Evaluation of Construction Demolition Wastes of Buildings in Addis Ababa to be used as a Sub-base Material: Case study Around Mexico Area
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Date
2022-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Utilizing recycled materials and wastes like construction wastes and demolition reminders is one
of the justifiable solutions in terms of both cost minimizing and environmental concerns of
transportation infrastructure constructions.
The main objective of this study is to evaluate the suitability of the usage of Construction
Demolition wastes of buildings in Addis Ababa to be fully or partially used as sub-base layer.
The scarcity and difficulty of providing construction materials like sub-base has been a challenge
that drags the road construction and the pavement industry not to be continued as expected. On
the other hand, in Addis Ababa the extensive production of construction and demolition waste
and lack of disposition areas due to the overpopulation of the city have a great contribution on
the environmental pollution and it is also becoming a problem.
In this research, Construction Demolition Waste samples were collected from Addis Ababa
around Mexico Area. Four samples were collected which are CDW1 (from Previous GomaKuteba
compound),
CDW2
(from
left
side
of
Yobek
Building),
CDW3
(from
the
back
of
Wabishebele
Hotel)
and
CDW4
(in
front
of Ministry
of Health).
Gradation, Proctor Compaction, CBR, Atterberg Limits as well as LAA tests were conducted on
all of the collected samples. However, all the samples pass the gradation requirement but could
not pass the CBR requirement for subase material. Their Maximum Dry Densities (MDDs) are
also lower than the expected MDD for subase.
Therefore, in order to increase their densities and their bearing strength, it was tried to mix two
of the CDWs with Clay material with four proportions (10%, 20%, 30% and 40% by weight of
the sample). The MDD and the CBR have shown a big increment when 20% to 30% of Clay
material is mixed with both of CDW samples and fulfill the CBR, Liquid Limit and Plasticity
index requirements for subase material in accordance to the ERA specification.
However, all the CDW samples have higher LAA value than expected for subase material.
Therefore, it was required to reduce the LAA value of the samples and it was tried to mix two of
the samples with approved subase material with four proportions (10%, 20%, 30% and 40% by weight of the sample). In doing that, both of the samples fulfill all the ERA specification
requirements and the LAA requirement as well.
In addition, it was tried to simulate the compaction during construction on site by proctor
compaction and study the gradation curve after compaction. In order to do that, the samples left
from pure CDW1 and CDW1 + 20% Subase were taken and compacted by standard proctor
compaction procedure and the gradation of pure CDW1 after compaction tends to cross the upper
limit allowable for subase material, whereas the CDW1 + 20% subase sample’s gradation lies in
between. Therefore, CDWs + 20% subase pass all the laboratory test requirements in this
research for subase material and 20% subase content is recommended as the optimum proportion
of subase which is the minimum requirement. However, using more than 20% subase also fulfil
all the requirements specified for subase material.
Description
Keywords
CDW, Clay, Subase, CBR, Gradation, Proctor Compaction, LAA, Liquid Limit