Construction Materials: Their Nature and Behavior - Report Example

Materials Assignment Student Name: Student No: Course: Faculty: University: Lecturer: Date of Submission: Table of Contents Table of Figures 2 Introduction 3 Procedure 4 4 A Comparison of the Strength of the Hardwood and Softwood 5 Difference between the Parallel and Perpendicular Column 7 Timber Compression Test 7 Figure 1: Timber Compression Test Hardwood Column 8 Figure 2: Timber Compression Test hardwood parallel to grain 9 Figure 3: Timber compression test. Hardwood perpendicular to the grain 10 Timber Shear Tests 10 Figure 4: Timber Shear Test. Hardwood Paralle to Grain 11 Figure 5: Timber Shear Test-Hardwood Perpendicular o the Grain 11 Figure 6: Timber Shear Test-Softwood Parallel to Grain 12 Figure 7: Timber Shear Test-Softwood Perpendicular to Grain 12 Timber Compression Test 12 Figure 9: Timber Compression Test-Softwood Parallel to Grain 14 Figure 10: Timber Compression Test-Softwood Perpendicular to Grain 15 Discussion 15 Concrete Lab Test by Group Three 15 Introduction 15 Method used in Performing Regional Mixing of Concrete 16 A Comparison of the Regional Mixing of Concrete with the Results 18 Conclusion 18 Research Poster on a Rubber Material 19 References 20 Table of Figures Figure 1: Timber Compression Test Hardwood Column 8 Figure 2: Timber Compression Test hardwood parallel to grain 9 Figure 3: Timber compression test. Hardwood perpendicular to the grain 10 Figure 4: Timber Shear Test. Hardwood Paralle to Grain 11 Figure 5: Timber Shear Test-Hardwood Perpendicular o the Grain 11 Figure 6: Timber Shear Test-Softwood Parallel to Grain 12 Figure 7: Timber Shear Test-Softwood Perpendicular to Grain 12 Figure 8: Timber Compression Test-Softwood Column 13 Figure 9: Timber Compression Test-Softwood Parallel to Grain 14 Figure 10: Timber Compression Test-Softwood Perpendicular to Grain 15 Figure 11: Relation between Stress and Strain 18 Introduction The properties of wood are both unique and independent in their axes that are mutually perpendicular. While the tangential axis is perpendicular to the grain, the longitudinal axis is parallel to the grain. The radial axis is also normal to annual rings whereas the tangential axis is tangential to the annual rings. The structural elements of wood are made up of cells which are generally tubular, and firmly grown together. Most of the wood cells are largely elongated, and their ends are pointed. This form of cells is called fibers. What affects the usefulness of a given piece of wood is the direction of the fibers because they influence the strength of wood. Equipment: Universal testing machine, and compressometer. Sample: A clear wood specimen of Alder, Walnut, Maple, Pine and Fir will be tested. For each, six samples with nominal dimensions ¾” x ¾” x 3” are to be tested. Procedure The method of testing small specimens of timber was guided by the BS 373:1957 code. The machine used for testing the specimen is as shown in Figure 1 below. It has a capacity of 50KN, with a speed rated at 1mm/min. 1. The ends of the specimens should be level 2. The distance between grain & the angle of the grain is measured. 3. The specimen is positioned under the crosshead of the testing machine, and the load is applied apply continuously at 0.024 in. /min. 4. Continue with loading till the proportional limit is passed appropriately. 5. Take the deformation readings to the nearest 0.001 inch. For each of the specimen, compressive strength and elastic modulus is calculated, alongside the average compressive strengths and elastic modulus of each specimen. The tabled results are plotted and graphs drawn in order to compare the results. Failure strength for each piece of wood is compared, and comments made on the kind of variation due to compressive strength of each. A Comparison of the Strength of the Hardwood and Softwood In terms of tension, compression, and shear, there is a great difference between hardwood and softwood. Hardwood is stronger in tension, compression, and shear whereas softwood is only stronger in tension but weaker in shear strength. In other woods, softwood is stronger both across and along the grains whereas softwood is only stronger along the grains. The fibers for hardwood have a length that ranges between 1/25 of an inch whereas that of softwood ranges between 1/8 to ¼ of an inch or even longer. For softwoods, a plot of stress against strain would be as shown in the figure below. For medium strength woods, the graph for stress against strain is as shown Finally, the graph of stress against strain for hardwoods is as shown below Difference between the Parallel and Perpendicular Column Further, in terms of column arrangement, the relationship between parallel and perpendicular columns show some differences in their compressive, tension and shear strength. Timber Compression Test Figure 1 bellow shows the relationship between force and position of a compression test of hardwood column. This plot shows that the force applied on a hardwood column increases with increase in distance up to an optimum of 2.4 – 2.8 mm after which the force starts to decrease. Figure 1: Timber Compression Test Hardwood Column For a hardwood parallel to the grain, the strength of the column increases gradually to a maximum falling between 1.8 and 2.10 mm, after which in quickly declines. This is illustrated as shown in the figure 2. Figure 2: Timber Compression Test hardwood parallel to grain However, for a hardwood that is perpendicular to the grain, the force increases sharply to about 0.60mm after which there is an observable decrease in the rate of increase of force against the position, up to 5.4 mm, from which in sharply decreases as illustrated in Figure 3. Figure 3: Timber compression test. Hardwood perpendicular to the grain Timber Shear Tests Hardwood Parallel to Grain Figure 4 shows a plot of shear strength against position shows a slowed increase in shear force between 0- 0.3 after which the increase becomes very sharp up to 1.8 mm. From this maximum point of 1.8mm, the force decreases sharply. Figure 4: Timber Shear Test. Hardwood Paralle to Grain Hardwood Perpendicular to the Grain Shear strength against position shows a sharp increase in shear force between 0- 0.3 after which the increase becomes very slow with a sharp increase towards the peak point of between 10 and 12 mm. From this maximum point, shear force decrease sharply. This is as shown in Figure 5. Figure 5: Timber Shear Test-Hardwood Perpendicular o the Grain Softwood Parallel to the Grain The force in shear strength increase fairly slow and gradual up to a maximum between about 2.4 mm. From this point the decreases is very sharp. Graphically, this is as shown in Figure 6. Figure 6: Timber Shear Test-Softwood Parallel to Grain Softwood Perpendicular to the Grain Increase in shear force is very sharp from the origin to about 10mm. Between 10 mm to 13mm, there is a sharp increase followed by a sharp decrease. Figure 7: Timber Shear Test-Softwood Perpendicular to Grain Timber Compression Test Softwood Column Compressive tests show a gradual increase up to 2.0 from which there is an observable slowed decrease. This relationship is illustrated in Figure 8. Figure 8: Timber Compression Test-Softwood Column Softwood Parallel to the Grain The increase in compressive strength for softwood parallel to the grain is gradual and slow from zero distance to maximum falling between 1.0 mm to 1.2 mm. Figure 9: Timber Compression Test-Softwood Parallel to Grain Softwood Perpendicular to the Grain The increase of compressive strength increases sharply between zero positions up to 0.6 mm. From this point the increases is slowed down and is non uniform. Figure 10: Timber Compression Test-Softwood Perpendicular to Grain Discussion Grain direction determines the strength of timber. For instance, in parallel, timber has got higher compressive strength then when the grains are perpendicular. This is because when a force is applied parallel to the grain, it makes it harder for compression whereas when force is applied perpendicular to the grain, it makes it easier to compress. This accounts for the reason as to why the graphs for hardwood and softwood are different. Concrete Lab Test by Group Three Introduction In engineering field, testing of materials is crucial. Therefore, this section offers some information about tests on concrete material so as to determine the material strength. The materials are subjected to a number of tests, under different conditions such as such as tensile strength, shear test, and compression This section will go ahead to provide a comparison of the properties of a given tested concrete specimen obtained from a trail mix and the design of concrete mix depending on the specifications provided. A concrete design form is provided, alongside the required batch quantities for the trial mix. In the first task, the following information is provided. That is, batching the trial mix, carrying out slump test on fresh concrete, manufacturing about three 100mm cubes out of the concrete mix. After 14 days, the density and compressive strength on the concrete that has been hardened is measured. Method used in Performing Regional Mixing of Concrete The experiment methods are based on the concrete mixing standard, and the understanding of a student about concrete mixing. Several steps are followed, starting with setting up of the concrete machine, and moving it out to the working lab. Next, the mixing bucket the cleaned and the weighting scale adjusted to zero during the support of the empty buckets self weight. The material to be mixed in accurately measured, and then added to the mixing barrel. Cement and water are then added to the mixing barrel using the right ratio and the barrel is kept in a proper position before switching on the machine. After concrete has been mixed appropriately, the mixing machine is turned off and the concrete that has been prepared is poured on a wheelbarrow. Another important aspect is on getting a four mold and filling it with some concrete in three different layers. 1/3 of every concrete is compacted with 25 strokes of a steel rod. The top most part of the concrete is then smoothened using a trowel, and then let to develop its main test in the concrete mold for about 24 hours. In the end, the concrete is removed from the mold and three of them placed in a curing path whereas the rest are left in the working lab. So as to perform concrete tests on crushing abilities, the lab is visited after 7 days and the concrete removed out of the curing path to allow curing. Results Characteristic strength of the concrete is 30 N/mm2 at the end of 28 days with a proportion defective of 5 percent. Standard deviation is 5 N/mm2, and margin is 1.64 x 5 = 8 N/mm2. Therefore, target mean strength = 30 + 8 = 38 N/mm2. Water cement ratio = 0.53, and slump = 30-60 mm. Maximum aggregate size is 20 mm and free water content is 180 kg/m3. The cement content = 180 ÷ 0.53 =340 kg/m3 and relative density of aggregate is 2.6. Concrete density is 2370kg/m3 and the total aggregate content = 2370-180 = 1850 kg/m3. Percentage of fine aggregate that passes through 600 micrometer sieves = 60% whereas the proportion of tine aggregate is 33%. Fine aggregate content = 1850 x 0.33 = 611 kg/m3 The content of coarse aggregate is 1850-611 =1239kg/m3. Quantities Cement (Kg) Added Water (kg or liters) Oven Dry Fine Aggregate Course Aggregate (kg) 10mm 20mm 40mm Per m3 to nearest 5 kg 340 192 599 413 826 - Per trial mix of 0.01 m3 3.40 1.92 5.99 4.13 8.26 - Table 1 The dimension of the concrete cube is 100 mm X 100 mm. Cube Mass in Air (g) Mass in water (g) Density Kg/m3 Failure Load (KN) Failure stress 1 2360 1355 2348 413.4 41.1 2 2399 1384 2364 432.4 43.243.2 3 2372 1368 2363 420.9 42.1 2358 42.2 Table 2 Slump = 25 mm Density ( ) = = Failure Stress = = =41.34 A Comparison of the Regional Mixing of Concrete with the Results From Table 2, there is clear relationship between density and the failure load of different concrete cubes. The more the density, the more the failure load and vice versa. The graph bellow shows typical results that can be obtained for this test in terms of stress against strain. Figure 11: Relation between Stress and Strain Conclusion The main challenges experienced under this experiment included both experimental errors and errors due to measurement. However, accurate readings will reduce errors due to parallax, thus giving more accurate results. Research Poster on a Rubber Material Rubber is one of the materials that have a wide application in the construction industry. Uncured rubber has many uses than vulcanized rubber. Vulcanized rubber is used for insulating, adhesive, cements, and friction tapes. Abrasion resistance is used to make soft forms of rubber that are used in the manufacture of important treads in the vehicle industry, such as conveyor belts and the vehicle tires. Rubber is also flexible and as such it is used in tires, rollers and hose, with different devices cutting across domestic clothes and printing presses. The elasticity of rubber makes it valuable in manufacture of shock absorbers. Rubber is also resistant to water and the effect out of most fluids used in some chemicals, thus making it valuable in the manufacture of diving gear, rainwear, medical tubing, and chemicals. Further, rubber has some electrical resistance. This makes it useful for insulation, shoes, blankets, and protective gloves. Hard rubber is used in the manufacture of some parts of meters, radio sets, telephone housings, and other forms of electrical equipment. Rubber has a property of dampening by transforming of the kinetic energy (KE) into static energy. Therefore, this fundamental property is useful in offering protection against explosions and impacts. This effectively reduces noise, water hammer in reaction tanks and pipelines, minimizes vibrations. Rubber is used in sealing because it is elastic and pliable. This makes it a best choice for water, oil, and gas seals, especially in the most demanding environmental situations. What make rubber useful in offering corrosion resistance are its chemical resistance towards gases, salt, corrosive liquid, UV light and ozone. References British Standards Institute. (1957). BS 373: Methods of Testing Small Clear Specimens. Domone, PL & Illston, JM. (2010). Construction Materials: their nature and behavior. Edward, A. & Joseph, I. (2011). Fundamentals of Building Construction: Materials and Methods. New Jersey: John Wiley & Sons. Haroid, NA. (2003) Highway Materials, Soils, and Concretes. London: Prentice Hall. Jackson, ND. (1996). Civil Engineering Materials (5th Edition). Macmillan. Nevill, A.M. & Adom, M. (2011). Properties of Concrete Pierre, H. (1983). An Outline of Soil and Rock Mechanics. Melbourne: Press Syndicate for the University of Cambridge. Surinder, V. (2012). Construction Science and Materials. West Sussex: John Wiley and Sons Ltd. William, A. (2006) Building with Reclaimed Components and Materials: A Design Handbook for Reuse and Recycling. New York: Earthscan. . Read More