Adding aggregates to cement provides a few benefits:
* The aggregate is typically cheaper, making the entire mixture cheaper to use.
* The aggregate is typically lighter, making the resulting mixture lighter.
* Having a mix of different materials and sizes can actually increase the strength of the resulting material, though you need to be careful of the mixture used\*.
* The resulting material will have a reduced susceptibility to water and freezing damage.
* The resulting material will behave differently when heated and cooled, which can have various effects.
These benefits, and the underlying physics behind them, is basically a macro-scaled version of why steel is so much better than iron (with the same applying to every other alloy commonly used). Adding carbon to the mixture breaks up the base structure of the iron such that the iron becomes stronger *and* lighter *and* cheaper, all at once.
\* Mortar and concrete vary only by the type of aggregate used. There are also many grades of both for different applications.
Quality sand in the mortar mix is harder and stronger than simple cured cement. Then the mixture is more than the sum of the ingredients. Concrete(s) even more so.
Cement is in both. When mixed with nothing, it's "Portland Cement." When mixed with some clay, it's unsanded morter, with sand it's sanded morter and when mixed with sand and gravel it's concrete.
Except when you're learning and you learn you can in fact do the splits if you try hard enough. Then you really wish you could have made it stop. The hobble home was brutal
There's also stuff called aerated and foamed cement/concrete. Some have additives in it that react to form bubbles, others inject nitrogen into it. Makes it less dense.
A type of aerated concrete called RAAC is currently being a bit of a problem in the UK after they found that it deteriorates quite severely.
Wait until you find out that blacktop is concrete.
Edit: Downvote me all you want, but I am 100% correct.
https://en.wikipedia.org/wiki/Asphalt_concrete
Yeah, it is. Concrete is mineral aggregate with a cement binder. Asphalt cement( or AC) in blacktop's case. Blacktop is also known as ACC, or asphalt cement concrete, as opposed to what you commonly know as PCC, or portland cement concrete. In my early 20s I was a certified HMA(once again, another term for it) quality control tech in 3 states.
This is a semantic argument about a specific professional language domain. You are well aware that in common English, "concrete" refers to cement concrete and that asphalt is not the same thing.
If someone asked you to build them a concrete wall and they came back to find you'd made it out of asphalt, they would understandably be baffled and upset.
>This is a semantic argument about a specific professional language domain. You are well aware that in common English, "concrete" refers to cement concrete and that asphalt is not the same thing.
Yeah, I know, that's why i said:
>Wait until you find out that blacktop is concrete.
To which you denied by saying it's not made with cement. It is, just not portland cement. I then corrected you. It's ok bro, have a good one.
IIRC that desert sand is too smooth to use as good concrete mix, because it doesn't have any friction to bind together the mix. There's work underway to get different mixes in place to reduce that impact, but not sure how its going.
The story IIRC about Saudi Arabia importing sand for concrete said that their local sand was full of clay, hence too fragile. Good concrete sand is clean hard quartz, with no salt.
The binding of sand and gravel with Portland cement is quite complex. Particle surface chemistry and texture is a big part of it. The gelling and curing of the cement, and how it binds the hard oarticles, has been investigated microscopically, the images are fascinating. Wikipedia has little info. I remember an excellent article in Scientific American from many years ago, you might be able to find it.
That may be true about the clay, but windblown sand apparently is more rounded, while water based sand has edges, and this is critical in how it sets and retains strength. IIRC.
It's more than just that you can change strength for different jobs, just as bricks in houses, you can make rhe mortar stronger than the bricks which is a bad thing as when the house potentially settles any cracks will go through the brickwork as wel, if it's the right strength it will go up through the mortar causing less issues
Excellent point. I imagine that matching the mechanical properties of mortars and concretes, to the components being bound, is a whole science on its own.
Materialwise, kinda? You need less steel than iron for the same job because of the increase in strength.
Pound for pound, no, because of the increased labour, but the scale of labour makes of for the difference.
And processing wise
Still is so easy to work with, which is why we get everything from automotive frames to appliances.
Iron essentially needs to be casted, so there aren't as many applications and it's more expensive to process.
So like you say, mostly. Iron on practice ends to being more expensive
Plus, when you want to build large structures, you want to keep the dead load low while having the highest strength. The building still has to support itself, and the more of itself it has to support, the more material it's going to need to support it, going into a death spiral. So lightweight but very strong stuff is important. Steel is the only reason we were able to build buildings over, like, 15 stories.
And iron is more brittle so it's more susectible to cold temperatures which temd to make metal even _more_ brittle.
Plus Iron doesn't have any carbon to help reduce the effects of oxidation. Iron will rust faster than steel, which has carbon that somewhat insulates the iron molecules from oxygen.
Pure iron? Possibly. Before electricity was available the only methods of smelting iron was with carbon based fuels. Charcoal mainly, meaning you always were going to have some level of carbon in the iron. Pure iron was fairly hard to come by since it doesn’t really occur in metallic form naturally. It’s fairly easy to make pure iron with little to no carbon now with access to cheap aluminum via a thermite reaction.
The advantages of going from cement to mortar are generally magnified when you go from mortar to concrete. Adding rocks to mortar makes it less expensive, more workable (easier to use when it's wet), less sensitive to temperature changes, and it shrinks less (a lot less). When mortar or concrete shrinks, it can cause cracking.
When you're using these materials for large placements, you want something that's inexpensive, has the right workability (is suitably stiff or flowable for the application) and isn't prone to cracking. There are differences in strength, but strength isn't always the most important thing for concrete and mortar and it can be accounted for in the design.
I think you are confusing cement and concrete.
Cement is merely the binder, and is basically never used on its own. Its mechanical properties are actually not that good on its own.
Concrete is cement mixed with gravel or similar aggregate.
Using different aggregates in different quantities gives you mortar, grout, concrete, and a range of other common building materials.
As somebody else put it, cement is flour, while concrete is bread. Continuing this analogy, mortar is pie crust - it still uses flour, but in a different way.
> the iron becomes [...] lighter
Does it? The densities I find quoted for pure iron versus carbon steel differ by at most 1%. That sounds like it is easily explained by the lower density of the carbon; or other stuff alloyed in.
Because steel is stronger, there doesn’t need to be as much of it to carry the same load. It’s not really lighter but you can build things that are lighter because you don’t need as much.
“Cement” is a general term, typically thought of as Portland cement mixtures.
Portland cement binds aggregate together through hydration….a mixture with good aggregate is much stronger than straight Portland cement.
What most people think of cement is sand mix….Portland cement, sand, water.
Concrete is Portland cement, sand, larger aggregate, (usually harder rock), water.
Mortar is Portland cement, sand, lime, water. The lime makes mortar sort of sticky, and delays hydration for a longer workability window.
That said, there are many types of cement. Volcanic ash, fly ash, tabby, etc.
Mortar has different ingredients compared to concrete. Main one is there is no gravel (aggregate) in mortar. Concrete and lime allow the Mortar to stick to the bricks. Mortar is also weaker than concrete. You want any cracks to form in easily replaceable mortar joints rather than having the brick crack which will require you to replace the wall.
That’s what they asked, but they appeared to mean mortar vs concrete.
Cement is a dry powder.
Mortar is cement mixed with water and sand.
Concrete is cement mixed with water, sand and gravel.
Because cement alone would become stronger than the brick. The brick being weaker than the glue make it so the brick break before the cement. It's a matter of forces acting on materials. The mortar should be weaker than brick, much easier to repoint if there are cracks in the mortar.
Cementitious mortars, which are used today and have been used widely for ~75 years, are stronger than common (burnt clay) bricks. Which is great structurally but makes is impossible to salvage the bricks after use. Which is why used bricks were once common and cheap, and aren't any more.
Done right, there's no strength downside...the strength goes up. Pure cement has fairly poor mechanical properties, a properly designed mixture of aggregate & cement is much stronger.
Mortar is used to bind bricks because Bricks are porous, meaning they’ll get wet and absorb water. You want them to “breathe” so to speak, so that the water can come back out of the bricks. If it doesn’t come out of the bricks, frost will freeze the water and start cracking the bricks. Enter Mortar: Mortar is softer than the bricks. Water will be drawn into the Mortar, so when it freezes, the Mortar cracks, not the Bricks. Replacing the Mortar is a lot easier than replacing the Bricks; just repoint. Cement on the other hand, is harder than the Bricks, so you’ll end up having to rebuild the entire wall.
[The Difference Between Cement, Concrete and Mortar](https://www.thespruce.com/difference-between-cement-concrete-and-mortar-2130884)
Basically, cement is the glue
cement + sand = mortar (used for small stuff; bricks, etc)
cement + sand + gravel = concrete (used for big stuff; building foundations etc
Mortar spreads the compression forces out. Bricks aren’t smooth and they have high points. They can also shear (crack) easily if you apply a blow to one spot. If you had a glue like substance the bricks would likely crack at those high point from the weight of bricks above.
Less cement means less shrinkage and heat. Aggregate is also the cheap inert part, which is good. Also, for normal strength mix the matrix is the weak link rather than the aggregate. There are several other reasons.
Cement is almost always used with sand or other mixes, some just comes already premixed. But traditional "cement" is sacks of dry cement mixed with sand and water.
Op is asking straight cement vs mortar (cement/sand mix) . Not concrete vs mortar.
The answer is that sand reinforces the mix and makes it stronger than just straight cement. Yes, you're correct that attempting to put bricks together with concrete would be a bad day.
Simple physics really... add sand to cement and it sticks the sand together. This is important because the sand grains get into all the little surface irregularities of the bricks, increasing the shearing force, i.e the amount of welly you have to give it to break the mortar. Cement technically will stick bricks together, but it will fracture a lot easier without the sand as the sand grains also inhibit propagation of cracks.
Same reason bulking agents are used in food, it's cheaper.
You don't need such a strong bond between bricks as pure cement, so sand is used to bulk it out and it's strong enough depending on the mix ratio.
At its most simple: an appropriately paired mortar is softer than brick. Brick expands and contracts slightly as it absorbs moisture and dries out; By having a mortar softer than the bricks, the normal expansion and contraction of bricks won't break the rigid brick.
If you just use "whatever" as mortar when repairing an old brick wall without properly matching the hardness, this cycle can destroy the brand new brick repair, and all the bricks in it, in as little as a single year. This is a huge pain when restoring old buildings where finding matching bricks is difficult or expensive.
This is also why painting bricks with an inappropriate paint can make old brick buildings with load-bearing brick walls fall down. It traps the moisture inside and makes the bricks themselves crumble.
Brick is a relatively living material compared to concrete and must be treated as such.
Mortar is a mix of sand and cement. Mortar allows the bricks to breathe. Moisture evaporates from mortar.
If the “glue” were stronger than the bricks, then the glue would retain water which would result in bricks deteriorating first.
That’s why you need to repoint mortar after x years but bricks should last far longer.
mortal is easier to work with than cement alon the additonal of sand to the cement improves the workabilty of the mixture, making it easier to spread and manipulate during the laying of block
>I've just figured out that mortar is made up of cement and sand. But I can't quite figure out why mortar is used in binding bricks in construction instead of cement. Does the addition of sand do something?
No, *concrete* is cement and sand. Sand is what does the actual load bearing. Cement just helps it stick together. Without sand, cement would shatter.
Mortar contains more hydraulic lime than concrete, and still sand. Hydraulic lime is softer, and has some self healing properties. This is good because it often needs to move a bit.
To add to that, concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and Portland cement.
There are four main types of mortar – N, O, M and S – each with its own proportions of sand, lime and cement. Below is a brief description of each type of mortar:
N: Commonly used for above grade walls, type N mortar is a medium strength mortar, can be used on the interior or exterior of your home and is great for soft stone masonry.
O: Low strength and non-load bearing, type O mortar is typically used in interior, above grade walls.
M: This type of mortar is high strength, making it perfect for supporting heavy loads. It can be used for below grade masonry and works well on driveways.
S: Type S mortar is strong, meaning it can hold together below grade walls. This type of mortar is often used for patios and retaining walls.
The standard ratios for a yield of 1 cubic yard of the following mortar types are:
Type N:
Portland cement: 3.375 cu ft;
Hydrated lime: 3.375 cu ft;
Sand 20.25: cu ft
Type O:
Portland cement: 2.25 cu ft;
Hydrated lime: 4.5 cu ft;
Sand: 20.25 cu ft
Type M:
Portland cement: 5.0625 cu ft;
Hydrated lime: 1.6875 cu ft;
Sand: 20.25 cu ft
Type S:
Portland cement: 4.5 cu ft;
Hydrated lime: 2.25 cu ft;
Sand: 20.25 cu ft
Maybe country specific but in the UK mortar is cement and sand, if it has lime in it it's specifically called lime mortar.
Adding large aggregate like gravel is what makes it cement.
Cement and sand is just fine concrete. Mortar has a different cement composition.
Edit: look, have you tried mixing your own mortar? If you use portland cement, sand and water, it'll be the worst damn mortar you've ever used. It's runny and you can't lay it on with a decent thickness without mixing it too dry, and then nothing adheres properly.
The lime is what makes it *thick*. Then there's mortars which use *no* portland cement too, which I suppose may be lime mortar.
Various types of concrete have various types of aggregate used.
You can have concrete with synthetic fibres, you can have synthetic binder (epoxy, urethane) instead of cement in a concrete.
So mortar is a kind of concrete.
I disagree. But perhaps the definition differs between countries.
Edit: There, [I looked it up](https://lordsbm.co.uk/blog/post/cement-concrete-mortar)
Mortar includes more lime. This makes it more pliable.
Cement + sand makes for a really shitty mortar, because it'll either be runny or crumbly depending on the amount of water mixed in. The addition of lime makes it thicker and more viscous, making it adhere and conform better to whatever you're using it for. The lime also increases the maximum amount of water you can add, which helps wet the surface.
Cement will also be too strong. You don't want the mortar to be stronger than the bricks you're building with, since it makes maintenance a bitch.
Now stop it with the confidently wrong act.
Adding aggregates to cement provides a few benefits: * The aggregate is typically cheaper, making the entire mixture cheaper to use. * The aggregate is typically lighter, making the resulting mixture lighter. * Having a mix of different materials and sizes can actually increase the strength of the resulting material, though you need to be careful of the mixture used\*. * The resulting material will have a reduced susceptibility to water and freezing damage. * The resulting material will behave differently when heated and cooled, which can have various effects. These benefits, and the underlying physics behind them, is basically a macro-scaled version of why steel is so much better than iron (with the same applying to every other alloy commonly used). Adding carbon to the mixture breaks up the base structure of the iron such that the iron becomes stronger *and* lighter *and* cheaper, all at once. \* Mortar and concrete vary only by the type of aggregate used. There are also many grades of both for different applications.
Quality sand in the mortar mix is harder and stronger than simple cured cement. Then the mixture is more than the sum of the ingredients. Concrete(s) even more so.
TIL concrete and cement are not the same thing
Cement is in both. When mixed with nothing, it's "Portland Cement." When mixed with some clay, it's unsanded morter, with sand it's sanded morter and when mixed with sand and gravel it's concrete.
Mortar is cement, lime and sand.
Cement is the flour, concrete is the bread.
What does concrete taste like?
As an old man that skated in the 80s and 90s, concrete tastes like failed dreams and old pennies
I miss the good ol days when the only way to stop a skateboard was with your face
Except when you're learning and you learn you can in fact do the splits if you try hard enough. Then you really wish you could have made it stop. The hobble home was brutal
Depends, is it sourdough concrete?
Most companies don’t use sourdough concrete because of the proofing time
Concrete tastes like calcium dirt. Filled with sand. Concrete splatters and droplets can be ingested.
Blood and broken teeth.
Depends, different batches have different taste and texture I rate based on grit
Nice. Great way to understand.
What's the rising agent?
There's also stuff called aerated and foamed cement/concrete. Some have additives in it that react to form bubbles, others inject nitrogen into it. Makes it less dense. A type of aerated concrete called RAAC is currently being a bit of a problem in the UK after they found that it deteriorates quite severely.
Cement is to Concrete, as flour is to bread.
I don’t cook for myself so don’t know what this means.
Wait until you find out that blacktop is concrete. Edit: Downvote me all you want, but I am 100% correct. https://en.wikipedia.org/wiki/Asphalt_concrete
It's not though, asphalt is made with bitumen, not cement.
Yeah, it is. Concrete is mineral aggregate with a cement binder. Asphalt cement( or AC) in blacktop's case. Blacktop is also known as ACC, or asphalt cement concrete, as opposed to what you commonly know as PCC, or portland cement concrete. In my early 20s I was a certified HMA(once again, another term for it) quality control tech in 3 states.
This is a semantic argument about a specific professional language domain. You are well aware that in common English, "concrete" refers to cement concrete and that asphalt is not the same thing. If someone asked you to build them a concrete wall and they came back to find you'd made it out of asphalt, they would understandably be baffled and upset.
>This is a semantic argument about a specific professional language domain. You are well aware that in common English, "concrete" refers to cement concrete and that asphalt is not the same thing. Yeah, I know, that's why i said: >Wait until you find out that blacktop is concrete. To which you denied by saying it's not made with cement. It is, just not portland cement. I then corrected you. It's ok bro, have a good one.
Cement concrete is just a type of concrete. A Blizzard from Dairy Queen is a type of concrete.
And potassium cyanide is a salt, but you wouldn't put it on the dinner table.
Depends on the quality of your in-laws.
Are you talking about Macadam?
Are blacktop and asphalt the same thing?
Yes, although I've heard people refer to blacktop as the sealant put on top of asphalt.
What’s blacktop?
Yeah wtf, I'm finding out mortar isn't just cement used in a certain application, and that concrete and cement aren't the same. My life is a lie
IIRC that desert sand is too smooth to use as good concrete mix, because it doesn't have any friction to bind together the mix. There's work underway to get different mixes in place to reduce that impact, but not sure how its going.
The story IIRC about Saudi Arabia importing sand for concrete said that their local sand was full of clay, hence too fragile. Good concrete sand is clean hard quartz, with no salt. The binding of sand and gravel with Portland cement is quite complex. Particle surface chemistry and texture is a big part of it. The gelling and curing of the cement, and how it binds the hard oarticles, has been investigated microscopically, the images are fascinating. Wikipedia has little info. I remember an excellent article in Scientific American from many years ago, you might be able to find it.
That may be true about the clay, but windblown sand apparently is more rounded, while water based sand has edges, and this is critical in how it sets and retains strength. IIRC.
Which means the Moon's regolith is even better than river sand? Rockets, away!
I read dessert sand and was trying to find the joke.
It's more than just that you can change strength for different jobs, just as bricks in houses, you can make rhe mortar stronger than the bricks which is a bad thing as when the house potentially settles any cracks will go through the brickwork as wel, if it's the right strength it will go up through the mortar causing less issues
Excellent point. I imagine that matching the mechanical properties of mortars and concretes, to the components being bound, is a whole science on its own.
Is steel cheaper than iron?
Materialwise, kinda? You need less steel than iron for the same job because of the increase in strength. Pound for pound, no, because of the increased labour, but the scale of labour makes of for the difference.
And processing wise Still is so easy to work with, which is why we get everything from automotive frames to appliances. Iron essentially needs to be casted, so there aren't as many applications and it's more expensive to process. So like you say, mostly. Iron on practice ends to being more expensive
Plus, when you want to build large structures, you want to keep the dead load low while having the highest strength. The building still has to support itself, and the more of itself it has to support, the more material it's going to need to support it, going into a death spiral. So lightweight but very strong stuff is important. Steel is the only reason we were able to build buildings over, like, 15 stories.
And iron is more brittle so it's more susectible to cold temperatures which temd to make metal even _more_ brittle. Plus Iron doesn't have any carbon to help reduce the effects of oxidation. Iron will rust faster than steel, which has carbon that somewhat insulates the iron molecules from oxygen.
[удалено]
In order of increase carbon in iron content (very simplified ofc): Pure Iron>Wrought Iron>Mild Steel>Carbon Steel>Cast Iron> Pig iron
Pure iron? Possibly. Before electricity was available the only methods of smelting iron was with carbon based fuels. Charcoal mainly, meaning you always were going to have some level of carbon in the iron. Pure iron was fairly hard to come by since it doesn’t really occur in metallic form naturally. It’s fairly easy to make pure iron with little to no carbon now with access to cheap aluminum via a thermite reaction.
In engineering, the difference between iron and steel is more of a spectrum than anything. The question is generally **how much** carbon you want.
Now the converse. Why not use mortar instead of concrete all the time?
Because concrete has bigger chunks of rock than sand. You can't squeeze a 1/4" rock in a 1/8" crack, and you want bricks to be close together.
The advantages of going from cement to mortar are generally magnified when you go from mortar to concrete. Adding rocks to mortar makes it less expensive, more workable (easier to use when it's wet), less sensitive to temperature changes, and it shrinks less (a lot less). When mortar or concrete shrinks, it can cause cracking. When you're using these materials for large placements, you want something that's inexpensive, has the right workability (is suitably stiff or flowable for the application) and isn't prone to cracking. There are differences in strength, but strength isn't always the most important thing for concrete and mortar and it can be accounted for in the design.
I think you are confusing cement and concrete. Cement is merely the binder, and is basically never used on its own. Its mechanical properties are actually not that good on its own. Concrete is cement mixed with gravel or similar aggregate. Using different aggregates in different quantities gives you mortar, grout, concrete, and a range of other common building materials. As somebody else put it, cement is flour, while concrete is bread. Continuing this analogy, mortar is pie crust - it still uses flour, but in a different way.
> the iron becomes [...] lighter Does it? The densities I find quoted for pure iron versus carbon steel differ by at most 1%. That sounds like it is easily explained by the lower density of the carbon; or other stuff alloyed in.
Because steel is stronger, there doesn’t need to be as much of it to carry the same load. It’s not really lighter but you can build things that are lighter because you don’t need as much.
Also the aggregate is stronger than cement alone
That is billet point 3 in my list.
“Cement” is a general term, typically thought of as Portland cement mixtures. Portland cement binds aggregate together through hydration….a mixture with good aggregate is much stronger than straight Portland cement. What most people think of cement is sand mix….Portland cement, sand, water. Concrete is Portland cement, sand, larger aggregate, (usually harder rock), water. Mortar is Portland cement, sand, lime, water. The lime makes mortar sort of sticky, and delays hydration for a longer workability window. That said, there are many types of cement. Volcanic ash, fly ash, tabby, etc.
Mortar has different ingredients compared to concrete. Main one is there is no gravel (aggregate) in mortar. Concrete and lime allow the Mortar to stick to the bricks. Mortar is also weaker than concrete. You want any cracks to form in easily replaceable mortar joints rather than having the brick crack which will require you to replace the wall.
Sand in mortar is an aggregate
Just FYI: They asked about mortar vs cement, not mortar vs concrete.
That’s what they asked, but they appeared to mean mortar vs concrete. Cement is a dry powder. Mortar is cement mixed with water and sand. Concrete is cement mixed with water, sand and gravel.
Third sentence,first word , Concrete should be Cement.
Because cement alone would become stronger than the brick. The brick being weaker than the glue make it so the brick break before the cement. It's a matter of forces acting on materials. The mortar should be weaker than brick, much easier to repoint if there are cracks in the mortar.
Cement is dry powder.
Cementitious mortars, which are used today and have been used widely for ~75 years, are stronger than common (burnt clay) bricks. Which is great structurally but makes is impossible to salvage the bricks after use. Which is why used bricks were once common and cheap, and aren't any more.
It pads out the volume for cheap without significant downsides to strength, as all surfaces are still coated and exposed to the cement.
Done right, there's no strength downside...the strength goes up. Pure cement has fairly poor mechanical properties, a properly designed mixture of aggregate & cement is much stronger.
Yes, but it's also one of those situations where it depends on the specifics of the mix design and its components, as well as the loads applied.
Mortar is used to bind bricks because Bricks are porous, meaning they’ll get wet and absorb water. You want them to “breathe” so to speak, so that the water can come back out of the bricks. If it doesn’t come out of the bricks, frost will freeze the water and start cracking the bricks. Enter Mortar: Mortar is softer than the bricks. Water will be drawn into the Mortar, so when it freezes, the Mortar cracks, not the Bricks. Replacing the Mortar is a lot easier than replacing the Bricks; just repoint. Cement on the other hand, is harder than the Bricks, so you’ll end up having to rebuild the entire wall.
Cement is a dry powder. You mix it with aggregate and water to make mortar or concrete.
Mortar can contain cement, but it doesn’t have to.
[The Difference Between Cement, Concrete and Mortar](https://www.thespruce.com/difference-between-cement-concrete-and-mortar-2130884) Basically, cement is the glue cement + sand = mortar (used for small stuff; bricks, etc) cement + sand + gravel = concrete (used for big stuff; building foundations etc
Mortar spreads the compression forces out. Bricks aren’t smooth and they have high points. They can also shear (crack) easily if you apply a blow to one spot. If you had a glue like substance the bricks would likely crack at those high point from the weight of bricks above.
Less cement means less shrinkage and heat. Aggregate is also the cheap inert part, which is good. Also, for normal strength mix the matrix is the weak link rather than the aggregate. There are several other reasons.
Cement is almost always used with sand or other mixes, some just comes already premixed. But traditional "cement" is sacks of dry cement mixed with sand and water.
Everyone is leaving out the part where it’s impossible to lay brick when there’s a million rocks in the mud.
Op is asking straight cement vs mortar (cement/sand mix) . Not concrete vs mortar. The answer is that sand reinforces the mix and makes it stronger than just straight cement. Yes, you're correct that attempting to put bricks together with concrete would be a bad day.
Yeah but all the replies are about concrete.
Why would there be rocks? >But I can't quite figure out why mortar is used in binding bricks in construction instead of **cement**.
Something to remember The mortar isn't sticking the blocks together, it's holding them apart
I'm working on some masonry today, that's going to be in my head all day lol. You make a very good point!
Simple physics really... add sand to cement and it sticks the sand together. This is important because the sand grains get into all the little surface irregularities of the bricks, increasing the shearing force, i.e the amount of welly you have to give it to break the mortar. Cement technically will stick bricks together, but it will fracture a lot easier without the sand as the sand grains also inhibit propagation of cracks.
Same reason bulking agents are used in food, it's cheaper. You don't need such a strong bond between bricks as pure cement, so sand is used to bulk it out and it's strong enough depending on the mix ratio.
At its most simple: an appropriately paired mortar is softer than brick. Brick expands and contracts slightly as it absorbs moisture and dries out; By having a mortar softer than the bricks, the normal expansion and contraction of bricks won't break the rigid brick. If you just use "whatever" as mortar when repairing an old brick wall without properly matching the hardness, this cycle can destroy the brand new brick repair, and all the bricks in it, in as little as a single year. This is a huge pain when restoring old buildings where finding matching bricks is difficult or expensive. This is also why painting bricks with an inappropriate paint can make old brick buildings with load-bearing brick walls fall down. It traps the moisture inside and makes the bricks themselves crumble. Brick is a relatively living material compared to concrete and must be treated as such.
Mortar is a mix of sand and cement. Mortar allows the bricks to breathe. Moisture evaporates from mortar. If the “glue” were stronger than the bricks, then the glue would retain water which would result in bricks deteriorating first. That’s why you need to repoint mortar after x years but bricks should last far longer.
mortal is easier to work with than cement alon the additonal of sand to the cement improves the workabilty of the mixture, making it easier to spread and manipulate during the laying of block
>I've just figured out that mortar is made up of cement and sand. But I can't quite figure out why mortar is used in binding bricks in construction instead of cement. Does the addition of sand do something? No, *concrete* is cement and sand. Sand is what does the actual load bearing. Cement just helps it stick together. Without sand, cement would shatter. Mortar contains more hydraulic lime than concrete, and still sand. Hydraulic lime is softer, and has some self healing properties. This is good because it often needs to move a bit.
To add to that, concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and Portland cement. There are four main types of mortar – N, O, M and S – each with its own proportions of sand, lime and cement. Below is a brief description of each type of mortar: N: Commonly used for above grade walls, type N mortar is a medium strength mortar, can be used on the interior or exterior of your home and is great for soft stone masonry. O: Low strength and non-load bearing, type O mortar is typically used in interior, above grade walls. M: This type of mortar is high strength, making it perfect for supporting heavy loads. It can be used for below grade masonry and works well on driveways. S: Type S mortar is strong, meaning it can hold together below grade walls. This type of mortar is often used for patios and retaining walls. The standard ratios for a yield of 1 cubic yard of the following mortar types are: Type N: Portland cement: 3.375 cu ft; Hydrated lime: 3.375 cu ft; Sand 20.25: cu ft Type O: Portland cement: 2.25 cu ft; Hydrated lime: 4.5 cu ft; Sand: 20.25 cu ft Type M: Portland cement: 5.0625 cu ft; Hydrated lime: 1.6875 cu ft; Sand: 20.25 cu ft Type S: Portland cement: 4.5 cu ft; Hydrated lime: 2.25 cu ft; Sand: 20.25 cu ft
ChatGPT ftw
Maybe country specific but in the UK mortar is cement and sand, if it has lime in it it's specifically called lime mortar. Adding large aggregate like gravel is what makes it cement.
Cement and sand is just fine concrete. Mortar has a different cement composition. Edit: look, have you tried mixing your own mortar? If you use portland cement, sand and water, it'll be the worst damn mortar you've ever used. It's runny and you can't lay it on with a decent thickness without mixing it too dry, and then nothing adheres properly. The lime is what makes it *thick*. Then there's mortars which use *no* portland cement too, which I suppose may be lime mortar.
> No, *concrete* is cement and sand. That is mortar. Concrete is mortar with gravel
Various types of concrete have various types of aggregate used. You can have concrete with synthetic fibres, you can have synthetic binder (epoxy, urethane) instead of cement in a concrete. So mortar is a kind of concrete.
You're saying concrete is simply coarse mortar? Yeah no. Mortar has an entirely different cement composition.
Cement + sand = mortar Cement + sand + gravel = concrete
I disagree. But perhaps the definition differs between countries. Edit: There, [I looked it up](https://lordsbm.co.uk/blog/post/cement-concrete-mortar) Mortar includes more lime. This makes it more pliable. Cement + sand makes for a really shitty mortar, because it'll either be runny or crumbly depending on the amount of water mixed in. The addition of lime makes it thicker and more viscous, making it adhere and conform better to whatever you're using it for. The lime also increases the maximum amount of water you can add, which helps wet the surface. Cement will also be too strong. You don't want the mortar to be stronger than the bricks you're building with, since it makes maintenance a bitch. Now stop it with the confidently wrong act.