Where to buy type s lime

Limewash is highly alkaline pH 12 until CO2 fully adsorbs and the limewash converts to calcium carbonate or calcium and magnesium carbonate and it becomes pH neutral. The high pH at the time of application has made it a useful historical antiseptic method for killing bacteria, algae and mold on buildings, barns and fences. When worked with a float, it is possible to force hairline cracks to close up, but it is not possible to dent or significantly reshape the mortar mass. This is the point when your fingers can no longer make an impression in the stucco or plaster, but you can still easily scratch the surface with your fingernails.

At this stage the plaster or stucco feels slightly cool to the touch, indicating that there is still water in the mortar. Void Space Ratio. Lime should fill the entire void space between the sand. Excess lime pushes the particles apart and weakens the mortar. To little lime will leave voids and weaken the mortar. A test to determine the void space in sand is fill a clear mL beaker with dry sand. Measure mL of high proof grain alcohol.

Add enough alcohol to the dry sand to wet the top of the sand and ensure all the sand is saturated. The alcohol will fill the space between the sand particles. The amount of alcohol you add, determines a lime-to-aggregate ratio. This is the method that determines the sand-to-lime ratio for all sands in the making of lime putty mortar. Particle Size Distribution of Aggregates Sand for building should be clean, sharp, and angular.

These will pack together tighter, providing a structural matrix. For example, golf balls are somewhere between angular and round because of their multi-faceted surface. A stack of golf balls has huge gaps between the balls in the same way that sand comprised of only one particle size would not pack together tightly. The sand is then passed through a series of screen sieves that are supposed to begin with a 4 and continue with 8, 16, 30, 50, , and sometimes But often the sequence varies with a more random selection, jumping from a 4 to a 10, then maybe a 20, then a 50 or The weight of the sand retained on each screen is noted and sometimes its percentage of the total is listed.

Usually this is followed by a recommended formula for a replica mortar. Almost always, the recommended binder consists of 2 parts lime to 1 part Portland cement followed by 9 parts sand. These days various ASTM guidelines are inserted for the type of cement or lime and aggregate, and are usually irrelevant to the task at hand: matching a historic mortar.

More than once I have seen ASTM guideline used for specifying the type of lime to be used in matching a historic lime mortar. This standard is for S-type lime that is hard-burned and finely ground for use with Portland cement.

It is completely unsuitable for making a high-quality lime mortar. C is specified because the mortar being recommended is really a Portland cement mortar with added lime. Often pigments are specified to create an approximation of the color of the original mortar. The more lengthy reports may include some thin section information, all kinds of USA Today-type pie charts and graphs, and, most disturbingly to me, many pages of instructions to the site workers on proper techniques for making, storing, and using the mortar, stucco, or plaster.

You are right to wonder about the value of these reports. What do you learn that is useful? You do not learn much about the components of the original mortar. But then again, you are being given a formula that contains very different materials from the original anyway. What is the purpose of the analysis? Why do these reports state that matching the original mortar qualities is so important and then provide no information to do this?

What is the purpose of the sand sieve information? All good questions, and later I will try to provide some better descriptions of onsite preparations and methods for determining much of this information yourself.

For now, stick to learning about and finding good quality lime and begin collecting sand samples from your area.

Presumably a mason with considerable experience has spent a lot of time looking at old masonry in many states of preservation, repair, and disrepair, paying attention to how the joints were struck and tooled.

For example, masons in the past must have had many tools similar to ours, but also many that were different. The trick in all of this work is to see clearly, a real skill that takes years to develop. The first thing to realize when we are repairing older work is that we will be attempting to imitate an appearance that was created in a way we may not be able to precisely duplicate. The original mason was working with a freshly laid wall where he was mixing mortar to the consistency required for laying brick, mortaring, and setting the brick in place.

Depending on his judgment, the joints were struck in certain ways and at certain times to achieve the finished appearance. Often our repairs consist of removing some deteriorating mortar or previous repair to a depth of an inch or so, packing the new mortar in, and tooling it straight away. We need to adjust the consistency of the mortar, the moisture content in the joint, the pressure of our tools, and the sequence and timing of work in order to imitate the appearance of the best preserved of the original work.

Then we must complete the process with more tooling, brushing, washing, etc. By careful examination of well-preserved early masonry, we can determine the shape and size of some tools, the sequence of tooling, and consistency of the mortar which may be different on the surface than deeper in the joint.

Examining old texts on the masonry arts and making replica tools is also essential. And finally, there is no replacement for lots of practice. This answer may seem long-winded, but I think in order to get at the heart of your concerns I must first run through a bit of information about quality lime for use in lime mortar, getting and mixing the right materials, and application.

Well-calcined high-quality lime is usually very white. Some lime putties on the market these days are touting their off-white, almost tan color. Often these lime putties are from poor quality limestone and are improperly fired. More about this another time. For the moment, stick with one lime to three sand unless this is a special pointing mix. Is the original surface mortar different than the mortar deeper in the joint? After acid digestion, look closely at the sand and the fines.

These components will largely create the color of the mortar. The fines give it an overall shade or hue and the sand contributes to the weathered color and texture. Therefore you are not slaking, but rather soaking the hydrate. It is good to mix it a few times, but then you want to let it sit. Our hydrate is only lime I would consider to be of high enough quality that you could feel sure of a good product just after a few days of soaking.

Using hydrates for mortar to point with is perfectly adequate. Not so when plastering or stuccoing. Lime putty should not have much excess water or be runny-think more along the lines of Philadelphia cream cheese. Your fears of shrinkage will be realized if you have too much extra water in the mix.

A nice putty has the water it needs already bound up in the matrix; you release the water for your needs through mixing the mortar. Very little additional water will need to be added to your mix. Trust me on this one: elbow grease is the answer. But as you mix, the lime will appear to get wetter. Keep this in mind also as you are applying the lime mortar. Often during the summertime, the mortar on your trowel will appear to dry out rapidly, but with a little beating the mortar is usually ready again without more water.

Properly prepared and beaten mortar will have virtually no shrinkage. It is preferable to make the mortar before the day you use it since the longer sand and lime are in contact, the better the working qualities will be. As long as these are kept moist, we have found that the working qualities keep improving over months, and even years.

By using our Lime, using our mixing advice, properly wetting the joints well in advance not just immediately before adding mortar as water can easily be drawn out by the surrounding masonry and undermine the bond -water an hour ahead, then again a bit before, but save yourself messy brick faces and ensure the surrounding brick faces themselves are not wet when you point , and preparing the joints properly, you should not have problems with shrinkage or cracking.

You should not have problems with this unless you make the mortar too wet. Could you send us an emailed picture? The rule of three times as deep as the joint width is okay, but not to be taken to extremes. Ignore the standard advice about letting each lift set up carbonate before you apply the next one. Think of it this way: you want to achieve a mortar that is as densely packed as possible. This allows you to compress the mortar minus extra water with your tool or a hammer and wooden wedges before applying the next lift.

In other words, for a joint that is one inch deep, I would easily be able to fill it with two lifts and tool and finish the joint in a single day. One more word of caution here: many people overwork the surface of their mortar by slicking it too much.

Compression does not mean slicking, because over-tooling creates a condition of too much lime on the surface and a plane of aggregate just below the surface that has been starved of its cement binder. This can create a weak plane below the surface that has the potential to fail later for a variety of reasons, but in particular due to freezing.

Usually, we will slightly age mortar within a day or so of applying it by hitting it moderately with a stiff bristle brush to open the surface a bit and expose the aggregate. That is something we can talk about another day.

The mortar we have been discussing here should be adequate for all the locations on this building. The key to good cement-aggregate ratios is that a range and distribution of particle sizes fills in nearly all the voids. Imagine a box filled with tennis balls, golf balls, marbles, and lead shot, with the idea that there is much point-to-point contact between all of the aggregate particles and the minimum of cement necessary to bind the particles together.

Make sure that the work is covered from weather — hot sunlight, wind, and rain — for a few days until you get surface carbonation light color and hard surface. After the initial surface carbonation, rain will actually increase the rate of carbonation beneath the surface, so further protection of the mortar at that point is counter-productive.

Is this true? What is the difference between dolomitic and high-calcium limes, and what does this mean for lime mortars? Are there weather-related restrictions to working with lime-only mortars? How does the sand content of a lime-only mortar affect the project? When is it best to add some Portland to lime and when are all-lime or all-Portland mixes best? Andy, a conservator from Pennsylvania The Brick institute of America states that the softest mortar that can be used for a given unit of masonry is always the best choice.

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. 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.

During the eighteenth century there were substantial developments in the understanding of cementitious materials, the first since the time of the Romans. In , a patent was granted to Rev. Many other types of natural cement then began to appear on the market, all with varying characteristics.

They are classified as natural because all of the necessary materials needed are already present in the limestone. The calcium in the limestone combines with the alumino-silicates in the clay to form hydraulic minerals.

Natural cement is a hydraulic binder with rapid setting due to the production of calcium aluminate hydrates. 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 was patented by Joseph Aspdin in , 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. Johnson in by firing limestone and clay at such high temperatures that the final product was a vitrified mass. Firing of the original product at this temperature results in the production of tricalcium silicate C 3 S, alite , dicalcium silicate C 2 S, belite, the only active compound in hydraulic lime , tricalcium aluminate C 3 A , and calcium alumino-ferrite C 4 AF.

This reaction is what causes the cement to harden and gives it its hydraulic properties as well as its high strength. 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 C 3 S. C 3 S is what gives Portland cement its fast hardening time and high strength.

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. 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. Lectures on Materials Science for Architectural Conservation.

Los Angeles: Getty Conservation Institute, Building Limes in Conservation. Shaftesbury: Donhead, Nijland, and R. Van Hees. Columbia University, 6. Astier UK.