Omar's Portfolio
OMARI MUSA MWAMAIKA
PORTFOLIO CIVIL & STRUCTURAL ENGINEER|CAD
TECHNICIAN|AutoLISP Developer-
RESUME
EXPERIENCE
ADDRESS
03.2018 - present
Freelancing- CAD Consultant Engineer/Highway Engineer
-, Mombasa, Kenya
Junior Civil Engineer
CONTACT
• Acted as an assistant in geometric road design of Nyamira-Igonga-
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Nyabioto/Nyamatutu-Igonga-Riana/Riana-Iyabe-Chisaro/Motonto-Suneka roads
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using Novapoint software.
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• Managed to develop an AutoLISP program to estimate as-built road quantities.
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• Was involved in the estimation of quantities and material costs during project
PROFILE
Dedicated civil engineering graduate with a strong understanding of
engineering principles and theories, bringing two years of experience and
hard work to the table, and a track record of delivering road and building
design projects ahead of schedule.
planning to support budgeting and costing.
• Performed structural design and detailing of box culverts, access culverts, and
pipe culverts using RebarCAD and AutoCAD software.
11.2021 - 01.2022
KURA
Industrial Attachment 2
COMPETENCIES
• Performed structural analysis and design of Likoni Bridge in Nairobi.
• Highway Design
• Inspection of concrete works for the Upper Hill Bypass road project.
• Structural analysis and design
• Was involved in traversing and topographical survey of Blue sea road project in
• Building code compliance
Nairobi.
• Drafting
• Design and inspection of drainage works along Moi Avenue in Nairobi.
EDUCATION
• Worked with the materials department in checking the integrity of pavements.
The tasks performed include CBR testing, field density tests, concrete mix design,
09.2017 - 12.2022
and gradation of aggregates.
Masinde Muliro University of Science and Technology-Kakamega, Kenya
• Performed survey works like leveling, setting out, and traversing to measure
BSc. Civil and Structural Engineering.
completed works.
• Performed visual inspection of construction works
CONTENTS
PROJECTS
THESIS
SKILLS
Geometric Road
Design
PROJECTS
AutoLISP Program
Development: Building
Customized Solutions
Highway Mapping
Geometric Road Design: BomasKona Baridi Project (Kenya)
Project Description
Steps
Sorting of topographical data in Microsoft
Excel and then converting it into a CSV
format. This is done prior to importing the
The Project demanded a safe, efficient
data into the Quadri interface, which is
and economical dual carriageway road
used to generate the topographical map.
design. Additionally, the project
required the design of junctions, bus
bays, and u-turns, the production of
plans and profiles for the alignment,
and the provision of construction
setting out data.
Topographical survey map creation in the
Despite the project's estimated
Quadri interface. Once the map is
completion time being one month, the
produced, it can then be imported into
design was successfully finished in just
AutoCAD interface for design.
five days. The budget for the project
was a significant constraint, and the
alignment had to remain within the
existing road to avoid compensating
those affected by the project.
The Bomas-Kona Baridi Road Project
posed a significant challenge that
demanded ample expertise to ensure
its success. Nonetheless, the dual
carriageway met the required design
standards, exceeded stakeholders'
expectations, and was completed within
a tight schedule and budgetary
constraints.
AutoCAD's interface and Novapoint
plugin's road design tool used to create a
horizontal alignment that considers
minimum curve radii, superelevations,
and widenings.
Deliverables
Design of vertical alignment which was accomplished through the use of
Novapoint plugin's design tool, that takes into account various factors
such as sight distance, road gradient, terrain, cross section type, road
class, and traffic level.
Exporterd finished road levels and horizontal setting out data
from the Quadri design database to Excel, with some
modifications made to produce the final data for construction.
Plan and profile presentation plots generated from AutoCAD's
layout tab prior to being printed and archived.
AutoLISP Program Development: Building Customized Solutions
Project Description
This was a personal project aimed at assessing
my coding abilities, which involved leveraging
AutoLISP to automate as-built road cross
section design and quantity estimation process.
The inspiration for this project arose from the
absence of a comprehensive software that
could estimate road quantities for the majority
of items typically included in bills of quantities
for Kenyan road projects. My primary objective
was to incorporate features such as stripping,
rock filling, compaction of existing ground, and
bench work into a cross-section, and enable
AutoLISP to perform calculations to determine
the exact quantities utilized.
Steps
Deliverables
Cross-section drawings that demonstrates the successful utilization of AutoLISP
The quantities of the items depicted in the cross-sections were exported to an excel
code to automate the process of incorporating essential items like rock fill, fill in
sheet, assuming a 20-meter interval between each cross-section.
soft, fill in hard, and benchwork.
Highway Mapping
Steps
Importing of horizontal alignment
from design files into AutoCAD to
ensure adherence to the specified
coordinates. This was achieved
through a copy-and-paste
operation while maintaining the
original coordinates.
Capturing of overlapping google
earth images around the project
area at an eye altitude of 2.01km,
to ensure comprehensive
coverage. The resulting images
Project Description
were then stitched together using
the Photoshop interface, resulting
This project entailed the integration of Muhoroni-Chemelil-Kipsitet and its associated spur roads,
in a high-resolution Google Earth
namely Koru and Songhor Road, into a Google Earth image for the purpose of presentation. The task
image that covers a wider area.
was assigned to me subsequent to an inadequate presentation of the map, which failed to provide a
comprehensive view of the project area. The primary objective of the presentation was to depict the
alignment's features clearly, allowing the map to be utilized in stakeholder engagement. However, the
previous presentation did not meet this requirement. Consequently, I utilized my expertise in
Photoshop and AutoCAD to generate an improved and more distinct presentation suitable for that
purpose..
Importing of the image using
"attach" command in AutoCAD
and aligning it to fit the designed
horizontal alignment.
Subsequently, printing plots for A1
were generated in the layout tab,
and then presented to
stakeholders for approval.
THESIS
Introduction Cont.’
Development of Rebound Hammer Strength
Curves for Glass Fibre Reinforced Concrete
Bernard Omondi1,2, Omar M. Mwamaika1, Loice C. Satia1
1Masinde Muliro University of Science and Technology, P. O.
Box 190 – 50100, Kakamega, Kenya
2Corresponding author:-
Fig. 1: Rebound Hammer
In 2007, more enhancements were made to digitize the method of reading compressive
strength from the instrument. However, its application has been limited to normal
Abstract
Rebound hammer test is an essential NDT tool in appraising the structural integrity of
existing concrete structures. However, its application has been limited to normal
concrete structures. Its application on novel concrete such as Glass Fibre Reinforced
Concrete (GFRC) structures can lead to unreliable results. This study aimed at developing
the correlations between compressive strength and rebound hammer index for GFRC.
The fibres used were 12 mm long at a percentage of 0% to 0.12%, at intervals of 0.03%.
The analysis resulted in the creation of new curves that can be applied to GFRC. A
logarithm curve was determined to be the best curve for GFRC.
Keywords: Non-destructive test, rebound hammer index, glass fibre-reinforced concrete,
Strength curves
Introduction
A rebound hammer (see Fig. 1) is an instrument used to non-destructively test the
compressive strength of concrete based on surface hardness and penetration resistance
(Kocáb, D., Misák, P., & Cikrle, P., 2019). The instrument typically operates under impact
mechanism in which, upon impact, a rebound index is recorded and a compressive
strength estimated from strength curves located on the instrument's shell.
concrete (Ali-Benyahia, 2017). For example, one study discovered that the rebound
hammer test gives an abnormal compressive strength upon adding basalt fibres in
concrete (Ali Benyahia, 2017), This is owing to the fact that rebound hammer test is
sensitive to tiny changes in concrete autonomy.
Despite this limitation, advancements in concrete technology has led to novel concrete
such as Glass Fibre Reinforced Concrete (GFRC). This GFRC has gained acceptance due to
its high durability, superior compressive and tensile strengths over normal reinforced
concrete. In order to appraise structures made using GFRC, a sustainable NonDestructive Test (NDT) tool should be used. A rebound hammer is more suitable but it
must be calibrated for reliable results.
From this background, this study aimed at developing the rebound hammer strength
curves for GFRC. The fibres used were 12 mm long and incorporated into the mix at
various percentages from 0% to 0.12%, at intervals of 0.03%. The mix with 0% of GFRC
acted as the control mix (normal concrete). A total of 90 concrete cubes were tested by
rebound hammer method. The study confirmed that the curves that were invented by
Ernst Schmidt, were solely intended to be used on normal concrete. The work was
therefore extended to include the creation of new curves that could be applied to GFRC.
Four functional forms were tested and a logarithm function curve was found to be the
best curve for GFRC. The results of this study will be significant for non-destructive
evaluations of GFRC structures.
Methodology
Results and Analysis
A) Compressive strength and Rebound hammer Index.
The research design is as represented in Fig.2.
The results confirmed that increase in % of glass fibre led to increase in compressive
strength at all ages of concrete (See Fig. 6 being typical for 28-day strength). It’s noted
that beyond 0.06% addition of glass fibre, there was insignificant increase in compressive
strength. Furthermore, the rebound hammer index reduces with increase in compressive
strength and increase in % of glass fibre. Thus, glass fiber affects negatively the accuracy
of rebound hammer index.
Fig. 2: Research design
(1) Preliminary tests (sieve analysis, specific gravity, moisture content, and water
absorption) were conducted for quality control. (2) Concrete class C20/25 was designed
using British (BRE) standard. Glass fibre (See Fig. 3) quantities were varied from 0% to
0.12% at interval of 0.03% of mass of wet concrete. (3) Batching was done by mass
followed by dry mixing to ensure even dispersal of glass fibres before adding water.
Workability of the mix was tested through slump test. Cubes of 100mm were cast after
confirmation of the mix. After 24hours, the cubes were cured in water. (4) Rebound
hammer tests (see Fig. 4) were conducted followed by compressive strength test (see Fig.
5) after 7, 14 and 28 days of curing. A total of 90 samples were tested. (5) The
.
Fig. 6: A graph of 28 Days Compressive strength and Rebound Hammer Index
against the percentage of glass fibres
relationship between compressive strength and rebound index (Rm) were analyzed. (6)
Relative error and standard error were calculated based on comparison with the
B) Percentage Error induced by Glass Fibre.
strength curves on the rebound hammer. This was the basis of development of new
A comparative analysis was done based on actual compressive strength and the
strength curves.
estimated strength from rebound hammer index charts. Both relative error and standard
error were calculated based on JGT/T 23-2011 manual. Both relative and standard errors
gave similar values. Typically, Fig. 7 shows the relative error at different ages of concrete
and different % of glass fibre. It is seen that the relative error for control test was within
the acceptable error margin. However, on addition of glass fibres, the relative errors
were significant (above acceptable margin of 12%) at all ages of concrete accept for 7-day
strength at 0.03% and 0.06%. It was imperative that a better correlation be developed for
Fig. 3: Glass Fibre
Fig. 4: Rebound hammer
test
Fig. 5: Compressive
strength test
strength curves from rebound hammer index. This was done only optimum addition of
glass fibre which in this study was 0.06%.
Results and Analysis Cont.’
Results and Analysis Cont.’
ADD A MAIN POINT
Fig. 8: Logarithm Curve with high R2 value
Fig. 7: Relative Error based on measured and estimated
compressive strength at different concrete ages
C) Validation of Strength Curves
hammer index (Rm) as:
𝐹cu=59.198In(𝑅m )−171.62
In order to validate most appropriate strength curve for GFRC, different curve fitting
were used on data points for measured compressive strength and the rebound hammer
index. The curves tested and the resulting R2 values are given in Table 1.
Curve Fitting
R2 Value
Linear
0.9003
Logarithm
0.9136
Exponential
0.8478
Power function
0.8738
Table 1 shows that logarithm curve gave highest R2 value. The corresponding logarithm
curve is shown in Fig. 8.
Based on the logarithm curve, the strength of GFRC, (Fcu) can be derived from rebound
Conclusion
Based on results and analysis, the following conclusions were made:
1. The recommended percentage of glass fibres should be 0.06% of wet concrete. This
translates to increase of compressive strength of concrete by 16%.
2. Incorporation of glass fibres in concrete lowers sensitivity of the rebound hammer
indices resulting into unacceptable relative error.
3. Strength curves for GFRC from rebound number can described using logarithm curve
denoted by the equation: 𝐹cu=59.198In(𝑅m )−171.62
References
1. Kocáb, D. M. et al. (2019), Characteristic curve and its use in determining the
ADD A MAIN POINT
compressive strength of concrete by the rebound hammer test. Materials, P 12(17), 2705.
2. Ali-Benyahia, K. S. (2017), Analysis of the single and combined non-destructive test
approaches for on-site concrete strength assessment: General statements based on a
real case-study.
3. JGT/T-23-2011 Manual for Rebound Hammer Test.
SKILLS
CADS & MODELLING
STRUCTURAL ANALYSIS
BUILDING CODE COMPLIANCE
PROGRAMMING
CREATIVE EDITING
MICROSOFT OFFICE