Tradesmen that work on building sites, know that to have a mixer is important, this photo above shows an average mixer used on building sites, it saves a lot of hard work, if we compare to the times when everything was mixed by hand. Anyhow in this post we are talking about how to use it.
Welcome to our article, Mix your own cement.
Dear readers, this is going to be a long blog, because we
want to explain how to mix concrete and mortar, in several ways. We are writing this article how to mix your
own cement, because we want to pass our knowledge of how these things are
done. So, we are writing this article for
those people that are willing to do building work themselves, but they need a
bit more knowledge to give them the courage to do it; and above all for those
people that live in poor countries, where building skills and material are
scarce, therefore, they need some knowledge to try building themselves, as long
as they can buy Portland cement and/or lime to mix it with; so, this article can
be D.I.Y article.
This article “mix your own cement” (concrete) is going to be
a long and detailed way of how to make concrete from scratch, using Portland
cement and other basic materials, we will also describe how to mix mortar for the
bricklayer and cement plaster, just by using the most basic building materials,
by mixing them with Portland cement and/or lime. We will describe how these
things were/are done, because we believe that some people will find it helpful to know.
We must say that today building anything has become easier,
because most things that we need are ready made for us to use, provided we are
living in a city or large town in the western world and in many other parts of
the world. In our case we are talking about how to use cement and the things
that we can do with it. So, let us suppose that today we need concrete; we can
order it, and have it delivered whenever we want it.
But these things were not so in the past, in the past people
that were building had to have their own skills how to mix their own concrete,
how to mix their own mortar and other things, and sometimes they had even to
find the building materials themselves, before they could start to build
anything, they were not easy times and people in the know, kept their knowledge
for themselves. But today it is different, the knowledge they had and kept to
themselves has become insignificant compared to the things that we know and do. Anyhow, this knowledge can be useful for people that happen to be in a different part of the world, so, they do not know yet.
Therefore, this article is being written, in the hope that
our articles can help those poor people that are not aware that they can build
a better place for themselves, if they learn to recognize the basic materials,
they need to use for building a place for themselves. Most of the building
materials that we are talking about are available anywhere in the world,
because they occur in the natural state as they are part of this great planet
earth, so, what are those building materials you may ask? And how we mix them you may want to know, so,
here is a link from YouTube that shows you how to mix concrete.
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What are
these building materials?
Anyhow, I know a lot how to mix concrete, since I have mixed
it by hand and with a mixer hundreds of times, so, let us see these building
materials and how to use them.
First, let us see what these materials are, then we will
take you through how to mix them. Today you can buy these building materials
ready to mix, and all you need to do is to add the right amount of water and
mix them, but here we want to start everything from scratch:
In building anything with cement, there are five main sort
of materials that we need to recognize, before we start mixing our batches of
whatever we want to mix, they are; bricklayers’ loam, plaster sand, river sand,
gravel, and Portland cement; with these materials you can build anything, some
of these materials sometimes are called with different names, but let us
describe what these material are like:
Bricklayers’ loams is a very fine sand, some of these fine
sands could be a tiny bit sticky and when it is wet enough you can almost make
a small ball in your hand, but it will always collapse as there is not enough
sticky material in it, but if you add the right quantity of cement and water (and
perhaps something else if required) it is easy to lay bricks.
Plaster sand is very fine sand but not as much as
bricklayer’s loams it does not stick together by itself, therefore, it will
stick together only when you add cement and water to it, this type of sand is
used to plaster the walls and can be used to lay concrete blocks it is ideal to
use this sand provided it is very fine, in this part of the world we call this Besser
sand.
River sand, or washed river sand is a type of sand coarser and
thicker than plaster sand, as the name suggests it comes from the river, in
this parts of the world because Brisbane river is salty water it is washed and
sieved, but it is possible to find deposit of this sand in some rivers that can
be used straight away, sometimes this
sand can be used by itself to lay a top layer on a fresh laid concrete, but its
use is mainly used to mix it with gravels to make concrete.
Gravel or gravels are small stones again these small stones
can be found in or near the rivers; in most places if there is proper supplier,
gravels are graded so one can order them as they are required, and this is what
we need to make good concrete. But if you happen to be in the middle of nowhere,
they don’t need to be graded properly to use for concrete and one could use a
mix of different size provided you know what you are doing. But one must be
careful that this ungraded building material is free from silt and organic
stuff.
Today of course building people rely more from the
specialized suppliers, and they order through these suppliers what they need. You
can even buy bags of ready mixed materials that you can use just by adding
water. These materials are good to use, if you have a small job to do, but they
become expensive to use if you have a large job.
What we have described above are the main materials required
to build most cement things, of course, you must know how to use them, and that
is what we are going to write next.
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This photo above, is to show that there are several concrete plants in large cities. They are there to supply the growing city with the concrete it requires. This way is a lot easier than the old time, when builders had to mix their own concrete.
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Now, let us describe the cement properties; cement is
like the glue that when mixed with sand, gravels and other aggregates makes
these materials stick together. The word “cement” can be traced back to the
Romans, who called this “opus caementicum” to describe masonry that resembles
concrete. We dare say that the Romans used burned limestone which when you add
water turns into hydrated lime and also they used something called pumice that
was collected from some part on Vesuvius it was a sort of cement that when you
added water would become harder than if you just used lime, this is more or
less how I have been told. As you can see there are two main bonding materials
that can be used to make concrete and mortar.
Mixing your
own concrete from scratch.
Because I am an old tradesman, I have been asked a few times how to make concrete.
To make normal concrete you need to mix by volume six
containers of concrete blend to one container of Portland cement, depending on
the quality of the concrete blend this may vary, so what we do next; we know
that we need a lot of concrete, so, you measure say twelve bucket of concrete
blend and put that on our platform, then you measure two buckets of cement to
mix with the blend. These are the quantities to keep in mind, (6 to 1) this is
a small batch of concrete, and you can make it bigger or smaller, if you keep
that 6 to 1 ratio. Sometimes this ratio may vary.
Now before you mix your cement with your blend; make sure
that everything is ready, because once you start this process you must continue
until you finish. Since everything is ready you can spread the cement on the
concrete blend, after doing that you take your shovels fill them up and start
turning your mixture around, by pushing the shovel under and turning it over,
you need to turn your mixture a couple of time; say first from A to B and then
from B to A, so, everything is in the same place, after doing that and you are
satisfied that your mixture is mixed even, you can make a well in the middle of
it, and add a bucket of water, if the water is absorbed quickly, then you know
that you must add more water, if a fair bit of water remains in the centre then
you can start folding the outside mixture in the middle, you can add some water
as required, but don’t get carried away with adding too much water, because you
need to add water bit by bit, you see this is one of those things that you
learn as you do it and not before.
You have done all that and now you have a heap of this
mixture half mixed; here again you take your shovel and turn your mixture from
A to B while sprinkling some water on it, you may need to do this a few times
sprinkling water and turning your concrete mixture from B to A and from A to B,
you need to do this until you have an even mixture that it is well mixed. Now
you have your concrete ready to place wherever you need to place it.
This is how mixing concrete was done in the old days, it was
a hard work and it was not as accurate as it is today with the ready mixed
concrete truck that can deliver concrete to your job whenever you need it, and
all you have to do is to lay your concrete slab, or whatever you need to do.
Anyhow, the description above, can be used if you are in the middle of nowhere,
and you need concrete.
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Learn the
art of mixing cement.
Learn to recognize and use the building materials when we
mix cement.
Now, that we have written what are the building materials, and
we have explained how to mix concrete by hand, this procedure can be applied to
mix mortar and plaster etc. We have also explained how you can recognize the
raw building materials.
You see, let us imagine that you need concrete, you live in
the middle of nowhere and you have only a few tools, but you now a faraway
place where you can go and buy Portland cement; you are not going to buy
anything else at that place, because it is too far, it will be costly to bring
it in, so, the rest of the concrete materials you are going to find near the
river banks. I know it is like going back in time a hundred years ago, but
there are parts of the world that are still that far back. Therefore, learning
how to recognize the basic building materials for making concrete, and then
mixing concrete by hand can still be useful today.
Now, we have to add that what we are writing here is how we
have done these things, and we know they work, however, it is only our view,
and they work well in all minor jobs, but if you have large important jobs, you
must consult the local experts.
Now let us see how we mix concrete with a mixer.
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Mixing
concrete with a mixer.
Okay, let us make this clear, there may be
several ways how to mix concrete; you can mix it on the ground, as we have described
above, you can mix concrete in a wheelbarrow, if you have a wheelbarrow with a
good tray, or you can mix it with a mixer which is helpful to have. But what
are the different procedures when you mix, in order to achieve the best result
with the least amount of time and work:
The greatest difference for mixing concrete and
other cement materials is mainly this: when you mix by hand you can achieve the
best result by mixing the materials with the cement before you add water, as
this helps to make a more even mixture quicker: But when you use the mixer you
don’t need to do that, in fact, you can have better and quicker result, by
following this procedure hereunder:
Start the mixer and put in the mixer some
water, approximately the proper amount to mix the whole batch, you know how
much water to use once you have made a few batches.
Now before we proceed to mix, let us talk
about the water amount. On building sites, it is near impossible to tell you
how much water you need exactly, since the materials you are using contains an
unknown quantity of water, therefore, the quantity of water varies, you see,
the wetter the materials are, the less water you need and vice versa if they
are dry.
Now, let us assume that because you are new
at doing this job, you are using a dry small bucket to measure the quantities
of the building materials; in this case you have gravel and river sand in separate
heaps, you know that this concrete is going to be mixed 6 to 1, but overall,
this batch you are going to mix 8 small buckets of gravel four of river sand
and two of Portland cement:
Now the quantities above are how the best and
strongest cement can be achieved, with a minimum of Portland cement used; very
likely these quantities are written in the specifications, if you have any
specification written, and the ready mix people use those amounts and have a
perfect concrete, because the concrete mixer will mix it well and as dry as
possible. But by experience on building sites, we use a bit more river sand and
a bit less gravel, as this makes it easier to work with overall.
Now let us go back to mix our concrete:
So, after you have poured the water into the
mixer, you put one single bucket of gravel and while the mixer turns put the
two small bucket of cement into the mixer, the cement in the mixer will
immediately mix in the water and the first bucket of gravel will make sure that
it does not stick to the mixer, because it will cut though any lumps easily,
now you add four buckets of river sand, and this again will mix very quickly
and become like a thick cream, all you have to do next is to add the other
seven bucket of gravel, once you have done that you only need to wait a little
bit for the mixer to mix it properly and your concrete is ready. Now all you must
do is to tip your concrete in a wheelbarrow and take it to the place you need
to concrete.
This is the quickest and best way to mix
concrete in a mixer, as I have done it for thousands of times, but I need to
say that on building sites, where there is plenty of cement to mix and the
workers have to try not to injury themselves, by lifting hundreds of bucket
full of material all day long, they use to measure the materials by the
shovelful, but you have to be an expert at doing that to get everything
measured right.
Before we leave this concrete discussions, we
want to add more information; you see, concrete in itself is very strong in
compression, but is lacks strength under tension, so, to make concrete very
strong and last a very long time you need to use steel in the concrete; here is
a link that will help to understand some of these issues.
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Mixing mortar, plaster, or cement topping.
Now that we have described how to mix
concrete by hand and by using a mixer, the same ways can be used to mix mortar, hard plaster or cement topping etc. So now, we need to describe only the different amount of
things that are used; but try to remember that when you mix by hand, it is a
lot easier to mix the dry materials first and then add water, but when you use
the mixer it usually is better and quicker to start with the water first.
To mix mortar for the bricklayer.
Just by using brickies loams and Portland
cement, this mixture by volume is most likely 4 part brickies loams to one part
Portland cement, but it could vary from (3 to 1) to (6 to 1) the aim here is to
give the bricklayers what is easy to work with, and at the same time you don’t
want to make the mortar a lot stronger than the bricks when it dries, and you don’t
want to make it too weak for the job you are doing, so, it makes sense to see
what the bricklayer reckons is good enough for the job; sometimes when making
mortar you can replace part of the Portland cement with hydrated lime, plus
other things to make the mortar easy to work with.
Mortar for cement blocks
The mortar for cement block is usually three
parts fine plaster sand and one-part cement, it is a bit different from the brickie’s
loams, as it is thicker and stronger and very close to the block’s colors when
dry.
To mix cement plaster to plaster walls.
This mixture is usually 3 parts plaster sand
and 1 part Portland cement, in some countries where lime is easier to have than
cement it can be made by using a mixture of lime and cement for the interior,
we believe that there are a lot of old places that they have used lime only,
the cement mixture is used wherever it is too wet.
Cement topping.
This mixture is usually 3 parts river sand to
1 part Portland cement; it can be used straight on the cement if it is still
green, but when the cement is dry you need to make sure it is clean and rough
for the cement to bond, you may have to use tools to indent the existing
concrete, then you have to wet the cement and also you may need to use some
cement bounding agent and/or paint to concrete with this cement glue called Weldbond
or Bondcrete or whatever and place the
topping cement according to the instruction supplied, if these concrete glues
are not available, you have to wet the concrete that you have to lay the
topping on, then make some slur of water and cement and somehow work it in with
a brush as if you paint the concrete, and before this starts drying lay your
topping on it.
These three mixtures plus the concrete are
the main things that are required when we build with cement, of course. Anyhow, I
have described several things already, but I think that I need to describe how
to mix mortar with lime only, as it was done in the old days and here I am not
talking just hydrated lime that you can buy at the hardware store, but I am
talking about quick-lime as it comes from the kiln and slacked lime.
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Lime use in building.
Quick-Lime and slacked or hydrated lime
Today when we talk about lime, we
see a bag of white powder that we buy at the hardware store, we know that we
can use this powder to replace some cement when we make mortar, but we don’t
know much more than that, But lime is a lot more than just a white powder in a
bag, because lime is one of those materials that has been and is being used a
lot in many ways, its’ largest use is in making mortar for the master builders,
but it has other uses also. So, let us talk about lime and where it comes from,
so that we can understand things about lime and its several uses, of course,
here we are mainly interested about its use in the building industry for making
mortar etc. But there is more to say about lime, to do that let us
check out how the Wikipedia explains quick lime etc. Where you can find a lot
of information about lime if you care to know, click on the links.
Slaked or Hydrated Lime
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From the Wikipedia:
Calcium oxide (CaO),
commonly known as quicklime or burnt
lime, is a widely usedchemical
compound. It is a white, caustic, alkaline crystalline solid at room temperature. The broadly used
term "lime"
connotes calcium-containing inorganic materials, which include carbonates,
oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron
predominate, such as limestone. By
contrast, "quicklime" specifically applies to a single chemical
compound.
Quicklime is relatively
inexpensive. Both it and a chemical derivative (calcium hydroxide) are
important commodity chemicals.
Calcium oxide is usually made by the thermal decomposition of
materials such aslimestone, that
contain calcium
carbonate (CaCO3;
mineral calcite) in a lime kiln. This is accomplished by heating
the material to above 825 °C (1,517 °F),[5] a process calledcalcination or lime-burning, to liberate a
molecule of carbon
dioxide (CO2);
leaving quicklime. The quicklime is not stable and, when cooled, will spontaneously react with CO2 from the air until, after enough time,
it will be completely converted back to calcium carbonate.
Annual worldwide production of
quicklime is around 283 million metric tons. China is by far the world's
largest producer, with a total of around 170 million metric tons per year. The
United States is the next largest, with around 20 million metric tons per year.[6]
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As we have said, lime has been used for a
very long time its use could be prehistoric, nobody seems to know when it was
first used in making mortar and plaster for buildings and for other things, it
was/is used even to disinfect places, when there is no much else to use, and I
know that there is a lot more to say about the use of lime even today; up to
the time when I was young it was used even to whitewash the walls in spring
once a year, after a long winter all the walls were darkened with smoke, I am pretty sure that even today this is the cheapest way
of cleaning rustic building, as, it is one of the cheapest ways to make
everything clean. But let us tell you it’s use as a building material to make
mortar.
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From quick lime to hydrated lime.
From quick lime to slacked lime the old ways
Here we are talking about the late forties
and early fifties, when I was young learning what was happening around me.
In the town where I come from in southern
Italy; in the early fifties when there was a new building to be build or
alterations to existing buildings to be done, one of the first things we would
see was that the master builder would get ready a good supply of slacked lime,
because this was one of the most important building materials, he needed to do
the job. In those times bagged hydrated lime and cement was very expensive, and
bagged cement has a short life shelving span, as it reacts when humidity
infiltrate the bags, therefore, most people or builders that needed to build
used lime wherever they could; they would buy quick lime and get it process
immediately on delivery themselves or with the help of the people that
delivered it, of course, one needs to know how to do that, because it is
dangerous while you are doing it. Now, let us see how it was done, and then we
will tell you where else the lime was used.
Anyhow, the master builder before delivery had
to build a square wall like a box, and in this large box he would process the quick
lime, because the quick lime cannot be held the way it is for any length of
time, since it reacts to humidity and violently to water, so, it is necessary
that it is turned into slacked lime as soon as possible after delivery.
Okay,
the cart or the lorry is on the way, so, the master builder gets his worker to
start filling the pit with water, and when the quick lime arrives they start
carefully throwing this burned lime stones into the pit in very small
quantities, as soon as the quick lime comes in contact with the water it reacts
and the water starts boiling, everybody is banned to approach the pit accept
the people that must work there, and they ware some protective gear, because it
is dangerous to handle quick-lime and around the pit, this process goes on
until all the quick lime is thus treated, once they have done that it is left
to cool down for a few days; after it has cooled down it is a lot less
dangerous, but still you need to be careful near the lime pit. You see, the
lime pit is now filled up with slacked lime, which looks like curd when you
make cheese, but it is still dangerous and it can easily kill you if you fall
in it, its contend must be handled with caution, but anyhow the slacked lime is
now ready to be used, this is how the builders used to get ready the lime to
make mortar. Now to use this lime to make mortar is different from using bagged
hydrated lime or cement; so, we are going to tell you how to make mortar with
slacked lime.
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How to make mortar with slacked lime.
This is how it was done in the old
time, perhaps for thousands of years, anyhow, let me describe the procedure. Let
us suppose that you have the slacked lime in the pit or in a container; you
have brickies loams ready, so, let us start:
Start by making a hip of your sand on a
platform; now that you have done that, make a well in the center and place your
slacked lime in it. The quantities in here may vary a lot more than when we use
cement or hydrated bagged lime, because the slacked lime can be as liquid as
thickened cream to as compact as feta cheese, so, you have to learn as you go
about the quantities, but if you have mixed mortar before, you soon work it out
yourself, or if there is any tradesman that is going to use the mortar he can
tell you just by looking at the mortar being made, whether you need more lime
or more sand and water etc.
Okay, now that you have the lime in the
middle of the sand, with a Larry start pushing this devise up and down through
the lime by adding a bit of water as needed and slowly mixing some sand with
the lime; you need to do this until you have mixed the whole lot evenly. This
is hard work but that is how it was done when there were no mixer and no bagged
hydrated lime around.
Here we need to note that this mixing of
slacked lime to mix mortar is completely different from mixing other mixture,
because the slacked lime is already wet, and it is like a paste.
Now, let me talk about, lime use in farming.
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Lime use in farming
You know, lime is a very useful commodity, in
fact they are countless places where we can use it, I only happen to know a few
of them, so, let me say how we were using lime in our small
family farm at the time when I was young.
We would use it like the builders use it when
we had to repair or replace a few stone that were falling apart in the old
stone building, so, instead of using clay like the first time, we would mix a
small quantity of mortar using lime and sand; then, we used lime to whitewash
the farm house, the stables, the pig stay, the chicken coop and sheds or other
buildings near the farm house once a year in spring.
We could use it to disinfect stagnant water
ponds that showed signs of vermin, or the water were too dirty, so, we would
dilute some lime in water and then pour it in the water ponds, and next day the
ponds would be clean, as the lime would kill the vermin and would make the water
clear because all the dirt would sink to the bottom of the pond; you see, in
our small farm we used to have a kitchen garden, so, we would dig up a few
ponds beside the garden that would feel up with water during winter or when it
rained, we used this water to water the plants when the soil was becoming too
dry for the garden plants to grow.
In the farms of those days lime was also used
to spray vines and trees, sometimes there were diseases that could be
controlled by applying a coat of lime to the trunk of those trees; but there is
one thing that always comes to my mind; it is when we were spraying the grape
vines with a copper sulphate and lime, we would have two containers one with
diluted copper sulphate and one with diluted lime, some people used to spray
first with copper sulphate and then with lime, so that they would help each
other to kill the mildew, but my grandma had worked a way how to avoid this
double spraying and it worked thus;
In those times it was not like today and even
the vine spraying pump was a devise that you would put on your back, and with a
handle that you moved up and down you would spray your vines and trees as well;
this devise could hold about three gallons of liquid, so, every now and then
you needed to fill it up; as I have said we had two containers one holding
diluted copper sulphate and one with diluted lime; (of course you had to know
how much diluted you had to do your mixtures but that does not mutter here this
time) anyhow, when the pump was/is empty you would go to these containers to
fill it up: here is my grandma way to avoid to spray twice, when filling the
pump, first of all you had to make sure than the mixture were well stirred,
then you would put the copper sulphate in the pump and at the last minute you
would add the lime, and immediately start to spray. This was my grandma way and
it worked because the mixture would not have time to settle down and become
stale. There you are this is just another way of how lime is useful in the
farms.
Anyhow, I think that this article is too
long, and I have said enough about how to mix your own cement or mortar, about
lime and lime use in farming, so, see you next time with our article, Bricklaying is competitive.
To see more click on this link, Mix your own cement.
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