University of North Carolina Charlotte
Soil Testing Laboratory
Consolidation Test (ASTM D 2434)
Submittal Date: October 25, 2011
Consolidation Test (ASTM D 2434)
Who: and Group 1 What: This test is performed to determine the magnitude and rate of volume decrease that a laterally confined soil specimen undergoes when subjected to different vertical pressures. From the measured data, the consolidation curve (pressure-void ratio relationship) can be plotted. This data is useful in determining the compression index, the recompression index and the preconsolidation pressure (or maximum past pressure) of the soil. In addition, the data obtained can also be used to determine the coefficient of consolidation and the coefficient of secondary compression of the soil. When: Tuesday October 25, 2011
Where: Smith building soils lab 131, At the University of North Carolina Charlotte. Charlotte North Carolina
Why: This test method is most commonly performed on undisturbed samples of fine grained soils naturally sedimented in water, however, the basic test procedure is applicable, as well, to specimens of compacted soils and undisturbed samples of soils formed by other processes such as weathering or chemical alteration. The consolidation properties determined from the consolidation test are used to estimate the magnitude and the rate of both primary and secondary consolidation settlement of a structure or an earthfill. Estimates of this type are of key importance in the design of engineered structures and the evaluation of their performance.
How: Experiment 1: Consolidation Test
* Measure the height of the ring and its inside diameter * Remove soil sample and determine moisture content * Place the sample in the consolidation ring and cut around the outside to ensure the excess soil is inside the diameter of the ring. * Place the soil sample in the brass consolidation container and close the top * Fill the reservoir with water into the specimen is completely covererd * Carefully place the load plate centrally on the upper stone and adjust the loading device. * Adjust the dial gauge to a zero reading. * Record the consolidation dial readings at the elapsed times given on the data sheet. * Use the preselected pressures includes loading pressures of elapsed time from 1 to 960 seconds. * At the last elapsed time reading, record the final consolidation dial reading and time. * Weigh an empty large moisture can and lid. Calculate the initial water content and specific gravity of the soil.
Apparatus and Supplies * Consolidation device (including ring, porous stones, water reservoir, and load plate) * Dial gauge (0.0001 inch = 1.0 on dial) * Sample trimming device * Glass Plate * Metal straight edge * Moisture can * Filter paper * Timing Device * Thermometer * Compaction Equipment * Vacuum pump or water-faucet aspirator
Summary and conclusions: Our group was the first to perform the in the consolidation experiment. The soil that we used was light brown, lumpy clayey silt. Only a small portion of the original sample was used in the consolidation experiment. The depth of the soil was eight feet and the container sample was one. A brass consolidation apparatus was used because they do not rust as other metals and can be easily submerged for the saturation of the soils. After the procedure and time recording was explained to our group by professor begs, we loaded the sample into the loading device and recorded our values. Since the sample was first being consolidated, the deformation dial read higher values than the other groups. Our first value read a deformation reading of .680 and after the final time of 960 seconds we recorded a value of .632. At first we had to quickly read the deformation value reading on the needle because of the speed at which it was going, however…