Shadowing Practice: Introduction 1, Context - Learn English Speaking with Video
בחר מצב תרגול
כל מצב פותח חדר תרגול במסך מלא.
115 משפטים
אם המשפטים קצרים או ארוכים מדי, לחץ על ערוך כדי להתאים אותם.
1
Cement Chemistry for Sustainable Cementia Materials Hello and welcome to this series on Cement Chemistry for Sustainable Cementia Materials.
2
In this series of modules, we're going to look at the cement chemistry and how this helps us to understand the sustainability of these very important materials.
3
Most of the modules should be really understandable to anybody with a fairly basic knowledge of high school chemistry.
4
So in this first module, we're going to look at the overall context.
5
We're going to look at the role of cementitious material in the world today
6
and what are the origins of their CO2 footprint.
7
Now, in this first slide, we can see the overwhelming dominance of cementitious materials.
8
They make up between 30 to 50 percent of everything we produce,
9
probably about 50 percent of solid materials and 30 percent if we include things like fossil fuels.
10
And in the light of that, the fact that they're responsible for CO2 emissions of around 5 to 10 percent is a very good ratio.
11
But more importantly, we can really see
12
that it would in no way be possible to replace semantitious materials with alternatives at any meaningful level.
13
For example, if we look at the amount of wood produced worldwide, this is between 10 and 15% the amount of cementitious materials.
14
And already it's estimated that this amount of wood is beyond the limits of sustainability.
15
That's to say we're cutting down more trees than we're planting.
16
So while this may be a nice option in Europe and North America, it's really not practical for the many people who need to be housed in countries like China,
17
India, Africa, South America.
18
This slide here really shows how the environmental footprint of concrete is very low.
19
And we should talk about concrete because concrete is the final material we really use.
20
Cement is the precursor and there's roughly about 10% of cement in concrete.
21
On the right here, I've normalized these figures compared to the highest, which is aluminium.
22
You can see very vividly just how much energy and CO2 you can save by recycling aluminium.
23
And I hope after seeing this, you don't throw your Coke can in the bin anymore.
24
But concrete is really extremely low, lower than almost all other materials.
25
Of course, this is just on a weight basis.
26
When you put this into a structure, it becomes more complicated.
27
We're not going to go into that here, but generally, even in that situation,
28
concrete still comes out very strongly as an environmentally friendly material.
29
The amount of cement we're using has increased very, very dramatically in the past few decades.
30
Since 1950, the population has increased about threefold, and in the same period,
31
the amount of cement we use has increased by about 34 times.
32
In recent decades, this has really been driven by the development in China.
33
And we should not view this negatively because this development has lifted a lot of people out of poverty.
34
It's provided them with decent homes, with roads, railways to get around and everything like that.
35
But we certainly cannot imagine that this growth in demand for cement is going to slow down because there are many,
36
many other parts of the world where people still haven't had decent housing or transportation systems.
37
Finally, what we do with our lives and the CO2 produced is a question of choices.
38
And here again, you know, if we decide to build a house, we make maybe a house for a family of three people,
39
this will typically take about 10 to 20 tons of cement and last for about 50 years.
40
So we can calculate from that
41
that the CO2 to do with your materials in your house is about 12 kilograms a month.
42
Now, if you're driving a car, which you almost certainly are,
43
that same family of three will probably drive at least 10,000 kilometers a year.
44
And then they'll be consuming fossil fuels, which will be producing about 90 kilograms of CO2 per year,
45
seven or eight times more than the materials in their house.
46
But we should also reflect on our other choices in life, for example, the food we eat.
47
Here you can see for a very meat intensive diet,
48
the associated CO2 production would be around five to seven kilograms of CO2 per day.
49
whereas a vegetarian diet is much lower at around 3 to 4 kilograms of CO2 per day.
50
And so if we calculate for the same imaginary family of three that they went from eating meat to being vegetarian
51
maybe for just two
52
or three days a month this would be equivalent to saving all the CO2 that they needed to build their house.
53
So rather than just blaming the producers of these materials we have to think about what we're doing in our lives
54
and what we choose to do that produces CO2.
55
Okay, there's no reason for complacency because if we did nothing about the CO2 footprint of cementitious materials,
56
we could end up in a situation like this.
57
Here we see the blue line is the trajectory
58
that has been estimated we should try to meet if we're to restrict global warming to this two degrees temperature rise.
59
Whether we're going to do that or not is another question, but that's the trajectory of overall global emissions if we're going to do that.
60
If we achieve that blue line and we did nothing about cement,
61
then the emissions from the production of cement and cementitious materials would follow the red line.
62
And we see
63
that by 2050 we would end up in a situation where
64
cementitious materials would be responsible for something like 30% of world CO2 emissions, which is clearly unacceptable.
65
So where is the consumption of cement taking place?
66
What we see here is the distribution of cement use around the world.
67
And only about 10% of cement use is taking place in OECD countries.
68
And in these countries, it's forecast that demand will really stay pretty much constant.
69
More than 90% of consumption is taking part in the developing world,
70
particularly in China, which has been very dominant over the past two decades.
71
It's been estimated in the last three years, China produced more concrete than was produced in the whole of North America in the 20th century.
72
and many other countries like India in particular are looking to follow this development path to provide decent houses for their people,
73
decent rail systems, decent road systems and this will inevitably mean that the growth in use of cement is going to increase.
74
So if we're going to meet this challenge of the growing demand for cement we need solutions
75
which are first of all practical, They can be used by unskilled workers.
76
And, you know, this shows you the kind of typical situation you can have for mixing concrete.
77
The example is from India.
78
And also economically.
79
Now, you know, cement is an incredibly cheap material.
80
In most of Europe, you can buy a ton of cement for less than 100 euros for a whole ton.
81
In many developing countries, though, the prices are actually higher, even though the incomes are lower.
82
So it's very important that we have solutions
83
which are really economically viable for these countries where there's this huge need for building infrastructure and housing,
84
etc. So let's look at where these CO2 emissions are coming from.
85
Unlike most other industrial processes, only a minority of the CO2 emissions are coming from the energy consumption.
86
Producing cement is a high temperature process.
87
you're going up to temperatures of 1450 or so and this does take energy but it's still the minor amount.
88
A cement kiln as we see here looks like a fairly unsophisticated type of instrument.
89
But this is in fact not true
90
because in the past few decades there's been very dramatic improvement in the amount of energy needed to produce cement.
91
And in really state-of-the-art equipment now the production process is highly optimized up to nearly 80% of the thermodynamic limit
92
which is those of you who or study thermodynamics will know, is very close to the maximum you can achieve.
93
Another factor which is important is that rather than using fossil fuels, which used to be the dominant means in the past,
94
nowadays we can use a wide variety of waste fuels.
95
So for example, off cuts from producing furniture,
96
old car tires, Many, many different kind of waste can be burnt in a cement kiln.
97
And in many parts of Europe, plants are using more than 80% of waste fuels.
98
So this is a very efficient tool for valorizing waste materials.
99
So if we're going to make improvements, we need to turn to the other side, to the 60% of the equation.
100
And this 60%, this comes from the breakdown of calcium carbonate into calcium oxide and CO2.
101
Calcium carbonate, this is in fact limestone, which is 80% of the raw material used to make cement.
102
Now, the fact we have this chemical CO2 means that if we're going to reduce this, then we're going to have,
103
this has implications for the chemistry of the cement.
104
And that means it has implications for the whole way it behaves, in use, etc., etc., which of course is a big challenge.
105
So what have we seen in this lecture?
106
Well, we've seen how important semantitious materials are, how they make up by far the overwhelming majority of all the materials we used
107
and therefore cannot be replaced by other materials.
108
We've seen that in fact the environmental footprint from these materials is in fact quite low
109
and we've looked at where the CO2 emissions come from
110
and we've seen that most of the CO2 emissions come from the chemical breakdown of limestone,
111
that's calcium carbonate, and therefore we can't really imagine to do much about CO2 emissions by, for example, looking at alternative energies.
112
So in the next lecture, we're going to go into more detail about why the chemistry of cement is as it is.
113
So I look forward to seeing you next time and I hope you've enjoyed this first module.
114
If you want to find out more, then this publication, Ecoefficient Cements, which we published in November 2016,
115
gives you a very good background to all the aspects I will tackle in this first module.
הורד אפליקציה
כל מה שאתה צריך כדי לדבר בשטף
הגיית AIציון לכל משפט
תרגול IPAשלוט בכל צליל
אוצר מיליםבנה את מאגר המילים שלך
משחק אוצר מיליםלמד תוך כדי משחק
אותו ערוץ
FOR YOU
המלץ על סרטון
C11
506 משפטים
Analyzing Statements of Cash Flows 1 (2025 CFA® Level I Exam – FSA – Learning Module 4)
Business EnglishUniversity StudentsWorking Adults
C12
133 משפטים
Carbon Fiber - The Material Of The Future?
Business EnglishUniversity StudentsWorking Adults
C14
466 משפטים
English Podcast for Learning English | Talk About Climate Change in English | B2-C1 Conversation
Business EnglishDaily ConversationUniversity Students
C13
51 משפטים
Business Partner C1. Unit 1. Video 1.1.1.
Business EnglishUniversity StudentsWorking Adults
C16
114 משפטים
Introduction to Contract Law
Business EnglishUniversity StudentsWorking Adults
C12
106 משפטים
What is Engineering?: Crash Course Engineering #1
Business EnglishUniversity StudentsWorking Adults
C11
56 משפטים
MinuteCement - LC3
Daily ConversationUniversity StudentsWorking Adults
C15
119 משפטים
01 English Vocabulary in Use Advanced Unit 1-4
Business EnglishInterview EnglishUniversity Students
C11
218 משפטים
Introduction to Marketing: The Marketing Mix
Business EnglishUniversity StudentsWorking Adults
C11
689 משפטים
Natural Stone 101: Everything You Need to Know About Designing with the Oldest Building Material
Business EnglishUniversity StudentsWorking Adults
C17
111 משפטים
Contemporary topics 2| Unit 4 BUSINESS Success in the global economy
Business EnglishUniversity StudentsWorking Adults
Vocabulary and speaking notes for this lesson
This C1 speaking lesson is built on the video “Introduction 1, Context”. The speaker keeps coming back to these words: cement, material, emissions, concrete, amount. This video has 115 sentences and 1706 words to shadow. The speech runs for 11:57. The speaker talks at a steady 143 words per minute, a comfortable pace for shadowing. 86% of the words are among the 3,000 most common in English; the rest is worth studying before you start.
Key vocabulary in this video
The 15 most advanced words in the video, with pronunciation and meaning:
| Word | Pronunciation | Meaning |
|---|---|---|
| cement noun | /səˈmɛnt/ | A powdered substance produced by firing (calcining) calcium carbonate (limestone) and clay that develops strong cohesive properties when mixed with water. The… |
| emission noun | /ɪˈmɪʃ.ən/ | Something which is emitted or sent out; issue. |
| cementitious adjective | /ˌsɛmɛnˈtɪʃəs/ | Resembling or having some properties of cement; containing cement. |
| module noun | /ˈmɑd͡ʒul/ | A self-contained component of a system, often interchangeable, which has a well-defined interface to the other components. |
| kilogram noun | /ˈkɪləɡɹæm/ | In the International System of Units, the base unit of mass; conceived of as the mass of one litre of water, but now defined by taking the fixed numerical… |
| footprint noun | /ˈfʊtpɹɪnt/ | The impression of the foot in a soft substance such as sand or snow. |
| calcium noun | /ˈkælsi.əm/ | The chemical element (symbol Ca) with atomic number 20: a soft, silvery-white alkaline earth metal which occurs naturally as carbonate in limestone and as… |
| carbonate noun | /ˈkɑɹbəneɪt/ | Any salt or ester of carbonic acid. |
| fossil noun | /ˈfɑsl̩/ | The mineralized remains of an animal or plant. |
| kiln noun | /kɪln/ | An oven or furnace or a heated chamber, for the purpose of hardening, burning, calcining or drying anything; for example, firing ceramics, curing or preserving… |
| overwhelm verb | /ˌoʊ.vɚˈwɛlm/ | To engulf, surge over and submerge. |
| implication noun | /ˌɪmpləˈkeɪʃən/ | The act of implicating. |
| trajectory noun | /tɹəˈd͡ʒɛktəɹi/ | The path an object takes as it moves. |
| aluminium noun | /ˌæl.(j)uˈmɪn.i.əm/ | A light, silvery metal extracted from bauxite, and a chemical element (symbol Al) with an atomic number of 13. |
| limestone noun | /ˈlaɪmˌstoʊn/ | An abundant rock of marine and freshwater sediments; primarily composed of calcite (CaCO₃); and occurring in a variety of forms, both crystalline and amorphous. |
Phrasal verbs you will hear
| Word | Pronunciation | Meaning |
|---|---|---|
| make up verb | /ˌmeɪk ˈʌp/ | To constitute, to compose. |
| come out verb | /ˌkʌm ˈaʊt/ | To be discovered; to be revealed. |
| cut down verb | To cut downward. | |
| find out verb | To discover, as by asking or investigating. | |
| get around verb | To move to the other side of (something, such as an obstruction) by deviating from a direct course or following a curved path. | |
| look forward to verb | To anticipate, expect, or wait for, especially with a feeling of approval or pleasure; to be excited or eager to. | |
| slow down verb | To decelerate. |
דקדוק בסרטון הזה
המבנים שהדובר משתמש בהם הכי הרבה, עם המילים המדויקות מהסרטון:
| מבנה | בסרטון |
|---|---|
| הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו | I've normalized · has increased · has really been driven |
| משפטי זיקה (Relative clauses) who / which + clause — מידע נוסף על אדם או דבר | people who need · highest, which is · fuels, which will |
| סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה | be housed · been driven · has been estimated |
Pronunciation to watch
The speaker uses 29 contractions and reduced forms, such as we're, we've, you're. Say them the short way, as you hear them.
- The “th” sounds: thermodynamic /ˌθɝmoʊdaɪˈnæmɪk/, thermodynamics /ˌθɜː(ɹ)moʊdaɪˈnæmɪks/
- The “sh” and “zh” sounds: emission /ɪˈmɪʃ.ən/, cementitious /ˌsɛmɛnˈtɪʃəs/, implication /ˌɪmpləˈkeɪʃən/, equation /ɪˈkweɪ.ʒən/
- Long words — get the stress right: cementitious /ˌsɛmɛnˈtɪʃəs/, implication /ˌɪmpləˈkeɪʃən/, trajectory /tɹəˈd͡ʒɛktəɹi/, aluminium /ˌæl.(j)uˈmɪn.i.əm/, sustainability /səˌsteɪnəˈbɪlɪti/
How to practise with this video
- Listen to the whole video once without speaking and note the words you do not know.
- Shadow it sentence by sentence at normal speed, repeating each one until your rhythm matches the speaker.
- Record yourself and compare with the original, paying attention to words like cement, emission, cementitious.
מהי טכניקת השאדואינג?
שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.