The moisture probe may only be used for granular soils and may not be used in soils with organic material. Guidelines for the stabilization of subgrade soils in. Jerzy and leszek 2014 who reported that in cultivated soils compaction of soil. This process is an essential part of the construction of any structure, as it strengthens the soil. This can be measured by mainly two methods standard proctor compaction test and modified proctor compaction test. Soil structure also affects the shape of the soil moisture characteristic curve. Ii introduction a particle density soil particle density g cm3 is mass of soil solids ovendry per unit volume of soil. Ct 417 method of testing soils and waters for sulfate content ct 422 method of testing soils and waters for chloride content aashto m 145 standard specification for classification of soils and soilaggregate mixtures for highway construction purposes aashto t 180d standard method of test for moisturedensity relations of soils stabilization. To determine any of these ratios for a particular soil sample, the water mass must be determined by drying the soil to. Soilmoisture properties of subgrade soils transportation. In some literature the moisture content is expressed in wet weight basis that is defined as the ratio between water mass and the mass of wet soil.
From the above two known weights w and w solid, the weight of water m. Note significant increase in water content on the dry side of the compaction curve this is why it is so important to moisture condition expensive soils wet of optimum moisture content. So that deformation characteristics of compacted soils can be compared at various moisture contents, compactive efforts, and methods of compaction, the creep modulus e. The soil moisture content may be expressed by weight as the ratio of the mass of water present to the dry to the dry weight of the soil sample, or by volume as ratio of volume of water to the total volume of the soil sample. The bulk density increased with increased moisture content. For a particular compaction effort, the dry density of soil increases with the moisture content of the soil up to the optimum moisture content beyond which it decreases. Prediction of compaction and compressibility characteristics. In contrast, sand grains cannot be molded together.
Inherent factors affecting bulk density and available water. Effect of soil moisture in the analysis of undrained shear. Similarly, soils compacted to wet of optimum will produce more stress even for smaller stress. Soil compaction decrease in soil volume and porosity, or increase in soil bulk density, due to mechanical stress on soil, for example, from traffic of agricultural machinery. Natural soil reconsolidation wellgraded soils more susceptible to natural compaction than poorly graded soils 0 20 40 60 80 100 10 0. Laboratory 2 soil density i objectives ii introduction.
A compacted soil has a reduced rate of both water infiltration and drainage. Soils field testing north dakota department of transportation. The determination of maximum dry density and optimum moisture content of the soil is a measure of compaction level of soils. Maximum soil compaction occurs when soil moisture is at or near field capacity figure 1 because soil moisture works as a lubricant between soil particles under heavy pressure from field equipment. The soil is then removed from the mould and is mixed with the original sample. High soil moisture increases soil compaction caused by field traffic and machinery. Ii introduction a particle density soil particle density g cm3 is mass of soil solids ovendry per unit volume of soil solids. To further understand the compaction behavior of these forest and range soils, six representative soils of different textural characteristics were subjected to proctor compaction, with 30, 50, and 100 blows at three to four.
Factors affecting compaction of soil types of soil. At this moisture content the soil can be compacted most ef. Using both the rheological and the conventional soil parameters to evaluate the compaction of the soils, the optimum combination of the principal variables was studied. Rain, for example, may transform soil into a plastic state or even into a liquid. Compacted soils usually have unsatisfactory physical conditions for plant growth, but the extent of loss of productivity depends on soil type, plant species, and weather conditions effects on germination and establishment. Compaction can prevent the build up of large water pressures that cause soil to. When the moisture content is gradually increased and the same compaction effort, the weight of the soil solids in a unit volume gradually increases. Compaction of soil is the compression of soil particles into a smaller volume, which reduces the size of pore space available for air and water.
Effect of moisture the response of soil to moisture is very important, as the soil must carry the load yearround. Effects of compaction increased soil erosion effects of compaction increased soil erosion. Compaction can result from equipment traffic, especially on wet soils, and tillage pans. In this method of moisture content determination of soil, a known weight w of the representative wet soil sample is dried over night in an oven operating at temperatures between 105c and 110c. Moisture content and compactive effort, which can be controlled, are important factors influencing soil compaction. However, these relationships in the ascompacted state i. Factors affecting compaction soil type in poorly graded sands the dry unit weight initially decreases as the moisture content increases and then increases to a maximum value with further increase in moisture content.
The moisture content at which the greatest value of dry density is reached for the given amount of compaction is the optimum moisture content omc, and the corresponding dry density is the maximum dry density. For the purpose of this study soil specimen were compacted and the optimum moisture content was identi. Modulus of compacted soils depends not only on dry unit weight and moisture but also on matric suction and soil structure or fabric resulting from the compaction process. Compacted soils usually have unsatisfactory physical conditions for plant growth, but the extent of loss of productivity depends on soil type, plant species, and weather conditions. The e 0moisture content relation exhibits a similar trend to moisturedensity and shear strengthmoisture content relations fig. Inherent factors affecting bulk density and available.
Pdf effect of moisture content on soil density compaction. Soil moisture conditions consideration for soil compaction. Therefore, a moisture content determined by this method will be affected by approximately 0. The response of soil to moisture is very important, as the soil must carry the load yearround. Soil compacted at moisture content greater than the optimum moisture content has exactly the opposite characteristics to the one compacted below it. Compact soils result in cloddy seedbeds after primary. The relation between the moisture content and dry unit weight for saturated soil is shown on the graph in figure 3. In this study, the soil materials with varying moisture content were compacted with the same duration and settings.
Jul 07, 2008 modulus of compacted soils depends not only on dry unit weight and moisture but also on matric suction and soil structure or fabric resulting from the compaction process. Both the tests help to determine the optimum moisture content that is required for soil to attain maximum compaction i. Guidelines for the stabilization of subgrade soils in california. Part 2 why do we compact soil missouri university of. Moisture vs soil density moisture content of the soil is vital to proper compaction. Laboratory determination of compaction properties namely the maximum dry density and optimum moisture content is both time consuming and costly. If, with increasing moisture content, the wet mass of compacted soil markedly increases and then starts to decrease, the optimum moisture content probably has been straddled adequately. Compaction properties of silty soils in relation to soil. The soil particles slip over each other and move into a densely packed position. Ct 417 method of testing soils and waters for sulfate content ct 422 method of testing soils and waters for chloride content aashto m 145 standard specification for classification of soils and soil aggregate mixtures for highway construction purposes aashto t 180d standard method of test for moisture density relations of soils stabilization. In this state, soil has very little or no loadbearing ability. Density of soil in place by the nuclear gauge soil density testing flow chart setting.
A representative sample is taken from the centre of compacted soil for moisture content test. It affects infiltration, rooting depthrestrictions, available water capacity, soil porosity, plant nutrient availability, and soil. Determination of moisture content in soil protocol. Soils are compacted more readily when soil moisture is at or near.
The determination of maximum dry density and optimum moisture content of soil is a measure of compaction level of soils. Many factors influence the degree with which the soil is compacted. Determining moisture content in soil materials txdot designation. About 2% more water is added in the sample and the test is repeated. Performancebased measurement of optimum moisture for soil. Soil compaction compaction, in general, is the densification of soil by removal of air, which requires mechanical energy. The focus of this work is to explain possible connections between surface temperature and soil moisture in order to carry out suchataskinthefuture. As soil moisture levels increase, infiltration rates decrease. Maximum dry density of soil and optimum moisture content test. However, these relationships in the as compacted state i. Laboratory 2 soil density i objectives measure particle density, bulk density, and moisture content of a soil and to relate to total pore space.
Initially then, as the moisture content increases so does the dry. Soil structure also affects the shape of the soil moisture characteristic curve, particularly in the high matric potential range. Soils containing gypsum lose water of crystallisation on heating. Over the past decade the size of iowa farms has increased, leading to larger and heavier equipment. Soils typically contain a finite amount of water, which can be expressed as the soil moisture content. Experiments were carried out in a sandy loam soil at soil moisture content of 10. Pdf effect of soil moisture content and dry density on cohesive. Moisture exists in soil within the pore spaces between soil aggregates, called interaggregate pore space, and within pores in the soil aggregates themselves, called intraaggregate pore space. Subgrade soil moisture measurement, soil compaction, soil water. The loam soil showed rather higher values of bulk density than the other two soils fig.
Compaction of soil process, necessity and theory of. Strength and deformation parameters of compacted soil are known to be related to soil. There are potential penetration problems at 145 psi. At lower moisture content, the capillary tension inhibits the tendency of the soil particles to move around and be compacted. The e 0 moisture content relation exhibits a similar trend to moisture density and shear strength moisture content relations fig.
The nuclear gauge is specifically designed to measure the moisture content and density of soils, aggregates, cement and lime treated materials, and to measure the density of bituminous concrete. Compacted or impervious soil layers have pore space and less restrict water movement through the soil profile. Hence, stressstrain curve, in this case, is much flatter and plastictype failure occurs at a larger strain. Therefore, it is useful if simple correlation equations can be developed to estimate the compaction. In construction of highway embankments, earth dams and many other engineering structures, loose soils must be compacted to increase their unit weights.
Road builders make use of this principle when they apply water to dry soil to make it compact more easily. Soane, in encyclopedia of soils in the environment, 2005. Influence of moisture content on intelligent soil compaction. The microwave oven may be used for most soil types except for soils that. The size and shape of a site will also affect the accessibility and manoeuverability of equipment. Interpreting compaction indicators the impact of compaction on crop productivity.
As water is added to a soil at low moisture content it becomes easier for the particles to move past one another during the application of the compacting forces. Dcp criteria for chemical modified soils were developed at optimum moisture content. The degree of compaction of the soil largely depends upon the quantity of moisture in it however, if the moisture increases beyond a certain limit, compacting strength starts to decrease. As the soil compacts the voids are reduced and this causes the dry unit weight or dry density to increase. Increasing the water content for a saturated soil results in a reduction in dry unit weight. This critical value varies with soil type and moisture content of the soil when tested schuler et al.
Effects of soil properties, water content, and compactive. Moisture density curve for a mediumtextured soil for a given compactive effort. It has a great impact on the consistency of the soil, its density, and its compactability. Soil compaction occurs when soil particles are pressed together, reducing pore space between them figure 1. In this paper we study the relationships between soil moisture and temperature at the surface and various. Because of the importance of compaction in most earth works. Moisture content of soil can be determined by two methods. The combined effects of compactive effort, type of compaction, moisture content at compaction, and moisture gain after compaction on the physical parameters ar1d engineering proper ties were noted and compared for field and laboratoryprepared soil. The appropriate decompaction technique will depend largely on the characteristics of a reclaimed site, including clay content, soil moisture and the severity and depth of compaction table 1. The moisture content will decrease with an increase in atmospheric temperature. However, equipment size is only one factor among many causes of the soil. Performancebased measurement of optimum moisture for.
Traction force in arable soils also is affected by soil physics parameters as soil moisture and compaction increasing the power consumption. Bulk density can be managed, using measures that limit compaction and build soil organic matter. The red color in the spectrum indicated the strength of acceleration signal at fundamental and harmonic and subharmonic. The dry unit weight after compaction first increases as the moisture content increases. Moisture content this is a measurement of how much moisture a soil is holding in its void spaces. Compaction of soil process, necessity and theory of compaction. Moreover, the difference in the bulk density among these three soils seemed to decrease as the moisture content increased and. Bulk density is an indicator of soil compaction and soil health. September 2014 class g2 in accordance with tex901k for specimens with a mass greater than 200 g. Both the test helps to determine the optimum moisture content that is required for a soil to attain maximum.
Soil compaction compaction is the application of mechanical. This spring most parts of iowa have had plenty of rainfall, causing many producers to enter fields at lessthanideal soil conditions. Oct 28, 2016 factors affecting compaction soil type in poorly graded sands the dry unit weight initially decreases as the moisture content increases and then increases to a maximum value with further increase in moisture content. Each combination of these variables results in a different state of the compacted soil. The principal variables which affect the state of compacted soil are the type of soil, the moisture content, and the amount and type of compaction energy. Compaction of the soil is the process where the dry density of soil is increased by reducing air content or air voids present in the soil. The mould along with the compacted soil is then weighed to get the mass of the compacted soil. Soil moisture content rausser college of natural resources. Soils field testing compute and record dry density to nearest 0. Moisture content tests of the soil are required to be conducted during mixing and the day after mixing and shall be at or above the optimum moisture content. Roots usually cannot penetrate soil compacted to 300 psi or more. Compact material to at least 95 percent of the maximum dry density with moisture content no less than 4. If it is suspected that gypsum is present in the soil, dry the moisture content samples at not more that 80 c, for a longer period and report the method used. The bhps showed a strong correlation between measured temperature rise and water content but in its current configuration is.