History of Cement

Summary

In this engaging video, we explore the fascinating history of cement from ancient times to the modern era. The journey begins with early non-hydraulic cements used by Egyptians, Greeks, and Romans, and moves through the evolution of hydraulic cements, which could set in water. Along the way, we delve into the chemistry behind cement production, including the processes of calcining limestone and creating calcium silicate hydrates. The video also highlights the contributions of the Romans and the Industrial Revolution to cement development, concluding with the invention of Portland cement in the 19th century.

Takeaways

• 🏗️ Cement has a long history, from ancient times to Roman innovations and modern developments.
• 🌊 Hydraulic cement is stable in water, while non-hydraulic cement is not, making the latter unsuitable for wet environments.
• 🔥 Calcinating is a process that uses heat to break down chemical compounds, essential in making both ancient and modern cements.
• 🏛️ Ancient civilizations, like the Egyptians and Romans, used non-hydraulic cements made from limestone, but it wasn't suitable for high moisture environments.
• 🌋 Romans developed hydraulic cement using lime and volcanic ash, creating durable cement that could set in water.
• 🧪 The key to Roman cement's strength was the production of calcium silicate hydrates (CSH), a substance still crucial in modern cements.
• 🇮🇹 The best volcanic ash source for Roman cement came from Pozzuoli, Italy, giving rise to the term 'pozzolanic reactions.'
• 🏰 Roman structures like aqueducts, the Colosseum, and the Pantheon were built using their advanced concrete, which has lasted over 2,000 years.
• ⚒️ In the Industrial Revolution, volcanic ash was replaced by clay and shale, and Joseph Aspdin’s patent for Portland cement in 1824 revolutionized modern cement production.
• 🧱 Modern cements primarily rely on tri-calcium silicate (C3S), discovered by William Aspdin, which provides rapid strength gains and forms the basis of today’s concrete.

Q & A

What is hydraulic cement and why is it important?

Hydraulic cement is a binder or glue that is stable in water. This property is crucial because it allows structures made with hydraulic cement to withstand exposure to moisture without falling apart, making it ideal for durable construction in wet environments.

What is the difference between hydraulic and non-hydraulic cement?

Hydraulic cement is stable in water, meaning it can be used in wet conditions without degrading. Non-hydraulic cement, on the other hand, is not stable in water and will deteriorate if exposed to moisture, making it less suitable for environments where water exposure is likely.

What is the process of calcining, and why is it significant in cement making?

Calcining is the process of using heat to break apart chemical compounds. In cement production, limestone (calcium carbonate) is heated to produce lime (calcium oxide) and carbon dioxide. This process is essential for creating the key ingredients for both ancient and modern cement formulations.

How did ancient civilizations like the Egyptians and Romans use non-hydraulic cement?

Ancient civilizations used non-hydraulic cement by heating limestone to create lime, which they then mixed with water to form a slurry. This slurry would absorb carbon dioxide from the air and eventually harden into calcium carbonate, creating a solid but water-soluble material suitable for construction in dry environments.

What innovation did the Romans introduce to improve cement durability in water?

The Romans developed hydraulic cement by combining lime with volcanic ash, creating a material that could set in water. This innovation allowed them to build durable structures like aqueducts, which transported water, and large public buildings, such as the Colosseum and the Pantheon, that could withstand wet conditions.

What are pozzolans, and why were they important in Roman cement?

Pozzolans are minerals, like volcanic ash, that react with lime to create hydraulic cement. The Romans used pozzolans to create strong, water-resistant cement that could be used in a variety of structures, including aqueducts and temples. This material is known as pozzolanic cement.

What limitations did the Romans face with their pozzolanic cement?

Roman pozzolanic cement had several limitations: volcanic ash was not available everywhere, meaning the material could only be produced near volcanic regions. Additionally, the strength gain of the cement took months, making it less efficient for rapid construction projects.

How did the industrial revolution impact cement development?

During the industrial revolution, demand for hydraulic cement increased, especially in England and France. Scientists and builders began experimenting with alternative materials like clay, shale, and slate to replace volcanic ash. These materials required higher heat and energy, but allowed for the production of cement in areas far from volcanic regions.

What was Joseph Aspdin's contribution to modern cement, and why is it significant?

Joseph Aspdin, an English mason, patented Portland cement in 1824. Although his formula was not successful, the name 'Portland cement' became the standard for modern cements because of its resemblance to high-quality Portland stone. His son, William Aspdin, later improved the formula to produce a more reactive cement that gained strength faster, leading to the creation of modern cement.

What is tri-calcium silicate, and why is it important in modern cement?

Tri-calcium silicate (C3S), also known as alite, is the main reactive component in modern cement. It is responsible for the rapid strength gain in modern cements, making it an essential ingredient for today's construction materials.

Outlines

00:00

🛠️ Introduction to Cement: Origins and Concepts

The speaker introduces the history of cement, from ancient times to the Roman period and modern developments. They highlight the importance of understanding cement terminology, especially the distinction between hydraulic and non-hydraulic cement. Hydraulic cement, stable in water, is essential for construction, while non-hydraulic cement disintegrates when exposed to moisture. Key terminology such as 'calcining'—a process where heat breaks down chemical compounds—is also explained. The speaker prepares the audience for the technical details ahead, especially chemistry related to cement production.

05:01

🏛️ Ancient Cements: Solubility and Limitations

This section explores how ancient civilizations, including Egyptians, Greeks, and Romans, used non-hydraulic cements made from calcined limestone. When mixed with water, limestone forms slaked lime (calcium hydroxide), which could harden by absorbing carbon dioxide from the air, transforming into calcium carbonate. However, this material had limitations, especially its solubility in water, making it unsuitable for wet environments. The speaker emphasizes that ancient cements hardened by drying, not hydration like modern cements, and took a long time to gain strength.

10:02

🌋 The Roman Innovation: Hydraulic Cements and Pozzolans

The Romans revolutionized cement by developing the first hydraulic cements. They combined lime with volcanic ash, producing a durable material that could set in water. The calcining process was key, but it had to be done twice to create calcium silicates, the main component of Roman cement. This mixture formed calcium silicate hydrate (CSH), the same compound used in modern cement. The speaker explains the Roman process of using volcanic ash, known as pozzolanic reaction, and how this technology led to long-lasting structures such as aqueducts and the Colosseum.

15:02

🏗️ Roman Engineering Marvels: Aqueducts, Colosseum, and More

Roman hydraulic cements enabled the construction of remarkable structures like aqueducts, the Colosseum, temples, and public baths, many of which still stand today. These cements were water-resistant, a crucial factor for aqueducts that transported water. The speaker also highlights the variability of volcanic ash, which could affect the quality of Roman cement, and the long curing times that delayed construction projects. Despite these challenges, Roman engineering was highly advanced, but cement technology saw little improvement during the Dark Ages.

🛠️ The Industrial Revolution and Portland Cement

In the 19th century, the Industrial Revolution reignited the demand for hydraulic cement. By studying Roman methods, scientists experimented with new materials like clay, shale, and slate to replace volcanic ash. This led to the development of di-calcium silicate (C2S), but it was slow to gain strength. In 1824, Joseph Aspdin patented 'Portland cement,' named for its resemblance to Portland stone. However, his formula was flawed, and it wasn’t until his son William improved it in the 1840s by using more lime and higher temperatures that the modern, fast-strengthening tri-calcium silicate (C3S) cement, known as 'alite,' was created, laying the foundation for modern construction.

Keywords

💡Hydraulic cement

Hydraulic cement is a type of binder that is stable in water, meaning it can set and harden even when exposed to moisture or submerged. This term is critical in the video, as it distinguishes between ancient cements that dissolve in water and the more durable hydraulic cements developed by the Romans, which allowed for structures like aqueducts to remain intact even in wet conditions.

💡Non-hydraulic cement

Non-hydraulic cement is a binder that cannot withstand water exposure, as it dissolves when wet. In the video, the presenter discusses how ancient civilizations, such as the Egyptians and early Romans, used non-hydraulic cements that worked well in dry climates but would collapse in moist environments. This distinction highlights the need for more advanced cements for modern construction.

💡Calcining

Calcining is a process where heat is used to decompose a material, often by breaking down chemical compounds. In the video, calcining is discussed in the context of heating limestone (calcium carbonate) to produce lime (calcium oxide) and carbon dioxide. This process was essential in the production of both ancient and modern cements, as it forms the basis for creating reactive materials for cement.

💡Lime (Calcium Oxide)

Lime, or calcium oxide, is a key ingredient in both ancient and modern cement. It is produced by calcining limestone and is used to create slaked lime when mixed with water. In the video, lime serves as the foundational component in early cement mixtures and is later combined with volcanic ash by the Romans to make hydraulic cements. Lime is also integral to modern Portland cement.

💡Slaked lime (Calcium Hydroxide)

Slaked lime, or calcium hydroxide, is formed when lime is mixed with water. In ancient times, this was used as a binder in non-hydraulic cement. The video explains how slaked lime reacts with carbon dioxide in the air to harden and form limestone again, but it is vulnerable to water, which is why it was less useful in wet environments. Slaked lime was a critical element in early construction before hydraulic cements were developed.

💡Pozzolanic reaction

The pozzolanic reaction occurs when volcanic ash (rich in silica) is mixed with lime, creating a durable, hydraulic cement that can set in water. The video describes how the Romans discovered this reaction and used it to build long-lasting structures like aqueducts and the Colosseum. Pozzolanic materials, such as the volcanic ash found near Pozzuoli, Italy, were essential for Roman concrete's strength and longevity.

💡Calcium silicate hydrate (CSH)

Calcium silicate hydrate, or CSH, is the main binding component in both Roman and modern cements. The video highlights how the Romans accidentally created CSH through the pozzolanic reaction, and how this compound is responsible for the strength and durability of concrete. Modern cements also rely on CSH, formed when lime and silicates (from materials like volcanic ash or clay) are mixed with water.

💡Tri-calcium silicate (C3S)

Tri-calcium silicate, or C3S, is one of the key components of modern Portland cement, responsible for rapid strength gain. In the video, it is explained how Joseph Aspdin’s son, William Aspdin, improved on his father’s failed formula by increasing the lime content and heating the materials to higher temperatures, resulting in the formation of C3S. This discovery allowed for faster-setting and stronger cements, revolutionizing construction.

💡Roman concrete

Roman concrete refers to the advanced hydraulic cement the Romans developed by mixing lime with volcanic ash, which allowed them to build durable structures that could withstand water exposure. The video showcases how Roman concrete, due to its pozzolanic reaction, enabled the construction of landmarks like the Pantheon, aqueducts, and the Colosseum, which have stood the test of time for over 2,000 years.

💡Portland cement

Portland cement is a type of hydraulic cement invented by Joseph Aspdin in 1824. Named after the high-quality Portland stone, it became the foundation of modern construction. In the video, it’s explained that although Joseph’s original formula was flawed, his son William Aspdin later improved it, leading to the widespread use of Portland cement in contemporary building projects due to its quick-setting and high strength properties.

Highlights

Introduction to the history of cement, from ancient times to modern cements.

Explanation of the difference between hydraulic and non-hydraulic cements.

Discussion of calcinating limestone to make lime, a process used by the Egyptians, Greeks, and Romans.

The role of non-hydraulic cement in early civilizations and how it gains strength by absorbing carbon dioxide from the atmosphere.

Limitations of non-hydraulic cement, particularly its solubility in water, making it unsuitable for wet environments.

Romans as the first civilization to develop hydraulic cement using volcanic ash and lime, making it stable in water.

The importance of volcanic ash in Roman cement, specifically from Pozzuoli, Italy, which produced durable, water-resistant structures like aqueducts.

Roman cement technology enabled long-lasting structures such as aqueducts, the Colosseum, and the Pantheon.

Challenges of Roman cement: inconsistent volcanic ash availability and long strength gain periods.

Revival of hydraulic cement during the Industrial Revolution using shale and clay to replace volcanic ash.

Joseph Aspdin's invention of Portland cement in 1824, named after the Portland stone.

Although Joseph Aspdin's original Portland cement formula didn’t work, his son William Aspdin improved it by using more lime and higher temperatures.

William Aspdin’s development of tri-calcium silicate (C3S), which became the foundation of modern cement.

Modern cements are based on tri-calcium silicate, which provides rapid strength gain, a critical feature for construction.

Roman cements, similar to modern cements, form calcium silicate hydrate, which acts as the binding glue in construction.

Transcripts

welcome concrete friends today is an

exciting day we're gonna be talking

about the history of cement ah yeah yeah

all the way from early early ancient

times through Roman cement through

modern cement I know

exciting right yeah we're gonna explain

it all we're gonna talk about

terminology we're gonna talk about the

saga the history the drama of how the

cement modern cements were developed

alright I gotta warn you though it's

gonna be some terminology along the way

there's gonna be some chemistry along

the way chemistry yeah I know it'll be

okay

don't worry don't worry stay with me the

history of cement first and foremost we

need to start out with some terminology

that's way we make sure we're all on the

same page first we're gonna talk about a

hydraulic cement that is a binder or

glue that is stable and water

and that's the type of cement you want

one that's stable in water because if

it's not stable once it rains it falls

apart that's not good so if a hydraulic

cement is stable in water what do you

think a non hydraulic cement is you got

it

it's a binder or glue that is not stable

in water

wha-wha-wha that's the one that's not as

valuable not as much as what we're into

that's one that if you build your house

out of it a trained your house is gonna

be falling down that's that's not good

and this is a term called cal signing

we're gonna use cal signing a lot cal

signing is to use heat to break apart

chemical compounds

and there's a very very classic version

Cal something I'm going to talk about in

just a second first let's start out

talking about the ancient cements the

non hydraulic cements these were used by

Egyptians by the Greeks by the early

Romans as a cement how did they make

them well they took limestone what's

limestone it's a rock yeah calcium

carbonate a rock and they cooked it to

about 2300 degrees Fahrenheit about and

they made lime and carbon dioxide yeah

carbon dioxide this process is called

cal signing and this carbon dioxide this

is the greenhouse gas that everyone's

kind of scared about gas goes into the

atmosphere not around anymore used to be

part of the rock you cook you cook you

cook it's not there anymore it floats

away all right but it leaves lime behind

you take the lime you add water to it

and you make something called slaked

lime or calcium hydroxide this is like a

slurry okay and these calcium hydroxide

crystals will talk more about calcium

hydroxide coming up their plate like and

I'm drawing is like a big plate but it's

not big no it's big underneath maybe a

scanning electron microscope or a really

really high power optical microscope

these things are maybe 20 microns in

size 20 microns how big is that it's

about half the size of a human hair

about okay a little bit less than that

but with enough water and mixing this

calcium hydroxide is actually soluble in

water so you get this slurry you make

this slurry of material and you glue

stuff together like bricks or stones or

whatever you want and then once it sits

out it absorbs carbon dioxide from the

atmosphere yeah I know pretty cool right

yeah it absorbs it and what does it make

it

makes calcium carbonate it makes what

you started out with and water that

water usually evaporates and goes away

but this is left as a solid so as the

material dried it truly gained

strengthen when you hear people say

concrete's drying if we talk about

modern concrete's that's not true that's

not true

concrete hydrates I'll talk more about

that coming up but old ancient cements

that's what they did they did dry right

they did as they gained carbon dioxide

from the atmosphere they would form a

solid limestone and then the water would

evaporate off they actually formed

artificial rock they could cast stone ah

pretty cool but sadly this limestone is

soluble in water remember that's the non

hydraulic cement that means if it rained

wouldn't it fall apart

good thing it doesn't rain in Egypt

right or very often this limestone

soluble in water so the cement could not

be used in high moisture environments

this is helpful and good but not exactly

what you want this material also took a

long time to gain strength for it to be

usable it's another thing that just

doesn't lend itself to rapid modern

construction those Romans they're pretty

clever cats they came up they're the

first ones to actually develop hydraulic

cements remember those are the cements

that set and are not soluble in water

you can actually use them in water if

you want that's amazing that's really

powerful so the Romans needed his cement

that was durable in water so they made

mixtures of line that's the same stuff I

was just talking talking about and

volcanic ash where do you get that from

a volcano right after it's already like

erupted you basically mine or dig up the

sides of it you mix it up with your lime

and again uuugh

take this limestone and you cook it to

get lime and carbon-dioxide this is

again cal signing remember cal signing

this is Cal signing this carbon dioxide

goes into the atmosphere

yikes but then you take this lime and

you mix it up with this reactive silicon

dioxide from the volcanic ash you

basically take the lime in in the

volcanic ash and then you cook that so

you've had to cook it twice and you end

up making a calcium silicate now you

notice I have an X and a Y here and an X

and a Y here because we don't really

know the Roman recipe we don't really

know how much quick lime they used and

how much volcanic ash they used but it's

likely that they didn't that this

reaction produced some calcium silicate

and there was actually probably some

volcanic ash left over okay

so not all the volcanic ash was used up

in this reaction and some of it was

probably available for further reactions

anyway

this makes something called a calcium

silicate right

some kind of calcium silicate so we take

this calcium silicate and we add water

to it and it makes something called the

calcium silicate hydrate and ladies and

gentlemen this is the Roman cements and

this is actually a kissing cousin to our

modern cements some some definite

similarities here calcium silicate

hydrates are the glue that we use in our

modern Smiths it is the good stuff

formed in our modern cements and we're

pretty sure and other experiments have

shown that the Romans produced it as

well calcium silicate hydrate also known

as cs8 or simple people and the world of

cement and we like to shorten things

this is cement chemistry shorthand every

time you see calcium oxide we call it C

in cement chemistry language every time

you see silicon dioxide we call it s

okay this really ticks off the chemists

they get so upset and we just think it's

funny and there's water h2o we just call

it h ha they think this is carbon sulfur

and hydrogen but not the cement chemists

this is calcium silicate hydrate this is

the good stuff this is what we're all

about

CSH and the best source of volcanic ash

in the world the best source that the

Romans knew about was in Basel I Italy

right this reaction was therefore named

pozzolanic and any minerals that led to

these reactions are called pozzolans

these hydraulic cements were used on

several major projects that are still in

existence today let's take a look this

is the Roman aqueducts this is what the

Romans used to build to take water from

miles away from their cities and bring

them in bring them in bring them in to

the city centre where they could drink

from it bathe in it do all kinds of

things in it when you can control and

produce fresh water that is really

powerful for a civilization but how

would I make these I'm gonna these

things actually transport water yeah

yeah there's actually water carried in

these channels and in this channel right

here there's water that actually goes in

there if I made this with a non

hydraulic cement the water itself would

cause and make it to collapse

the Romans had to have a hydraulic

cement just like the ones I was talking

about before but they didn't just fill

aqueducts right Romans built all kinds

of things like the Colosseum this is

like their big amphitheater where they

had battles and they actually had sea

battles inside of here all kinds of

crazy stuff with monsters and humans

fighting the Colosseum like our modern

sports stadiums also their temples this

is the

theone again built with roman concrete

lasting over 2,000 years it's pretty

amazing right and then the baths of

caracalla

okay these are huge public baths or

where they would go and bathe and hang

out again all made with Roman concrete

those Romans pretty clever cats right

there's a big problem though there's a

big problem with these cements volcanic

ash isn't available everywhere you got

to be near a volcano also when they were

digging it out of the volcano it's quite

variable as in one area may produce

great cement and another area would

produce horrible cement that's a problem

so the cement is variable you had to

have an actual volcano another bad thing

is the strength gain took months months

they wouldn't be able to use these

structures for months after being built

but they were long lasting there were

very little improvements in the cement

technology during the dark ages actually

not much technology at all developed

during the dark ages

except for weapons I guess but about

1800 years later during the industrial

revolution demand was again increased

for a hydraulic cement is in England now

they're really pushing for this France

as well the first thing they did is they

studied what the Romans did and they

looked at this volcanic ash and they

said you know what maybe we could use

clay or shale or slate okay the silicon

dioxide was in this form kaolinite had

aluminum in it as well think of it as

like tile but it's not as reactive as

this ash so more heat was required again

but more heat what's that gonna mean

that means more energy more energy means

cost more cost more for the environment

to make but that's what they needed to

do

so it took the quick climb they got this

sio2 silicon dioxide they cooked it at a

height or higher temperature and they

were able to produce dye calcium

silicate dye calcium silicate and this

in cement chemistry shorthand is known

as c2 s or also known as B light B light

this solved the problem of the

availability of the volcanic ash but

again

the cements took months months to gain

strength and that just wasn't what

people wanted so in 1824 an English

Mason named Joseph Aspen was actually

awarded a patent for something called

Portland cement and this name was given

to the product because it resembled the

prestigious cliffs of Portland the

prestigious Portland stone let me show

you a picture that this is the Portland

stone this was a highly sought after

known as super high quality wouldn't it

be amazing if you could sell somebody a

bag that you would mix up with water

that would make a stone that looked like

this this was oh my gosh

people wanted this and Joseph Aspen was

an amazing marketer he was actually way

better marketer than he was a Mason and

way better marketer than he was a cement

manufacturer I tell you why the reason

why I said he was such a better marketer

than he was a cement manufacturer was

because the cement at least as it's

written in his patent because of lots

and lots of people tried to develop it

it didn't work it didn't work it's kind

of crazy that

that basically gave the name Portland

cement and all modern cements are

Portland cements they're called that

Portland cements that name from Joseph

Aspen his formula didn't work it didn't

but in 1840 Joseph's son William Aspen

actually solve this problem he he

actually finally made material that

would gain strength at a rapid rate by

using a larger amount of lime and higher

temperatures so he used more lime higher

temperature and he produced something

called tri calcium silicate did he know

what he was doing no he was just trying

stuff he got lucky he produced tri

calcium silicate which we call C 3s and

this ladies and gentlemen is also called

a light and this this is the building

block the main reactive component of our

modern cements today