The change in our world is unavoidable. We outface with this current situation because of the fast change that have become undisciplined. Belonging to the present time of our economic and industrial evolution appear to be unsustainable. Population increase, urbanization, technological advancements, and their effect on the environment are undoubtedly in the company of the key factors that are setting today’s world.  At the beginning of the twentieth century, the world’s population was 1.5 billion people, 6 billion at the end of the twentieth century, the exponential increase from 1.5 to 6 billion people during the short span of time is eruptive (population matters , 2018). The increase of urbanization of our planet is proportionate to the population growth in the last years. Both have contributed to the huge increase in size of energy, transportation, and manufacturing of the world economy through twentieth century. The biggest mistake in our technology world was that the choices was limited because they did not anticipate the effects of their use overall but in the short term, so the consequences were unpredictable.
For example, according to Hawken  only 6% of the total worldwide flow of materials, approximately about 500 billion tons a year, ends up in consumer products, while the rest (94%) ends up to the environment in the form of damaging solid, liquid, and gaseous wastes resulting into pollution. And unfortunately, this phenomenon is going on for a couple of centuries now (Malhotra, 1986). However, because of the increase in pollutants, the environmental challenge that we are facing is for the whole of the world and not for a regional. The past 100 years the earth’s atmosphere have a rapid increase concentration of greenhouse gases and pollutants which are caused from human activities which is driving the climate change due to global warming. Based on scientific research, this is the most important challenge in our days. Therefore, the Worldwatch Institute has recorded that, since 1990s, a lot of environmental and weather associated disasters are getting worse and worse with the passage of time all over the worls..  As a result, without exhausting natural resources, we risk the environment in which we live and from which we derive the whole economy.
Environmental impact of concrete
Portland cement is the main hydraulic binder that is used in concrete production (PCA, 2018), is an industry product that has very high embodies energy and thus consumes large amounts of energy and also emit large emissions of carbon dioxide (CO2), greenhouse gas to manufacture (Milne, 2018) . Specifically, concrete consists of 12% Portland cement, 8% water (any natural source), and rest aggregate (PCA, 2018). With all the construction going around the whole world, we are consuming more than 10 billion tons of aggregate (sand and rock), and 1 billion tons of mixing water annually in addition to the 1.6 billion tons of cement. 
Thus, in total the concrete industry uses 12.6 billion tons of natural resources per year, which is more than any another industry in the world. Another reason that affect the ecology of the planet apart from manufacturing cement are mining for raw materials, manufacturing/processing and transportation, which consume significant energy additionally to the 3 billion tons of the raw materials that are used for cement production every year.
How can we cut down the environmental impact of the concrete industry?
To reduce the environmental impact due to excessive use materials in the long term, their consumption should be reduced. For the next 50 years, the concrete rate consumption is hard to be reduced, so we must embark on using industrial ecology for short-term sustainable development. Which can be achieved by using the waste from one industry can be used as the source of raw materials for another industry. Also, reportedly, every year over 1 billion of tons of construction/demolition wastes are generated. Many cost effective methods as segregation of waste or others are available to recycle most of the materials including the requirement of aggregate for the fresh concrete mixtures. 
As a result, if we start making improvements to our resource efficiency, sustainable development will come soon.
The aim is to emphasis the use of concept of embodies energy of the materials and thus figuring out the best combination of materials/waste that can be utilized to prepare concrete for better sustainable environment.
The main issues discussed in the dissertation are:
1. To review the materials available to replace the use of concrete.
2. To review the need of recycled materials.
3. To review the ways that we can achieve sustainability in concrete.
2. Energy consumption in buildings
The ever-increasing use of energy worldwide has prompt major issues about impediments in supply, depletion of energy sources and the huge environmental burden involving global warming, ozone layer depletion and climate change. Energy consumption associated with buildings, both residential and commercial, has, in developed countries, significant contribution (between 20% and 40%) to the global energy consumption, outreaching other main sectors, such as industrial and transportation. The continuously growing population, the increased need for building services, along with occupants spending more time in the buildings, further strains the energy supply and demand crisis. Because of this, efficiency of energy utilization in buildings has become a major priority of energy policy regionally, nationally, and internationally. HVAC systems in the buildings are the main nodes where most of the energy use is concentrated. The present study examined the information available involving energy consumption in buildings, and especially information associated with HVAC systems. Several questions emerged: for example, was the essential information accessible for analysis? Which were the major types of buildings? In the breakdown, what end uses should be considered? Information from different countries was compared, particularly for commercial type buildings, and offices were analyzed separately in greater detail.
2.1. Energy usage worldwide
As mentioned above, energy use has become a major problem worldwide. Data on consumption of energy from the International Energy Agency (IEA) (IEA, 2018) indicate that, in the period from year 1984 to year 2004, primary energy usage has increased by 49% and carbon dioxide emissions by 43%, with a mean annual increase of 2% and 1.8%, correspondingly (Fig.1). Interestingly, data from prediction studies show that this rapid increase in energy use will continue in the future. Particularly, emerging nations, such as Middle East, Southeast Asia, South America, and Africa, are expected to increase their energy use at a mean annual rate of 3.2%, and to even outgrow the mean annual rate in the developed countries, like North America, Western Europe, Japan, Australia, and New Zealand, by 2020 (Fig.2). Noteworthy is the example of China that according to the study, the energy consumption will increase two folds by the year 2020 with a mean rate of 3.7% annually.
Figure 1: Primary energy consumption, carbon dioxide emission and world-population
Reference year 1984. Source: International Energy Agency (IEA) (IEA, 2018).
Figure 2: Global energy use by region (IEA, 2018).
Source: Energy Information Administration (EIA) (IEA, 2018).
Interesting results can be obtained from the analyzing of the trend of world energy indicators  between 1973 and 2004 (Table 1):
(1) Population growth is well below the GDP, thus with time the per capita income for the households is set to increase.
(2) Energy demand is growing at a higher rate than population stressing the already strained primary energy supply and demand, leading to the increase of its per capita value on 15.7% over the last 30 years,
(3) Carbon dioxide emissions growth rate is lower than energy consumption, but still showing a significant 5% increase during this period,
(4) electrical energy consumption has seen an explosive demand increase (over two and a half times) leading to a 18 % percentage increase in final energy consumption by the end users in 2004,
(5) Advancement in technology has decreased the energy consumption rate for obtaining the raw materials/primary energy, has resulted in the decline of 7% points.
(6) Higher GDP growth has a positive impact on the energy extraction, generation, transmission and utilization, resulting in an overall improvement of the global energy efficiency.
Figure 3:Global energy indexes from 1973 and 2004 (Brunel University, 2018)
Source: International Energy Agency (IEA) (IEA, 2018) (Brunel University, 2018).
Taken together, the above data support the link between energy use, economic progress and population increase, and challenge global policy efforts to reverse this course by implementing renewable and green technologies to increase energy efficiency. The truth is that globalization, the increased need for comforts and facilities, especially in emerging nations and the expansion of networks of communication, all lead to increased energy demand and, subsequently, to fossil fuel exhaustion and profound environmental consequences.
2.2. Energy usage in the buildings
For the most part, the energy consumption as a whole can be broken down into three wide categories: industry, transport and ‘other’, with the last category including service sector, agriculture and residential (Seed, 2018). Therefore, gathering data on building energy consumption becomes extremely challenging since it only accounts for a fraction of the services incorporated in the category ‘other’. However, taken its huge impact in total energy consumption in developed nations (taking up 20–40% of the total of the final energy consumption) (Seed, 2018), it becomes apparent that it should be regarded as a separate category and the third main sector, along with industry and transport, and be divided, at least, in two sub-sectors: dwellings and commercial buildings.
The continuously growing human population, the increased need for building services and amenities, along with the increase in time spent indoors, have resulted the energy consumption levels in the buildings comparable to the that of transportation and industrial activities (Table 2). In fact, industrial energy consumption has experienced a significant reduction in energy consumption ratio of nine points from 1973 to 2004, whereas the ‘other’ sector shows an increase in ratio for the same time period that is believed to be due to buildings.
Figure 4:World final energy consumption by sector (Seed, 2018)
Source: IEA (IEA, 2018) (Seed, 2018).
Despite the difficulty in gathering data on building energy consumption, by analyzing findings on the evolution (Fig. 3) and importance (Table 1) of building energy consumption (Seed, 2018), we were able to make some comparisons between countries or continents and to draw some conclusions:
(1) Fig.3 demonstrates building energy consumption use from 1994 to 2004 among UK, EU, Spain and USA. There was observed an annual 0.5% increase in UK building energy consumption, which falls below the EU annual rate of 1.5%. Interestingly, in Spain, energy consumption in the buildings was found to increase at an annual rate of 4.2%, much higher than both of the EU and Northern America’s (1.9%) rates combined. Potential causes may well be the economic expansion, the development of the building infrastructure and the advancements in building-services and particularly environmental control systems.
(2) Table 1 demonstrates final building energy consumption (%) both commercial and residential among UK, EU, Spain and USA for the year 2004. Notably, in 2004, EU total (residential and commercial) building consumption was found 37%, higher than industry (28%) and transport (32%). Even higher in total building energy use was found to be the UK with 39%, which is slightly above the EU figure. Partly, this was due to a deviation from the industry towards the service sector. Spain had the lowest rate of 23% consumption, but this number is predicted to increase rapidly the following years, due to the growing economic development, and to meet the EU average.
Figure 5 Energy consumption of buildings. Reference year 1994 (Luis Pe´rez-Lombard, 2007)
Source: Eurostat and EIA.
Table 1 Weight of buildings energy consumption (Seed, 2018).
Final energy consumption (%) Commercial Residential Total
USA 18 22 40
UK 11 28 39
EU 11 26 37
Spain 8 15 23
World 7 16 24
Year 2004. Sources: EIA, Eurostat, and BRE (Seed, 2018) (IEA, 2018).
Commercial and public-sector buildings, for e.g. hospitals, schools, museums, restaurants, hotels etc make up the service sector and require a number of energy services like HVAC, lighting and refrigeration. The continuously increasing population and the growing economy generate increasing needs in health, education and comfort services. In turn, increased demands in services lead to increased energy consumption. For instance, in USA, service energy consumption increased by 7% from 1950s to 2004. In addition, in the UK energy use in the service sector in 2004 reached 11% of the total energy use, same as the average European service energy consumption. In Spain, however, service energy consumption was relatively low, only 8%, but it is expected to increase massively, considering that it has multiplied by 2.5 between the years 1980 and 2000.
With regards to the residential sector, the factors determining energy consumptions are mainly the size and location. For example, small apartments consume less energy since there is less conditioned and transfer area, and less occupation (Seed, 2018). Other factors determining consumption as well as type of energy in residencies are the architectural design, the weather, energy systems and the economic level of the residents (Luis Pe´rez-Lombard, 2007). It is estimated, that dwellings in developed nations consume more energy (primary and final) compared to dwellings in emerging nations and will keep increasing with the establishment of new appliances, such as air conditioners and computers (Seed, 2018). Residencies in the USA use 22% of the final energy consumption, while in the EU it is 26%. In UK it accounts for 28% of the total use, compared with 15% in Spain. That is largely due to the climate difference, UK has a more severe weather, as well as on building architecture, prevalence of independent houses over blocks.
A prediction study performed by the EIA (Energy Information Administration) International Energy Outlook , examined future possible trends in building energy consumption(Fig.4). It was found that in the following 20 years, energy consumption in buildings will increase by 34%, at a mean rate of 1.5%. It was further estimated that in 2030, non-domestic sectors and dwellings will account for approximately 33% and 67% of total consumption, respectively. Southeast Asian spreading and subsequent construction rising will lead to an increased demand of energy in the residential sector. Interestingly, it is expected by 2020, that developed and non-developed nations will have analogous energy consumption in buildings. Rapidly growing emerging nations with galloping economies, trading and population, are followed by pressing demands for education, health and other services and, therefore, higher energy consumption. Particularly, it is believed that in the next 25 years, non-developed countries will double their energy use in the public services sector, with mean increase rate approximately about 2.8% per annum.
Figure 6 Buildings energy consumption outlook (Luis Pe´rez-Lombard, 2007).
Source: EIA (Luis Pe´rez-Lombard, 2007).
2.3. Heating, ventilation, and air conditioning (HVAC)
Due to the continuously increased energy consumption and release of CO2 in the build environment, energy efficiency in buildings and savings methods have become a main concern of energy policy globally (Luis Pe´rez-Lombard, 2007). An obvious example is the European Energy Performance of Buildings Directive (EPBD) (Luis Pe´rez-Lombard, 2007) . Particularly significant is the heating, ventilation, and air conditioning (HVAC) system that comprises the largest energy end use in both the commercial and non-commercial sectors and has become a necessity along with the need for thermal comfort (Seed, 2018).
Its prevalence becomes apparent when it is examined in contrast with another end uses. Table 4 represents energy-consumption percentage by various end use in the domestic sector among four different regions, Spain, Europe, USA and UK. It can be seen, that, at large, in dwellings HVAC takes up about three times the energy use than that of Domestic hot water (DHW). In the non-residential sector, HVAC energy consumption is estimated by the IDEA , as well as by other sources , to take up about 48%, still lower than the 57% observed in the USA. The burden of the HVAC at the European level remains unknown. Nevertheless, several sources have identified an important increase in air conditioning, particularly in southern regions, such as Spain and Italy.
Table 2 Energy consumption by end uses in the residential sector.
Figure 7: Energy usage (Luis Pe´rez-Lombard, 2007)
European administration data at national, regional or local levels are inadequate to provide the necessary information for effectively planning future energy policies and for directing action upon each of the end uses (Luis Pe´rez-Lombard, 2007). Governmental funded research by sector should be initiated for residential  and commercial buildings  in order to produce a complete database of the building stock (such as location, type, area, and age) and of energy parameters (such as, consumption, expenditures, and end uses) that will enable efficient planning for the future (Seed, 2018).
In developed regions, HVAC use takes up about half of the energy use in buildings which is almost 1/5th of the total national energy consumption. In addition, predictive studies estimate a huge increase of approximately 50% in energy use and conditioned area in the European Union  in the following 15 years.
2.4. Commercial buildings
In commercial buildings, the amount and form of energy needed depends hugely on the type of use and activities. This makes the data analysis very complicated since very few sources present findings typologically. Nevertheless, following reviewing of numerous data sources, some generic conclusions may be drawn:
(1) In the last few years in the UK, due to the expansion of floor area and the enhanced servicing levels outweighing increased efficiency, energy use in the non-commercial sector has been stabilized to some extent. This sector expands at a higher rate in other European countries mainly because of the enhanced application of HVAC systems in new buildings . Furthermore, new building construction rates in the UK are normally approximately 2%, whereas in Spain, for example, the mean annual new build rate is 6.1% increasing since 2000 and estimated to keep increasing. In 2003, service sector accounted for 11% of total energy use in the UK and was lower than the USA rate (18%) and equal to the EU (11%) (Seed, 2018). From the above, it becomes apparent that the service sector should not be overlooked when planning energy policies, since it has the highest growing rate compared to other sectors like residential and industrial.
(2) From the non-residential building, office and retail are the most energy consuming categories taking up more than 50% of the total energy use. Hotels and restaurants, hospitals and schools follow in that order (Figure 8).
Figure 8: Energy use in the commercial sector by building type (Seed, 2018)
Year 2003. Sources: EIA, IDAE and BRE.
(1) As it is being illustrated in Fig. 5, HVAC is the major end use in all building types with a load reaching almost 50% for office buildings. Lighting is next in the rank with 15% weight and appliances follows with 10%. How energy end use is allocated depends on the building type (Fig.5) as well as in the energy intensity of the buildings (Table 6). Thus, it is apparent that independent studies would develop according to building types.
Figure 9 Consumption by end use for different building types.
Figure 10: Average energy usage by buildings type in USA
Year 2003. Source: EIA.
2.4.1. Office buildings
Among commercial buildings, offices have the greatest energy consumption and CO2 emissions along with retail. US offices, for example, take up 17% of total non-residential area and approximately 18% of the final energy consumption. Offices in Spain take up one third of the energy consumption of the non-residential sector and around 2.7% of the total energy use. In UK, the offices account for 17% of consumption and 2% of the total use. From the above, it becomes clear that commercial analysis should begin with office buildings. Further reasons in favor of energy surveys on the office sector:
(1) The economic prosperity led to several new business developments in main sub-urban areas and subsequent enhancement of total built area for office buildings . In Spain, 9.3 Mm2 were built during 1990-2000. Furthermore, per capita area is around 4 m2 in the USA double times the EU figure of 2 m2. Lastly, between 2000 and 2005 the total floor area in offices was increased in the UK by approximately 4% (Seed, 2018) .
(2) Lighting services, IT equipment and air-conditioning needed have been continuously increased. Above 90% of offices in Spain make use of IT equipment and almost every new office has air-conditioning. In the UK, although the mild weather, above half of the new offices use air-condition.
(3) Table 7 presents the energy-consumption percentage in offices by different services. It is seen that three key services, namely: HVAC, lighting, and small power, make up around 5/6th of the total (Seed, 2018).
Figure 11: Energy consumption in offices by end use (Luis Pe´rez-Lombard, 2007) (IEA, 2018) (Seed, 2018)
In developed countries, end energy usages in buildings accounts for 20-40% of total energy consumption and in EU and USA is above industry and transportation usage. Nevertheless, accessible data are inadequate and not relative to the significance of this sector. Moreover, it is not studied as an independent sector making hard to identify the underlying alterations that influence energy consumption in buildings (Luis Pe´rez-Lombard, 2007) (Seed, 2018). Therefore, it is necessary that detailed information becomes accessible to allow for proper analysis and future policy energy planning. Therein, EIA studies in the USA on residential and commercial building energy consumption are a precious source.
Due to increased consumption of energy and CO2 emissions on the build environment, energy policies have focused in establishing new building regulations and guarantee programs with the lowest demand based on energy efficiency strategies. The inescapable need for thermal services and HVAC systems (and their related energy consumption) account for around half the energy consumption in buildings and approximately 10-20% of total energy use in developed countries (Seed, 2018) (Luis Pe´rez-Lombard, 2007).
During the following years, it is expected that building energy consumption will continue its growing trend as a result of the development of built area and related energy requirements, in case, of course, exhaustion of energy resources, environmental decay and economic recession permit it. A viable energy future will depend upon private initiative, as well as, government involvement with the development of policies focusing on energy efficiency, novel technologies for energy production, reducing energy use and enhancing social awareness on the balanced use of energy (Seed, 2018) (Luis Pe´rez-Lombard, 2007).
3. Typical construction materials
Whichever material is used for construction aim is a building material. Many of materials that are used to construct buildings, such as wood, clay, rocks, sand and twigs, are naturally occurring substances. Except of them, numerous of man-made products are in use which some of them are synthetic and some do not. For a lot of years now, the manufacturing of construction materials is an established industry in the majority of the world and it provide the constitution of habitants and structures containing homes. 
Concrete is a building material which is a mixture of crushed rock or gravel and fine aggregate, bound together with a paste of cement and water (PCA, 2018). A series of concrete variants which can have the desired properties for both fresh and hardened states for a wide range of applications can be created from a variety of different types of cements, aggregates, chemicals mixtures, and additions.
Concrete was popular to the Romans, Egyptians and to earlier Neolithic civilizations (Concrete network, 2018). The secrets of concrete were rediscovered in recent times after the collapse of the Roman Empire. The first use of the Portland cement; the most significant date in the history of concrete, was in 1824 (Concrete network, 2018). From the middle of the 19th century, a large number of projects have been made with base material the concrete, such as big buildings, networks of roads, and rivers dammed. The face of whole world has been revolutionized because of this invention namely concrete. 
3.1.2. Use of concrete
Concrete role is often unseen but is major in our everyday lives. For example, North Sea oil platforms make full use of and derive benefit from its strength and durability to sea defenses. The thermal mass and acoustic properties results in better indoor environments for the occupants. Thermal mass makes the building’s indoor environment more resistant to the outside temperature changes and the acoustics properties attenuates the outside sounds that reaches inside (CIBSE, 2016) (CIBSE, 2017).
Concrete use in roads, runways and motorways assist in transportation and trade, while in rivers, lakes and parks it assists in making exceptional landscapes (masterbuilder, 2018).
Its ability to hold water makes it possible to make dams, ring mains and small river beds. While its inertness and strength make it the best choice for drainage systems, underground drains etc. (masterbuilder, 2018)
3.1.3. The future
The most important aspect in terms of concrete usage will be judicial use, lean use and green use of the earth’s resources (Greater London Authority, 2016).
Concrete can play an impeccable role in the sustainable environment. It can easily have recycled, thus, requiring less energy in its manufacture and supply and resulting in the overall reduction of the embodied energy. Also, the benefits from high thermal thermal mass in buildings due to use of concrete, can help reduce the energy requirements for environment conditioning services (CIBSE, 2017).
Cement is the main material in concrete. It binds the aggregates together to provide strength and durability (PCA, 2018).
Through the years many types of Portland cements have been developed and introduced in the industry. Such as cements for fast hardening, cements for sulfate resistance and white cement for architectural finishes and what are called composite and combination cements. The European and British Standard for cement (EN 197-1) lists a number of common types of cements, all of which include Portland cement clinker (BS EN, 2011). Except Portland cement (CEM I), all the other cements contain other main constituents such as fly ash, limestone or ground-granulated blast furnace slag. These cements are called ‘factory made composite cements’ with nomenclature CEM II to CEM V (BS EN, 2011).
Hydration is a chemical reaction between cement and water which is the setting and hardening of cement. It produces heat and is not able to be undone. Setting involves cement paste from being a wet and workable material into hardened solid form. The strength of the hardened state at first increase, then becoming gradually slower and continuously obtain the strength for a significant period. Cement strength classes introduce a cement rating and quality standard system based on prisms of mortar tested in a laboratory.
All of the British cement manufacturers have to comply with the appropriate British and European Standard by preparing the cement test reports, bags, delivery documents with the name, number, and date of the Standard used. Most cements are manufactured and supplied in compliance with Standards with statement and certification revealed by affixing the CE marking. In addition, they also have to be verified by the nationally-recognized third-party product certification scheme – “the BSI Kitemark Scheme for Cement”.
3.2.1. Delivery and storage
Cement can be delivered in bulk(tankers) or in bags. Tanker delivers bulk cement in cargo of more than 20 tones and put them into storage containers by compressed air. Bagged cement comes in bags weighing 25kg, while one tone bags can also be obtained from some suppliers for different purposes.
To prevent the formation of lumps of cement because of moisture it should be kept in storage in dry conditions, if that does not happen we will have the phenomenon called air-setting. This kind of cement should not be used as the concrete strength have reduced considerably.
3.2.2. Sampling and testing of cement
To have great effect of sampling and testing of cement it is necessary to have a well- equipped laboratory with controlled environment.
Cement test reports which includes results from various physical and chemical tests are provided to the users. While doing so the concrete producers can monitor cement quality by continuously assessing the data, thus avoiding unnecessary duplication of costly tests on cement and save time.
Aggregate is the mixture of gravel, sand and crushed rocks which are then mixed with cement and water to make concrete. The choice of appropriate material is important as the major component of concrete is aggregate.
Two types of aggregate mixtures are used, namely:
• Fine aggregate; which consists of fine sand and gravel and can easily pass through 4-millimeter opening.
• Coarse aggregate; as the name suggests consists of larger pieces of gravel/ crushed rocks.
Both the British guide UK guidance documents i.e. BS EN 12620 and PD 6682, state the requirement that concrete must be made from natural aggregates. BS 8500-2 specified about recycled aggregate (RA) and recycled concrete aggregate (RCA) that can be used in specific circumstances. Manufactured lightweight aggregates comply with standards of BS EN 13055-1 are occasionally used.
To prevent the change of their volume, aggregates should be hard and resilient enough not to erode or decompose from weather under any circumstances, to ensure longevity of the concrete structure. To provide high-strength concrete need special properties. BS EN 12620 provide information about these properties. Unfortunately there aren’t any tests to check the durability of the aggregate and thus the selection mostly relies on the experience of the person in charge of preparing concrete mixture.
3.3.2. Recycled aggregates (RCA & RA)
RCA & RA are two types of recycled aggregate that BS 8500-2 give authorization to use in concrete. RCA consists of crushed concrete and RA resulting from reprocessing of inorganic material that is used before in construction.
3.3.3. Aggregate delivery:
As mentioned above there are no tests except physical inspection to check the quality of aggregate, thus a simple physical check on the fine-ness and cleanliness are conducted before the delivery. If a sample of fine aggregates are not washing enough, the material will have rubbed between the palms of the hand. BS EN 1097-3 can help to distinguish changes in grading or shape that have been caused by the loose bulk density in aggregates.
3.3.4. Storage of aggregates
To protect aggregates from intermingling and contamination from other materials they should be stored in a concrete base and separate them in different sizes to prevent spillage from one bay to another. Concretes that are delicate to in aggregate moisture, e.g. self- compacting concrete, materials must be covered.
In our days, steel construction gives architects the opportunity to create one of the most challenging constructions that they might be sketch in their minds. Art, imagination, ad steel taming can work together to in a lot of ways. 
Figure 12 City of Manchester Stadium – Watson Steel Structures Ltd (World stadiums, 2018)
3.4.1. Strength and durability
Steel due to its high strength to weight ratio allow any construction to extend in any distance in sophisticated and low-cost way more than any other construction material. It can provide ductile and flexibility under extreme loads without crushing. Also, steel have the ability to resist from intense winds and earthquakes due to its impressive strength and elasticity. Some of the beam-to- column connections in a building are made with the help of steel and are solely designed to support vertical or gravity loads.
More than any other building material, steel-framed structures are highly durable, do not age or decay and they last more than refurbishment is needed.
Steel is a sustainable construction material. Good design of steel can minimize the energy use and the environmental impact of a building. Codes of practice and design standards provide the possibility of a better choice of materials. Long-life-span structures encourage adjustment and re-use.
Many new fabrication technologies including CADICAM have help in producing less waste material a has improved productivity. Moving to off-site manufacture also helped to give a better quality and less faults.
Figure 13 Canary Wharf , London (72,3OO tons of steelwork supplied by Cleveland BMge UK LM) (Tighe, 2018)
3.4.3. Speed and productivity
Fast building manufacture is crucial as it can greatly decrease the budget, financial costs and overhead expenses. And if steel is utilized in the structural works it can reduce both cost and time on construction due to its lighter compared other framing materials and it needs a smaller space for foundation.
UKs annual steel production has made huge improvements in efficiency, technology and productivity and as a result of it has managed to export around 10% of its steelwork industry in world- wide companies with large contracts in Japan, China, Gulf, Africa, South America, and Europe.
In UK 80% of the structural frameworks are carried out using steel (McCann-Bartlett, 2018)
Figure 14: Different materials used in Construction in the UK (McCann-Bartlett, 2018)
The past 20 years has seen the industry winning 95% of all single store framed construction and 70% of all multi-story construction (McCann-Bartlett, 2018).
UK economy have reached a significant financial contribution by The Brick Industry which amounts to 550 £ million from which the clay construction products is about 670£. 
Figure 15: Value of UK production of heavy clay construction products (ONS, 2018)
The varieties of brick are around 1200 types which some of them are from hand-made manufactured by traditional techniques or innovative clay cladding systems. Depending to use or by manufacturing technique they can be categorized (AzoBuild, 2018).
Production Techniques and Brick Types (AzoBuild, 2018)
There are three techniques used to form bricks (AzoBuild, 2018):
1. Soft mud process (AzoBuild, 2018).
This kind of brick is a soft irregular outline which is made from a free-flowing clay mix with more than 30% content is putted in carton boxes by hand or machine and then dried and fired (AzoBuild, 2018).
2. Extrusion process / wire cut.
Wire cut is the brick that is cut into columns using tightly strung steel wires. Through a lubricated die clay forced by an auger to form columns of stiff clay which can be deal with roll-texturing, pigment and sand-blasting spraying to create a series of textures and other aesthetic result (AzoBuild, 2018).
To create a regular size, shape and square edges brick its necessary to press the clay into a mold box. Fletton bricks from Lower Oxford are the almost entirely confined of manufacture of clays. Bricks are mentioned to as Facing (aesthetic), Engineering (strength) and Common (utility) (AzoBuild, 2018).
Clay, water, and energy are the main materials of brick. The principal materials are clay, energy, and water (AzoBuild, 2018). The consumption of clay per annum in UK is 8.0 million tones and energy consumption at 5.4 Terawatts. (AzoBuild, 2018)
Table 3 Consumption of clay by heavy clay construction products (AzoBuild, 2018)
UK Production Of which used for heavy clay products
Common Clay and Shale 10,838 7,880
Fireclay 595 287
Non-energy minerals 306,875
Heavy clay construction products consume less than 3% of the non-energy minerals extracted in the UK. Year 2000 Source: British Geological Survey (AzoBuild, 2018)
3.5.3. Concrete bricks
Concrete bricks usually named as blocks and they have the color of pale grey. Their main composition is a small dry aggregate which is take the form in a steel molds by vibration and compaction in a static machine or in an ‘egg layer’. At the end of this process the blocks are cured using a low-pressure steam. In contrast with clay bricks, concrete blocks are produced in wide range of shapes, weights and sizes and they are also available in a larger range of face treatments. 
Concrete bricks can be obtainable in many colors as it made with sulfate-resisting Portland cement or equal. For harsh environments like retaining walls or wet conditions it need a sufficient amount of cement. They must follow to standards BS 6073, EN 771-3 or ASTM C55.
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