An Overview of Sustainable Construction ProductsMicromechanics to Full Scale Structures
Barzin Mobasher Professor School of Sustainable Engineering and the Built Environment Arizona State University Tempe, AZ 85287-5306
June 13th, 2012 You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Construction Products: Temporal, Spatial, and Scientific Span Disciplines
nanometers to kilometers (1x10-8 to 1x103 meters)
Length Scale
• Materials Science • Engineering • Chemistry • Mechanics • Computational Techniques • Manufacturing products and systems • Sustainable development • Technical & non-technical labor pool
hydration
Early age
Service life
Seconds to Centuries (1 to 3x1010 Seconds)
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Time Scale Long term Performance
Construction Products
Societal Challenges – What are the challenges that we face in the next decade?
Sustainability – – – –
Reuse and recycle, Blended Cements Design for durability Quality control Structural mechanics, new materials and design systems
Composite systems – Short fiber, Continuous fiber systems, internal curing – Development of Ductility Based design guides for nonlinear material properties – Self Consolidating, Aerated Concrete
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Sustainability of Construction Materials •
•
At one ton per person per year Concrete is the 2nd consumed material per capita in the world. $1.6 trillion is needed over 5-years to upgrade the US's infrastructure to a good condition. (ASCE,09)
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Sustainability of Construction Materials •
How do we address sustainability? – Efficient use of resources in concrete production such as use of byproducts, less cement consumption, less CO2 production - Novel construction techniques and materials, low-energy and longlasting concrete structures. - Development of Design and Analysis tools to address service life.
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Construction Products
Societal Challenges – What are the challenges that we face in the next decade?
Sustainability – – – –
Reuse and recycle, Blended Cements Design for durability Quality control Structural mechanics, new materials and design systems
New Construction systems – Composites, short or continuous fiber and fabric systems – Development of design guides – Innovative products self consolidating, Aerated Autoclave Concrete
Repair and Retrofit – Earthquake Mitigation, FRP applications – Ductility Based Design
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Concrete Specified vs. Delivered
Delivered Strength, psi
10000
8000
All concrete classes 28 day strength
Each data point = 100 cubic yards
Over-strength Level
6000
4000
Source: ADOT Database for One ready mix supplier over a course of two years
2000 2000
4000 Specified f'c, psi
6000
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Long Beach, Mississippi- Reinforced Concrete House
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Hurricane Katrina, August, 2005
Long Beach, Mississippi, October 30, 2005 -- A lone, mitigated home stands alone in Hurricane Katrina Photo Credit: FEMA/Mark Wolfe
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Bam Earthquake, Iran, Dec. 2003
Approximately 60% of the deaths in the earthquakes in the past 60 years stem from the collapse of unreinforced masonry structures. 74,000 persons died, 70,000 injured, more than 3 million people became homeless during the Kashmir earthquake on October 8, 2005. New Orleans, California, Bam, Kashmir, and many areas devastated by natural disasters use Construction systems based on empirical approaches
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Hurricane Katrina, August 2005
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Natural disasters are a "growth" industry
Since the 1960s, economic losses from natural disasters on a global scale have tripled, while insured losses have quintupled. (after Berz, 1992, Natural Hazards, 5, 95-102)
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Innovations - as the cost of raw materials changes, many cost effective alternatives are developed
High performance Composites– performance enhancing admixtures, manufacturing processes – Supplementary waste by-products and materials. – New testing and specifications.
Durability– increasing service life through more durable construction. – Need a better correlation between the current test methods and predictive models for durability.
Quality– Quality control (QC) parameters. – better understand the quality control measures
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Multi-Scale, -Level, and -Discipline Approach Performance
Code Implementation Long term Performance Durability Field implementation Full scale tests Optimization
Structure Durability, early age and long terms, Mechanical properties, modeling, Code development Repair and retrofit
Processing & Manufacturing Property Matrix modifications, Blended cement systems, Insulated Concrete Forms, Autoclaved aerated Concrete, Composites processing,
Materials characterization, Test procedures, QC/QA Methods
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Multi scale, multi discipline approach
Materials Science – Characterization of Microstructure – Activation of systems – Mechanical properties, fracture, fatigue, constitutive properties
Address Durability Concerns – Physical and chemical degradation – Freeze-thaw, shrinkage, creep, cracking – Characterization of degradation mechanisms
Innovative Systems – Sustainable Materials – Specifications and Codes – Identification of limits of acceptable use of different classes of additives
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Core areas of ConcentrationMicro to macro
Materials Science – Characterization of Microstructure and Chemistry – Mechanical properties, mechanics, constitutive models, structures
Innovative Construction Materials and Systems – Sustainability: stronger, less volume, more durable – Specifications and Codes – High performance composites
Durability of infrastructure systems – Repair and retrofit techniques – Characterization of degradation mechanisms
Environmental aspects – Production, utilization, and waste management
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Mechanical & Computational Mechanics Approaches
Sample Preparation Laboratory Composites Laboratory Structures Laboratory CSSR microanalysis facilities Computational Mechanics Laboratory Interaction
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Structural testing- Full scale
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Durability Testing- Performance Based Design
Early age shrinkage cracking Freeze thaw Chloride permeability Creep Thermal properties Corrosion Chemical Attack
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Housing is a human rights issue • Navajo Nation is 27,000 square miles in the states of AZ, NM, and UT, geographically is the largest Native American reservation in the U.S. •The Navajo Nation has the highest poverty rate in the U.S. More than 56% of Navajos live below the poverty level •Unemployment rate is 44 percent, median family income is $11,885, Per capita income is $6,217. •The population has increased 3.5 times from the 50,000 people in 1940. •Most homes do not have electricity, running water, or telephones.
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Aerated Fiber-Reinforced Concrete (AFRC) Manufacturing, ICC certification & Construction Methods
Demonstration Home in Town of Guadalupe, AZ Designed by ASU Stardust Center
Thermal Mass Airtight, Whole wall coverage reduce HVAC Equipment Reduces energy consumption Fire Resistant, 8” Bearing wall, 4 hour UL fire rating
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Aerated concrete (AC)
Cellular or Aerated Concrete (AC) is a lightweight, noncombustible cement based material manufactured from a mixture of Portland cement, fly ash or other sources of silica, quick lime, gypsum, water, and aluminum powder or paste. It has a very low thermal conductivity. Approximate porosity of 80%, 50% air-pores, 30% micro-pores
2 Al 3Ca (OH ) 2 6 H 2O 3CaO . Al2O3 . 6 H 2O 3H 2
Fluoresce image (AC)
Scanning Electron Microscopy (AC)
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Advantages of aerated concrete
Energy Efficient Fire Resistant, Durable Acoustical Insulation Easy to Use
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Experimental Program and Results: AFRC manufacturing process
Raw materials are weighted and mixed automatically The fresh slurry is then poured into large (8x1.2x0.6 m) steel molds Once AFRC is hardened (5-7 days from casting), the cake is demolded Large loaves (8x1.2x0.6 m) of AFRC are cut using wheel blades Material (each batch)
Weight (kg)
Cement
1,240
Fly ash
1,870
Water (~ 38 °C)
1,270
Fiber (Polypropylene)
18
Aluminum Paste
3.8
Other additives (Accelerator, Epoxy, etc.)
15.2
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Compression test: 3x6” (75x150 mm) cylinders
COD gage
LVDT gages
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Flexure test: 6x6x18” (150x150x450 mm) blocks
time =0 min COD=0.0 mm fR=0.00 MPa
time =3 min COD=0.9 mm fR=0.24 MPa
time =6 min COD=3.6 mm fR=0.28 MPa
time =12 min COD=9.2 mm fR=0.25 MPa
time =24 min COD=18 mm fR=0.13 MPa
Loading Edge
LVDT Gage
AFRC beam Simple Support
CMOD Gage
Actuator
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From Microstructure to full scale wall testing Actuator
LVDT-1
LVDT-2
-Durable, Energy efficient, Effective R-value, 3.4/in, - Fire, Pest resistant, no autocalve -Acoustical insulation, impact resistant Easy to use
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High Performance Fiber and Fabric Reinforced ConcreteLow cost equipment set up Uniform production high performance fabric-cement composites Tension, Compression, beam members High pressure pipes
Sandwich layers
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Bonded Fabrics- Alkali Resistant Glass and Polypropylene fabrics
500 mm
Mobasher, B., Peled, A., and Pahilajani, J., Materials and Structures, (2006) 39:317–331 You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Mechanical Characterization Homogenization of Crack spacing 25
1
Stress, MPa
20
Cumulative Distribution Function
Zone 3 Zone 2
15 Zone 1
10 AR-Glass Fabric
5 0
0
0.02
0.04
0.06
Zone 3 = 0.0387 Zone 2 .0273
0.8
Zone 1 = 0.015
0.6
0.4
AR-Glass Fabric
0.2
0
0
10
Strain, mm/mm
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20 30 Crack Spacing, mm
40
Uniaxial Tensile Response
20
60
40 12
Stress-Strain Crack Spacing
8 20
Crack Spacing, mm
Stress, MPa
16
4
Pultrusion 0
0
0.02
0.04
0.06
0
Strain, mm/mm
Peled, A. and Mobasher, B., (2005), “Pultruded Fabric-Cement Composites,” ACI Materials Journal, Vol. 102 , No. 1, pp. 15-23. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Videos of PE Fabric and PE Composite
PE Fabric
PE Composite with Silica Fume
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Structural components
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3-D Shapes , airfoils for power generation
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Honeycomb Structural bricks
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Shelter, Perm. or Temp. Structures
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Natural Reinforcing SystemsThe Sisal Plant and its Fibers
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Sisal fiber microstructure
Average annual production:153,000 t (1996-2000,Prosea 2003) Good engineering properties Environmental impact and costs are low Mainly used today to make twines, ropes, strings, fishing nets. Energy-saving material Middle Lamellae
Fiber cell
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Lumen
Applications
Exterior walls (Office building, Dortmund , Germany)
Bridges (Technical University, Dresden)
Shells and roofing applications (COPPE/UFRJ)
Pipes and other tubular structures (RWTH Aachen)
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Structural Design with FRC Materials Requires proper guidelines for testing, analysis and Design
Elevated slabs
Precast panels
Shotcrete applications
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Stress-Strain for Hardening and Softening FRC
Material parameters are described as a multiple of the first cracking tensile strain (cr) and tensile modulus (E)
Compression model
t
cy=cr γE
c
Tension model cst=mcrE, m>1
cr=Ecr E
cr
trn=cr
t
tu= tucr
c cy=cr
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cu=λcucr
Moment-Curvature Diagram
Incrementally impose 0 < t < tu Strain Distribution Stress Distribution SF = 0, determine k (Neutral axis) M = SCiyci+ STiyti and f=c/kd Normalization M’=M/M0 and f’=f/fcr strain
c
f c1 y dy
0
b yc1 Fc1
stress
k f
Fc1 b
kd
M
kd
0
f c1 y ydy
Moment curvature diagram
C2 C1 T1
d
T2 T3
0 < t < tu You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
f
Stress and Strain Distribution Tensile Regions 1.0, 2.1 and 3.1 1 < β < α and λ < ω
0 < β < 1 and λ < ω (1)
1
Fc1
1 hc1
ctop=lcr
fc1
ctop=lcr kd
1
(2.1)
yc1
yt1 1
1
cr
ht2
2
ft1
tbot=bcr
ht1
1
Ft1
α < β < βtu and λ < ω
trn 3 tbot=bcr
2
Fc1
1 hc1 kd
1
cr
fc1
1
(3.1)
ht1 ht2 ht3
yc1 d
ft1
1 ft2 2 ft3 3
kd
yc1 d
1
ft1 2 ft2
tbot=bcr
ctop=lcr
Fc1
1 hc1
d ht1
fc1
yt1 yt2 Ft1 yt3 Ft2 Ft3
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yt1 Ft1 yt2 Ft2
Closed Form Solutions for Strain Hardening/Softening material M =M' M cr 1 M cr bd 2 E cr 6
'cr 2 cr cr d
Soranakom C, Mobasher B. “Correlation of tensile and flexural responses of strain softening and strain hardening cement composites”, Cem Concr Comp 2008;30:465–477. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Load Deflection Response Applicable to 3PB and 4PB Tests Moment
Moment area method Crack localization rules
Non-Localized Zone
Localized Zone
fj-1,Mj-1)
P/2
P/2
M0 fj,Mj)
S
Mmax
S
Mfail Non-Localized Zone
P Localized Zone
S Loading Unloading
L
cS S
Axis of Symmetry
S/2 Curvature
M M0
f f0
cr
23 2 L cr in elastic region 216
L2 µ>µcrit: u 2Mu2 Mu M cr M cr2 u Mu2 Mu M cr cr 2 24Mu
u L p 2 L L p M ucr L L 2 L p µ<µcrit u 8 12M cr
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Back Calculation Parameters
Tension Model
Compression Model
6.0000
Compressive Stress
40
Tensile Stress
5.0000
4.0000
3.0000
2.0000
1.0000
0.0000 0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
35 30 25 20 15 10 5 0 0.000
Tensile Strain
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0.001
0.002
0.003
0.004
Compressive Strain
0.005
0.006
Evolution of Profile of Stress Distribution Stress, MPa 0
2
80
Distance along depth, in
Distance along depth, mm
3
Distance along depth, in
(C)
4
60
2
40 1
20 0
0
-20
-1
-40 -2
-60 -3
-400
-80 0
400
800
Stress, psi
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Distance along depth, mm
-2
Distance along depth, in
(B)
Distance along depth, mm
(A)
Data Reduction by ARS Method Stress, MPa 0
5
10
15 80
3 N.A. (Present Method)
2 Stress Distribution in Softening Zone
1
60 40 20 0
0 N.A. (ARS method)
-20
-1 Present Method, Elastic Softening ARS Method, Linear Elastic
-2 -3
-400
-60 -80
400
1200
2000
Stress, psi
-40
The ARS value does not represent an equivalently elastic stress associated with the post crack tensile strength
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2800
Curve Fitting of ARS versus Post Peak Residual Strength (μσcr) 2.4 Polymer - Type A
2
Polymer Type B
1.6 Polymer - Type C
1.2
Hybrid (B&D or C&D)
0.8 AR-Glass Fiber
0.4 0.2 0.3 0.4 0.5 0.6 0.7 Post Peak Residual Strength ( cr), MPa Bakhshi M, Mobasher B. “Sustainable Design of Structural Concrete Materials: a Case Study of Materials Science, Structural Mechanics, and Statistical Process Control”, A Report (SR-633) to Arizona Department of Transportation, Tempe, AZ, 2010.
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Comparison with JCI Method Steel Fibers JCI-SF4 GJCI-SF4 = 6.31 cr R2 = 0.99
6
JCI method overestimates the residual strength of – synthetic fibers by 1.4 times – steel fibers by 6.3 times
4
Synthetic Fibers JCI-SF4 GJCI-SF4 = 1.39 cr R2 = 0.94
2
0
0
0.4
0.8
Post Peak Residual Strength (
1.2 ), MPa
cr
Bakhshi M, Mobasher B. “Sustainable Design of Structural Concrete Materials: a Case Study of Incorporating Materials Science, Structural Mechanics, and Statistical Process Control”, A Report (SR-633) to Arizona Department of Transportation, Tempe, AZ, 2010. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Size Effect- Back Calculation of UHPFRC Steel Fiber Reinforced Concrete
Small: 50x25x300 mm Medium: 100x100x300 mm Large: 150x150x450 mm 20 Exp. (Small) Sim. (Small) Exp. (Medium) Sim. (Medium)
Stress, MPa
16
Exp. (Large) Sim. (Large)
12 8 4 0
0
2 4 Deflection, mm
6
Kim D-J, Naaman AE, El-Tawil S. “Correlation between Tensile and Bending Behavior of FRC Composites with Scale Effect”, Proc FraMCoS-7, 7th International Conference on Fracture Mechanics of Concrete and Concrete Structures, May 23-28, 2010, Jeju Island, South Korea You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Ultra-High Performance FRC3000 2500 2000 1% steel Fiber 80kg/m3
1500 1000 500 0
steel Fiber 20-60 kg/m3
0
40 80 120 160 200 240 Post Peak Residual Strength ( cr), psi
Kim D-J, Naaman AE, El-Tawil S. “Correlation between Tensile and Bending Behavior of FRC Composites with Scale Effect”, Proc FraMCoS-7, 7th International Conference on Fracture Mechanics of Concrete and Concrete Structures, May 23-28, 2010, Jeju Island, South Korea You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Round Panel specimens-Continuous support
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Round Panel 3P-support specimen, ASTM C1550
(a)
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Fiber Reinforced Concrete for 2-way elevated slab structures Composition
Amount
Cement Type I
350 kg
Fly ash
60 kg
Aggregate (1.1:1) W/C Supper plasticizer
1800 kg < 0.5 1.25 % by Vol.
Vf = 80 - 100 kg/m3
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Full Scale Elevated Slab
Vf=100 kg/m3 in construction Square grid floor 18.3 m x 18.3 m (3 bays each direction) Slab thickness of 0.2 m Column size of 0.3 m x 0.3 m
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Test rig centre span
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Construction and Field Testing
Cast in place SFRC Use minimum reinforcement along the column lines to prevent progressive collapse
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Service Load, 4kNm² udl, (83 psf)
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End of Test
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320kN cracking
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Crack Predictions
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Safety and Cost
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Precast panels
Panels are made of plain concrete and steel rebar to be installed on site
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Installation of pre-cast water tank
Panels are assembled on site The wall joints are connected using bolts and epoxy The base slab is connected to the periphery walls by friction through slots
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Analysis of Wall Panels
Assume continuous wall, pin connection at the bottom and free at the top Lateral water pressure in ultimate and serviceability limit states
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Analysis Results
Load Case1: – 1.4 Self weight + 1.4 Water pressure – Moment in short span direction SM1
Load Case2: – 1.4 Self weight + 1.7 Earth pressure + 1.7 Uniform pressure due to surcharge – Moment in short span direction SM1
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Septic Tanks
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Repair of Unreinforced Masonry Walls Large scale tests
In-plane shear tests to simulate seismic action. B. Mobasher, N. Jain, C. Aldea, C. Soranakom, ACI, Textile Reinforced Concrete (TRC) - German/International Experience symposium, 2007. You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
2 plies
Large scale tests Test results, cont’d Backbone curves for strengthened wall vs. control
60 40
HF
20 0 -20 (+) Backbone (+) Control Backbone (-) Backbone (-) Control Backbone
-40 -60 -0.4
0
0.4
0.8
D4-D7
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0/90
ASU –Meccano Project
“Meccano de Mexico, SA de CV” is a Mexican Company founded in 1982. It has presence in most of the Mexican States. Its main product is “The Total Mold”, Made out of Steel, Aluminum, or composites. The whole house is built out of concrete. There are more than 500 molds in use in Mexico. Another 500 molds are expected to be introduced in the next 4 years. Every year more than 80,000 units are built with Meccano molds. The amount is expected to be doubled in 4 years.
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Construction steps
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Introduction: Meccano’s Monolithic Building Systems
The total mold is a unique system of metallic forms and accessories that once assembled will form a complete mold that allows walls, roofs, and stairs to be constructed in one cast with a minimum number of workers. This construction technique is applicable to many regions of the world. Potential utilization of alternative construction products such as aerated concrete where steel and wood are scarce.
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Comfort Zone
One of the main goals of the present approach is to develop an understanding in the human aspect of the comfort level within a structure. The objective is to minimize the time period associated with the threshold comfort temperature if no energy intensive cooling is desired. Zone t3 represents the uncomfortable time zone which is the overlapped time zone when both the inner and outer temperatures are higher than the comfortable temperature. Our objective therefore is to minimize t3. t1 40 Comfortable temperature T = 32 0C 30
t3 t2
20
Tout Tin
10 0
10
20
Time, h You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
Experimental Program and Results: Thermal Conductivity Test
Samples tested per ASTM C177-97 “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus.”
Guarded-hot-plate test set up
Diagram of Guarded-Hot-Plate Apparatus
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Experimental Program and Results: Results of ASTM Test C177 (cont.)
Temperature, oC
This procedure applies a one dimensional direction heat flow Qx through a specimen of a cross section A, to produce a temperature gradient across the thickness dT/dx. This allows for the thermal conductivity k of the material to be determined (in Wm1K-1) from Fourier’s Law: Qx = -kA*dT/dx
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Thermal Conductivity, W / K-m
Thermal Insulation of Cast in place Walls
Temperature, 0C
50
Experiment, Tout Experiment, Tin Simulation, Tin 40
30
20
0
10
20
30
Time, h
Experimental and thermal simulation of insulation of concrete walls
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40
Experimental Program and Results: Full-Scale Testing
Six month long thermal and humidity monitoring stations were set up inside several model built single cell structures with dimensions of 3 m by 3 m by 2.9 m. Three different structural modules were built and subjected to the ambient thermal cycling under natural climatic conditions.
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Remote Monitoring Project Meccano with Centre de Investigacion en Energia, Mexico City
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Experimental Program and Results: Full-Scale Testing Results
The temperature on the interior and exterior face of each wall and roof were recorded as a function of time as these model structures were subjected to climatic conditions of Torreόn Mѐxico from March 2009 to August 2009. 40 32 24 40
Side 1
32 24 40
Side 2
32 24 40
Side 3
32 24
Side 4 34
36 38 Time, Days
40
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Finite Element Analysis: Theoretical Program
The experimental results of insitu external and internal temperature variations of model concrete structures were studied using a transient finite element analysis.
Time-temperature history during a one-week period, on two separate instances was used.
A heat transfer step was initially carried out on a 2D wall system. Once the accuracy of the system was verified the analysis was completed on a 3D whole house system.
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Finite Element Analysis: 2D Results
The 2D results show there is good agreement between the simulation and the experiment.
In the period of temperature rising, the simulation matches the experiment very well.
There is a slight difference between them when the temperature drops.
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Finite Element Analysis: Results (cont.)
The post-processing tools in ABAQUS were used to determine the materials response through the thickness.
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Recent Publication
Mechanics of Fiber and Textile Reinforced Cement Composites, Published by CRC press, 2011. E-mail:
[email protected] http://enpub.fulton.asu.edu/cement/
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Conclusion
New technologies and directions are clearly available in our future progression in Construction industry. Use scientific, physics, chemistry, and mechanics based approaches to obtain better ways to characterize, model, analyze, and design. Better train, communicate, and follow through – respect the construction component of the manufacturing process.
Address specifications, quality, and long term performance.
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Empirical Approaches Still Dominate the Field Estimation of Initial Rate of Evaporation
ACI 305 nomograph estimates rate of evaporation of concrete by Menzel’s Formula
E = 0.313(es0 - ea ) (0.253+0.06V)
Based on water evaporation on lake Hefner near Oklahoma city (1950-2)
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Early Age Crack Control improves long term performance Fiber content = 3 kg/m3
Plain Concrete
Fiber content = 6 kg/m3
0.08 Control ARG2.5 ARG5.0 ARG7.5
Crack Width, in.
0.06
0.04
0.02
(image analysis on 2D cracks)
0 0
5
10
15
20
25
30
Time, Days
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