Lime and hydraulic lime are both materials used in the construction process, but they are not the same.
Lime is a natural material made from limestone, that is burnt and then ground down into a powder. It can be used as a binding material, or as a plaster and mortar to create a slow-drying, breathable finish.
Hydraulic lime, on the other hand, is a type of lime that has been modified to act as a hydraulic binder due to its ability to set through chemical reaction with water. It is produced using other materials, such as clay, which are added to the mix to produce more consistent and stronger binding results when water is added.
One of the main differences between the two materials is that hydraulic lime remains plastic and flexible for a longer time before it dries and sets, making it ideal for traditional construction methods and for the repair of older buildings and structures.
In comparison, ordinary lime dries quickly and cannot be used for repointing or other repair activities.
Additionally, lime mortar has a whitish color and a smooth finish, while hydraulic lime mortar has a more yellowish color and is more course in texture. The longer setting time of hydraulic lime also allows it to be used in cold temperatures and exposed to freezing.
What is hydraulic lime used for?
Hydraulic lime is a type of lime that sets and hardens due to the presence of impurities in the limestone from which it is produced. It is used in building and construction for a variety of purposes, such as making mortars and plasters that are used to glue and bind stones together.
It is also used to make concrete and strengthen walls and foundations, as well as to waterproof roofs, floors and walls. Hydraulic lime is often used as a mortar between building stones, such as in the construction of historical buildings, while it can also be used to make decorative finishes, such as stucco.
It sets quickly, meaning it can be worked more quickly than regular lime, while its waterproof properties make it suitable for use in areas of high water exposure.
Why hydraulic lime is not used in plastering?
Hydraulic lime is not used in plastering because it is much less workable than the more traditional plastering limes and can be difficult to work with. It also takes longer to set and can be more prone to cracking than the other types of limes available.
Hydraulic lime takes a longer time to develop its strength, which can be a disadvantage as it may require additional time and effort to complete a job. Therefore, it is generally not suitable for use in plastering.
How long does hydraulic lime last?
Hydraulic lime is a very long-lasting product with a life span far greater than that of many other construction materials. When properly installed and maintained, it can last for centuries. The grade and quality of the particular lime being used will play a large role in determining how long it lasts.
For instance, a higher quality, harder grade of lime will have a much longer life than a softer grade. In addition, proper sealing of the surface is crucial for extending the life expectancy. The environmental conditions in which the hydraulic lime is installed will also have an effect on its lifespan, as humid climates or areas prone to the freezing and thawing of ice and snow can cause hydraulic lime to deteriorate over time.
In general, with proper care and maintenance, hydraulic lime can last anywhere from 50 to 100 years or more.
Why is it called hydraulic lime?
Hydraulic lime is so named because of its ability to harden underwater, or by the presence of moisture. This distinguishes it from non-hydraulic lime, which hardens through the loss of carbon dioxide and is therefore unsuitable for use in damp or wet conditions.
Hydraulic lime has the ability to absorb and chemically react with water, forming a concrete-like material that can bind together building elements such as blocks, stones, and bricks. The process of hydration creates a strong, hard material that will resist the effects of water, temperature, and exposure better than non-hydraulic lime.
It also has higher compression strength, making it useful for constructing walls, arches, vaults, and other elements in architectural structures. The hydraulic lime used in building construction origins from the ancient Greeks, who developed hydraulic binder from naturally occurring rocks.
It was later popularized during the Roman period.
What is the composition of hydraulic lime?
Hydraulic lime, also known as Natural hydraulic lime (NHL) is a type of hydraulic binder (a material with the ability to set and harden under water) made of natural lime with clay and other materials such as sand,opx and shell.
The source, quality and properties of the limestones used all affect the properties of the hydraulic lime, as do the proportions and quality of the other ingredients.
Hydraulic limes have a number of different grades which can be determined based on their chemical, mechanical and engineering properties. The grades are identified as NHL 1, NHL 2 and NHL 3, with NHL 3 the strongest and most flexible.
The strength, plasticity and workability of the lime mix is affected by the composition of the materials.
The composition of hydraulic lime can can differ widely, depending on the individual materials used. Common constituents for the compositions of lime include limestone, chalk, clay and sand. The proportions of these materials will differ depending on the type of hydraulic lime used, with at least 80% of the mix being limestone, while the remaining 20% is made up of the other materials.
The types of clay used in the mixture also affects the properties of the hydraulic lime, with an increase in the clay content of the mix resulting in greater plasticity and a higher water-retention capacity.
The presence of materials like pozzolana can also affect the properties of the hydraulic lime, with pozzolanas often used to increase the strength and workability of the mix. Pozzolanas, such as volcanic ash and other finely-ground siliceous-rich materials, can act as a filler for the mixture, increasing its strength and increasing its ability to set and harden.
This increases the longevity, strength and durability of the hydraulic lime, making it an ideal material for a number of building applications.
Is hydrated lime the same as cement?
No, hydrated lime is not the same as cement. Hydrated lime is a type of mineral lime composed of calcium hydroxide and water, while cement is a binding material manufactured from limestone and clay. Hydrated lime is highly alkaline, with a pH of 12.
4, while cement is a combination of minerals and typically has a pH around 10. Hydrated lime is sometimes used as a soil amendment, with the purpose of increasing pH and providing more magnesium, calcium, and sulfur to the soil.
Cement is also used for many construction projects, as a binding material for mortar and concrete. The two materials have different properties and should not be confused with one another.
Should I use hydraulic lime or hydrated lime?
The decision of whether to use hydraulic lime or hydrated lime largely depends on the project you are undertaking. If you are working on an outdoor project such as historic building conservation works, then the best option would be to use hydraulic lime as it is less likely to be affected by the elements, such as rain or frost.
Hydraulic lime is also well suited for use in mortar and concrete restoration works. On the other hand, hydrated lime is better suited for internal projects as it is far less vulnerable to changes in temperature and moisture levels.
And hydrated lime is also well-suited for lime plaster and as a treatment for contaminated land. Ultimately, which type of lime you should use for your project depends on the specifics of the job. Both hydraulic and hydrated limes have their own advantages and disadvantages, and it is important to weigh those factors before making a decision.
Can you use cement with hydraulic lime?
Yes, cement can be used with hydraulic lime. This combination is commonly referred to as a “hydraulic lime and cement” or “HL/C” mix and is used in many different applications. Hydraulic lime helps to increase the overall strength of a concrete mix and is often added to cement to create a hard-wearing mortar.
Depending on the desired application, cement and hydraulic lime can be blended together in different ratios. The ratio of cement to lime may range from 1:1 for general use mortar to approximately 4:1 for structural grade concrete.
Additionally, other materials such as aggregate may also need to be added to the mix in order to achieve the desired consistency and strength.
What is lime putty made from?
Lime putty is made from a material known as slaked lime or “quicklime”. It is composed of calcium hydroxide, which is created by heating limestone or other calcium-bearing stone to a high temperature.
Slaked lime is then mixed with water to create a soft paste. This paste is left to mature over a number of months, during which time the calcium hydroxide combines with carbon dioxide from the air to slowly form calcium carbonate.
The result is a thick, creamy-coloured paste known as lime putty, which has a variety of uses in different industries. Lime putty has been used as a binding agent in lime mortar and plaster and as an adhesive in furniture making since ancient times.
It can also be used to create traditional lime wash, which is a popular choice among those wishing to give walls the traditional look of lime and sand render.
Is hydraulic lime waterproof?
No, hydraulic lime is not waterproof. While it will protect against water damage better than regular lime, it will not provide a completely waterproof barrier. This is due to the fact that over time, the lime will eventually suffer from water damage and deteriorate.
Although it can be used as a waterproofing material, it should be used in conjunction with other waterproofing materials for maximum protection, such as a building paper, mastic or a waterproofing membrane.
Additionally, due to its high alkalinity, it should not be used in areas that are prone to water buildup or in areas that could be subject to water splashback, such as showers or baths. However, for areas that are relatively dry and not prone to water damage, hydraulic lime can provide an added layer of protection.
Why cement is used instead of lime?
Cement is used instead of lime because it is more durable, has a low shrinkage rate, is less prone to cracking, and can be molded into a variety of shapes when mixed with water. Cement is manufactured at a much higher temperature than lime, resulting in a product that has lower porosity and higher strength.
This makes it more resistant to harsh weather conditions and also decreases the rate of cracking and deterioration due to settlement and changes in the environment. Additionally, cement is an economical option because it requires fewer resources and is less labor-intensive to install.
It is also a very versatile product which can be used in a variety of applications, such as foundations in new buildings, patchwork repairs on existing structures, and surfaces for playgrounds, roads, and sidewalks.
Why lime is added to cement?
Lime is an important component of cement and is added for several reasons. First, it increases the strength and durability of the cement. This is due to the chemical reaction between the lime (calcium oxide) and the other components in the cement which creates a stronger binding material.
The addition of lime also helps to reduce the shrinkage of the cement which can reduce cracking and provide a more even bond. Additionally, the presence of lime can help to reduce the drying time of the cement which can help reduce the cost of construction.
Finally, lime helps to reduce the permeability of cement, making it more resistant to water, which can improve the weathering resistance of the cement. All these factors make lime an essential ingredient in cement which is why it is added.
Is lime a cementing material?
No, lime is not a cementing material. Cement is a binder that is used to bind together materials such as sand and gravel. Lime, on the other hand, is a calcium-containing inorganic mineral that is used for many different applications, including soil stabilization and acid neutralization.
Lime and cement are sometimes used together in mortars, stuccos, and grouts to improve their strength and durability. However, lime itself is not a cementing material and cannot be used to bind materials together on its own.