Determine In-Situ Density Lab Report
Figure 12.4: e – log sv’ plot
5. Recompression Index. Determine it from the plot of voids ratio (e) vs log σ plot as (Figure 12.4 or 12.5) 12.11
6. Coefficient of compressibility. It is calculated as follows av = 0.435 Cc/Avg. pressure for the increment 12.12 where Cc = compression index av = Coefficient of compressibility
6. Coefficient of permeability. It is calculated as follows k = cv.av x (unit weight of water)/(1+e). 12.13
12.4.3 Graphs
1. Dial reading VS log of time or Dial reading VS square root of time.
2. Voids ratio …show more content…
While preparing the specimen, attempts should be made to have the soil strata orientated in the same direction as in the consolidation apparatus.
2. During trimming, care should be taken in handling the soil specimen with least pressure.
3. Smaller increments of sequential loading than stipulated above should be adopted for soft soils.
13.0 FIELD DENSITY TEST
13.1.1 Aim
Determine in-situ density
Determine, if required, percent of maximum density which has been achieved
13.1.2 Learning Outcome
Describe the Field Density Test theory and its use
Explain the Principle
Determine Field Density by the Sand Replacement and Rubber Balloon Methods
Calculate Dry Density and Relative Compaction
Write a report on each test exercise
13.1.3 NEED AND SCOPE
The in-situ density of natural soil is needed for the determination of bearing capacity of soils, for the stability analysis of slopes, for the determination of pressures on underlying strata, for the calculation of settlement and the design of underground structures.
It is also used as a quality control test, where compaction is required, in cases like embankment and pavement construction. In such cases, relative compaction is typically used as an index to compare the field density with the laboratory density. Many authors (Adeyeri, 2015) define Relative compaction …show more content…
To achieve the best results, it is necessary that the soil is compacted in the field within specified limits. During construction, control tests are run to find out to what extent the compaction specifications are being met. This is usually done at regular intervals. The objective is to determine (a) the dry density and (b) the moisture content, and then find the relative or degree of compaction using equation 13.1.
There are three methods commonly used for determining the in-place or field density. These are the sand-cone method, the rubber balloon method and the nuclear density meter method. The procedures for the sand cone and rubber balloon methods are fairly similar. Both are displacement methods, Adeyeri (2015). In each method, a small pit is excavated in the compacted soil, Figure 13.1. The excavated material is weighed and its water content determined. The volume of the hole can be measured either by the sand-cone, the rubber-balloon or the oil (or water) method, Figure 13.2. In the sand-cone method, Figure 13.2a, the weight of clean dry uniform sand of known density to fill the hole exactly is measured. The volume of the soil and hence of the hole is then calculated from the weight-volume-density
5. Recompression Index. Determine it from the plot of voids ratio (e) vs log σ plot as (Figure 12.4 or 12.5) 12.11
6. Coefficient of compressibility. It is calculated as follows av = 0.435 Cc/Avg. pressure for the increment 12.12 where Cc = compression index av = Coefficient of compressibility
6. Coefficient of permeability. It is calculated as follows k = cv.av x (unit weight of water)/(1+e). 12.13
12.4.3 Graphs
1. Dial reading VS log of time or Dial reading VS square root of time.
2. Voids ratio …show more content…
While preparing the specimen, attempts should be made to have the soil strata orientated in the same direction as in the consolidation apparatus.
2. During trimming, care should be taken in handling the soil specimen with least pressure.
3. Smaller increments of sequential loading than stipulated above should be adopted for soft soils.
13.0 FIELD DENSITY TEST
13.1.1 Aim
Determine in-situ density
Determine, if required, percent of maximum density which has been achieved
13.1.2 Learning Outcome
Describe the Field Density Test theory and its use
Explain the Principle
Determine Field Density by the Sand Replacement and Rubber Balloon Methods
Calculate Dry Density and Relative Compaction
Write a report on each test exercise
13.1.3 NEED AND SCOPE
The in-situ density of natural soil is needed for the determination of bearing capacity of soils, for the stability analysis of slopes, for the determination of pressures on underlying strata, for the calculation of settlement and the design of underground structures.
It is also used as a quality control test, where compaction is required, in cases like embankment and pavement construction. In such cases, relative compaction is typically used as an index to compare the field density with the laboratory density. Many authors (Adeyeri, 2015) define Relative compaction …show more content…
To achieve the best results, it is necessary that the soil is compacted in the field within specified limits. During construction, control tests are run to find out to what extent the compaction specifications are being met. This is usually done at regular intervals. The objective is to determine (a) the dry density and (b) the moisture content, and then find the relative or degree of compaction using equation 13.1.
There are three methods commonly used for determining the in-place or field density. These are the sand-cone method, the rubber balloon method and the nuclear density meter method. The procedures for the sand cone and rubber balloon methods are fairly similar. Both are displacement methods, Adeyeri (2015). In each method, a small pit is excavated in the compacted soil, Figure 13.1. The excavated material is weighed and its water content determined. The volume of the hole can be measured either by the sand-cone, the rubber-balloon or the oil (or water) method, Figure 13.2. In the sand-cone method, Figure 13.2a, the weight of clean dry uniform sand of known density to fill the hole exactly is measured. The volume of the soil and hence of the hole is then calculated from the weight-volume-density