Sub-Systems Design Review
P14416
Concrete Arborloo Base
October 29, 2013
Team Intro
Member
Role
Victoria Snell (ISE)
Project Manager
Evan Burley (ME)
Engineer
Joe Omilanowicz (ME)
Engineer
Mac Keehfus (ME)
Engineer
Anthony Deleo (ISE)
Engineer
Agenda
•
•
•
•
Background
Functional Decomposition/Architecture
Updated Customer Requirements
Subsystems
– Geometry
– Composition
• Compression Test Results
– Features
• Cost/Trade-off Analysis
• Engineering Requirements
• Project Management Updates
Arborloo
• 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 (Peter Morgan)
Functional Decomposition
Functional Architecture
Meeting with Francius Estimable
(Johnny)
• Weight
• Price: ~25 USD = 1100
HTG
• Type of Cement is still
unknown
• Prefers a DIY kit to educate
locals
• Design should be simple
Updated Customer Requirements
1) Cost
• 25 dollars
• Make it available to
all Haitians coming
from different
economic states
2) Weight
• Make it
transportable
through all
environments
• Can be moved by
1-2 people
comfortably
2) Simpler the better
• Easy to make
• Simple mold
• Limited materials/
ingredients
Meeting with Manitou
• Self consolidating Concrete
– Self Leveling
– Higher Slump
– No Vibration
– Chemical Needed (Water Reducer)
• More Efficient Mix Ratio
– More Aggregate
– Less Cement
• Specific Gravities
• Finishing Tools
• Use of Fibers
Geometry
• Shape
• Thickness
• Feasibility of
Molds
Theoretical Analysis
Θ
b: width into the board
𝐹∗sin(𝑡ℎ𝑒𝑡𝑎)
σcomp=
𝑑∗𝑏
𝐹∗cos(𝑡ℎ𝑒𝑡𝑎)
σflex=
(3∗ 𝐿−𝐿𝑖 )/(𝑏∗𝑑 2 )
• Maximum allowable
flexural and
compressive strength
for each mold design:
• Assume square slab
• To make up for the
lack of stress
concentrations due to
the hole: Factor of
Safety of 3
Theoretical Graph
Flexural Strength vs Theta
Compressive Stress vs Theta
1200
70
Shear Stress
Compressive Stress
60
1000
50
Stress (psi)
Strength (psi)
800
600
40
30
400
20
200
0
10
0
50
Theta (Degrees)
100
0
0
50
Theta (Degrees)
100
Feasibility of Molds
•
•
•
•
•
Wood
– Plastic sheets
(release agent)
– Reusable
– Not as precise
Metal
Plastic
Plastic injection methods
Foam
– Expensive
(concrete
canoe~$800)
– Very accurate
– Trying to figure out
the release agent
Composition
•
•
Aggregates
• Bind properly
• Provide strength
• Reduce cost
Cement Replacements
Mixtures
• 6 different mixtures (each contained cement, course
aggregates, fine aggregates, and water)
• Cement (ternary mix)
– Portland, slag, fly ash (improves strength, workability,
and requires less water)
• Aggregates (all mixtures contained sand)
– Course
• Coconut shells
• Rubber
• Limestone
– Fine
• Sand
• Plastic Beads
• Styrofoam
Why?
• Slag and fly ash improve strength
of concrete when combined with
Portland
• Aggregates can be found in Haiti
• Coconut shells
– considered trash/ in
abundance
• Rubber
– Need to figure out a way
to grind up tires
• Limestone/Sand
– In abundance in Haiti
• Plastic Beads/Styrofoam
– Could grind up plastic
water bottles
Cylinder Testing Procedure
• Slump test: General idea on mold capability as well as the
proper amount of water
• After 7 days/28 days of curing
– ASTM C39: radius= 4” height= 8” Cylinder is loaded
axially. Determines maximum compressive strength (psi)
Test Mixtures (lbs.)
Units (lbs)
Mix 1
Mix 2
Mix 3
Mix 4
Mix 5
Mix 6
Mix 7
Mix 8
Mix 9
Cement
12.49
12.49
12.49
12.49
12.49
12.49
2.35
4.83
2.96
Slag
5.85
5.85
5.85
5.85
5.85
5.85
0.83
X
1.05
Flyash
4.82
4.82
4.82
4.82
4.82
4.82
0.65
X
0.82
Sand
1.50
1.50
1.50
1.50
1.50
1.50
6.95
8.87
8.87
Rubber
1.20
X
X
1.20
X
X
2.21
X
X
Styrofoam
0.01
0.01
X
X
0.01
X
0.04
X
X
Plastic
X
X
0.68
0.68
X
0.68
X
X
X
Coconut
X
1.20
1.20
X
X
X
X
4.14
4.14
Limestone
X
X
X
X
1.77
1.77
X
X
X
Water
7.75
7.75
8.26
7.5
8
8.26
1.72
2.18
2.18
Glenium
X
X
X
X
X
X
10mL
8mL
8mL
6.77
6.70
6.73
6.88
7.08
4.53*
7.16*
7.32*
Weight/cyl 6.45
*weight measured before curing
Cylinder Plan
• 70% Strength at 7 days
• 28 day Accepted
Standard
• Fibers add mild
Compression Strength
• Limestone/Rubber/
Coconut/Shells/Sand/
Stryofoam/Plastic
Results from 7 Day Cylinders
Trial
1 (7 days)
2 (28)
3
Trial
1 (7 days)
2 (28)
3
Max Compressive Force For Mix (Kips)
1
2
3
4
5
22.64
37.67
34.67
21.35
47.07
6
58.58
Area of Test cylinder=
Recorded
Max Compressive Strength (psi)
1
2
3
4
5
6
1801.634 2997.683 2758.95 1698.98 3745.71 4661.65
0
0
0
0
0
0
0
0
0
0
0
0
Mix Tensile Strength (psi, assume 15% compression)
Trial
1
2
3
4
5
6
1 (7 days) 270.24509 449.6525 413.843 254.847 561.857 699.247
2 (28)
0
0
0
0
0
0
3
0
0
0
0
0
0
A=
π*r2
σ=F[lbf]/A[in2]
12.56637
Mix performance
Mixture lb/ft^3
Mixture Compressive Strength
5000
122
4500
120
4000
118
3500
Compressive Stress (psi)
124
lb/ft^3
116
114
112
110
3000
2500
2000
1500
108
1000
106
500
104
0
Mix 1
Mix 2
Mix 3
Mix 4
Mix 5
Mix 6
Mix 1
Mix 2
Mix 3
Mix 4
Mix 5
Mix 6
Improvements Moving Forward
• Add more aggregates
– Used too much cement in first round of testing
– Will reduce weight
• Make more viscous (less water)
– Styrofoam floated to the top of cylinders
– Use Glenium
• Use of finer aggregates
– Sand is more dense than concrete
– Higher strength with less voids
Features
• Modular upgrades for additional cost
• Prepare basic design to allow for add-ins
• Handles
• Textures
• Shelter connection points
Transportability
• Handles
• Wheels
• Rope Attachments
$5.98
All require
holes and
screws
• Terrain is too rough for wheels
• Anchor bolts require $ and drill
• Mold holes in sides for handles/hooks
– Can this be done?
• Multi-functional attributes  simplicity
$2.80
$4.12
$0.48
Shelter Interface
• Holes?
– Consistent with transportability features
– Pole connection
• Grooves?
– Sheet metal
connection
• Small size?
• Also reduces
material and
weight
• Depends on
ground hole
Odor/Pest Reduction
• Cheap, simple cover
• What can be reused?
• Simple hinge?
• Additional holes for toilet seat
cover?
• Recommendation for household
materials to use
– Five gallon bucket
How to make it visually appealing and
simple at the same time:
Material Costs
Materials
Rubber Mulch
Coconut*
Limestone
Sand*
Styrofoam
Plastic
Cement*
Slag
Fly Ash
Cost Weight (lb) Cost/lb
$ 10.98
19.8 $ 0.55
$ $ $ 10.00
2000 $ 0.01
$ $ $ 14.99
2 $ 7.50
$ 7.99
2 $ 4.00
$ 6.28
94 $ 0.07
$ 90.00
2000 $ 0.05
$ 70.00
2000 $ 0.04
*Reflects Cost in Haiti
Fly Ash/Slag?
• Need to evaluate cost/strength trade-off
– Fly ash and slag are not produced in Haiti
– Shipping costs are unknown
– Currently testing mixes with and without flyash and
slag
Cost Breakdown
Cement
Fly Ash
Slag
Rubber
Coconut Shells
Weight
Cost/lb
Weight Cost
Weight Cost
Weight Cost
Weight Cost
1 Cylinder
4.2 $
0.28
1.6 $ 0.06
2.0 $ 0.09
0.2 $ 0.11
0.2 $ Arborloo
117.0 $
7.82
45.3 $ 1.58
54.8 $ 2.47
5.6 $ 3.12
5.6 $ Limestone
Sand
Weight
Cost
Weight Cost
1 Cylinder
0.6 $
0.00
0.5 $ Arborloo
16.6 $
0.08
14.1 $ -
Styrofoam
Plastic Pellets
Weight Cost
Weight Cost
0.003 $ 0.02
0.2 $ 0.92
0.079 $ 0.59
6.5 $ 25.84
Summary of Results
Mixtures Coarse Ag Fine Ag
PM Arborloo
Cylinder Strength (psi)
Total Cost Weight Compressive Tensile*
Mix 1
Rubber
Styrofoam $ 15.58
Mix 2
Coconut Styrofoam $ 12.46
Mix 3
Coconut Plastic
$ 37.71
Mix 4
Rubber
Plastic
$ 40.83
Mix 5
Limestone Styrofoam $ 12.54
Mix 6
Limestone Plastic
$ 37.80
* Assume 20% of compression strength
181.41
190.41
188.44
189.28
193.50
199.13
1801.63
2997.68
2758.95
1698.98
3745.71
4661.65
360.33
599.54
551.79
339.80
749.14
932.33
Ranking
Total Cost Weight Strength
4
6
2
6
4
4
3
5
3
1
3
1
5
2
5
2
1
6
Score
Total
12
14
11
5
12
9
Engineering Requirements
– Purchase Cost
• Plastic expensive
• Ranges from $12-$40
• Target <$25
– Load it can support
• Compression Results
• Only 70% strength
• Ranges from 1500 psi to 4600 psi
• Target >2500 psi
– Ground Hole size  Over design
– Weight
• Average weight per/cylinder = 6.832 lbs.
• Per/arborloo= 190.36 lbs.
Project Schedule: Past/Current
Project Schedule: Future
Budget Tracker
Item
Store
Price
94 lb Portland Cement
Home Depot
$10.47
40" PVC Fencing
Home Depot
$9.97
48"x.25" Round Steel Rod
Home Depot
$9.26
Bird Netting
Home Depot
$14.47
.8 cu ft Rubber Mulch
Home Depot
$5.97
Plastic Sheeting
Home Depot
$10.98
Hardware Cloth
Home Depot
$9.22
Chicken Wire
Home Depot
$7.97
Bean Bag Filler
Bed Bath and Beyond
$14.99
Cement Mixer
Lowes
$8.54
Platic Beads
Jo-Ann Fabrics
$14.99
2 gallon Bags
Target
$8.18
Styrofoam
Michael's
$8.99
4”x8” Test Cylinders
Forney LP
$57.06
Total:
$191.06
Updated Risk Assessment
Moving Forward
• Refining concrete mixtures
– Aggregates for low cost compressive strength
• Flexural testing
– Mold for test block
– Finalize reinforcements
• Cost estimates
– Availability in Haiti
– Shipping costs
• Finalizing features
– Continue to assess feasibility
• Divide team between mold and mixtures