Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Subbase

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.

Assessment of Bearing Capacity of Subbase Contaminated with Kerosene

Zeena W.Abbawi; Kawther Y.Al-Soudany; Makki K.Al-Recaby

Engineering and Technology Journal, 2013, Volume 31, Issue 19, Pages 159-172

The present paper is focused towards evaluation bearing capacity of subbase layer which is contaminated with Kerosene.
Seven series of model tests were performed using steel container (500*300*300mm). The bed of subbase was compacted in three layers inside the container; each layer was 100mm in depth. Circular footing 65mm in diameter resting on the bed of subbase were loaded incrementally up to failure. Different percentages of Kerosene (0%, 5%, 12% and 20%) were added, the first series consists of uncontaminated soil layer, the second series covers the model tests with added (5%, 12% and 20%) to the top subbase layer and third series covers the model tests with added (5%, 10% and 20%) to the top and second subbase layers. Each percentage was added separately. The results showed increase in ultimate bearing capacity; with increasing of Kerosene content up to 5% then a decrease with further increase of Kerosene content.

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.