Buildings, Materials and Fire - Assignment Example

Running Head: Title of the Work Name Name of Instructor Subject Institution Date 1) Calculate and then place in descending order the density of the following materials: a) 3.6m3 C25 concrete of mass 7920kg, b) 2m3 Vermiculite of mass 160kg. c) 3200 x 50 x 75mm Mahogany of mass 7800g, and d) 10cm3 water of mass 0.01kg, 2) A concrete lintel has the following dimensions 1.600m x 0.160m x 0.100m and a bulk density of 2100kg m3. The lintel contains 2 reinforcing bars of diameter 25mm which run its full length. If the density of the rebar is 7830kg m-3 calculate the mass of the concrete in the lintel. 4. Three classes of stones, their formation and difference in strength and durability. Building stones are divided into three classes namely, Igneous or metamorphic rocks, the sedimentary rocks and the marbles Igneous They are the rocks which apparently are believed to originate from heat, probably the volcanoes. The crystallization of the molten magma in the earth’s crusts causes the formation of these rocks. When there is an extrusion of lava to the surface the rocks are termed as igneous. The metamorphism ones are formed due to the realignment of the molecular structure in solid state. Sherwyn (2008, pp66-78) .They contain silicate minerals such as feldspar, and quartz. In addition they have ferromagnetic minerals which include pyroxenes and mica. These rocks have an accumulation of molecules making them to be very strong. The chemical action of the dissolved salts leads to the formation of limestone. Sedimentary rocks The sedimentary rocks are formed due to the deposition of the rubbles and, the solutes as a result of physical and, chemical breakdown due to weathering process of the parent rock. They assume a layered structure due to the successive overlapping of the material. Their joints seem to be at right angles. Their joints are closely spaced and may be beneficial in building process, as it reduces the building material. They contain silicate minerals in conjunction with congloremmete and the sandstone .In practice they may be grouped into three the course grains, the fine grains and the mineraled clayed. Metamorphic rocks They are rocks that arise due to the effect of metamorphism of re crystallization of either igneous or sedimentary rocks. The effect of heat and pressure has also contributed to their change. For instance slate resulted from shale. They tend to have small particles and are relatively strong. 3. Define the terms “Bulk density” and “Solid Density Bulk density is the weight of a given particle per unit volume Solid density is the weight of a given fixed volume within a material which is solid. 5. Which of the three types of rock has the greatest percentage porosity? How does this relate to the grain shape? The sedimentary rocks tend to possess a lot of porosity. This attribute is due to their largely irregular shaped grains. 6. Provide an example of 1 type of stone from the rock classes – metamorphic, igneous and sedimentary and give examples of their use in construction. Igneous Granite which has quartz. Used for building houses Sedimentary Sandstone and shale. Lime stone in making cement. It may undergo processes and used in the manufacture of cement. Metamorphic Slate Used for building houses 7. From your results answer the question: “Does a high porosity value increase or decrease the water absorption coefficient Porosity gives the ratio of the voids to the overall volume of a given substance. It gives the capability on how a geological substance may store water. When the aggregates are tightly packed the porosity of the material is reduced. 8. Define the terms “Initial rate of absorption” and the term “capillary action” and the affect that pore size will have on them Initial rate of absorption is the amount of water a substance would take in water into its particles Capillary action is the act whereby water rises in substances via narrow tubes or pore. This is usually as a result of adhesive forces between water molecules and the substances. The size of the pore has great impact on the initial rate and the capillary action. Wide pores would lead to an increase in the initial rate of absorption and the capillary action whereas, small pore size would lead to decreased initial rate of absorption and capillary action. 9. How does initial rate of absorption affect the bond between bricks and the mortar? The aspect of initial rate of absorption has a massive effect in the bond between the bricks and the motors. This is because; each of them tries to compete to retain water which ensures proper cement is created at the bond. When the brick is the one that sucks a lot of water from the motor, it will lead to depreciation of the motor making it to stung out from the joint making it to become stiff. This ultimately, hinders the next layer from bonding correctly. On the other hand if the motor wins the battle, the bricks would appear to float the bed of the mortar. 10. Water absorption is an important factor in the durability of a brick. State two adverse conditions that could arise from excess water in bricks There may be occurrence of efflorescence where by the bricks would absorb much water, and when it freezes the bricks would appear to crumble. 11. What affect does the carbon content have on the ductile/ brittleness properties of mild steel? Carbon tends to increase the ductility of a material. The carbon bonds tend to weaken the mild steel structure making it to 12. Describe briefly, the following heat treatment processes: a. Annealing, This is the process whereby the material is softened to achieve properties which can be machined. Takadoum (2008, 88-97) .The material is slowly transformed in an Austenite region. The material then undergoes a cooling till a ferrite cementite region. This may be achieved by a controlled cooling in the furnace. b. Normalizing Entails raising the temperatures to an austenite region in which it is held at this temperature till the material has been fully converted to austenite. Cooling then follows which leads to formation of pearlitic structures. The final product is soft. In a n alloyed steel there would be formation of a martens tic structure. Quenching The material is normally heated till the austenite region of which it is followed by cooling in oil or water. Hibler (2005, pp123-129) The product is usually transformed till it attains marten site state under oil cooling. 13. Explain why high-carbon steels would not be suitable for reinforcement for concrete. High steel carbon is much ductile and brittle due to the carbon content. This would make the concrete to succeed to the weight that is exposed, as ductile materials have low yield strength. 14. What happens when a metal is placed in an electrolyte? When a metal is place in an electrolyte there would be chemical actions depending on the relationship of the electrolyte and the metal itself. There would be an exchange of ions between the metal and the electrolyte. The reaction would either be anodic, if if the electro is lost or cathodic if the electro is gained. Oxidation normally takes place during the anodic process whereas reduction takes place in the cathodic stage. 15. Define the term “corrosion”. Explain the terms “Cathodic Protection” and “Sacrificial Anode”. Corrosion It the state in whereby, metals are deteriorated due to the chemical action of the metal with the environment. They undergo a process of oxidation that tends to weaken their structures. Cathodic protection. It is a method to prevent corrosion in metals where the metal in made to attain a stable state of immunity. The method which has to be protected would be put as the cathode whereas there would be an auxiliary anode to complete the circuit. It is usually separated from the cathode to give a true circuit. A dc current is set towards the metals. The structure of the electrolyte would be changed till an immunity state is attained. Sacrificial anode This is achieved by connecting a highly metal which being contact with, would say steel to direct the potential towards the negative direction till the immunity region is attained. 16. What affect does pH have on corrosion Low ph would lead to a high rate of corrosion as it fastens the reaction process Cement, concrete and cement replacements 17. Briefly explain what cement replacements are and discuss why they are used in the construction industry Cement replacement are alternatives components which are environment friendly that may be used to substitute cement. They are used because they are no prone to attack by the chloride and the sulphate impurities. 18. Briefly discuss why heat is produced when hydration occurs and explain why this relationship should change with differing cement / replacement mixes Heat is produced during hydration as there is subjection of the restraint material making it to generate heat. 19. Portland cement can be vulnerable to attack from sulphates and chlorides, this problem can be reduced by using PFA or GGBS, why? The problem of attack from sulphate and chlorides of cement may be solved by use PFAs or GGBs because they, react with the calcium hydroxide present that is was formed as result of hydration of dicalcium silicate, and the tricalcium silicate forming a material which is cementious. This will make the quantity of calcium hydroxide to greatly reduce, which is prone to chemical attack. In addition they have high resistance towards the diffusion of ions as compared to the normal cement. The GGBS have also small pores as compared to cement which would make them have low capillary pores. That leads to reduction n permeability. 20. Does the amount of water used in concrete mixes affect the strength, density and the durability of the concrete? If so why Amount of water will increase the strength of the concrete mixes as it reduces the aspect of porosity. This inhibits free water from entering into the concrete Aggregate 21. List any three characteristics of concrete aggregate and discuss their influence on the properties of fresh concrete Their grading that includes the distribution of aggregate particle size. This gives the standard type of aggregate particle that has to be used Durability This may affect the resistance of concrete to corrosion. Hard particles tend to last longer unlike soft particles. Shape and size They determine the texture that is used, and the shape. A workable concrete is produced easily by an angular rough textures particle which is elongated. Particles which are smooth and round pose a challenge in the production of workable concrete. 22. Define porosity? Explain how grain shape influences porosity. Would a well graded aggregate have a low or high porosity? Give reasons for your answer Porosity is the ability of a material to allow liquid substance to pass through. The size of grains, greatly influence the porosity of a given material. Large grained materials have a high porosity as compared to low grained materials. A graded aggregate would have low porosity. This is because , it has to inhibit more water from being absorbed that may cause interference with its structure. 23. What affect will chloride salts have on reinforcing bar within in concrete and therefore on the concrete as a whole? The chloride would react with the reinforcing bar causing it to weaken. This is because, it reacts with the steel hence reducing its cross sectional area. 24. Draw and label diagrams of the cellular structure of hardwoods and softwoods from the transverse view. From your drawings describe the differences between hardwoods and softwoods at the cellular level and discuss the function of the cells identified. 25. Define the term “coefficient of thermal expansion”. How does temperature affect the strength of wood? Coefficient of thermal expansion is the rate at which the material expands for a given increase in temperature. It is given by  given dl=change in length of a given substance l=total length dT =change of temperature 26. Define the terms “Modulus of Elasticity” and “Modulus of Rupture” for both a hard wood and softwood. Calculate the “Modulus of Rupture” using the figures obtained from the experiment you carried out. Modulus of elasticity- quantifiable means of determining the stiffness of wood. Hardwoods have low modulus of stiffness as compared to the softwoods Modulus of rapture- It is a quantifiable in which the breaking strength of wood may be determined. Softwoods have a high modulus of rupture as compared to hardwood. 27. Draw and label a diagram to show where the forces of compression and tension acting would act on a timber sample during the static bending test and state on which side did failure occur? 28. Draw a schematic of the structure of the following monomers: a. Nylon, b. Polypropylene, Polycarbonate 29. Discuss the hazards of polymers/ plastics in fire situations. Plastics pose as substances which tend to ignite easily. There is production of dense smoke when they are heated. They also produce various toxic gases depending on the type of polymer. For instance the polyethylene will burn out generating carbon monoxide which may cause suffocation in buildings. They also exhibit a flaming drip habit. The tar like substance which is produced may prove a challenge to extinguish the fire. 30. Draw a stress-strain curve and identify on the curve the areas for: a. The elastic region, b. The plastic region, c. The yield stress, d. The ultimate tensile stress, e. The elongation to failure, and f. The elastic (Young’s) Modulus, g. Define the terms “elastic and plastic deformation”. Elastic deformation is the capability of a material to stretch then returns to its original position. Plastic deformation is when the material has deformed after stretching and cannot return to its original position 31. Identify the members of a typical building team and their respective 31 roles. The building team comprises of the owner of the building. This is the key player in the implementation of a given project as the owner is the one who meets the financial needs and acquiring of land. The architects also serve an important role in designing the building to be lay down. The owner consultants may include the surveyors, geo engineers, civil engineers and interior designers who may offer advice to the owner. In addition there is a construction team which entails the contractors and sub contractors who perform the actual work. Describe the design process and the main principle requirements of a project. The design process entails the integrated design approach together with the integrated team process. There has to be a keen evaluation of the project objective, systems that are going to be used, availability of building materials, and different perspectives assemblies. The design team has to work in collaboration to ensure the project meets its efficiency, costs, environment relations and the future flexibility of the project. Levy (1990, pp87-99). The project should be such that its sustainable and serves a functional value in meeting its need. More over safety issues have to be addressed to ensure the users of a given project are protected from adverse conditions. Site Investigation Discuss the different types of site investigation and the purpose of each. Identify the most common types of shallow and deep foundations in use. Types of shallow foundations Spread foot foundation Used mainly in the basement of commercially oriented buildings..It has strips of concrete which serves the purpose of transferring the load from the walls Slab on Grade foundation Used mainly where there is no freezing and thawing of the ground.. The mould is initially placed in the ground then followed by the cement. Mat slab foundation Deep foundation Cast in drilled hole piles Employs the use of wet boring and the dry boring. What is the nature of the most common type of foundation failure? What measures are taken to prevent its occurrence? Boring Foundation failure may occur as a result of the movements that may make the foundations to undergo bulging and experience cracks. They failures include; the foundation settlement cracking. Allen (1995, pp43-45) .This may arise as a result varying loads on the foots of the walls or construction which was initially poorly done. The point loads-this is the concentration of load at one particular point. Premature backfilling-This is when the height is extremely high causing the buckling of the foundation. Draw the common alternative shallow foundations and describe the circumstances in which each is appropriate Draw the common alternative deep foundations and describe the circumstances in which each is appropriate With regards to the appropriate approved document discuss the purpose of ventilation and the different types of ventilation Ventilation is an important aspect in the design procedure of the building. It has to be considered In order to ensure the building is sufficiently aerated. The purpose of ventilation includes; it enables the movement of air to be kept at given levels so as to minimize heat effects. It ensures the flammable gases are kept at a lower level which is flammable It aids in keeping some toxic substance concentrations at a lower levels. It minimizes the presence of odours Regulates amount of carbon dioxide in the structure hence minimizing it. Types of ventilation The Dilution general ventilation type. This form of ventilation mostly uses air from outside to aerate the building structure. Local exhaust ventilation. This mode of ventilation is the one that tries to capture ant contaminant before the whole building space is contaminated. In this method less amount of air is required. Discuss the ventilation requirements for domestic buildings. Discuss the term performance types of loads and forces which act on a building throughout its life cycle. based ventilation There is the gravity force- This is the force that would always make the building to collapse. It acts towards the centre of the gravity and keeps the buildings unstable. Tensile and compression forces- This are forces that act on the building due to the weight of the building and its supporting loads. This makes the walls of the building to collapse. Part 3 – Loads and Forces on Buildings Describe compression and tension; give examples of where these can be found acting on structures. Compression and tension forces are exhibited mostly in the struts, lintels area of the building. When there is an exerted load, the building tends to sustain the load. This makes the upper part to undergo compression forces while the lower part experiences tensional forces. Briefly discuss the main aspects of behaviour of plastics, steel, concrete and wood in fire conditions. When steel is exposed to fire, it tends to expand and might bend. It is also observed that its length may elongate. On the other hand, concrete tend to resist most of the fire till a certain limit where it starts to crack. Wood would usually burn, when exposed to fire, and decompose. It gives off smoke while burning. When plastics are exposed to fire, Thee tend to behave differently depending on whether they are thermoplastics or thermosetting. Thermoplastics would change in their structure and can be reversed, whereas thermosetting would change so that they cannot be reversed. They melt off releasing flip drips. Identify and discuss the different types of failure modes that can occur within structures. What is the function of failure mode and effect analysis? This is an organized way of determining the consequences or effects of the failure mode of a given process or product. It also serves the purpose of identifying the ways in which the product or process failure may be minimized. Part 5 – Legislation Discuss the importance of the Building Regulations, identifying the different Approved documents and highlight the main points of guidance given in each. The building regulations provide the guidelines with which the building is supposed to be constructed. It gives the standard measures that are to be adhered to when setting up a project. Various documents have been approved that give the guidelines in the building of structures. For instance, par L stipulates the conservation of fuel and power in a given building. Part F serves the purposes of ensuring fire fighting mitigations are up to standards. References Allen, E and David S, 1995. How Buildings Work: The Natural Order of Architecture. New York/London: Oxford University Press, Hibbler, R.C. 2005 Mechanics of materials. U.S.A: Pearson prentice Hills.pp127-205 Levy, S, Mathys and, Christopher R. 1990. Why Buildings Stand Up. New York: W.W.Norton Senior, J. 1985 Ventilation in Buildings: Standards and Legislation. Pretoria: Council for Scientific and Industrial Research, National Building Research Institute Sherwyn S. 2008. Building and Construction. [Wellington, N.Z.]: New Zealand Law Society, Family Law Section and Property Law Section. Takadoum, J, 2008. Materials and Surface Engineering in Tribology. 1st ed. U. S. A: Library congress cataloging publication Read More

This is because; each of them tries to compete to retain water which ensures proper cement is created at the bond. When the brick is the one that sucks a lot of water from the motor, it will lead to depreciation of the motor making it to stung out from the joint making it to become stiff. This ultimately, hinders the next layer from bonding correctly. On the other hand if the motor wins the battle, the bricks would appear to float the bed of the mortar. 10. Water absorption is an important factor in the durability of a brick.

State two adverse conditions that could arise from excess water in bricks There may be occurrence of efflorescence where by the bricks would absorb much water, and when it freezes the bricks would appear to crumble. 11. What affect does the carbon content have on the ductile/ brittleness properties of mild steel? Carbon tends to increase the ductility of a material. The carbon bonds tend to weaken the mild steel structure making it to 12. Describe briefly, the following heat treatment processes: a.

Annealing, This is the process whereby the material is softened to achieve properties which can be machined. Takadoum (2008, 88-97) .The material is slowly transformed in an Austenite region. The material then undergoes a cooling till a ferrite cementite region. This may be achieved by a controlled cooling in the furnace. b. Normalizing Entails raising the temperatures to an austenite region in which it is held at this temperature till the material has been fully converted to austenite.

Cooling then follows which leads to formation of pearlitic structures. The final product is soft. In a n alloyed steel there would be formation of a martens tic structure. Quenching The material is normally heated till the austenite region of which it is followed by cooling in oil or water. Hibler (2005, pp123-129) The product is usually transformed till it attains marten site state under oil cooling. 13. Explain why high-carbon steels would not be suitable for reinforcement for concrete.

High steel carbon is much ductile and brittle due to the carbon content. This would make the concrete to succeed to the weight that is exposed, as ductile materials have low yield strength. 14. What happens when a metal is placed in an electrolyte? When a metal is place in an electrolyte there would be chemical actions depending on the relationship of the electrolyte and the metal itself. There would be an exchange of ions between the metal and the electrolyte. The reaction would either be anodic, if if the electro is lost or cathodic if the electro is gained.

Oxidation normally takes place during the anodic process whereas reduction takes place in the cathodic stage. 15. Define the term “corrosion”. Explain the terms “Cathodic Protection” and “Sacrificial Anode”. Corrosion It the state in whereby, metals are deteriorated due to the chemical action of the metal with the environment. They undergo a process of oxidation that tends to weaken their structures. Cathodic protection. It is a method to prevent corrosion in metals where the metal in made to attain a stable state of immunity.

The method which has to be protected would be put as the cathode whereas there would be an auxiliary anode to complete the circuit. It is usually separated from the cathode to give a true circuit. A dc current is set towards the metals. The structure of the electrolyte would be changed till an immunity state is attained. Sacrificial anode This is achieved by connecting a highly metal which being contact with, would say steel to direct the potential towards the negative direction till the immunity region is attained. 16. What affect does pH have on corrosion Low ph would lead to a high rate of corrosion as it fastens the reaction process Cement, concrete and cement replacements 17.

Briefly explain what cement replacements are and discuss why they are used in the construction industry Cement replacement are alternatives components which are environment friendly that may be used to substitute cement.

Read More