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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 Lime Mortar as a Masonry Binder

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.

CSH•CAH•CH + C CC + SH + AH

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.

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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I have unusual details, could you explain or can I tell you what I know about the subject? https://www.limeworks.us/blog/i-have-unusual-details-could-you-explain-or-can-i-tell-you-what-i-know-about-the-subject/?utm_source=rss&utm_medium=rss&utm_campaign=i-have-unusual-details-could-you-explain-or-can-i-tell-you-what-i-know-about-the-subject https://www.limeworks.us/blog/i-have-unusual-details-could-you-explain-or-can-i-tell-you-what-i-know-about-the-subject/#respond Mon, 09 Mar 2020 15:18:58 +0000 https://www.new-limeworks.us/?p=28442 The post I have unusual details, could you explain or can I tell you what I know about the subject? appeared first on LimeWorks.us.

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*Using the modern grapevine jointer in brickwork is a form of what is also called “bastard pointing” whereby the genuine article which is being attempted to be copied is actually the ruled key and tuck point where the bed mortar receives a keyway into the first infill and then later tucked with usually a white or red colored lime putty. This “tuck pointing” was done to give a more formal, (gauged) appearance to a hand molded and irregular sized brick or irregular rubble, and a snecked rubble, stone wall. Bastard pointing in stonework is found in the forms of Ruled Ribbon jointing and further by Cobweb Ribbon jointing in both cases by the Raised Ribbon where material is added or raised to the base infill and not into a keyway first incised. It is also found in the form of Painted Ribbon where whitewash is used for the painted highlight lines in white, graphite black, etc. to create contrast.

Pencylling on both brick and stone joints is a form of trompe l’oeil where these colored limes are painted in straight thin lines on the joint. It really is a faux finish to what originally was genuinely designed to have depth and body to an infill material that would last longer as it wore away. New (colonial style) brick buildings, and reproductions of the same at historic sites, often get what is also called a Colonial style “grapevine jointing” the brickwork. This style is often being copied from the original buildings in which the remnant of the style hardly remains evident in regard to the in-fill of colored lime putty. It is often by an oversight, or by a new interpretation of only what is desired from what remains of the original style that the contrasting infill is not included in the new work. This oversight has happened to the degree that a new style all its own has been created, AKA the grapevine jointing in brickwork. Thus, now all repointing is often generically referred to as tuck pointing from the original meaning to tuck in the colored putty within the center of an incised joint. The grapevine joint in brickwork is now made with a jointer which makes a center impression which is close to straight, but not at all as straight as when using a rule to guide the impression. In nature a real grape vine would never normally grow in straight lines or be incised, unless you are pulling a grapevine out of a building’s mortar. Therefore it is just the grapevine joint in stonework which remains true to its name as a convex protrusion. In brickwork, the grapevine joint is a style of modern times. In brickwork a convex protrusion is called a beaded joint.

Overhung Ridge Joint

 

A very authentic historic style of pointing whereby a squared appearance is given to snecked rubble work is the Overhung Ridge joint. Snecked rubble is stonework cut in semi-squared blocks of stone laid in level, uniform coursing. Snecked rubble is sometimes wrongly referred to as Ashlar work. Ashlar work is actually perfectly squared blocks of stone, whether they be actually squares or rectangles, with very tight, (usually less than ¼) joinery. The Overhung Ridge joint is often misinterpreted as one of the ribbon joints mentioned above. Overhung Ridge is a joint that meets the flush face of the semi-squared block of stone above it, having a trailing edge to the stone above it and a ruled edge with a inward bevel meeting to the stone below it. Usually the left side of the head joint has the trailing edge and the right side of the head joint, the ruled edge with bevel.

Ecologic™ Mortar G #DGM 250

(greenish ochre-brown colored)

Tools- 1/2″ ribbon jointer, loop and a level

Note that often in Overhung Ridge pointing of snecked rubble stonework, the head joints can be perfectly perpendicular with the horizontally level bed joints or the head joints are angled from the level bedding plane. From a distance this joint appears to make the semi-squared stones seem more squarely shaped. It also makes the joints look a lot like a ribbon joint, which they are not. Although no painted lime lines or additionally material is added on the surface of the ruled lines, the tightly compressed flat area of the Overhung Ridge joint typically dries lighter than the trailing and ruled edge which is scraped away to bleed into the surrounding texture of stone. This gives the appearance of a painted ribbon joint, but is not to say that in some instances pencylling was not still carried out. In Chestnut Hill, Philadelphia many original Overhung Ridge pointed buildings throughout Germantown Avenue and all the surrounding side streets can still be viewed.

**Beveled Ridge is also known in various areas as a Beveled Ridge, Colonial Ridge, Inverted-V, V, Beaked, Peaked, Prism, Crown Ridge or as a Pointed joint along with other regional terms for the same thing. The term for placing mortar between any irregularly shaped stone or brick where the mortared sides of the squared unit and/or bed was not first buttered with mortar and then dipped on to its bed is called pointing or it is called repointing when it is renewed. An actually pointed joint, which comes to a peak in the center best describes the most functional shape for mortar placed between irregular sized, random laid rubble stonework because the protrusion of the mortar allows for more material to be weathered away than any joint which is struck back. It also happens that rain coming at an angle toward the building would deflect away from the wall when the force of the rain hits a beveled edge and bounces away. Finally, in randomly laid rubble stonework where the mosaic-like pieces of stone come together to form one unified wall, a hand struck Beveled Ridge joint follows the contours of the stones’ joinery. This allows the size of each bevel to conform with the opening which it fills. This is aesthetically pleasing and is further improved in aesthetic quality when sunlight casts shadows on the lower half of the bevel making wide joints appear half their size. So, the terms Pointing and to Repoint may have remained because of the shape that mortar for this type of stonework was originally designed to have.

Surface pointing, (also known as a “scrub joint” ) is commonly applied as a pasted joint with little depth of material. It is in fact the most common method of “repointing” a whole building but contributes very little. In fact many times this method accelerates deterioration by trapping water in the wall with high concentrations of Portland cement in the mix used.

Many “Restoration masons” utilize this method because pasting over the top of slightly recessed joints with a thin overlay goes up very quickly and gives the appearance of a lot of work received for what is a small amount of money charged for the work. In the end, the less savvy building owner thinks that since the entire wall has been “repointed” and the uniform look of all joints being filled is a complete job they received a good value.

What actually has happened is that the joint profile is not restored to a tooling within the edges of the brickwork but instead is now a flat joint on the faces of the brickwork much wider than the original joint profile.

The fineness of Portland cement and fine play sand made in a 1:1 ratio with little or no lime content is what makes this fine paste. The brittle, often gray Portland cement colored, scrub joint cracks and falls out within a few years.

Where it does not fall out and was filled into deeper voids it helps to keep moisture trapped in the bedding mortar and only allows any moisture in the wall to escape through the face of the masonry unit, if it were to get out at all. A resulting “picture frame” of proud gray mortar remains with hollowed back masonry units as the final irreversible damage. “Tuck pointing” is what some inappropriately call the scrub joint. The scrub joint is very similar to grouting the face of tile although the scrub joint is applied course by course on the brick joints. The actual root of the name “Tuck pointing” comes from a narrow keyway cut into the center of a molded brick joint and then filled or “tucked” with a bright white, red or black lime putty to give a more formal and gauged appearance to the brickwork.

Prior to the tucking in of this lime putty a red color wash is first applied to the bricks and mortar joints to give uniformity and aid as a shelter coat. Remnants of this color wash and infill of putty can be found on many historic brick buildings in the eastern states. The “grapevine joint” has taken the place for the name of a true ruled key and tucked joint and what is often reproduced in a restoration effort is simply the grapevine joint without the proper color wash and lime putty in-fill.


Example of “stone-filled framing” often found in early house construction. This is not how the interior walls were intended to remain. Owners in later years took off the interior plaster and exposed the brick or stone-filled framing and pointed up the work. This cobweb ribbon style mortar joint is considered a “bastard pointing.” It was not achieved by white material placed over gray background mortar nor was it painted on white lines. Simply by compressing the wet mortar in the center and scraping away and leaving an open texture to the feathered edges of the mortar did the centerline dry whiter and more prominent.

Another example of how the exterior plaster used to cover the rubble fieldstone foundation was “lined-out” to look like cut blocks of stone. The exterior plaster render above it is harling. A type of plaster harled (literally hurled) at the wall while wet. The English call it Rough Cast and the Scots call it Harling.

An example of squirrel tail bake oven underside: Slates were used for the underside of a bake oven again arranged in the same successful pattern. Slate was an available local stone in the area of PA were this photo was taken.

 

The “grapevine” joint in stonework is a protruded bead. Easton, PA Note to those in College Hill and the Easton, PA area- 1 part Ecologic™ Mortar G #DGM 200 (brown/grayish color) and 1/4 part washed coal flecks, (or medium grade slag bits), is a good match for most mortar repointing work needed on buildings built there before 1940.

 

The “beaded joint” in this brickwork is a protruded bead. Annapolis, MD

 

Metal sheets from late 1800’s into early 1900’s meant to reproduce the work of early brick masons correctly interpreted a detailing that was found in most all old brickwork where some detail, whether a bead or a tucked-joint ribbon or a slight raised “V” from cutting the lime mortar usually was the finished profile. Today a concave, 1/2 round, striking is commonly done to cement mortars so that they are tightly compressed using a convex or “bucket” jointer. Unlike lime mortars, which allow absorption and evaporation of all water, modern Portland cement joints must keep water out by being tightly compressed.

 

Find the original whitewash on a building and you will often see bluing. Ultra Marine Blue was added as well as other types of bluing pigments to help a not so white lime wash to become whiter. I have heard tales of superstitions about putting blue in the whitewash but I don’t have substantial information to offer about whether they have any truth to the tales or not. A very white whitewash helped to increase moonlight reflection and often one can see plaster remaining over the brick or stone under a front porch for this very reason.

 


Example of “brick-filled framing” often found in early house construction.
Example using over-burned “clinker brick” which twists out of shape from over firing and then laid in a wall as a decorative form of brickwork called “skintled” brickwork

 

A pent roof was removed from a rubble fieldstone farmhouse in Pennsylvania and the owner’s who did this work showed me this beautiful original lime plaster which was “lined-out” to look like cut ashlar blocks of stone. For some reason we often see these blocks scribed around 26-27″ long and 9″ high. We have also measured many other variations but the 26 x 9 is common.

 

You know that you are dealing with historic fabric when you see greater detail in the use of lime/sand mortars. Above are down-draft kiln fired red brick with a pigmented red lime mortar. The black painted “ribbon joint” found on the stonework was originally installed to create a more formal appearance of gauged joinery. This creates contrast between the stone and the colors of the brick above it. Ask for Ecologic™ #DGM Black mortar

 

Another couple of examples of “lining out” where incised lines were scored into wet lime/sand exterior plaster to simulate brick and their joints. Although the mosaic of rubble fieldstone is considered a desirable thing of beauty today, it was more a sign of affluence to have had brick made and delivered to a building site rather that using scrap fieldstone laid up in a rubble wall. So, the shelter coat of lime/sand plaster was often embellished with lining-out to create something more sophisticated such as cut blocks of stone or expensive bricks.

 

I would love someone to tell me what this is. A 250 year old threshold stone made of granite had an inlaid area. However, nothing was inlaid. The imprint of a center “mat-like” area is actually the original stone with only a vermiculated center area tooled in, as if to catch dirt. Something may have been poured in to the crevices and sat up on top of the stone but it is now worn completely away. Montgomery County, PA.

 

Another example of Pencylling. Cut blocks of sandstone were color washed and pencylled-in with a ruled black line to give the appearance of even a closer tolerance to the stonework’s joinery. The white part of the mortar would have been stained the uniform color applied to all of the stonework’s faces and joints except for the prominent black line.

 

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How to Save Money with your Historic Restoration Project https://www.limeworks.us/blog/how-to-save-money-with-your-historic-restoration-project/?utm_source=rss&utm_medium=rss&utm_campaign=how-to-save-money-with-your-historic-restoration-project https://www.limeworks.us/blog/how-to-save-money-with-your-historic-restoration-project/#comments Wed, 24 Jul 2019 16:10:29 +0000 https://limeworks.us/?p=15430 LimeWorks.us was commissioned by Zion Evangelical Lutheran Church of Tamaqua, Pa., to diagnose and address the failure of a church tower which utilized man-made cast stone for trim details.

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Picking the Right Product for the Job

Labor, materials, consultations, and other similar expenses are all factors that can really rack the price up of any restoration or construction project. Everyone would agree that the lower the cost of these expenses the better; however, always choosing the cheapest option may not be in the best interest for your project.

Choosing the right materials that will perform over the lifespan of your structure should be your highest priority because that will save you the most money and time in the long run. The cheapest, quickest option, like using a Portland cement-based material where not suitable, can carry many unintended consequences in the future for your historic structure.

How our technical install team repaired the cast-stone work at Zion Evangelical Lutheran Church in Tamaqua, Pa.

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The Project

LimeWorks.us was commissioned by Zion Evangelical Lutheran Church of Tamaqua, Pa., to diagnose and address the failure of a church tower which utilized man-made cast stone for trim details. At the time the original building was built in 1914, as a cost-effective solution, Zion Evangelical Lutheran decided to use the cement-based cast stone. Almost 100 years later, a first and second campaign was undertaken to repair the cast stone by using modern Portland cement and sand in a compound made to carry out the repairs. Both campaigns failed within a few years of their installation.

Why Did the Cast Stone Fail?

Figure 1 – Restored cast stone cracking and falling off.

One of the most common problems associated with cast stone is its propensity to shrink and crack when the cast does not cure sufficiently.[1]

After our evaluation of the facade, we believe the use of Portland cement in the application of the repair material caused the water that entered the system to activate the solution sulfates already present in the structure and deposit additional sulfates into the system. If these sulfates crystallized beneath the surface then the cast stone would begin to deteriorate.

Pro Tip: When salts crystallize, a force of about 4000 psi is exerted (about the same force as a saltwater crocodiles bite strength (3,700 psi)

The “accumulation of water-soluble salts that re-crystalize just beneath a masonry, stucco, or concrete surface,” is known as subflorescence.[2] This subflorescencent activity beneath the cast stone, along with freezing and thawing would first form minute micro fissures that lead to larger cracks after multiple freeze/thaw cycles.

Some Portland cement-based materials can even innately contain “soluble salts such as calcium sulfates and sodium… which can leach out over time” and begin to break down the existing mortar and stone.[3] Cast stone is a cheaper alternative to using quarried stone, which is highly labor intensive and cost-prohibitive. Using a cast stone cement mix was well intentioned and even took into its purview the original building material. However, using the exact building material to create an exact historic replica is what caused the first cast stone patches to fail. A closer historic simulation can more effectively be achieved by using lime in the restoration process, because of its workability and chemical properties.

Using Lime to Mitigate Environmental Factors and Save Money

Heritage conservation, sustainability, and environmental factors should come into play when approaching your restoration project.[4] Materials such as our Lithomex, Lithostep, and Lithocast were used in the restoration process in order to address the underlining issues which caused the cast stone patches to fail. Our Lithomex products are created primarily from pure St. Astier brand natural hydraulic lime and aggregates.

Overall, the Lithomex products have a good modulus of elasticity and an excellent water permeability which enables Lithomex to re-release water back to the atmosphere before it has time to freeze. Since there is no common building stone on our planet that can re-release water back to the atmosphere quicker than Lithomex, water can never get trapped behind the patch. Trapped water which freezes and expands can push off stone repair patches. This is the biggest problem with many commercially available and, yet, exorbitantly expensive stone patching materials on the U.S. market.

Figure 2 – Corroded section of the building surface.

By using lime-based products in the restoration of the church, we will mitigate the environmental and material related factors that caused the previous stone patches to fail while also increasing the over-all longevity of the church building.  

The Restoration Process

 In our restoration of the stone tower the LimeWorks.us Technical Install Team removed the corroded cast stone down to sound material and then used our Ecologic Waterglass as a conditioning primer to stabilize the loose powdery particles on the surface of the cast stone before carrying out the detailing for final cast stone repairs. This will ensure that our Lithomex patches will bind to the wall and not fall off due to a corroded application surface (see Figure 3).

Figure 3 – Stainless Steel rods and wire armature.

After the Waterglass cured, we installed an armature (interior skeletal structure) of stainless-steel rods and wires to create a mechanical connection between the new mortar and the original cast stone surface (see Figure 3). The chemical properties of the lime mortar will allow water to exit the structure because of its high porosity, which combined with the mechanical structure of the armature will hold the material there for years to come.

Many of the columns were so deteriorated that they had to be rebuilt by hand. Our expert craftsmen hand tooled our St. Astier Lithomex to give the surface of the columns a rough, aged look that would simulate the natural appearance of the original elements.

 The Technical Install Team cleaned and repointed the existing ruled ribbon joints around the granite and created a custom mortar simulation of the original pointing mortar. Visible in Figure 5 is the new repointing work. We performed a light and diluted wash down using NMD 80 50/50 with clean water for cleaning sharpening the lines of the repointing work along with slightly raising the grain of the aggregate so the new work would compliment and blend in with the remaining original working mortar.

Restoration Project Before and After

Do Your Research First and Pay Less Later

When approaching your next restoration project, remember to consider the long-term effects the materials you employ may have on the building you are attempting to repair. Just choosing the cheapest alternative or the original building material may not always be the right option or save you the most money in the long run. Lime’s ability to allow water to pass through a structure, its resistance to sulphates and salts, and its elastic properties make it the perfect solution to fix the problems caused by the use of Portland cement on Zion Evangelical Lutheran Church. To learn more about our lime and how it may be able to save you a headache in the future visit https://limeworks.us/about/lime/.

Interested in the work we did at Zion Evangelical Lutheran Church? Join us for our next hands-on workshop at The Craftwork Training Center and increase your knowledge in the field of historic masonry restoration! Visit https://limeworks.us/events/hands-on-workshops/ to learn more.


[1] (Page 7-8) Man Made Vs. Natural Stone A Study On Cast Stone https://ilco-indianalimestone.netdna-ssl.com/wp-content/uploads/2016/01/caststone-whitepaper.pdf

[2] https://www.buildingscience.com/glossary/subfluorescence

[3] (Page 63) LIME MORTARS FOR THE CONSERVATION OF HISTORIC , BUILDINGS  https://pdfs.semanticscholar.org/4b5b/b5290e75c12a219ecc0c23ab78004e2968aa.pdf

[4] (pg. 10-11) LIME AND ITS PLACE IN THE 21ST CENTURY: COMBINING TRADITION, INNOVATION, AND SCIENCE IN BUILDING PRESERVATION,  https://limeworks.us/wp-content/uploads/2017/07/LimeAssociation.pdf

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Regional Heritage Charleston, South Carolina https://www.limeworks.us/blog/regional-heritage-charleston-south-carolina/?utm_source=rss&utm_medium=rss&utm_campaign=regional-heritage-charleston-south-carolina https://www.limeworks.us/blog/regional-heritage-charleston-south-carolina/#respond Wed, 27 Feb 2019 19:28:24 +0000 https://limeworks.us/?p=11276 For the record, Doug Scott a local mason to Charleston for over 25 years, had a hand in all this!

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For the record, Doug Scott a local mason to Charleston for over 25 years, had a hand in all this!

The history of Charleston, South Carolina is one of the longest and most diverse of any community in the United States, spanning hundreds of years of physical settlement beginning in 1670 through modern times.

After Charles II of England, Scotland and Ireland (1630-1685) was restored to the British throne following Oliver Cromwell’s Protectorate, he granted the chartered Carolina territory to eight of his loyal friends, known as the Lords Proprietors, in 1663. It took seven years before the Lords could arrange for settlement, the first being that of Charles Town. The community was established by English settlers in 1670 on the west bank of the Ashley River, a few miles northwest of the present city. It was soon chosen by Anthony Ashley-Cooper, one of the Lords Proprietors, to become a “great port towne”, a destiny which the city fulfilled.

Wikipedia


Need Ecologic™ Natural Hydraulic Lime Mortar ?

You can get LimeWorks.us Ecologic™ Mortar for historic mortar simulation in the Charleston, South Carolina area at Hughes Supply. Phone 843-577-6671.

Ed Burn, President
Hughes Supply
82 Mary Street
Charleston, SC 29403

Serving Charleston since 1888. Note- Left of Ed is the sample Mortar Kit display containing the 16 cured strips of Ecologic™ Lime Mortar. These mortars contain no Portland Cement and are ready for repointing historic masonry. Just add water. Kit cost $30 (at the time of writing).


This brick wall can be found just outside Randolph Hall at Charleston College along St. Phillips Street.

Ecologic™ Mortar DGM 100 simulates the color of the original bedding mortar found at this brick wall in Charleston, South Carolina. The wall can also be found just outside Randolph Hall at Charleston College along St. Phillips Street. Note that DGM 100 could be modified with 2 lbs of screened oyster shell bits to more closely simulate the original mortar texture.

The bedding mortar, simulated by DGM 100, is a buff shade. The pointing mortar is very white in the center and has only become an off-white shade from reacting with the atmosphere over time.

The original bright white pointing mortar is simulated by the Ecologic™ Mortar strip found in the LimeWorks.us Mortar Kit of 16 cured strips. It is comprised of one part NHL 2 and 1 part marble sand.

Ecologic™ Mortar DGM SCG (Standard Construction Grade-Non-pigmented) “G” for granular or “coarse” sand.

Blend used simulates the color of the original pointing mortar after is has reacted with the atmosphere and has developed an off-white patina.

This cured sample strip found in the LimeWorks.US Mortar Kit of 16 cured strips shows a blend of 25% DGM 100, 75% DGM 050 and 2 lbs of screened oyster shell bits.

The brownstone wall cap at the College of Charleston just out Randolph Hall had exfoliating Brownstone which was similar to our Lithomex Stone Patching Material code #EMEXST0035.

Located at 329 E. Bay Street. The Philip Gadsden House. Ecologic™ Mortar DGM SCG (Standard Construction Grade-Non-pigmented) “G” for granular or “coarse” sand.

Blend used simulates the color of the original pointing mortar after is has reacted with the atmosphere and has developed an off-white patina.

The original bright white pointing mortar is simulated by the Ecologic™ Mortar strip found in the LimeWorks.us Mortar Kit of 16 cured strips. It is comprised of one part NHL 2 and 1 parts marble sand.

The joint style is regionally known as a “Beaked joint”.

Samples of LimeWorks.us stock lime paint colors. These were observations made using the stock lime paint Swatch fan deck to demonstrate that a color may suffice directly from the pallet. Custom colors may also be obtained by sending us a sample of a Benjamin Moore sample card and corresponding color code.

317 East Bay Street. The Dupre’ House. Lime Paint color #342

81 East Bay Street. Green Lime Paint Color #346, Blue Lime Paint Color #343

79 East Bay Street. Green Lime Paint Color #346

4 Legare Street. Lime Paint #350

Again, 4 Legare Street. Lime Paint #350

21 ½ Legare. Beaded joint profile with various concentrations of DGM 300. Here cut at 50% with SCG Non-pigmented Ecologic™ Mortar.

21 ½ Legare. Full strength DGM 300 Ecologic™ Mortar.

21 ½ Legare. Side of the building has a bedding mortar similar to the hue of DGM 100 Ecologic™ Mortar.

21 ½ Legare. Side of the building has a pointing mortar similar to the hue of DGM SCG “G” Ecologic™ Mortar.

16 Meeting Street.

Beaded joint profile with various concentrations of DGM BLACK Ecologic™ Mortar.

Again, 16 Meeting Street.

Again, 16 Meeting Street.

South End Brewery, 161 East Bay Street. Originally a beaded joint profile as discovered at the protected area under an eave. A simulation is DGM BLACK Ecologic™ Mortar.

The beaded joint profile was discovered at the protected area under an eave. This is a clue to the architect’s original intent in the design and color scheme of this beautiful historic building.

South End Brewery. Under sills an original red mortar could be simulated using DGM RED Ecologic™ Mortar.

The repressed yellow brick may originally have had a mortar similar to the color of the brick.

(Close up of yellow brick above)


“Nou pa bezwen mare bouch bèf la pou enpoze l’ manje lè l’ap vire moulen pou kraze ble pou nou.”

Deteronòm 25:4  No man, we did not!

Photo of Andy deGruchy and Douglas Scott of Summerville at the South End Brewery.

The Angel Oak in the land of Ophrah.

“The Angel of the LORD came and sat down under the oak in Ophrah that belonged to Joash the Abiezrite, where his son Gideon was threshing wheat in a winepress to keep it from the Midianites.”

Judges 6:11

Life is old here.

The +1500 year old Angel Oak Tree off Bohicket Road, John’s Island just outside Charleston, South Carolina.

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Regional Heritage Lancaster, Pennsylvania https://www.limeworks.us/blog/regional-heritage-lancaster-pennsylvania/?utm_source=rss&utm_medium=rss&utm_campaign=regional-heritage-lancaster-pennsylvania https://www.limeworks.us/blog/regional-heritage-lancaster-pennsylvania/#respond Wed, 27 Feb 2019 15:16:00 +0000 https://limeworks.us/?p=11231 The post Regional Heritage Lancaster, Pennsylvania appeared first on LimeWorks.us.

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For the record, Randy Ruth a graduate of the Thaddeus Stevens College of Technology had a hand in all this!

Originally called Hickory Town, the city was renamed after the English city of Lancaster by native John Wright. Lancaster was part of the 1681 Penn’s Woods Charter of William Penn, and was laid out by James Hamilton in 1734. It was incorporated as a borough in 1742 and incorporated as a city in 1818. During the American Revolution, it was briefly the capital of the colonies on September 27, 1777, when the Continental Congress fled Philadelphia, which had been captured by the British. After meeting one day, they moved still farther away, to York, Pennsylvania. Lancaster was capital of Pennsylvania from 1799 to 1812, after which the capital was moved to Harrisburg.

Wikipedia

John McGrann, Owner
Penn Stone
190 West Ross Street
Lancaster, PA 17603

Need Ecologic™ Natural Hydraulic Lime Mortar ?

You can get LimeWorks.us Ecologic™ Mortar for historic mortar simulation in the Lancaster, Pennsylvania area at Penn Stone.

 

 

 

Phone 843-577-6671

Visit the Penn Stone Website!


235 East King Street
The only architectural Brownstone in Lancaster. The mix that simulates the original is 1 part NHL 2 and 1 part marble dust.

Just a walk down one street, East Orange, demonstrated that most of the colors in the Ecologic™ Mortar Kit were represented in the historic mortar color.


317 East Orange at the Young Funeral Home. Ecologic™ Mortar color code DGM RED simulates the hue of this mortar.


337 East Orange Street. Ecologic™ Mortar color code DGM BLACK simulates the hue of this mortar.


343-345 East Orange Street. Ecologic™ Mortar color code DGM GREY simulates the hue of this mortar.


351 East Orange Street. Ecologic™ Mortar color code DGM 300 simulates the hue of this mortar.


355-357 East Orange Street. Ecologic™ Mortar color code DGM SCG (G) simulates the hue of this mortar.

336 East Orange Street. Ecologic™ Mortar color code DGM RED with slag fleck inclusions will simulate this mortar.

 

 

 

322 East Orange Street. Ecologic™ Mortar color code DGM 050 simulates the hue of this mortar at the foundation.

 

 

 

 

The Central Market.

 

 

 

 

 

Ecologic™ Mortar color code DGM 300 simulates the hue of the stone foundation mortar.

 

 

 

 

Ecologic™ Mortar color code DGM 300 simulates the hue of the original bedding mortar. Top red pointing is a repoint with colored cement which demonstrates the brittleness and cracking of cement based mortar.

 

Unclear what the mock-up of white mortar is, however it demonstrates that the color scheme of mortar and brick as originally specified by the designing architect was very important and lends to a beautiful, effortless appearance of complementing components which result in elegant masonry work which soon becomes a defining feature of a region such as Lancaster city.



Jonathan Owens of Brookline Builders, Inc. from Lancaster, PA is serious in readying his sons to be the next generation of educated historic restoration conservators by allowing them an opportunity for some practical experience. The boys were not shy about trying their hand at repointing using lime mortar at the LimeWorks.us “hands-on” training booth.

 

Wow, the work looked great and it is obvious that these boys both have some natural skills. Met with the user-friendly Ecologic™ Mortar, (and not knowing the boys were not really masons), even a child can repoint with great success! LimeWorks.us set up the display panels at the Lancaster Historic Home Show on February 26-28, 2010 and invited the public to try some repointing and brick and stone repair materials.

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Trinidad and Tobago https://www.limeworks.us/blog/trinidad-and-tobago/?utm_source=rss&utm_medium=rss&utm_campaign=trinidad-and-tobago https://www.limeworks.us/blog/trinidad-and-tobago/#comments Thu, 21 Feb 2019 14:44:37 +0000 https://limeworks.us/?p=11221 The post Trinidad and Tobago appeared first on LimeWorks.us.

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They seem to love me in de Islands. Got invited to Barbados and others to run more workshops. I guess I better get on a frequent flyer program.

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Misc Training Work https://www.limeworks.us/blog/misc-training-work/?utm_source=rss&utm_medium=rss&utm_campaign=misc-training-work https://www.limeworks.us/blog/misc-training-work/#respond Wed, 13 Feb 2019 18:56:34 +0000 https://limeworks.us/?p=11132 The post Misc Training Work appeared first on LimeWorks.us.

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The following are examples of training work we have done. We
have provided training for volunteers of non-profit run historic sites
and for contractors as specified by preservation architects for other
projects:

Here’s an example of an all volunteer workshop lead by Andy deGruchy
over a two week period. The group saved the little historic bridge and
did it for no cost to the Weisel International Youth Hostel and the
Bucks County and Nockamixon Park Systems. deGruchy Masonry, Inc.
contacted the Heritage Conservation Organization in Boulder, CO who put
the word out and organized the workshop. Andy deGruchy has a philosophy
that a workshop for masonry restoration should not be done inside a
building where work is practiced only “In theory” and then the work is
torn down and material and labor wasted. Instead, Andy believes that
using the labor and material to accomplish a needed work for an ailing
structure serves many purposed simultaneously. One purpose is to
accomplish some needed intervention immediately rather than talking
about it and letting the historical object fall down while well-intended
plans are being made. Andy was the “fearless leader” and worked along
side everyone to coach and encourage all the participants until the
final completion. Oddly the work began on a September 11 morning, a
poignant date that counters the painful legacy it conjures up by instead
having a group of committed people choose to start saving, healing,
helping and rebuilding.

 

A small historic country bridge in Bucks County, PA was stabilized with NHL lime/sand/casein grout and then repointed after laying up all the fallen stonework using Pure Natural Hydraulic Lime mortar throughout.

 

In 2006 we coached a crew of masons in mixing up St. Astier Natural Hydraulic Lime #3.5 with black slag inclusions to reproduce a similar mixture tooled to an inverted-V style joint on the Burgess Foulke House Museum in Quakertown, PA.

 

Previous Portland cement patches held water into the bedding mortar so that after the Portland cement was removed we took moisture meter readings to see that the levels of moisture in the wall dropped prior to repointing. This workshop was done at no additional cost to the Historic Society that owns the building after they awarded the bid to the lowest qualified bidder at a fixed, quoted cost.

 Additional Resources:

On-site Training / Guidance Referrals

AIA/CES Accredited Lime Presentation DVD

 

We demonstrated to local crews the use of St.Astier Lithomex and Natural Hydraulic Limes for applications on the St. John the Divine Church in New York City.

deGruchy Masonry, Inc trained a local crew in Atlanta, GA to use Ecologic™ DGM 50 colored mortar for repointing work at the historic Fox Theater.

MINOLTA DIGITAL CAMERA

We provided training for another set of contractors who did the repointing work performed at the Ephesus Seventh-Day Adventist Church in Harlem, NY who also utilized Ecologic™ DGM 50 colored mortar and St. Astier Lithomex stone repair material to repair the damaged brownstone on the church.

MINOLTA DIGITAL CAMERA

We provided training for another set of contractors who did the repointing work performed at the Ephesus Seventh-Day Adventist Church in Harlem, NY who also utilized Ecologic™ DGM 50 colored mortar and St. Astier Lithomex stone repair material to repair the damaged brownstone on the church.

The National Park Service hired deGruchy Masonry, Inc. to train and inspect work done by a contractor to the new Visitor’s Pavillion at Grey Towers, the home of the founder of the National Forest Service. They used St. Astier Natural Hydraulic Lime for interior and exterior plaster and for building stone walls.

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2012 APT/PTN Convergence Workshop at American College of the Building Arts (ACBA) https://www.limeworks.us/blog/2012-apt-ptn-convergence-workshop-at-american-college-of-the-building-arts-acba/?utm_source=rss&utm_medium=rss&utm_campaign=2012-apt-ptn-convergence-workshop-at-american-college-of-the-building-arts-acba https://www.limeworks.us/blog/2012-apt-ptn-convergence-workshop-at-american-college-of-the-building-arts-acba/#respond Wed, 13 Feb 2019 17:34:50 +0000 https://limeworks.us/?p=11108 The post 2012 APT/PTN Convergence Workshop at American College of the Building Arts (ACBA) appeared first on LimeWorks.us.

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Charleston, SC – September 30 to October 4, 2012

Cap is missing bricks on both ends of entrance arch to ACBA

Huge crack needed to be stitched and grouted on the side of the entrance to ACBA

Original bricks were missing on the front wall of ACBA

Close up of cap bricks missing at the entrance to ACBA

“Before” photo at 2nd Presbyterian Church retaining wall in Charleston

“Before” photo at 2nd Presbyterian Church retaining wall in Charleston

“During” the workshop at ACBA with students from Savannah Technical College

“During” the workshop at ACBA with students from Savannah Technical College

Another “During” photo of the workshop at ACBA with students from Savannah Technical College

Another “During” photo of the workshop at ACBA with students from Savannah Technical College

Another “Before” photo of the 2nd Presbyterian Church retaining wall in Charleston

Another “Before” photo of the 2nd Presbyterian Church retaining wall in Charleston

These bricks were original historic fabric taken from the surrounding wall of the old jailhouse in the back region which was not as prominent and used at the front wall sourounding the jailhouse

These bricks were original historic fabric taken from the surrounding wall of the old jailhouse in the back region which was not as prominent and used at the front wall sourounding the jailhouse

“During” the workshop at 2nd Presbyterian Church, Charleston where many volunteers came out to use a pure lime mortar placed between the bricks and finished to the orginal profile of the joints

“During” the workshop at 2nd Presbyterian Church, Charleston where many volunteers came out to use a pure lime mortar placed between the bricks and finished to the orginal profile of the joints

“After” photo of the front entrance after the bricks that were missing on the ends were replaced

“After” photo of the front entrance after the bricks that were missing on the ends were replaced

This is the front wall where the replacement bricks from the back wall were laid just below the burlap shown in the photo so as to complete the wall

This is the front wall where the replacement bricks from the back wall were laid just below the burlap shown in the photo so as to complete the wall

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Building a Lime Test Wall https://www.limeworks.us/blog/building-a-lime-test-wall/?utm_source=rss&utm_medium=rss&utm_campaign=building-a-lime-test-wall https://www.limeworks.us/blog/building-a-lime-test-wall/#respond Wed, 13 Feb 2019 16:49:44 +0000 https://limeworks.us/?p=11105 The post Building a Lime Test Wall appeared first on LimeWorks.us.

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Please watch our 3 part video series on our Lime Test Wall in Cameroon Africa

 

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Restore Wesley United https://www.limeworks.us/blog/restore-wesley-united/?utm_source=rss&utm_medium=rss&utm_campaign=restore-wesley-united https://www.limeworks.us/blog/restore-wesley-united/#respond Wed, 13 Feb 2019 16:27:43 +0000 https://limeworks.us/?p=11101 The post Restore Wesley United appeared first on LimeWorks.us.

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