Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : CBR

Using Recycled Construction Rubbles to Improve the Properties of Subbase

Shakir A. AL-Mashhadani; Shatha Sadiq

Engineering and Technology Journal, 2013, Volume 31, Issue 21, Pages 549-564

Demolished concrete structures proven to be a good source of construction materials. This paper studies the utility of using recycled construction rubbles to improve some properties of compacted subbase .Different subbase materials were produced with 0%, 25%, 50%, 75% of recycled construction rubbles aggregate as a partial replacement of natural subbase. The standard tests were conducted on the choosed maerials before and after the replacement. It is found from the test results that the recycled construction rubbles can be used significantly to improve the properties of some types of subbase. The CBR values of the subbase materials prepared with crushed concrete, recycled bricks, and ceramic rubbles as a partial replacement were better than those of natural subbase materials. The performance of subbase containing crushed concrete rubbles was better than the performance of subbase containing crushed clay bricks and ceramics. The CBR values for all subbases were greater than 45%, which is accepted as per the requirements CRB specifications in Iraq.

A Laboratory Evaluation of Stabilization of Silty Clay Soil by Using Chloride Compounds

Muhanned Qahtan Waheed

Engineering and Technology Journal, 2012, Volume 30, Issue 17, Pages 3054-3064

Large areas of Iraq consist of soils with high clay contents which have low
strengths and bearing capacity.This problem has an influence on construction of
road and highway, if adequate support does not exist, the road will rapidly
deteriorate. The solution to these construction problems is by soil treatment with
chemical additives. The main objective of this study is to investigate effectiveness
of salts used as an additive in stabilization of silty clay soil. Three types of salts
used which are sodium chloride (NaCl), magnisum chloride (MgCl2) and calcium
chloride (CaCl2). Various amounts of salts (2%, 4%, and 8%) were added to the
soil to study the effect of salts on the consistency limits, compaction characteristics
and CBR value.The test results indicated that the liquid limit, plastic limit and
plasticity index decreased as the salts content increased. The addition of salts to the
soil increased the maximum dry density and reduced the optimum moisture
content. The addition of (2 %) salt to the soil causes increases the CBR value
between (8 to 28 %), while, in samples containing large amount of salt (4 and 8 %)
the increase was between (55 to 80%).The CBR value increased as the salt content
increases for different type of salt and the greatest value is found in the soil treated
with (4%) calcium chloride which was equal to (80 %).

Effect of Soaking on the CBR-Value of Subbase Soil

Zeena Tariq Jaleel

Engineering and Technology Journal, 2011, Volume 29, Issue 6, Pages 1069-1079

The effect of soaking on the top and bottom CBR value of a sub-base is studied
in this paper.
Fourteen CBR samples were prepared at 95% relative modified AASHTO
compaction .Two CBR samples were prepared for each soaking period of
0,4,7,14,30 and 60 days. These samples were prepared and compacted
mechanically in the laboratory. The first group was tested in case of unsoaked
while the second group was tested in case of soaking.
The results showed that, a significant drop in the CBR for top and bottom due to
the soaking was observed compared with natural case due to softening of soil
particles Which means that the bearing capacity of subbase soil decrease with
increase of soaking time. Most of decrease in soaked CBR value is pronounced
inthe first days for top and bottom CBR, respectively. And it dropped to 20%
and23%value for top and bottom after 60 days soaking period and this drop is in
full of weakness of soil with soaking.