The mix is usually a 4:1:1 mix – that is – 4 sand, to 1 lime, and 1 cement – this should be pointed into joints which are raked out to at least 25mm (1 inch) and the joint should be cleaned of dust and moistened before the cement mortar is pushed into the joint.
How do you mix cement and lime together?
Mixing procedures. 1 Add ¾ of the water required. 2 Add half of the sand. 3 Add all of the Type S hydrated lime. 4 Mix for two (2) minutes. 5 Add all of the cement. 6 Add the remainder of the sand. 7 Add remaining water needed to obtain a workable consistency. 8 Mix for three additional minutes or a total mix time of five minutes.
How to choose lime mortar for pointing?
The single most important principle to observe when looking for lime mortar for pointing is that the mortar should be slightly weaker and more permeable than the masonry substrate. More rigid mortar will speed the decay of the masonry, causing it to crack with water damage or temperature changes.
What tools do you use to point Lime?
Artisans should use lime pointing tools that are narrow enough to fit in the joint. They will also need a hook for removing embedded debris, a chisel, and a hacksaw blade if there are narrow joints. Starting at the top, rake out defective pointing with chisels or other hooked tools.
What is the best mortar mix to mix with sand?
If you are going to do remedial/repair works, go for a 5 sand, 1 cement and 1 lime, and use some Cementone to get a near match. Doubtful wether you will get an exact match, if you invest in a electric mortar raking tool it wont take long to cut it all out, then you can repoint in a lime mortar mix, colour matched from Tradlime Co.
How do you finish lime pointing?
2:213:41Pointing with Lime Mortar from Lime Green Products - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo that the lime mortar isn't being left on the face of the brick to finish. The mortar you can useMoreSo that the lime mortar isn't being left on the face of the brick to finish. The mortar you can use a stiff bristled brush to beat the mortar into the joints.
Do you put cement in lime mortar?
The addition of cement to lime mortars is a widespread, almost traditional practice, but few consider why it is done or the consequences.
What mix is best for pointing?
The standard ratio for average mortar mix is 3:1 or 4:1 for bricklaying. If you are using a pointing mix, then you should have a ratio of 1:4 or 1:5 mortar to sand. As for concrete, it depends on the strength you need it to be at. Usually, it is good practice to mix concrete at 1:2 mix to materials.
Should I use lime mortar for pointing?
The use of a lime mortar for pointing in general masonry allows you to use a material that is both porous and softer compared with mortars that feature cement. This allows the moisture to evaporate from the joints more effectively which reduces the level of moisture in the fabric of the building.
What is the best mix for lime mortar?
We recommend the following procedure:Start with an empty mixer.Add 1 part sand.Mix in 1 part lime.Followed by 1.5 parts sand.Mix dry for at least 5 minutes.After 5 minutes slowly add water until the desired consistency is reached, it is very important not to drown the mix by adding too much water.More items...
What sand do you use for lime mortar?
The aggregates most commonly used with hydraulic lime are sand and grit, although for the purpose of matching historic mortars various impurities may have to be added. A good sand should be a washed, sharp sand with angular grains to ensure good bonding qualities.
What is the mix of sand and cement for pointing slabs?
The Patio Mortar Ratio The best mix for pointing patios is ideal at a ratio of 1:4 – one part concrete and four parts sharp sand. In some cases, you can use 1:3, but that's only really going to help when you're pointing.
Does adding more cement make mortar stronger?
To make the concrete stronger, add more cement or less sand. The closer you bring the ratio to an even one-to-one of sand to cement, the stronger the rating becomes.
What type of mortar is used for repointing?
Type O mortar, or high-lime mortar, a softer mortar with a low compressive strength of 350 psi, is best suited to repointing for several reasons. The first reason is that type O mortar is softer than the older bricks, and it allows the bricks to expand or contract from temperature changes or stress.
How do you stop lime pointing from cracking?
In drying conditions, new lime pointing will need to be dampened regularly (by lightly spraying) to prevent rapid drying. Over-rapid drying will result in shrinkage cracking due to rapid loss of water and will inhibit curing because the lime will only react with carbon dioxide in the presence of moisture.
How long does lime pointing take to cure?
3-5 days“Curing” Lime If at all possible protect your pointed walls with dampened burlap raised 1-2 inches away from the wall for a period of at least 3-5 days.
Is lime mortar better than cement?
Lime mortar has better properties than straight concrete mortar. These qualities help structures withstand weathering and aging better than before. If your stonework has an ordinary concrete mortar between the stones, you will have probably noticed cracking, pitting and crumbling.
Can lime be mixed with cement?
Incorporating an appropriate proportion of hydrated lime into a cement-based mixture improves plasticity and workability, making the product easier to handle on the trowel. Hydrated lime also increases water retention which helps to improve the contact and bond with the substrate.
Does lime mortar set hard?
Lime mortar does not require water to grow crystals, cure and get hard like cement based mortars. Limes get hard by absorbing carbon dioxide from the atmosphere.
Is lime mortar better than cement?
Lime mortar has better properties than straight concrete mortar. These qualities help structures withstand weathering and aging better than before. If your stonework has an ordinary concrete mortar between the stones, you will have probably noticed cracking, pitting and crumbling.
Can you mix lime with Portland cement?
If you decide to use the hydrated lime, you can use this recipe for the mortar: Three 5-gallon buckets of dry sand, 6.38 gallons of Portland cement and 1.12 gallons of hydrated lime. Blend these ingredients well before adding any water to the mix.
Why use lime mortar for pointing?
The use of a lime mortar for pointing in general masonry allows you to use a material that is both porous and softer compared with mortars that feature cement. This allows the moisture to evaporate from the joints more effectively which reduces the level of moisture in the fabric of the building. It can also decrease the likelihood of soluble salts appearing on the surface of the stone. Over time these salts can build up and cause the brickwork to spall or the surface to break down.
How to keep mortar from cracking?
If it feels quite stiff and dry when first working with it, keep going working the material, only adding a small amount of water if needed. Be careful however, because adding too much water can increase the natural shrinkage of the mortar and result in the material cracking.
How to cover a mortar joint in winter?
If you are applying the mortar in the winter, you may need to cover it once this process is complete with a polyethene or hessian sheet to stop frost attacking and damaging the mortar.
Can lime mortar cause brick to break down?
Over time these salts can build up and cause the brickwork to spall or the surface to break down. The application of lime mortars will require meticulous and careful control within the drying process. Before you begin any repointing project, it’s good practice to start by undertaking an assessment of the building.
Can you putty lime mortar?
Many lime mortars can be putty based, and these will work best if they have been pre-mixed a couple of weeks or even months before it is required. It should be agitated and mixed again to soften them before application which reduces the likelihood of shrinkage. Pre-mixed lime mortar can be purchased which makes the process quicker and this can be applied immediately.
How long to mix sand and lime?
Now add the rest of the sand and dry mix for at least 5 minutes. Now add water gradually until the desired consistency has been reached and mix for another twenty minutes.
How much sand to lime ratio?
For the best results, it’s essential to match the lime to sand/aggregate ratio of the existing historic mortar. However, a ratio of three parts sand to one part lime is generally used. Don’t be tempted to measure by shovelfuls – instead, use smaller gauging boxes.
How does hydraulic lime set?
However, hydraulic lime contains impurities that let it set in two stages – first when you add water and again when the mortar is exposed to the atmosphere.
How to make a malleable sand?
Mix dry, two parts sand (one soft, one sharp sand) with one part lime and add the final one part of soft sand on top. Being careful not to inhale the dust. Ensure the dry materials are evenly mixed prior to slowly adding water, mixing using hand tools to a smooth malleable consistency.
What is lime mortar?
Lime mortar has been in use for centuries and derives from calcium carbonate, including limestone, bone and shell. Two types of lime mortar can be used for restoration and pointing – hydraulic and non-hydraulic. Chemically both are very similar. However, hydraulic lime contains impurities that let it set in two stages – first when you add water ...
Can you use builders sand on lime mortar?
A washed sharp sand is ideal as the angular grains create a good bond. Using builders’ sand can result in excessive shrinking of the mortar.
Does adding water to mortar make it stronger?
The amount of water you add will directly impact the strength and durability of the finished mortar. Too much, and the final result will be weak. Too little and the initial hardening process won’t occur, resulting in a fragile final material.
How does hydraulic lime work?
The limestones from which hydraulic limes are formed naturally contain a varied range of minerals of which silica and alumina are the main ones for creating hydraulic lime. When these limestones are heated in the kiln at temperatures of around 1200oC, the resulting lime has different properties. From the pure limestone, the silica and alumina combine with the lime to form active compounds. These compounds combine in water to create a chemical set. The percentage of silica and alumina contained in the limestone will determine the main characteristics of the lime and of course the resulting mortar or plaster.
How long does high calcium lime putty last?
Manufactured in the U.K, high calcium lime putty is guaranteed to have been matured for a minimum of four months.
How to make mortar stronger?
Use clean water. The addition of water should be considered carefully, as it will directly affect the ultimate strength and durability of a mortar. The more water introduced into the mortar mix, the weaker will be the final result. However too little water will prevent the chemical processes taking place and weaken the material. Generally, water should be added sparingly, until a useable consistency is achieved. Adjust quantities to give a workability suitable for the application. It is important to use the minimum amount of water necessary so as to reduce shrinkage.
What is mortar matching?
Mortar matching is a process which enables our clients to use a mortar which is as similar as possible to the original or existing material.
How does hydraulic lime differ from non-hydraulic lime?
Hydraulic limes differ from non-hydraulic limes in that they have a chemical set as well as the process of carbonation. The limestones from which hydraulic limes are formed naturally contain a varied range of minerals of which silica and alumina are the main ones for creating hydraulic lime.
Does limewash hold mineral pigments?
Limewash gives great coverage, a brilliant rich finish and can hold mineral pigments extremely well.
Can lime mortar be balled?
Lime mortars mixed in drum mixers can be prone to balling. Use of particular mixing techniques can reduce this. We recommend the following procedure:
How to mix cement lime mortar?
The following steps should be taken to maximize the performance of cement-lime mortars mixed at the jobsite: 1 Add ¾ of the water required 2 Add half of the sand 3 Add all of the Type S hydrated lime 4 Mix for two (2) minutes 5 Add all of the cement 6 Add the remainder of the sand 7 Add remaining water needed to obtain a workable consistency 8 Mix for three additional minutes or a total mix time of five minutes
What is X2 in lime?
X2 = Units of volume of lime ( lime putty or hydrated lime)
Why does CL mortar carry more sand?
CL mortar will carry more sand due to the presence of dolomitic autoclaved hydrated lime. Lack of the proper amount of sand creates not only poor board life and workability problems but also the possibility of shrinkage cracks in the hardened mortar.
When mixing separate bags of cement and lime, must hydrated lime be completely wetted out in the mixing process?
When mixing separate bags of cement and lime, hydrated lime must be completely wetted out in the mixing process or it will continue to absorb water after mixing. By following the proper mixing procedures, excellent board life, workability and sand carrying capacities are achieved with lime mortars.
Where should cement and lime be stored?
Cement and lime products should be stored in a dry location at the jobsite to prevent deterioration of performance. Sand should be covered to minimize the potential contact with salts in rainwater.
How long to mix cement and sand?
Add all of the Type S hydrated lime. Mix for two (2) minutes. Add all of the cement. Add the remainder of the sand. Add remaining water needed to obtain a workable consistency. Mix for three additional minutes or a total mix time of five minutes.
How to measure sand?
The best method for measuring sand at the jobsite is the use of a cubic foot box. If a cubic foot box is not available, the number of shovels per cubic foot could be determined by shoveling the sand into five gallon pails. The number of shovels of sand required to fill up 1½ 5 gallon buckets is equivalent to one cubic foot. Once this number is obtained, the total number of shovels of sand per batch can be determined as follows:
What ratio of cement to sand?
In my experience I would normally do some test patches with different ratios of sand to cement eg ( 4:1 5:1 6:1) to see what matches the colours best.
What is the best ratio for repointing a house?
Hi. Your always best to use a 4:1 ratio for re-pointing at a depth of 10mm, this as a rule when you do re-point the entire house your colour matching will be accurate. Never do it any stronger as the morter will harden and shrink slightly causing it to crack and Ultimately fall out.
Can you repoint cement mortar?
hi,has you said after time cement mortar will crack .this happens as the lime mortar behind it recieves no moisture,drys up and turns to dust .so yes i would suggest you repoint it all.if you still wish to do a patch repair.try using a lime mortar with a mortar cement colouring.from builders merchant.or just lime mortar ,if you plan on repointing the rest in the near future.As for the damp issue you may wish to treat bricks before repointing with a waterproofer.
Can you use lime pointing on old cement?
I would remove all of the cement and start again,cement mortar in old buildings can cause damp and condensation problems so I’d strongly suggest going with a lime pointing with either 2 and a half sharp/ building sand and 1 lime then either finish in weather struck or a beaten finish
What to mix with sharp sand?
Mix the building sand with some sharp sand, it's what most people round here do. It's been done like that for the last 20 years without any failures as far as I know of.
How long to mix sand for a 443?
Country: The sand you use can also depend on the joint sizes. Really small joints need a finer sand. Some people use 50/50 sharp/building sand, others as you have seen. Mix up for about 20 minutes with not too much water to start with, then leave for 20 to fatten up, then mix for a couple more.
Can you tool lime joints?
It also seems that tooling a lime joint isn't the done thing as you have to leave the surface open. i.e overfill joint scrape back and then light taps with the churn brush.
Surface Preparation
Lime Repointing: Step by Step Process
Damp Down
- The next stage is to damp down the mortar joints and the brickwork. It is really important that this process is completed carefully, making sure that you wet down the whole wall (bearing in mind each brick can retain up to a pint of water). If the wall is very dry, such as during the summer and it hasn’t rained for a while, you might want to start spraying it the day before. This will stop the …
Preparing The Mortar
- The mortar should be adequately prepared. If you have a pre-mixed mortar, there may be some excess water on the top of the mortar. Tip the mortar onto a board and any excess water will drain away. Agitate the mortar to soften it so that it becomes malleable and workable. The more you agitate lime mortar, the better it works. If it feels quite stiff and dry when first working with it, ke…
Mortar Application
- Place a small amount of mortar onto a hawk and then take a pointing iron or trowel to apply the material to the brickwork. It should be the right consistency and always try to work the mortar in the same direction (towards the original mortar), pushing it into place as you go. A narrow pointing iron should be used to keep the mortar from the face o...
Finishing Off
- Leave the mortar for several hours (the length of time will depend on the weather conditions at the time and also the temperature). By this time, the mortar should be beginning to carbonate, and you shouldn’t be able to mark it with a nail or your finger. If the mortar is setting too quickly, lightly spraying it will slow the carbonation. Take a piece of wood which has been cut at a 45 degree an…
Final Touches
- You can now add the final touches, by using a stiff scrubbing brush to remove any excess mortar from the brickwork. You can also tamp the surface of the mortar with a hard bristled churun brush to stimulate some early weathering and to expose the aggregate as seen on our website. The lime mortar pointing process is now complete and is a material that should last for a long time if you …