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68 The Masterbuilder - August 2013 • www.masterbuilder.co.in

Use of Human Hair as Natural Fiberfor Fly Ash Bricks

Fly ash generated during the combustion of coal for energyproduction is one of the industrial by-products and it is recognized

as an environmental pollutant. Because of the environmental

problem of fly ash, a good deal of work and applications on

the utilization of fly ash has been undertaken world over. Fly

Ash bricks are made of fly ash, lime, gypsum and sand. Thesecan be extensively used in all building constructional activities

similar to that of common burnt clay bricks. The fly ash bricks

are comparatively lighter in weight and stronger than common

clay bricks. Since fly ash is being accumulated as waste material

in large quantity near thermal power plants and creating serious

environmental pollution problems, its utilization as main rawmaterial in the manufacture of bricks will not only create ample

opportunities for its proper and useful disposal but also help

in environmental pollution control to a greater extent in the

surrounding areas of power plants.

In this study, we have used Human Hair in fly ash bricks. Fiberfly ash bricks are made of fly ash, lime, quarry dust, sand and

natural fiber.

Fiber Fly ash made bricks uses all ingredients which are having

a minimum negative environmental impact. Hence, Fiber Fly ash

bricks provides a better way for achievement of real sustainable

development & can be considered as bricks for the next generation.

Fiber Fly Ash bricks are advantageous over conventional clay

bricks as per following aspects: Less water absorption, less

weight, better finishing, high strength, less mortar consumption for

joints filling, less number of bricks required, reduced wastage.

Looking to these advantages, more and more stakeholders fromthe construction industry are getting attracted towards using Fiber

Fly Ash bricks instead of clay bricks. But, it requires proper use of

a mix of various available ingredients so that quality is achieved

along with minimum investment.

The study has given findings in the form of different mixes for

Fiber Fly Ash bricks brick production in the central Gujarat region

of India.

Why Hair as a Fiber?

- It has a high tensile strength which is equal to that of a copper

wire with similar diameter.

- Hair, a non-degradable matter is creating an environmentalproblem so its use as a fiber reinforcing material can minimize

the problem.

- It is available in abundance and also at a very low cost.

- It reinforces the mortar and prevents it from spalling.

Experimental Work

To carry out a Techno-economical study of Fiber Fly Ash bricksmain ingredients are: Fly ash, Lime, Quarry Dust and sand. In

addition to these major materials, other less utilized ingredient

like: Human hair which is available from hair saloon as a waste

Darsh Belani1 , Prof. Jayeshkumar Pitroda2 , Dr F S Umrigar31Student of first year M.E (C.E & M), B.V.M Engineering College, Vallabh Vidyanagar2 Assistant Professor and Research Scholar, Civil Engineering Department,B.V.M. Engineering College, Vallabh Vidyanagar-Gujarat-India3Principal, B.V.M. Engineering College, Vallabh Vidyanagar

Thermal industry waste - fly ash is generated in huge quantities. The large quantities of human hair, unfortunately, is not always well

managed or utilized. These wastes can be recycled, such as by incorporating in brick-making. This way the fly ash bricks are made a

‘greener’ building material and the discarded natural wastes can be re-utilized, avoiding otherwise wasteful landfill and harmful open

incineration. The aim of the present study is to investigate the strength and water absorption of fiber fly ash bricks made of human hair

fiber and fly ash. This study examined the various properties of fly ash bricks made by adding human hair to a fly ash brick mix. The fibers

were replaced within the range of 0.1-0.7% by weight of fly ash. In the present study, 8 different mixes of fiber fly ash bricks are tested forparameters like: crushing strength, weight, water absorption and cost.

Figure: 1 Human Hair

Fiber Fly Ash Bricks




absorption is decreased, crushing strength is increasing

compare to fly ash bricks (see figure -4).

d) Problems Encountered:

It is well said that: “The taste of defeat has a richness ofexperience all its own.” During our research work we also

faced the problem of uniform distribution of hair in the fly

ash mix. So to overcome this problem we have adopted the

manual method of distribution of hair in the fly ash mix.

Acknowledgment

The Authors thankfully acknowledge to Dr. C. L. Patel, Chairman,

Charutar Vidya Mandal, Er.V.M.Patel, Hon.Jt. Secretary, Charutar

Vidya Mandal, Mr. Yatinbhai Desai, Jay Maharaj construction,

Dr. A. K. Verma, Head & Professor, Structural Engineering

Department, Dr. B.K.Shah, Associate Professor, Structural

Figure 2 :Different Mixes of Human Hair Fly Ash Bricks v/s Weight, % Water

Absorption

Figure 3 :Different Mixes of Human Hair fly ash bricks v/s Compressive

Strength (N/mm2) at 7, 14, 21 days

Figure 4 : Different Mixes of Human Hair Fly Ash Bricks Compressive Strength

(N/mm2 ) at 21 Days V/s Cost (in Rs./No.)

Engineering Department, B.V.M. Engineering College, VallabhVidyanagar, Gujarat, India for their motivations and infrastructural

support to carry out this research.

Reference

[1] Chee-Ming Chan, “Effect of Natural Fibres Inclusion in Clay Bricks:Physico-Mechanical Properties,” International Journal of Civil

and Environmental Engineering, March 2011.J. Clerk Maxwell, A Treatise on Electricity and Magnetism, 3rd ed., vol. 2. Oxford:Clarendon, 1892, pp.68–73.

[2] Jayesh Pitroda,Rajiv Bhatt, Indrajit Patel,and Dr. F.S.Umrigar,

“Techno-Economical Study Of FAL-G Bricks-A Case Study,”National conference on Fly ash/Futuristic Materials in CivilEngineering Construction For Sustainable Development, pp. 1-2,

2010.

[3] Jain D. And Kothari A., “ Hair Fiber Reinforced Concrete”, ResearchJournal of Recent Sciences, IISSN 2277 – 2502, Vol. 1(ISC-2011),

128-133 (2012)

[4] J.N. Akhtar and Sh. Ahmad, “The Effect of Randomly OrientedHair Fiber on Mechanical Properties of Fly-Ash Based HollowBlock for Low Height Masonry Structures”, ASIAN JOURNAL OF

CIVIL ENGINEERING (BUILDING AND HOUSING) VOL. 10, NO. 2(2009).

[5] Mohini Saxena, Asokan Pappu, Anusha Sharma, Ruhi Haque and

Sonal Wankhede , “Composite Materials from Natural Resources:Recent Trends and Future Potentials”, CSIR- Advanced Materialsand Processes Research Institute, Council of Scientific & Industrial

Research, Habibganj Naka, Bhopal, India

[6] Pandian NS, Rajasekhar C, Sridharan, “Studies on the specificgravity of some Indian coal ashes”, Journal of Testing Evaluation, ASTM, 26 (1998)177-86.

[7] Shakeel Ahmad, Farrukh Ghani, J.N. Akhtar and Muzammil Hasan

(2011),” Use of Waste Human Hair as Fibre Reinforcement inConcrete”, Journal, Institution of Engineers (India), Vol.91, February

2010

[8] Shakeel Ahmad, Farrukh Ghani, J.N. Akhtar and M. Hasan (2009),”Use of waste Human hair as fibre reifocement in concrete”, Proceeding,

International Symposium on Innovation & Sus-tainability ofstructures in Civil Engineering, ISISS, 2009, held at Guangzhou,China (Paper No. 341) November 28-30.

[9] Yadollah Batebi, Alireza Mirzagoltabar, Seyed Mostafa Shabanian

and Sara Fateri, “Experimental Investigation of Shrinkage of NanoHair Reinforced Concrete”, Department of Civil Engineering, BabolUniversity of Technology, Babol, Iran, Iranica Journal of Energy &

Environment, Special Issue on Nanotechnology: 68-72, 2013,ISSN2079-2115.

SampleFly Ash(Class-

F)Sand

SludgeLime

QuarryDust

HumanHairFiber

B5 59.5% 20% 10% 10% 0.5%

Figure 5 : Optimum Contents for Human Hair fly ash bricks

Fiber Fly Ash Bricks



1200SJP JLG Ultra Boom




Analysis, Design and Construction ofFabric Structures

The history of structural engineering can be viewed as

a movement towards lighter structures beginning with

heavy masonry arches and domes, transitioning in

the 19th century with the introduction of steel and iron,

and bringing us to the present modern world, where the

development of materials and methods continues to

improve our ability to create interesting and unique building

spaces. In this way, fabric structures represent the fore-

front of modern structural engineering; the result of cen-

turies of building history and engineering knowledge. In

its short history, fabric structures have fascinated architects

and engineers alike. Architects appreciate their unusual

shapes and forms while engineers delight in their “pure”

structural expression. Appearing as sports arenas,

Sonjoy Deb, B.Tech,

Civil Associtate Editor

Fabric Structures



www.masterbuilder.co.in • The Masterbuilder - August 2013 107

con-vention halls, or other publicly-exposed buildings, fabric

structures have often been regarded as iconic partly due to their

specialized nature and partly due to their short history or lack

of widespread precedential knowledge. The design and con-

struction of fabric structures requires both the development of

new analysis methods and construction procedures as well asan overall transformation in the way that designers work with

fabricators.

Fabric structures possess several advantages over con-

ventional structures. Perhaps most importantly, fabric can span

large distances without incurring much weight on supporting

structure or foundation. They are capable of carrying large applied

loads while weighing very little in com-parison to steel or concrete

structures of the same spans. This reduction in weight and

material translates into shorter construction schedules and

overall cost savings.

History of Fabric Structure

The following is a brief review of selected structures and their

contributions to the (Source: Berger, 2005) advancement of

fabric structure design and construction.

(A) J.S. Dorton Arena, Raleigh, North Carolina(C) U.S. Pavilion, World’s Fair, Osaka, Japan

Designed by architects William Deitrick, Matthew Nowicki, and

engineer Fred Severud, the Raleigh Arena is often cited as the

first modern, large-scale, cable-net structure. The famous saddle-

shaped roof is made from a set of upwardly-curved cables,

which intersect with perpendicular downwardly-curved cables.

The upward cables span approximately 95 meters between

two intersecting and inclined parabolic arches (Vandenberg).The cable-net roof supports a more traditional roof consisting

of rigid insulation and corrugated steel sheets, and creates a

30 meter diameter column-free plan.

(B) German Pavilion, Expo, Montreal, Canada

Designed with architect Rudolph Gutbrod, this structure covers a

total area of 8,000 square meters, spanning 130 x 105 meters

in two directions (see plan in Figure 4). The shape of the roof

is determined by a set of support masts, which vary in height

from 14 to 38 meters, and anchor points dispersed throughout

the site (German Pavilion, Expo ‘67, Frei Otto).

The U.S. Pavilion at the 1970 World’s Fair in Osaka,Japan is one

of the first, large-scale air supported structures constructed.

The lightweight roof option was first considered because of the

site’s poor soil conditions and high exposure to seismic activity.

Designed by architects Davis and Brody and engineered by

David Geiger, the 139 x 78 meter plan forms into the shape of a

super-ellipse, somewhere between ellipse and rectangle.

(D) Haj Airport Terminal, Jeddah International Airport,

Saudi Arabia

As the world’s largest roof structure to date, the Haj terminal

of the Jeddah International airport features a unique and

interesting radial tent design. It was designed by architect

Skidmore, Owings, Merrill and engineer Horst Berger in 1981.

Here again, one can see how fabric structures are efficient for

creating visual interest in a publicly exposed space. For this

project in particular, the properties of fabric chosen were of

special importance. Located in the middle of the desert, the tent

modules were designed to transmit daylight while protecting

Fabric Structures




Fabric Materials

Advances in the design of fabric structures often go hand-

in-hand with the development of new, high-performance

materials. Materials used for structural fabric satisfy all of the

requirements of a typical roof, while maintaining only a fraction

of the weight, volume, and cost. These requirements include,but are not limited to, coverage and protection from exterior

weather conditions, air tightness, waterproofing, fire-resistance,

durability, acoustic and heat-control.

A. Components of Structural Fabric

As implied by their name, the most important and defining com-

ponent of a fabric structure is the fabric material itself. Structural

fabric can be broken down into yarns, which in turn are made

of fibers. The basic element of fabric material is therefore the

individual fiber. There are a variety of ways to join fibers to create

yarn and a number of ways to weave yarn into fabric.

B. Behavioural Properties Of Fabric Materials

A proper understanding of elongation and elastic properties

of fabric materials is essential to creating a desired shape. The

application of new materials can be frustrating because if

one of the properties is not sufficient, it usually requires the

develop-ment of an entirely new fabric, with different yarns

and weaving techniques. Sometimes, the resulting new fabric

can have a totally different set of properties than the ones

previously specified. Conventional structures often require

lower factors of safety because the materials they use have more

dependable strength properties. In contrast, fabric materials

exhibit unreliable behaviour and low durability, as propertiescan change drastically over time as a result of weathering, UV

degradation, and repeated loading.

Tearing and Tensile Strength

Tearing and tensile strength describe a fabric’s ability to carry

load along the plane of the fabric. While tensile strength is a

measure of fabric stretching from opposite ends, tearing strength

refers to local failure, when forces are applied at one location in

opposite directions. The tear and tensile strength of fabric are

indirectly related; as tensile strength increases, tearing strength

decreases. This relationship is analogous to cutting a string; a

taut string is easier to cut than a slack one. Similarly, a fabric

that is capable of carrying higher planar stresses will tear more

easily.

Stretching and Dimensional Stability

As mentioned previously, the weaving process of fabric results

in a material that elongates and deforms a great deal. The main

way to mitigate this problem is to pre-stretch or pre-tension

the fabric. This can be done to the fabric as a whole before

installation or during the weaving process to individual fibers,

in which case the force in warp and fill fibers can be adjusted

to produce equal deflection in both directions. Fabrics tend to

have more strength in the straight, warp direction rather than

the huge number of people travelling through the airport on

their way to Mecca. The structure consists of 210 square tent

units, each measuring 45 meters along its edge cable.

Types of Fabric Structure

Though fabric structures come in varying size, scale, shape and

form, all of them consist of the same basic elements:

- A lightweight and flexible fabric membrane, tensioned for

stability and usually used as a roofing element,

- Flexible linear elements such as ties or cables, which are

commonly used at boundaries or edges, and

- Rigid supporting members such as masts, frames, rings,

arches, and edge beams, which usually transfer loads in

compression

Though there are a variety of ways to categorize tensionedfabric structures, Lewis (2003) divides them into three main

groups:

(1) Boundary tensioned membranes,

(2) Pneumatic or air-supported structures, and

(3) Cable-nets or cable-beams.

Fabric Structures




the “crimped” fill direction, and can often become dimensionally

unstable as a result of crimp interchange. Other factors can

affect the dimensional stability of fabric material. These include

changes in temperature and water content. Increases in tem-

perature will increase fiber elongation as a function of the

material’s coefficient of thermal expansion. Water is bad for

fabric materials for a number of reasons. In addition to promoting

freeze-thaw action, water also carries microorganisms that

degrade the material over time. For these reasons, water-proofing

is an important function of fabric coatings. Stretching and

dimensional stability are significant considerations because

fabric membranes must always remain in tension. If any section

of a fabric loses tension, it “bags” and “flutters” and can no

longer contribute to the load-resisting structural system.

Ultraviolet Radiation Protection

Many fabric structures degrade with exposure to UV light.

Though glass is not significantly affected, tests have shown

that polyester loses 20% and nylon 90% of its strength when

exposed for 110 weeks. UV protection can be achieved with

light-resistant additives in the fiber material or UV absorbers in

the coating.

Fire Protection

Fireproofing is a major consideration in the design of fabric

structures. Several common fire tests and standards exist forfabrics and other textile materials. These include:-

- The National Fire Protection (NFPA) 701 - Fire Tests for

Flame-Resistant Textile and Films.

- The American Society for Testing and Materials (ASTM)

- E84 - Surface Burning Characteristics of Building Materials

(Flame Spread Test)

- E108 - Fire Tests of Roof Coverings

Translucency and Thermal Resistance

Fabric materials feature several properties that render them

effective in warmer climates. These include low insulatingability, low thermal mass, high reflectivity of light, and low tran-

slucency. Translucency is an important material property of

architectural fabrics because it has both aesthetic and technical

implications: allowing natural daylight into a building space and

resulting in higher energy savings. Fabrics are available in a

range of translucency, from as little as 1% to as much as 95%,

though the most commonly-used fabric materials can only

achieve about 25%.

C. Comparison of Common Fabric Materials And Coatings

PVC Coated Polyester

PVC-coated polyester fabric is the oldest and one of themost commonly used materials on fabric structures. It has a

high tensile and tear strength but low durability as it tends to

deteriorate from UV radiation. It also exhibits creep behavior,

losing significant levels of pre-stress over time and sometimes

requiring membrane re-stressing. Their tendency to retain dirt

PVC-Coated Polyester PTFE-Coated Fiberglass

Base Fiber Tensile Strength 350-1200 MPa 3500 MPa

Weight 800 - 1100 g/m2 -----

Strip Tensile Strength 3100-5800 N/5cm 1600 - 8800 N/5cm

Tear strength Good Poor

Stiffness Moderate High

Creep Behavior Moderate ----

UV Resistance Coating protects for 10-15 years High resistance to UV degradation

Light Transmission Up to 22% translucency Up to 27% translucency

Fire Resistance Good Moderately good

Cost$90-$150/m2 (fabric)

$400-$700/m2 (entire roof)$60-$80/m2 (unfabricated)

$500-$1000/m2 (entire roof)

Strengths Least Expensive Good Tear Strength High durability

Weaknesses Relatively low durability Requires careful handling, highly susceptible to water damage and tear

Table 1: Comparison of PTFE coated fibreglass and PVC coated polyester

Fabric Structures




can be overcome with the application of fluro polymers on top

of the PVC coating. Though this material was popular in the

1960’s, it has since been surpassed by glass fiber fabrics,

partly because many consider its low durability and lifespan of

10-15 years a barrier to application as permanent structure.

PTFE-Coated Fiberglass

Teflon-coated glass and silicone-coated glass fabrics have

considerably higher tensile strengths, but poor tear strengths

in comparison to PVC-coated polyester. They also exhibit less creep

and require minimal maintenance, though water damage is

sometimes a serious concern. Because glass is more susceptible

to brittle failure, PTFE-coated fiberglass must be handled with care

during transport. Silicone-coated fabrics are more flexible and

therefore less brittle than Teflon-coated fabrics. It is worth noting

that fiberglass is typically much more expensive than polyester

both as a raw material and as a finished roof application.

How Fabric Structures Work

Depending on specified boundary conditions and internal

prestressing, fabrics can either form into an anticlastic shape

with negative Gaussian curvature or a synclastic shape with

positive Gaussian curvature. The term anticlastic refers to

the opposing directions of perpendicular fiber elements. Joining

together to form a saddle-like shape, these elements exert

equal forces on each other and internally brace against

themselves. Synclastic shapes consist of elements that are

curved in the same direction like a balloon. In the design of

fabric structures, upwardly curved elements are usually called

“ridge” cables while downwardly curved ones are “valley” cables.

The minimum number of anchor points needed for any sectionof fabric is four. Three points are insufficient because the

resulting surface is a simple, flat triangle; as mentioned in the

previous discussion about cables, fabric elements gain stability

with curvature. The four shapes consist of elements that are

curved in the point structure is therefore the most basic element

of a fabric structure. It can be created with an endless number

of boundary conditions and joined together to make a variety

of interesting shapes and patterns. Refer Figure below for four

point structure.

Analysis Methods - Theory and Methods For Shape-Finding

Analysis models for conventional structures assume a linear

relationship between applied forces and displacements. Theselinear models can accurately describe a structure’s shape,

but are limited to a range of small displacements. Conversely,

the design and analysis of fabric structures requires a

thoroughly non-linear approach, modelling large deformation

behavior through the use of iterative numerical methods. The

Newton-Raphson method is a classical approach to the

analysis of nonlinear structures, which does not apply well

to the behaviour of fabric because convergence is slow and

sometimes does not happen at all. However, Newton-Raphson

works better when an initial estimate of shape or geometry is

specified. Newer analysis methods have been developed for

the direct application of analysing cable-net and tensioned

fabric structures. These include the Grid Method and the

Force Density Method, which are both used to estimate initial

system geometries before applying Newton-Raphson. Another

nonlinear analysis that can be applied to fabric structures is

the Dynamic Relaxation Method. The theory behind each of

these methods is described in detail in the following sections.

Methods used for structural analysis are:-

(A) Linear Structural Analysis

(B) Tangent Stiffness Method

(C) Grid Method

(D) Force Density Method

(E) Dynamic Relaxation Method

Construction Considerations

The constructor of fabric structures has a more important

role to play than those of conventional structures, because

they are dealing with relatively new materials, methods, and

technologies. Indeed, fabric roof design is often considered

so special that it falls under a separate contract from the main

structural system of a building; clients will even sometimes

appoint a different structural engineer for the fabric and for

the main structure. More often than not, the design of fabric

structure is limited by manufacturing capabilities. A fabric

contractor must therefore be chosen with care.

Types of Connections

The design of connections in fabric structures often requires

careful and thorough consideration. Unlike connections in

conventional buildings, they play a crucial role in the creation of

architectural form and concept, as the geometry of a fabric roof

is entirely dependent on the proper placement and design of

these connections. Furthermore, they are often exposed to view

and must therefore be constructed with aesthetics in mind. One

of the most important considerations when designing fabric

connections is the stress concentration that may occur in the

local area surrounding it. Being highly sensitive to concentratedFigure : Examples of Various Four Point Structures

Fabric Structures




applied forces, clamps, cables, and seams should almost always

fully develop stresses into the fabric.

Patterning

Fabric patterning is the construction stage in which large fabric

rolls are cut into smaller, two dimensional sections. In the pastand up until the 1970’s, procedures for patterning fabric were

based on physical models and hand calculations. Today,

fabricators use form-finding software as well as geometry

monitoring technologies to ensure accuracy in production. The

process of patterning becomes complicated when pre-stresses

are considered. Because fabric membranes are stretched

during installation to produce a certain state of pre-stressing,

sections must be cut smaller than their final dimensions, a

consideration commonly referred to as “compensation”. The

problem is further complicated by the multi-axial nature of

fabric material, which generally causes it to elongate more in

the fill direction than in the warp direction. Biaxial tests on fabric

materials help to determine the compensation factors to be

applied for the reduction of each pattern section.

Erection and Installation

Fabric structures are more vulnerable to failure during

installation because they are not fully stable until they have been

fully erected and tensioned. For this reason, installation periods

for these structures should be minimized and construction

sequences must be carefully planned. The materials in fabric

structure form a hierarchy in terms of stiffness and flexibility.

Fabric membranes are more flexible than the edge cables and

ties, which are still more flexible than the supports. Typical fabric

structures are assembled in order from stiffest to most flexibleelement; beginning with rigid support members and ending

with the fabric membrane itself. In general, rigid frames or

masts are erected first, along with rings or structural units that

may be located at the top of vertical supports. These members

are usually held in place with temporary erection cables and

ties until cable and fabric panels are lifted up and connected.

Strips of fabric membrane are typically seamed together on the

ground and lifted as larger sections

Prestressing

Though pre-stresses in a fabric membrane are typically specified

by the designer, they constitute a big concern for the fabric

contractor. Pre-stressing is done for a variety of reasons. It can

control unnecessary flapping or flutter, which sometimes leads

to severe dynamic effects by imposing high forces on the overall

structural system. Pre-stress also helps to mitigate the effects of

ponding by decreasing the overall curvature of the membrane.Perhaps most importantly, the pre-stress allows the membrane

to sustain a certain amount of unloading without losing tension

and going slack. Though high levels of pre-stress are desirable

for these reasons, there exists a practical upper limit as more

accuracy and effort are required in patterning and assembly

when pre-stress levels are very high. Typical pre-stress levels

range from 2 kN/m to 10 kN/m, depending on the fabric

material and the design loads. There are several mechanisms

employed to pre-stress a fabric membrane. These vary from

simple fabric clamps to tensioning cable and mast systems.

Conclusion

Fabric structures represent a new chapter in the history of

building structures. Capable of spanning large distances while

incurring very little weight on supporting structure, developments

in the design of fabric structure can dramatically change

the way we conceptualize permanent building construction.

Though fabric materials, computational analysis techniques,

and construction methods have come a long way since the first

modern fabric structure which was built fifty years ago, there

are still several challenges to be overcome before fabric can

be considered a viable option for the majority of new building

projects. However a better understanding of fabric structures

design and construction may one day allow for the extensive

and common application of fabric to permanent structures.

Reference

- Armijos, Samuel J. “Designing Fabric Structures.” September 2008. ArchitectureWeek. 25 January 2009 <http://www.architectureweek.com/2008/0924/designl-1.html>.

- Berger, Horst and De Paola, Edward. “Tensile Terminal.” CivilEngineering November 1992: 40-43.

- Berger, Horst. Light Structures -Structures of Light. Bloomington, IN: Author House, 2005.

- Bird, Walter. “Role of the Fabricator - Large Fabric Structures.” ASCESpring Convention and Exhibit. Dallas, TX: American Society of CivilEngineers, 1977.

- Bradshaw, Richard R. “History of the Analysis of Cable Net Structures.”Structures 2005 2005.

- Caner, A. and Hsu, R. “Tensioned Fabric Shape-Finding.” Journalof Structural Engineering (1999):1065-1071. Drew, Philip. Frei Otto:Form and Structure. Boulder, CO: Westview Press, 1976.

- German Pavilion, Expo ‘67, Frei Otto. 28 April 2009 <http://www.greatbuildings.com/buildings/German PavilionExpo_67.html>.

- Huntington, Craig. “Structures Using Uncurved or Minimally CurvedTensioned Fabric Membranes.”Structures 2008: Crossing Borders(2008).

- The Design and Construction of Fabric Structures, Rosemarie Fang,B.S. Civil and Environmental Engineering, Cornell University, 2008

- http://fabricarchitecturemag.com/articles/0409_f2_structures.html

Fabric Structures




Metal Roofing Systems:

The Preferred Choice

For years now, metal has been proclaimed throughout the

industry as the most versatile roofing material available.

Proponents sing the praises of metal: it’s strong, long

lasting, low-maintenance, recyclable, predictable and reliable

nature. Metal roofing also lends itself well to many design

elements currently used in today’s architecture. Hips, valleys,

slope changes, transitions and dormers are all available to

the designer.

With metal roofing gaining ground as the roof of choice for

many commercial and industrial buildings, it is important that

owner’s know the benefits and downfalls of metal roofing

systems. Before making the choice to go with a new metal roof

system, many factors that will aid in helping one to choose the

right type of metal roofing for building must be considered.

Types of Metal Roofing

Metal roofing can be broken down into two main classifications

(A) Hydro-kinetic (B) Hydro-static

(A) Hydro-kinetic metal roofing:

Such roof systems are typically known as architectural style

metal panel systems. These systems are water shedding,

similar to the function of asphalt shingles, and do not

provide any structural integrity to the building. Hydro-kinetic

metal panel roof systems require moderate to steep slope

applications, and typically have a solid substrate, such as awood deck to provide stability to the system. A waterproofing

underlayment is installed beneath the panels to deter water

infiltration into the facility. The metal panels for these types of

systems can be purchased in many shapes and sizes, from

many different seam profiles, to metal roofing that resembles

shingles, tiles, and/or slate.

(B) Hydro-static metal roofing:

Hydro-static roof panels are a completely sealed panel system

that can add structural integrity to the building structure. In

many applications, these types of metal roofing panels act as

Metal Roofing

Sonjoy Deb, B.Tech,

Civil Associtate Editor




both the waterproofing and roof deck structure, spanning from

joist to joist with no underlaying support. Due to the water-tight

integrity of this type of metal panel installation, these systems

can be installed on lower sloping structures. These panel

systems can also be exposed fastener, or concealed fastener

systems, with a variety of different seam profiles.

Both the above variety of metal roofing comes in any of the

Copper / Aluminium/ Zinc/ Steel / Titanium / Tin / Stainless

Steel / Galvanised Steel / Alloys metal.

Coating on Metal Roof

The Need for Coatings- Metal roofing systems with original

factory-applied coatings will experience coatings degradation

due to weathering and are recoated with an appropriate

maintenance coating to restore and extend the life of the

roof. Uncoated metal roofing systems experience galvanic

corrosion and are also candidates for roof lifecycle extension

by being coated with a corrosion-inhibiting coating system.

White reflective coatings have the added benefit of a “cool

roof” for energy savings.

Factors Influencing Current Demand for Metal Roof Coatings :

Energy shortages are driving the need for energy savings, and

the building industry is also experiencing a greater sensitivity

to environmental concerns. These two issues are influencing

demand for field-applied roof coatings that deliver cool roofs

for energy savings as well as sustainability. Three industry

programs are leading this trend – Leadership in Energy and

Environmental Design (LEED) green building rating system,

Energy Star, and California Title 24

Newly Designed Coatings for Metal Roofs

One of the latest coatings designed for metal roofs are zinc-

rich metal roof primers that improve adhesion of finish coatings

while encapsulating rust and inhibiting the development of

new rust.

Polyurea is a relatively new two-component coating technology

that is well suited to metal roofing. It also has good elongation

and a high tensile strength, i.e., about 1,500 pounds per square

inch (psi) compared to 200 psi to 400 psi for other coatings.

Polyurea also results in a harder surface than other types ofcoatings, so rain will wash dirt off the hard surface relatively

easily; it is easy to keep clean. Another new technology is

based on fluoropolymer coatings, such as Kynar, which promise

high reflectivity, durability, and excellent cleanability

Type of Substrate for Roof Coating & Type of Coatings:

Both factory-applied coated metal roofing systems and

uncoated metal roofing systems are ideal candidates for

roof coating restoration, including steel, aluminum, and

galvanized metal systems. An adhesion test is recommended

prior to coating. Some factory-applied metal finishes, such as

Kynar-500 and some coatings such as silicone, are surfaces

to which acrylic products may not adhere well, and a differentsolution may be more appropriate. While acrylic coatings are

growing in popularity due to their environmentally friendly

attributes, polyurethane, silicone, and polyurea are used for

certain applications. Typically four products are used in a

metal roof coating system — a cleaner, a metal roof primer, a

flashing grade sealant, and a finish coating.

Preferred Method of Applying Coating to Metal Roofs :

Typically four steps are needed to properly coat a metal roof.

Metal Roofing




First, all loose coatings, heavy rust, debris, and fresh roof

cement must be removed, and the existing roof system must

be repaired — such as replacing missing or loose fasteners

and metal panels as needed. Then the roof is power-washed

at 2000 psi with a cleaner, using an airless spray rig. Step two

is to prime the roof with a metal roof primer using an airless

spray gun followed by a wet film gauge to determine the

proper mil thickness has been applied. Step three involves

flashing fasteners, penetrations, seams, and lap joints with a

flashing grade sealant that can be brushed, rolled or extruded.

The final step is to apply the finish coating, using the airless

spray gun, followed by the wet film gauge to ensure propermil thickness. A typical dry mil thickness for the finish coating

is 18 to 25 dry mils, achieved in two to three coats. The

finished coating system serves as the top layer of the roofing

system. This is quite different from a paint film thickness of

approximately three dry mils

Effect of Coating Color on Temperature - White coatings offer

the highest reflectivity and emissivity, but other “cool colors”

have been introduced that are listed by the Cool Roof Rating

Council (CRRC). Reflectivity is the amount of solar energy a

roofing material’s surface reflects. Emissivity is the amount

of absorbed energy a roofing material radiates from itself

because of the material’s own heat and temperature. A top

quality roof coating both reflects infrared and UV of the sun

and emits absorbed heat. A white or light “cool roof” reduces

air-conditioning costs and stress on the roofing system and

can extend the life of the roof.

Panel Installation Procedure:- Panel installation method is

provided by each manufacturer separately, however for the

benefit of the reader method of installation as provided by

Valley Rolling metal roofing is briefely mentioned below.

Panel Installation - Panels should be started at the end of

the building, opposite from the direction of prevailing wind.

Suggested minimum overhang is 2” and minimum pitch is

3/12. For pitches less than 3/12, sealant is suggested. Girt

spacing should be no more than 36” for siding application,

and purlin spacing should be no more than 24” for roof

application.

Cutting and Drilling Steel Panel - Steel panels may be cut with

metal snips, electric or pneumatic shears, a portable profile

shear, or an electric nibbler. Some installers prefer using a

circular saw to cut metal panels. Refer Figure below.

Screw Placement - Generally, 1” screw fasteners are placed in

the flat area of the panel at 24” on center, along the length of

the panel and next to each major rib approximately 1/2” from

the rib. If purlins are placed over 24” apart, stitching screwsare recommended on the lapping rib between the purlins.

Refer Figure below.

Lap Sealant - If roof pitch is less than 3/12, a side-lap sealant

is recommended. Caulk side-laps at the top of the rib. Seal

end laps across the width of both the top and bottom anels,

below the fasteners, and 1” to 2” above end of the overlap.

Refer Figure below.

Closure - 3’ Closure strips are available in all panel profiles.

Metal Roofing




Closures are recommended under the ridge cap, endwalls

and panels at the eave, unless ridge venting is utilized. Silicone

caulking is applied to the top and bottom of the closure, and

will assist in keeping closures in place. Refer Figure below.

pros that a building owner can expect from choosing to install

a new metal roofing system:

- Metal roofing is very durable. Manufacturer warranties

range from 20 to 50 years for defects, and warranties

range on average from 20 to 25 years on the coating

finish.

- Because metal roofing is non-combustible, most roofingapplications receive a Class A fire rating. Ratings may

be lowered if the metal roofing systems is installed over

existing wood and other combustible substrate.

- Metal roofing can be selected in a variety of colors, shapes,

and sizes for pleasing building aesthetics.

- Minimal maintenance and upkeep is required for the

performance and long term integrity of a metal roofing

system. This leads to a low life-cycle cost analysis of

expenses pertaining to the systems over a metal roof’s life

span. Additionally, concealed fastener type systems hide

the fasteners and clips that secure each panel.

- Metal roof systems reflect more of the sun’s radiant heatthan conventional asphalt based roofing components.

This leads to decreased heat loads that get transferred

into the building. Annual cost savings on heating and

cooling expenses can be 20 to 40 percent, depending on

application. Lighter metal panel colors can reflect up to

20% of additional radiant solar heat.

- Metal roofing systems are more capable to handle the

expansion and contraction caused by daytime heating

and evening cooling temperatures.

- These systems can be installed with ease and in certain

applications, can be installed directly over existing roofingcomponents.

Benefits of Metal Roofing

The choice to install a metal roofing systems on your building

comes with many benefits. The following is a summary of

Woodfast (No.9)

1”, 1 1/2”,2”,2 1/2”,3”

12” Hex Head

Panel to wood Studs (2x4, 2x6, etc)

Type “S” (No. 14)

1”,1 1/2”,2”,2 1/2”

5/16” Hex Head

Panel to Plywood (1/2”, 3/4” 5/8”)

Stitch (No. 12) 3/4”

1/4” Hex HeadTrim & Side Lap

Lap Tek (No.14) 7/8”

Self Driller 5/6” Hex HeadTrim & Side lap

Tek (No. 12) 1”, 1 1/4”, 2”, 21/2” Self Driller 5/16” Hex Head

Panel to metal purlin or decking

Metal Roofing




- Concealed fastener type systems hide the fasteners and

clips that secure each panel.

- Metal roof systems are typically lighter in weight compared

to conventional asphalt roof components.

Demerits of Metal Roofing:-

Just as metal roofing adds plenty of benefits and positives

to the facility on which they are installed , several cons are

related to certain metal panel systems:

- Metal roofing is typically more costly to install that con-

ventional asphalt based roofing components. A complete

life cycle cost analysis of the initial investment, and recurring

expenditure anticipated over the life of the system, should

be calculated prior to investing in a metal roof system.

- Exposed fastener systems require regular maintenance to

protect the seals where the fasteners penetrate the metal

roof panels.

- Increase in noise from rain on certain applications.

- Possible condensation at metal panels if not insulated

properly and/or voids are created in insulation exposing

metal panel system to interior conditioned air.

Conclusion

As a building owner, metal roof systems are just a few choices

of many for the building. Pros and cons of each system, along

with up front and life cycle costs should be analysed, as well

as aesthetics and future plans for the building before making

decisions on which roof system will be right for the particular

application.

Reference

- http://www.structuretec.com

- http://roofcoatings.org

- http://www.mbci.com- http://www.classicmetalroofingsystems.com

- http://www.valleyrolling.com

Metal Roofing




Hydrodemolition - An Overview

Concrete is a robust product having high compressive

strength which makes it ideal for all kinds of permanent

structures. As its strength is a great advantage for any

construction, it poses problem when it has to be demolished.

Hydrodemolition is one of the latest non-mechanical methods

used for concrete demolition in an efficient manner. It is

highly regarded as a best demolition method due to its

various advantages. This method can be used for variousapplications like concrete demolition, surface preparation,

concrete repairing, blockage clearing, creating opening or

recess in concrete, etc.

In this article, a general overview on Hydrodemolition method

is presented.

Technology

It is a technique of demolishing concrete structures using

high pressure water jet of upto 40000 PSI (2700 Bar).

Using this technology, we can demolish concrete of any

thickness quickly without damaging the reinforcement

steel. Aggregates may also be added along with water to

increase the demolition productivity.

Equipment

This system consists of engine-driven high pressure pump,

high pressure hose, gun equipped with spray nozzles, large

capacity water tank, etc. It is able to carry out Hydrodemolition

work 100m away from the equipment location.

The water jetting pumps ranges from 5 HP to 500 HP,

pressures from 1000 PSI to 40000 PSI and the flow rates from

20 GPM to 360 GPM. These pumps can be of stationary

type, skid type or trailer mounted type depending on its

capacity. The type and shape of the nozzle directly affects the

efficiency and effectiveness of the demolition operation.

Comparison

In the conventional method, with the use of jack hammers,

the time taken to demolish the concrete is considerably

very high. It also consumes huge energy, vibration, noise

pollution and causes unhealthy work environment during

its working.

Basil Manoj

Hydroblasting by robotic methodHydroblasting by manual method

It works on the process of disintegrating the materials of

concrete using high pressure water jet. The water jet destroys

the bonding of cement and sand with the aggregates,

thereby causing disintegration. During the Hydrodemolition

process, the reinforcement steel in the concrete is unaffected

due to the high compression property of steel.

If demolition has to be done in hazardous areas or at

locations where access is not proper, hydro demolition is

possible using robotics and remote control technologies.

Robots are also used in areas where the demolition has to

be done on large scale.

Stationary Hydroblasting Equipment

Trailer mountedHydroblasting Equipment

Demolition




In case jack hammers are used for concrete repair work

or surface preparation work, it creates micro stress fractures

within the concrete, which significantly reduces the strength of

the concrete and also leads to delamination of the material.

In hydroblasting, aggregate and cementious components

of concrete are separated by destroying the bonding

of cement with the aggregate, and finally the aggregate

remains intact within the concrete. Significant improvement

in bond strength is obtained using the Hydrodemolition

method. The quality of the surface preparation ensures the

long-term success and durability.

Use in Concrete RepairFor repairing the concrete, it is necessary to remove the

deteriorated concrete and prepare the surface. It is also

necessary to clean the reinforcement steel and embedded

items before restoration is done. Hydrodemolition method

WheeledHydroblasting Equipment

Robotic Hydroblasting Equipment

In Hydrodemolition method, the effect of erosion is utilized

for demolition instead of compressive impact to remove

concrete. The concrete which is in direct contact with the water

jet is only removed and no micro fractures are developed.

When compared with conventional method of demolition

like jack hammer, diamond wire cutting and saw cutting,

hydro blasting is an efficient method.

Use in Surface Preparation

Traditionally, surface preparation is being carried out using

sand blasting, grid blasting, chipping, etc. As these methods

are environmentally sensitive, the use of hydroblasting has

become an alternate method. Visually, the hydroblasted

surface is much different from the other surface produced

by the use of traditional methods. Hydroblasting can be

applied on variety of surfaces to remove surface materials

like mastic, rubber, curing compound, releasing agents, bond

breakers, leveling compounds, paint, thermoplastics, epoxy,

etc.

Concrete surface preparation by Hydroblasting

Steel surface preparation by Hydroblasting

Prepared concrete surface using Hydroblasting

Demolition




Blockage / Scale clearing in conduits using Hydroblasting

can be used for this purpose at ease expediting the repair

project.

Merits & Demerits

General

- Water is the main element utilized in this method whichis easily available.

- Minimal contamination to surrounding area.

- No damage to the reinforcement steel and embedded

materials.

- Minimal dust and noise pollution.

- High capital and maintenance cost.

- Trained and experienced operators are required.

- Creates fatigue to the operator within short period and

requires frequent rotation of operators.

For surface preparation:

- No vibration on the structure.

- Can be used in any type of structures either indoor or

outdoor demolition.

- Removes any type of deposits, scale, hulls, coatings

soluble salts and oils from the surface.

- Contaminant free surface after preparation.

- The sensitive areas such as welding and connection

joints are not damaged.

- Causes flash rusting in steel structures.

Safety

Hydrodemolition is a clean process which does not produce

silica dust during the demolition work and provide healthier

work environment. However, the fragments of removed

debris fly in all direction at high velocity during this operation

causing hazard at the demolition area. So, it is necessary

to shield the area with proper barriers.

As this method uses high pressure water jets which is very

dangerous and can cause serious injury and death, if it is

not handled properly. The operators should wear special

protective outfit fully covering their body to get protected

from the flying debris. To handle the high water pressure

during demolition, well trained and technically competent

operators should be involved in this operation.

Reference

Field Guide to Concrete Repair application procedures

– Concrete Removal using Hydrodemolition published by

American Concrete Institute, ACI RAP Bulletin 14

Concrete demolition using Hydroblasting

Before After

Demolition

mb_august2013.pdf

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