on D/2

·       1 gallon containers

·       5 gallon containers

·       No minimum

·       Proper Stone Cleaning

·       Cleaning effects continue over time after the initial application

10 % off D/2 SALE through March 31, 2015 (does not include shipping) 

We can ship directly to the location of your choice.

Call today to place your order:  215-536-6706 or you may order online at shoplimeworks.us.    You can find the D/2 under the Supplements Category.

Please share this with your purchasing agent or your contractor who will be performing the gravestone care.

Enter Code:  D2CEM15 at checkout or mention it when you call!

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Historic Preservation Video Contest Alert for 2015!


LimeWorks.us is offering a $500 prize for the best short video of the month and a $1000 grand prize for the best short video overall, to legal US residents over the age of 18.  The intent of our contest is to find someone who is talented in videography, who understands the message that we are encouraging, and can captivate and inspire our audience with a story of something historically or culturally noteworthy.

Submitted videos should be 3-5 minutes long featuring a person, place, or thing which exemplifies:

  • Keeping up the good fight for historic preservation.
  • Saving regional cultural heritage.
  • Designing, retrofitting and/or building sustainable structures in America.

The short segments that we currently produce in-house are known as
Limelight Spark Segments”.

An example of a Spark Segment can be found at: https://www.youtube.com/user/LimeWorksus

Contest Rules: 

All submitted videos must start with our intro clip and end with our logo (which we will provide upon request) and credits including your name and the name(s) of those who helped you in any way.  It is required that you sign a release indicating that everyone in the video has given you permission to use their image on the documentary short and that you take full liability and responsibility to have secured such permissions. LimeWorks.us will have full rights and ownership of the video to post it indefinitely on our YouTube channel with no compensation for it other than the one time prize award.

Submissions need to be electronically submitted or postmarked by 11:59 PM of the last day of each month to be considered for the next month’s contest.  A video may be submitted only once.  In the event of less than two entries in any given month, LimeWorks.us reserves the right to not award a prize for that month but instead add that video to the next month’s entries. The contest ends December 31, 2015.

Please do not send a propaganda piece, promoting a company or selling a product; it must be a pure “human interest” story meant to inspire. The winning videos will be chosen based on content, the quality of the video and adherence to the contest description as stated above. LimeWorks.us reserves the right to reject any and all videos for any reason. The winning contestants will be notified via email by the 7th of the following month of their submission and will be notified when the video will be posted on our YouTube channel.

Employees of LimeWorks.us and its affiliates and members of their immediate families and households are not eligible to enter the contest.

We look forward to seeing your entry.

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