P14416: Concrete Arborloo Base System Design Review October 1, 2013

MemberRole 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 Cost Easy Transport Quick to Assemble Strength Safe Visually Appealing Comfortable Accommodates Large Hole in Ground Modular Safe Visually Appealing Comfortable Accommodates Large Hole in Ground Modular Importance Scale - 9 Importance Scale - 3 Customer Requirements …. 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 compression Only basic Tools are needed Minimally skilled Haitian Mason can make Materials are cheap Easy to provide good tensile strength with the additions of reinforcement s 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 Generation

Concept Generation: Key Functions

Concept Selection Peter Morgan’s as Datum

Concept Selection Dome as Datum

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 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 CONS Less safe Mold design Cost Long assembly time

Selected Concept #3 - Triangle PROS Less Material Simple Mold Design Low Cost Visually Appealing 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 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 CONS Not modular Not comfortable Not visually appealing PROS Accommodates large hole in ground Safe Relatively easy mold Easy to transport 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 Risk ItemEffectCause Likelihood Severity Importance Action to Minimize RiskOwner Spend more than our budget allows Unable to purchase necessary items Overspending on unnecessary materials122 Develop a Bill of Materials that is well under our given budget Budget Tracker Anthony Hole in concrete is deemed unsafeChild could fall through Inability to follow customer requirements133 Pay close attention to the safety of the hole size relative to the rest of the base Check 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 heavy236 Research ways to make concrete more light and implement that into our design Research and test lighter aggregates Test multiple times and recreate Joe Base cracks under minimal loadUseless device Lack of reinforcement236 Obtain multiple reinforcement materials that increase tensile strength by November Mac/Evan Poor concrete mixture236 Research ways to mix concrete and talk to concrete expertsTeam

 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?