Energy And Indicators Related To The Construction Of Office

Concrete in the Sydney Opera House

Discuss about the Energy And Indicators Related To Construction Of Office.

Sydney house is a center of performing arts located in Sydney of the New South Wales. The building holds numerous venues for performing hosting 1500 performances yearly. The building occupies 1.8 hectares of land space and is 600 ft. tall and 394 ft. at widest point. Sydney house contains shells of precast concrete composing of 75.2 meters radius sphere mainly used to form the structure roof supported by ribs of precast concrete. In addition to shells of tiles and walls of glass, the exterior of the building is covered with granite quarried panels. The treatments of the interior is too conducted with concrete. The building hosts recording studio, restaurant and cafes, bars, concert halls and theatre for drama.

Concrete used for construction purposes is a hard structural material comprising of sand and gravel placed strongly together with cement and water. Sand and gravel are chemically inert particles commonly known as aggregate. Previously, clay was the main substance that was being used as a bonding material. Lime and gypsum were used as binders in developing a substance that closely resembled the today’s modern concrete (Adalberth, 2014). Lime which is the chemical calcium oxide, derived from limestone, chalk and oyster shells continued to be used as the main agent for forming cement till the 1800s. A few years later, a mixture of limestone and clay were burned and grounded together by Joseph Aspdin and the mixture was named Portland cement which dominantly existed as the main agent of cementing applied in the production of concrete.

Aggregates are commonly grouped in relation to their sizes generally as either fine which possesses sizes ranging between 0.025mm to 6.5mm or course ranging between 6.5mm to 38mm. aggregate materials must be free from unwanted mixtures such as soft particles and vegetable matter since even slight contents of organic compounds of soil usually encourage chemical reactions eventually affecting the concrete strength.

Methods of aggregate or cement production and the manifested qualities of the aggregate or cement that is utilized in making concrete usually defines the characteristics of the concrete. For example, the ratio of water to cement usually determines the character of an ordinary structural concrete (Allen & Iano, 2011). The concrete is stronger when the content of water ratio is equal or lower to that of cement.  Presence of water is needful for simply ensuring that all particles of the aggregate are surrounded by the paste of cement completely, aggregate spaces are filled and the concrete achieves the desired viscosity which enables it to be poured and spread efficiently and effectively. Another factor of concrete durability is also the cement amount in comparison to the aggregate which is usually expressed three-part ration – cement to fine aggregate to coarse aggregate. Relatively less aggregate is considered where a stronger concrete is desired.

Types of Concrete

Concrete strength is usually measured in either pound per square inch or kilograms per square centimeter of force required to crush a given sample of hardness or age. Environmental factors possess great impacts on concrete particularly moisture and temperature. Unequal stresses of the tensile are observed whenever a concrete is exposed to premature drying which can never be resisted in an imperfect state of hardness (Zhang et al, 2014). Concrete is normally kept damp for a while immediately upon pouring through a process called curing to slower the shrinkage process which frequently occurs as it hardens. The strength of concrete is also affected by adverse temperatures. With an aim of reducing the impacts resulting from this, calcium chloride and related additives are added to the cement mixture. These additives accelerate the process of setting thereby, in turn, generating sufficient heat which counteracts low temperatures. Concretes that are large and its proper coverage cannot be achieved are usually not poured in temperatures of freezing.

Concrete hardened onto embedded metal commonly steel often referred to as either reinforced concrete or ferroconcrete. The steel metal offers contribution to improving the tensile strength of the concrete. Stresses such as the action of wind, earthquakes, strong vibrations or forces triggering bending are not normally withstood by plain concretes hence making it not suitable for most applications. The tensile strength of steel and the compressional strength of concrete enables such reinforced concrete to withstand heavy stresses for a good duration of time (Bergsdal et al, 2015). The ease of positioning steel closer to or exactly at the point where strong stresses are expected is made possible through the fluidity of the concrete mix.

Prestressed concrete forms another innovation in the construction field. This type of concrete is obtained through processes of pre-tensioning and post-tensioning. Lengths of steel wire, cables and ropes are placed in an empty mold then stretched and anchored. After pouring of the concrete and its settlement, anchors are released and as the steel is adjusting to its original length, the concrete is compressed whereas, in the post-tensioning process, the steel is made to run through ducts created in the concrete. After hardening of the concrete, anchoring of the steel is done on the exterior of the member by use of a gripping device (Binici et al, 2012). The transmitted intensity of compression is regulated through the application of a measured quantity of stretching force to the steel.

Factors Influencing Consideration of Concrete

The following are the common types of concrete:

• High strength concrete. It is a type of concrete that contains the most strength of approximately 40Mpa.
• High-performance concrete. It is a modern way of referring to the modern and developed concrete of nowadays. This type of concrete outperforms the normal type of concrete in very many aspects such as lifespan mostly under corrosive environmental conditions, permeability, density and placement flexibility.
• Lightweight concrete. This type of concrete is obtained through using small, lightweight aggregates for example balls of Styrofoam or through the addition of foaming agents to the concrete mixture. Lightweight concretes are used in non-structural elements since they have low structural. The most suitable example is the aerated autoclaved concrete blocks which are frequently used in making walls (Van et al, 2010). It is also called cellular concrete.
• Self-consolidating concrete also known as self-compacting concrete
• Shot Crete or sprayed concrete. A thick or uneven coating is formed through spraying of concrete onto a surface. The main difference existing between this type of concrete and other types is that sprayed concrete is not poured into a form or mold but directly sprayed on a surface. It is commonly used in infrastructure projects and repairing old or cracked surfaces of concrete. It is at times also called hunting.
• Water resistant concrete. Most common concretes are usually permeable to water in that they allow water to pass through them. Water resistant concretes are developed to possess replacement of fine cement particles that resists the passage of water through them. They are very useful in the underground construction of structures such as basements and water storage structures or at times roofs.
• Micro reinforced concretes. These are newest and most complicated type of concrete. They are accompanied by small amounts of steel, fiberglass and fibers made of plastics that are meant to alter the concrete properties to meet the desired objectives (Cole, 2009).

• High compressive strength but a lower strength of tensile. Minus compensating, concrete would be failing from stresses from tensile even in situations of loading in compression. Instead, concrete elements exposed to stresses from tensile must be subjected to reinforcement s from materials such as steel which is stronger in handling tension.at low stresses, the elasticity of concrete is usually constant and begins to reduce at stresses which are of higher levels as matrix cracking develops (Tay & Show, 2014). Concretes usually possess very low thermal expansion coefficients and it eventually shrinks as it matures. As a result of shrinkage and tension, all structures of concrete cracks to some extent. Creeping, in turn, occurs to concretes that are exposed to the long duration of forces. The density of concretes usually varies but is generally approximately 2400kgs/m³. The most common concrete is usually the reinforced concrete which commonly utilizes steel as the main reinforcement material. With all factors constant and equal, lower water content concrete against cement usually forms the strongest concrete than that with a higher ratio (De et al, 2013). The resultant quantity of cement materials to influences the strength of the concrete, demand for water, shrinkage, resistance to abrasion and eventually density of the concrete. All concretes must crack regardless of the availability of enough or reliable compressive strength. In addition, high hydration rate makes high Portland cement content mixtures to crack more readily. Shrinkage usually occurs during the concrete transformation from plastic state to solid through hydration process. This often occurs during finishing operations whenever the rate of evaporation is high though, during normal environmental conditions, plastic shrinkage cracks happens almost immediately after placement.
• Elasticity (Sheety, 2013).  The concrete elasticity modulus is normally a function modulus of aggregates elasticity modulus and the matrix of the cement and its proportions. At low stress, the elasticity modulus of concrete is almost constant but progressively begin at higher levels of stress accompanied with crack development. A hardened paste elasticity modulus is usually in the order 10-30 GPa and aggregates ranging between 45 to 85 GPa whereas that of concrete composite falling between 30- 50 GPa.

• Shrinkage and expansion (Sharma et al, 2011). Concrete possess a low thermal expansion coefficient. In addition, whenever limited provisions are availed for expansion, large forces are created resulting to cracks in some parts of the structure that are not in apposition of either sustaining the force or the repeating contraction and expansion cycles.  
• Thermal conductivity concrete possesses almost average thermal conductivity which is way lower than those of metals but greatly higher than those of other materials used in building or construction for example wood which is a poor insulator. Fireproofing of structures made in steel is normally achieved through the erection of a concrete layer. In contradiction, fireproof forms a wrong term to prefer to insulators mostly in situations where fires possess very high temperature which might trigger chemical changes in concretes which eventually causes very significant damages to the concrete (Dimoudi & Tompa, 2008).
• Shrinking of concretes is a continuous process as it matures. This due to the continuous ongoing chemical reactions within the concrete material. In addition, the shrinkage rate rapidly falls over a time duration. Generally, concretes are considered not to shrink past the age of 30 years as a result of hydration. Concretes normally cracks due to either stress from tensile facilitated by shrinkage or usage or setting stress. Different mechanisms have been developed or adopted with an aim of overcoming this (Roodman et al, 2009). These mechanisms include: limitation cracks and its size is facilitated through fiber reinforcement concretes which uses fine fibers widely distributed all over the mixture or larger metals and other elements of reinforcement.  In most big structures, joints or concealed saw-cuts are enabled within the concrete with an aim of making inevitable cracks to be experienced in places where they can be easily and efficiently be handled.
• Shrinkage cracking. Cracks of shrinkage are experienced whenever members of concrete undergo controlled volumetric changes or shrinkage due to processes of drying, autogenous shrinkage and effects of thermal conductivity. Regulations are either provided internally exhibited through an ununiformed drying process, shrinkage and reinforcements or externally through supports, walls and various conditions of the boundary (Raut et al, 2011). Upon surpassing of tensile strength, a crack normally develops. The amount of occurring shrinkage frequently influences the number and width of crack shrinkage which develops. In addition to this factor of influence are the reinforcement amount and its spacing provisions. In 2-3 days of placement, plastic cracks are observed or visible as shrinkage resulting from drying develops over a longer time duration. When the concrete is in young age, autogenous shrinking also occurs resulting from a reduction in volume which concurrently originates from chemical reactions present in the Portland cement.
• Tension cracking. Concrete members are usually exposed to tension by the loads applied to it.
• This is a resultant deformation or permanent movement of a certain material with an aim of overcoming stress exposed to it. Creep is usually observed on concretes that are exposed to long duration forces. Creep is rarely caused by the short-term forces such as earthquakes and wind. Concrete structure or element may sometimes experience limited cracking as a result of creep existence but must rather be controlled. Shrinkage, creep and cracking are all reduced or regulated through by the quantity of primary and secondary concrete structures reinforcing.
• Water retention (Eguchi et al, 2010). Mote water is held by the Portland cement concrete. Other types of concretes usually allow more water to pass through them such as previous concretes hence provide the most suitable option or alternatives to Macadam roads since they do not demand storm drains fittings.

The current types of concrete are better than the older versions or types of concrete since the today concrete possess better and improved characteristics features which favors the objectives of building construction projects as discussed above.

• Concrete ingredients are easily obtained and available
• It is not affected by defects and flaws unlike natural stones as it is free from them
• Are easily manufactured to desired strength with economy (Pacheco & Jalali, 2012).
• It possesses high durability properties
• Easily cast to any desired shape in the working site making it economical
• It exhibits limited to cost of maintenance
• Can efficiently withstand high temperatures
• Facilitates safety of the fire safe building as it is noncombustible
• Resistivity to wind and water hence resourceful in storm shelters

• It contains a lower tensile strength when compared to other materials of binding
• It possesses limited ductility features (Okamara et al, 2011).
• It entails high weight compared to its visible strength
• Some concretes usually entails soluble salts causing efflorescence

Concrete possess several advantages as it is strong, durable and affordable but besides these many advantages, there stands a very significant limitation caused by the same concrete. This is its carbon-intensive process of production. Most of the elements of concrete such as sand, water, and gravel are natural apart from cement which possesses a very significant implication to the environment.

Its industrial process of extraction, development, and generation of increased temperatures during and in the process of production results to the emission of a very large amount of CO2 to the atmosphere of roughly 1 ton in every ton of produced cement (Naik, 2008). This limitation has led to the development of other most suitable alternatives which more environment-friendly in the placement of concrete hence Hempcrete is considered a better alternative.

Hempcrete as an alternative to concrete is a cost-effective and environmentally friendly alternative hence the most suitable alternative for housing and construction of large projects. It is developed from mixtures containing water, hemp a binder based lime. Concurrently blocks of hempcrete are capable of absorbing large quantities of CO2 forming the main environmental feature making the material most suitable house construction for human dwellings and commercial purposes.

There exist very many reasons and advantages triggering consideration of hempcrete as a construction material over other building materials such as concrete (Flower & Sanjayan, 2016). These advantages include the following:

• Friendliness to the environment
• The low footprint of carbon
• High resistance to wind
• It Is a very good insulator
• Possess limited risks and hazards during handling
• Has got low thermal conductivity properties
• It can be recycled completely or wholly
• High durability properties
• It possesses high resistance to pests

In addition to the advantages exhibited by the hempcrete as an alternative option to concrete, it also possesses the following disadvantages:

• It withstands limited load amounts (Morel et al, 2016). The loads are usually carried by a frame hence the frame is very essential. This challenge is widely minimized through the filling of earthbags with either hempcrete or a mixture similar to it. Wide walls of earthbags avail the desired thickness which supports single loads on small and simple structures.  
• In order to comfortable build, raising o forms are required. Earthbags get rids of the need of form and formwork. In addition, vetiver grass should be used in place of hemp which is also an insect resistor and rot resistant simultaneously.
• It is accompanied by increased costs, expenses and environmental footprints which originates from illegalizing of hempcrete in most places hence encouraging transportation of this material under long distance (Gonzalez & Navaro, 2014).

Most housing buildings usually possess 30-40 tons of embodied carbon which is absorbed by hemp as the plant grows hence saving buildings a larger part of CO2 creating a negative carbon footprint. It is thus very essential for the replacement of embodied energy with a negative embodied energy in almost zero homes of carbon.

Walls nature of being lightweight implies limited supports and existence of lighter foundations thus saving time and cost. Timber and permeable hemp blocks are used in the structural frame construction.

A lime of hemp is a product of low energy. Costs of construction can be lower compared to the prevailing traditional building materials (Khudhair & Farid, 2009). Transportation and handling of products are made easier since they are of lightweight together with shallower foundation requirements. Hemp lime being ductile too aids in avoiding costly movements of joints.

Advantages of Concrete

Reduced heating and cooling requirements lead to reducing the operational cost which is generally achieved by the enhanced insulation and the characteristics of the low U value of hemp-lime. The permeability to vapor of the products from hemp lime too helps in forced ventilation requirements reduction and de-humidification via installations of air conditioners. Concurrently, the continuous maintenance is reduced through utilization of durable lime binders (Guggemos & Horvath, 2010).

The warmth within a building is facilitated by the high thermal insulation of the hemp-lime products. Condensation of the trapped moisture within the building is avoided through the high permeability to vapor facilitating the through the transfer of humidity. This eventually assists in maintaining and improving the quality of the air within the building while controlling humidity together with limiting or discouraging the growth of molds and fungi that could interfere with human health.  

Hemp blocks usually hold back absorbed heat during sunny periods which the heat is not needed by the internal living but utilized later when its need arises for example during nights and overcast periods hence saving on other related costs.

Conclusion

Calculation of embodied energy of building materials

This is an energy required to construct and maintain a construction project premise i.e. with a wall of brick or even concrete and other materials hence it is the required energy in making bricks, transportation to site, bricklaying, plastering and maybe even painting of the same material (Harris, 2011). The most preferred practice that is encouraged is to include demolition and recycling energy requirements. The figure below provides a summary in form of a flowchart elaborating the essential elements for estimating embodied energy:

The below formulae and steps are applied in calculating embodied energy of building materials including concrete and hempcrete:

Constituent materials establishment.

Calculation of weights of the constituent materials in m² of the wall of cavity

Application of embodied carbon factor

Addition of constituent materials embodied carbon aimed at establishing the total embodied carbon

In conclusion, hempcrete is generally a better building material to applied during construction of housing projects in comparison to other building materials such as concrete since it possess several advantages as mentioned above with environmental protection being the main through emission of low carbon footprint.

References

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Allen, E. and Iano, J., 2011. Fundamentals of building construction: materials and methods. John Wiley & Sons.

Disadvantages of Concrete

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