hello I'm Dave whinger with the Missouri S&T geotechnical Labs today we are going to go over the laboratory procedures used for particle size analysis this short video will demonstrate how to conduct particle size analysis in accordance withm specifications a particle size analysis is used by geotechnical engineers to help easily classify soils the particle size analysis consists of two procedures the mechanical C analysis involves the use of a series of mechanical cves to help determine the grain size distribution within the coar grain fraction of the soil the hydrometer analysis is conducted on the fine grain portion of the material material that passes the number 200 Civ is considered fine grain material the resulting curves from these two tests can be used to character the soil and used to reject or accept the material for engineering applications the Practical applications of the particle size analysis and geotechnical Engineering include soil description quantitative soil classification and correlations to permeability based on the Hazen equation the devices required in order to conduct a mechanical C analysis are a stack of cves ranging from number four to number 200 4 10 20 40 100 200 the pan and a lid a mechanical Shaker a digital balance and a weighing pull in order to conduct the hydrometer analysis the following devices will be required 1,000ml sedimentation jar 1,000 m control jar ANM 152h hydrometer a soil dispersion device in this case a shake mixer a soil dispersion agent in this case sodium hexametaphosphate a squirt bottle filled with water an evaporation dish a rubber stopper and a thermometer measuring in Celsius the soil that we will be performing the particle size analysis test on is a l seal silt that was obtained from the Mississippi River Valley the soil has been mechanically pulverized some coarse material has been added to the sil for the purpose of this lab the documents pertaining to today's lab can be found on blackboard in PDF format the particle size analysis is part of a combination lab handout out entitled CE 215 lab number three and four index tests and classification of soils in addition ASM standards of the two tests have been posted on blackboard ASM c136 pertains to the Civ analysis of fine and course grain Aggregates by the mechanical Civ asmd 422 pertains to the hydrometer test also available is a data sheet for today's lab a Civ analysis is conducted determine the particle size distribution curve or gradiation curve the particle size distribution curve is a plot of the percentage of soil particles finer versus the log of the particle di diameter to determine this a soil sample is shaken through a series of cves the mass of the soil retained on each C is then determined from this the percentage passing can be determined start by weighing out a sample of 500 gr of the provided air dry soil start by weighing out a 500 G sample of the provided air dried soil it is important to mix the sample in between each scoop so that the 500 G sample of soil is an accurate representation of the provided soil sample record the total mass on the data sheet disassemble the stack of sives and brush out the wedged particles in the screens do not use the SI brush on the number 200 Civ for this could damage the screen with the smallest Civ on the bottom in this case the number 200 pour the soil sample into the top of the sives place the lid on top of the stack of sves and with two hands carry the SIV stack into the Shaker room load the stack of sves into the mechanical SIV Shaker place the Shaker lid on top of the stack of lower the Shaker hammer and turn on for 10 minutes remove the Shaker Hammer take off the Shaker lid and with two hands remove the stack of sves from the Shaker and carry into the other room empty the material in the pan in a bowl and record the weight this material is the material that has passed the number 200 Civ it is considered the fine grain portion of this material this material will be used in the hydrometer analysis portion of this lab compute the total retained mass by adding the individual masses retained on each C and the pan the total mass should be within plus or minus 2% of the original Mass if there is a greater difference than this the test must be rerun the percent passing a specific Civ is 100 minus the summation of all the percent retains on that Civ and the CV's prior to it to determine the particle size distribution of the soil particles finer than the number 200 Civ a hydrometer analysis must be conducted the hydrometer analysis measures the change in specific gravity of a soil water mixture over time as soil particles fall out of suspension the specific gravity of the soil water mixture decreases the application of Stokes law to Falling spheres is used to determine the grain size distribution of the particles falling out of suspension start the hydrometer analysis by weighing out exactly 60 G of the soil left over in the pan from the mechanical C analysis record the weight of the soil obtained on the data sheet in a small evaporating dish mix the soil with 125 mL of 4% sodium hexametaphosphate cover with a wet paper towel and allow to stand for 15 minutes the sodium hexametaphosphate is similar to laundry detergent it works to break down the cohesion between the particles so that the individual particles will not stick together note this is a deviation from the ASN standard ASM suggest that you let this sit for up to 24 hours we will only let it sit for 15 minutes in the interest of time while the soil is soaking for 15 minutes you can use this time to calibrate the hydrometer each hydrometer is unique and will have its own unique zero correction factor to determine the zero correction factor lower the hydrometer into a control jar a control jar is just a water solution with sodium hexametaphosphate without any sort of soil in the water the hydrometer will eventually stabilize the reading on the hydrometer staff from the top of the meniscus to the zero Mark is the zero correction factor also noted is the meniscus correction factor the zero correction factor is the distance from the zero Mark to the top of the meniscus on the hydrometer staff the meniscus correction factor is the distance from the water level to the top of the meniscus on the hydrometer staff record the meniscus correction factor and the zero correction factor on your data sheet after the 15-minute soaking period transfer the sodium hexaphosphate soil solution into a dispersion cup use a squirt bottle with water to ensure that all the material transfers out of the evaporation dish into the dispersion cup fill the dispersion cup with water until the water level is about halfway up the cup mix with the shake mixer for 2 minutes pour the sodium hexametaphosphate solution from the dispersion cup into a clean sedimentation jar again using a squirt bottle with water ensure that all the sediment has transfer from the dispersion cup into the sedimentation jar okay cap the cylinder with the rubber stopper agitate the solution for 1 minute by turning the cylinder upside down and back 30 times in 1 minute after 1 minute of agitation remove the rubber cap and use your water squirt bottle to ensure that all the sediment is off the cap as well as off the sides of the sedimentation jar fill the sediment solution up till it is at the 1,000ml Mark place the sedimentation jar on a table where it will sit undisturbed for the next 24 hours after 2 minutes of placing the jar on the table insert your hydrometer and take the first reading at 2 minutes record the reading on the hydrometer staff at the top of the meniscus of the dirty water after the reading remove the hydrometer place it aside and insert the thermometer to take a temperature reading continue recording the hydrometer and temperature readings at approximate elapse times of 4 8 6 16 30 minutes 1 2 4 8 and 24 hours from the hydrometer time history a gradiation of the particles falling out of the solution can be calculated that combined with the particle distribution curve determined from the mechanical c will give a full grain siiz distribution of the provided soil