Post on 12-Jan-2016
P14416: Concrete Arborloo Base
System Design ReviewOctober 1, 2013
Member Role
Victoria Snell (ISE) Project Manager
Evan Burley (ME) Engineer
Joe Omilanowicz (ME) Engineer
Mac Keehfus (ME) Engineer
Anthony Deleo (ISE) Engineer
Team Introduction & Roles
Agenda• Background/Problem
Statement• Open Items• Specifications• Benchmarking/Concrete
Introduction• Concept Generation• Concept Selection• Engineering Analysis• Test Plan• Materials Considered• Potential Risks• Plans Moving Forward
A latrine-like sanitation device designed to function over a small pit and to be moved to a new pit when filled
Utilize compost by planting tree in used pit Purpose to provide affordable sanitation in poor,
underdeveloped areas Originally designed for use in Zimbabwe
Arborloo
Current State Today’s arborloo takes two days to install and is not easily transportable.
The current design is also not socially appealing to the Haitian population. Desired State
Provide an affordable concrete base that is easy to move and install. The desired base should be aesthetically pleasing to users and a worthwhile purchase for sanitation improvements rather than storage or social status.
Project goals Low cost (<$50 to purchase) Base design that safely covers an 18-20” diameter, 3-4 ft. deep hole Easily constructed using simple hand tools Portable Resistant to environmental damage Has modular design Haitians want to purchase
Constraints Proposed budget= $1500 Base must be relatively lightweight for transportation Base must be made using concrete
Problem Statement
Safety Rating Considered separately from main function of
supporting weight Other factors (tripping and slipping hazards) don’t
influence design decisions as significantly Clarified that time constraint refers to home setup Changed tripping hazard definition to comply with
OSHA standard Changed survey method to choosing between
multiple alternatives
Open Items
Customer Requirements
9
The system costs less than $50-$100 to users (at production level quantities).
The system is lightweight and moveable (by donkey or person walking for up to 6 hours)
The system can be installed in less than 4 hours.
The system can be installed with simple hand tools.
The system confers social status to the owner.
3
The system supports the user over an arborloo hole 18-20” in diameter, 3-4 feet deep
The system is safe to use for users (falling, tripping, slipping, moving to new hole).
The system keeps pests out of the pit.
The system looks “modern” in a Haitian context.
The system is welcoming and comfortable.
The system can be financed in parts.
1 The system is a product, not a DIY project.
The system resists weather and pest damage.
The system minimizes environmental impact throughout the lifecycle.
Importance Scale
Cost
Easy Transport
Quick to Assemble
Strength
Safe
Visually Appealing
Comfortable
Accommodates Large Hole in Ground
Modular
Importance Scale - 9
Importance Scale - 3
Customer Requirement
s
…. Based on Concept Selection Criteria
Engineering Requirements
DIY Project Composition
Bag of cement “Good river sand” Thick wire
Mounted on a “ring beam” of bricks or concrete
Molded from bricks Addition of soil, wood
ash & leaves creates compost
Peter Morgan’s Arborloo
Current concrete Arborloos have typical cement, sand, and gravel composition Wire or rebar for
reinforcement Flat or slightly domed circle
and square shaped Catholic Relief Services
reports $5-8 for Arborloo in Ethiopia
2-3 slabs made from one bag of cement
Other Arborloos?
Benchmarking
• Effective fiber volume is at a 0.75% fraction
• Variety of Different aggregates and reinforcements
• Reinforcement patterns• Material Properties of
different fibers• Haitian Perspective
* Based on Pedro Cruz-Dilone Paper
Why Use Concrete?
Available in Haiti
Tough/ Durable
Strong in compressio
n
Only basic Tools are needed
Minimally skilled Haitian
Mason can make
Materials are cheap
Easy to provide
good tensile strength with the
additions of reinforceme
nts
Test standards already
created and available
• Holly Holevinski• Cement + water = paste• Aggregates: Coarse
(>1/4”) Fine (<1/4”)• Reinforcement (rebar)• Fiberglass, plastic, steel
• Add mixtures: reduce weight• Air-entrainment• Foaming materials• Accelerators and
retarders
Concrete Background
5 types of Portland cement
Types I – V Type I & II General use Type IV- “High Early”
Reaches its maximum strength within 24 hours
Window when paste is moldable 0-90 minutes
Final set at 120 minutes 3000 psi goal for slab
Concrete Background
Concrete Tips: Concrete cannot go below
80% RH during cure process Rebar should not touch any
open areas Use plastic to keep moisture
in, spray concrete regularly if possible
Mix parts of Portland cement with cheap substitutes (fly ash, silica fume)
Concrete must be at least 30% Portland cement
Concrete Background
Functional Decomposition
Functional Architecture
Concept Generatio
n
Functions
Covers Hole in Ground
Support Weight (reinforcement)
Support Weight(aggregates)
Transports Waste
Easy to Transport
Simple to Assemble
Withstands Damage During Transport
Remains Stable
Easily Cleaned
Withstands Environmental
Damage
Reduces Odor
Stability
No Pests
Modular
Interface with Shelter
Aesthetics
Ergonomic
Concept Generation:Key Functions
Functions
Covers Hole in Ground
Support Weight (reinforcement)
Support Weight(aggregates)
Transports Waste
Easy to Transport
A B C D E F G H
Selection Criteria
Dome(hollowed out)
Cone(hollowed out)
Peter Morgan's Arborloo
Oval(Puzzle)
"X" "Lincoln Logs" Square Triangular
Low cost - - 0 - - - 0 +Easy to transport - - 0 + + + - -Safe - - 0 - - - 0 0Quick to install 0 0 0 - - - 0 0Visually appealing + + 0 + + + 0 +High strength + + 0 - - - 0 0Comfortable + + 0 0 0 - 0 0Accomodates variable holes 0 0 0 0 - - 0 -Modular 0 0 0 + + + 0 0Can be done in 2 semesters + + 0 + + + + +
Sum + 's 4 4 0 4 4 4 1 3Sum 0's 3 3 0 2 1 0 8 5Sum -'s 3 3 0 4 5 6 1 2
Continue? Y Y - N N - Y
Concept SelectionPeter Morgan’s as Datum
Concept SelectionDome as Datum
A B C D E F G H
Selection Criteria
Peter Morgan's Arborloo
Cone(hollowed out)
Dome(hollowed out)
Oval(Puzzle)
"X" "Lincoln Logs" Square Triangular
Low cost + + 0 + + + + +Easy to transport + 0 0 + + + + +Safe + 0 0 0 0 - + -Quick to install 0 0 0 - 0 - 0 0Visually appealing 0 0 0 - 0 0 - +High strength - - 0 - - - 0 0Comfortable - + 0 - - - - -Accomodates variable holes 0 0 0 0 - - 0 -Modular 0 0 0 + 0 + 0 0Can be done in 2 semesters + + 0 + + + + +
Sum + 's 4 3 0 4 3 4 4 4Sum 0's 4 6 0 2 4 1 4 3Sum -'s 2 1 0 4 3 5 2 3
Continue? Y Y - - - N Y Y
Selected Concept #1 - Dome
PROS
Round edges allow for compressive strength
advantages
Attractive design
Safe
Comfortable
CONS
Difficult to make modular
Difficult mold design
Hard to transport
Cost
Selected Concept #2- Hollow “Puzzle Piece” Cone
PROS
Comfortable
Visually appealing
Modular
Pieces provide support for each other
CONS
Less safe
Mold design
Cost
Long assembly time
Selected Concept #3 - Triangle
PROS
Less Material
Simple Mold Design
Low Cost
Visually Appealing
CONS
Difficult to transport
Not modular
Difficult to interface with hole
Stress concentrations in corners
Concept Selection #4- Circular “Peter
Morgan’s”
CONS
Not modular
Not comfortable
Not visually appealing
PROS
Accommodates large hole in ground
Safe
Relatively easy mold
Easy to transport
Engineering Analysis
Using ANSYS and material properties of standard concrete: Poisson’s Ratio: 0.3 Elastic Modulus: 4e6
psi Assumed an applied
Pressue of 500 lbs
2D Circle and Triangle Slabs
3D Dome and Cone Slabs
Compression Test Verify strength of concrete Determine how aggregates/fillers effect
strength of concrete Flexural Test (with/without reinforcement)
Determine advantages of certain reinforcement concepts
Tensile Strength Transportation User Interaction
Test Plan
Flexural Test Compression Test
C150- Standard Specification for Portland Cement
C330-Standard Specification for Lightweight Aggregates for Structural Concrete
C470-Standards for Specification for Molds for Forming Concrete Test Cylinders Vertically
C39- Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
C78-Standard Test Method for Flexural Strength of Concrete
ASTM Standards
Materials to Test- Aggregates (course and fine)
Chopped up rubber tires
Sand Coconut shell Bean bag filler Glass bubbles
Grass/leaves
Styrofoam
Ground up water bottles
Clay
Effect the weight and compressive strength of
concrete:
Materials to Test-Reinforcements
Rebar Snow fence Window screen Chicken wire Corrugated metal
sheets Steel rods Fishing line Nylon rope
Onion bags (mesh)
Plastic bags Bicycle spokes Banana fibers Sisal fibers
Effect the strength by absorbing some of tensile stresses
Risk Assessment
Spend more than our budget allows
Unable to purchase necessary items
Overspending on unnecessary materials 1 2 2
Develop a Bill of Materials that is well under our given budgetBudget Tracker
Anthony
Hole in concrete is deemed unsafe
Child could fall through
Inability to follow customer requirements 1 3 3
Pay close attention to the safety of the hole size relative to the rest of the baseCheck against playground standard after design drawings are done
Mac
Design is too hard to transport
Device becomes immobile defeating the purpose of improved sanitation
Not modular and/or too heavy 2 3 6
Research ways to make concrete more light and implement that into our designResearch and test lighter aggregatesTest multiple times and recreate
Joe
Base cracks under minimal load Useless device
Lack of reinforcement 2 3 6
Obtain multiple reinforcement materials that increase tensile strength by November
Mac/Evan
Poor concrete mixture 2 3 6
Research ways to mix concrete and talk to concrete experts Team
Instructions do not allow for easy assembly or installation Plan: Provide simple picture instructions
Aggregate mixtures are inconsistent and unrepeatable Plan: Document every quantifiable value
for mixtures and measurement
Base is not “attractive” to purchase Plan: Research through interviews/surveys
with Haitian locals and visitors
Time constraint (EPA in DC) Stay ahead of Mycourses outline Work during Intercession break
Other potential issues
Specimen testing Continue aggregate research Optimize concrete performance
Create more detailed designs Update EDGE Continue to consider Customer requirements
as we make decisions
Moving Forward
Shapes Feasibility Additional materials
to test
Additional Questions/Opinions?