The Concept of Sieve Analysis - Essay Example

This plot is known as the grain distribution plot and will be used for the purposes of this report. More often, a relatively distributed curve shows well-graded or a soil which is poorly sorted whilst an extremely steep distribution curve, a curve with steep distribution shows poor grade or sufficiently sorted soil. Objectives of the experiment This lab was developed to determine the distribution of grain size for Concrete & Asphalt materials. This is achieved by the determination of the coefficient of uniformity, as well as the coefficient of curvature,

These describe the general slope and shape of the curve respectively for the grain distribution curve. Consequently, how good or poorly sorted a given soil sample is can be obtained using and. The equations are as shown below; showing the coefficient of Uniformity; and, which shows the coefficient of Curvature As per the equation D10 represents the size of the grain size where 10% of soil sample passes, as shown in the grain size distribution curve. D­30 and D60 correspond to the size of the grain size whereby 30% and 60% by weight of a sample of the soil passes through.

D10 also refers to effective size. Grain size, as well as distribution, is vital given that it directly affects the stability of slope as well as the soils drainage abilities. Equipment and Procedures This experiment was done in line with the instructions availed in the lab handout manual. The instructions are based on ASTM, AASHTO or University standards. The equipment used includes the following: Sieves Trays Oven which should be able to maintain a 110° uniform temperature Brush Weighing balance The standards are referenced in appendix 1.

The experiment layout and procedure Experiment layout The layout of the experiment is as shown in the diagram below: Figure 1: Experimental set up The sample is passed through the consecutive set of sieves as indicated in the diagram. Each sieve is then weighed using the weigh balance availed within the lab. Analysis procedure 1. Obtain around 15 lbs. of oven-dried concrete and asphalt sample. 2. Use a pestle to brakes break the sample into individual soil particles. 3. Measure the sample’s weight to the nearest gram and record the value obtained. 4. Make a stack of sieves as shown in figure 1 above.

Sieves with larger openings are placed on top of the ones with smaller openings. 5. Pour the concrete/asphalt sample into the stack and use the brush to move around and facilitate sieving. Do this gently to avoid forcible moving particles. Do this for approximately 10 minutes. 6. The amount retained in each sieve is then weighed and the value recorded in each case. The same is done for the fine material obtained at the bottom-placed tray. 7. Perform relevant calculations and draw the relevant plots.

Results and discussion The results are as displayed in the table below: Sieve Size (in.) Weight retained in each Sieve (g) Cumulative Weight Passed (g) Total Percent Passed 0.750 108.50 1179.40 91.6% 0.625 114.20 1065.20 82.7% 0.500 68.00 997.20 77.4% 0.375 75.30 921.90 71.6% 0.250 121.70 800.20 62.1% 0.187 57.10 743.10 57.7% 0.079 210.70 532.40 41.3% 0.033 155.90 376.50 29.2% 0.017 93.90 282.60 21.9% 0.010 65.50 217.10 16.9% 0.006 57.30 159.80 12.4% 0.003 83.90 75.90 5.9% 0.000 75.90 0.00 0.

0% Figure 2: Results table Based on these results the following grain distribution graph was derived, The % passed graph plot shown above reveals a mid-ranged curve indicating that the sample is neither well-graded nor poorly graded. The sample shows a relatively extensive variety of grain sizes which are fairly spread out across the entire sieve arrangement. The D10 value is obtained from and is estimated at 0.006 inches, while the D30 value obtained from the graph is 0.033 inches. On the other hand, D60 is set at 0.

250 inches. These values are estimated based on the graph. = 41.67 0.726 Based on these values, the coefficient of uniformity, Cu, was calculated as 41.67 while the coefficient of curvature, Cc is obtained as 0.726. Conclusions From the experiment, the sample of soil as obtained is considered as being neither well-graded nor poorly graded. This is further reinforced by the values of the coefficient of uniformity and coefficient of curvature, which is determined as 41.67 and 0.729 respectively.