FLATGEO Consulting Co., Ltd.

List of Standards

List of Standards

The list of standards (ASTM, BS and TCVN) which are commonly used in...

Holiday calendar in 2018

Holiday calendar in 2018

Date Number of days off 2017  New Year's...

Standard Penetration Test

Standard Penetration Test

Standard penetration test (SPT) is one of the most common in situ testing...

Precision or Accuracy ???

Precision or Accuracy ???

When working with technical documents, readers are often deal with specific...

Bulk Density

Bulk Density

1. Definition: A bulk density of a soil sample is defined as a mass per...

Compaction Test

Compaction Test

1. Definition: The bulk density or dry density of soils is not a constant...

Warning on Webpage Content Stealing

Warning on Webpage Content Stealing

On February 27, 2014, flatGEO Consulting Co. accessed to a webpage on...

Datalogger for Oedometers

Datalogger for Oedometers

After a four-month-trial period, flatGEO has finished a datalogger system for...

  • List of Standards

    List of Standards

    July 18, 2011
  • Holiday calendar in 2018

    Holiday calendar in 2018

    October 2, 2011
  • Standard Penetration Test

    Standard Penetration Test

    December 12, 2011
  • Precision or Accuracy ???

    Precision or Accuracy ???

    January 7, 2012
  • Bulk Density

    Bulk Density

    February 20, 2012
  • Compaction Test

    Compaction Test

    March 7, 2012
  • Warning on Webpage Content Stealing

    Warning on Webpage Content Stealing

    February 27, 2014
  • Datalogger for Oedometers

    Datalogger for Oedometers

    July 21, 2015
08976767
Today
This week
This month
1571
8730
27591
Your IP: 54.82.57.154

Thí nghiệm đầm nên1. Definition:

The bulk density or dry density of soils is not a constant value, it could be changed in relation with the moisture content of soils and the compaction effort.

 

compaction curve  

In order to realize the relationship between the moisture content and the compactness of soils, the compaction test is used (so called Proctor test) and its result is the compaction curve — a relationship between the dry density and its relevant moisture content (see a picture on the left).

Two important parameters should be derived from this curve: maximum dry density (denoted by MDD) and its corresponding optimum moisture content (denoted by Wopt).

Compaction curve (after BS 1377 : 1990 - Part 4)    

The gradation also affects to the compactness of a given soil sample. This relationship is demonstrated on the picture below:

compaction curve for different soil types   Some important points should be taken into account:

a) The compaction curve is a monotonic curve with one peak and two asymmetrical sides (one side with a steep slope and the other is more gentle).

b) The right side of the compaction curve theoretically never crosses the zero air voids line (ZAV line).

c) The more the clay fraction the lower maximum dry density and the higher optimum moisture content.

d) The more uniform gradation the lower maximum dry density and vice versa.

e) To a fine sand of poorly graded, the compaction curve represents a bimodal structure (see the curve No. 4 on picture on the left). However the true maximum dry density should be the value at the higher moisture content (approx. 20%, not a value of 12% on the adjacent picture).

Relationship between moisture content and dry density    

2. Apparatus:

Automatic
compactor
Rammer for standard Proctor test Rammer for modified Proctor test Mould for standard
Proctor test
Mould for modified Proctor test
(Source: www.humboldt.com)

3. Brief comparison of apparatus, methods for different standards

Applied
Standard
Method of
compaction
Dimension
of mould
(D × H) mm
Rammer
mass
(kg)
Falling
distance
(cm)
Number
of
layers
Blows
per
layer
TCVN Standard 100.0 × 127.0 2.5 30 3 different blows for different soil types
Modified 125.0 × 127.0 4.5 45 5 55
ASTM Standard rammer
(Method A and B)
101.6 × 116.4 2.5 30 3 25
Standard rammer
(Method C)
152.4 × 116.4 2.5 30 3 56
Modified rammer
(Method A and B)
101.6 × 116.4 4.5 45 5 25
Modified rammer
(Method C)
152.4 × 116.4 4.5 45 5 56
BS Standard mould,
standard rammer
105.0 × 115.5 2.5 30 3 27
Standard mould,
modified rammer
105.0 × 115.5 4.5 45 5 27
CBRmould,
standard rammer
152.0 × 127.0 2.5 30 3 62
CBRmould,
modified rammer
152.0 × 127.0 4.5 45 5 62

4. Referred standards:

a) ASTM D698 : Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort

b) ASTM D1557 : Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort

Add comment

Security code
Refresh