Flexural strength

, bend strength, or fracture strength, a mechanical parameter for brittle material, is

defined as a material's ability to resist deformation under load. The transverse bending

test is most frequently employed, in which a rod specimen having either a circular or

rectangular cross-section is bent until fracture using athree point flexural test technique.

The flexural strength represents the highest stress experienced within the material at its

moment of rupture. It is measured in terms of stress, here given the symbol  .

Introduction

Fig. 1 - Beam of material under bending. Extreme fibers at B (compression) and A

(tension)

Fig. 2 - Stress distribution across beam

When an object formed of a single material, like a wooden beam or a steel rod, is bent

(Fig. 1), it experiences a range of stresses across its depth (Fig. 2). At the edge of the

object on the inside of the bend (concave face) the stress will be at its maximum

compressive stress value. At the outside of the bend (convex face) the stress will be at

its maximum tensile value. These inner and outer edges of the beam or rod are known

as the 'extreme fibers'. Most materials fail under tensile stress before they fail under

compressive stress, so the maximum tensile stress value that can be sustained before

the beam or rod fails is its flexural strength.

Flexural versus tensile strength

The flexural strength would be the same as the tensile strength if the material

were homogeneous. In fact, most materials have small or large defects in them which

act to concentrate the stresses locally, effectively causing a localized weakness. When

a material is bent only the extreme fibers are at the largest stress so, if those fibers are

free from defects, the flexural strength will be controlled by the strength of those intact

'fibers'. However, if the same material was subjected to only tensile forces then all the

fibers in the material are at the same stress and failure will initiate when the weakest

fiber reaches its limiting tensile stress. Therefore it is common for flexural strengths to

be higher than tensile strengths for the same material. Conversely, a homogeneous

material with defects only on it surfaces (e.g. due to scratches) might have a higher

tensile strength than flexural strength.

If we don't take into account defects of any kind, it is clear that the material will fail under

a bending force which is smaller than the corresponding tensile force. Both of these

forces will induce the same failure stress, whose value depends on the strength of the

material.

For a rectangular sample, the resulting stress under an axial force is given by the

following formula :   . This stress is not the true stress, since the cross section of

the sample is considered to be invariable (engineering stress).

 is the axial load (force) at the fracture point

b is width

d is thickness

The resulting stress for a rectangular sample under a load in a three-point bending

setup (Fig. 3) is given by the formula below (see "Measuring flexural strength").

The equation of these two stresses (failure) yields : 

Usually, L (length of the support span) is much bigger than d, so the fraction   is

bigger than one.

\

Measuring flexural strength

Fig. 3 - Beam under 3 point bending

For a rectangular sample under a load in a three-point bending setup (Fig. 3):

F is the load (force) at the fracture point

L is the length of the support span

b is width

d is thickness

For a rectangular sample under a load in a four-point bending setup where the loading

span is one-third of the support span: 

F is the load (force) at the fracture point

L is the length of the support (outer) span

b is width

d is thickness

For the 4 pt bend setup, if the loading span is 1/2 of the support span (i.e. Li = 1/2 L in

Fig. 4): 

If the loading span is neither 1/3 or 1/2 the support span for the 4 pt bend setup (Fig. 4):

Fig. 4 - Beam under 4 point bending

Li is the length of the loading (inner) span

Concrete slump test

From Wikipedia, the free encyclopedia

A tester performing a concrete slump test.

The concrete slump test is an empirical test that measures the workability of

fresh concrete.

More specifically, it measures the consistency of the concrete in that specific batch. This

test is performed to check the consistency of freshly made concrete. Consistency is a

term very closely related to workability. It is a term which describes the state of fresh

concrete. It refers to the ease with which the concrete flows. It is used to indicate the

degree of wetness. Workability of concrete is mainly affected by consistency i.e. wetter

mixes will be more workable than drier mixes, but concrete of the same consistency

may vary in workability. It is also used to determine consistency between individual

batches.

The test is popular due to the simplicity of apparatus used and simple procedure.

Unfortunately, the simplicity of the test often allows a wide variability in the manner that

the test is performed. The slump test is used to ensure uniformity for different batches of

similar concrete under field conditions,[1]:127,128and to ascertain the effects of plasticizers

on their introduction.[1]:134 In India this test is conducted as per IS specification.

Principle

The slump test result is a measure of the behaviour of a compacted inverted cone of

concrete under the action of gravity. It measures the consistency or the wetness of

concrete.

Apparatus

Metal mould, in the shape of the frustum of a cone, open at both ends, and provided

with the handle, top internal diameter 102 mm, and bottom internal diameter 203 mm

with a height of 305 mm. A 610 mm long bullet nosed metal rod, 16 mm in diameter.[2]

[edit]Procedure

Slump cone

 

Tamping procedure

 

Removing cone

 

Height measurement

The test is carried out using a mould known as a slump cone or Abrams cone. The

cone is placed on a hard non-absorbent surface. This cone is filled with fresh concrete

in three stages, each time it is tamped using a rod of standard dimensions. At the end of

the third stage, concrete is struck off flush to the top of the mould. The mould is carefully

lifted vertically upwards, so as not to disturb the concrete cone. Concrete subsides. This

subsidence is termed as slump, and is measured in to the nearest 5 mm.

[edit]Interpretation of results

The slumped concrete takes various shapes, and according to the profile of slumped

concrete, the slump is termed as true slump, shear slump or collapse slump. If a shear

or collapse slump is achieved, a fresh sample should be taken and the test repeated. A

collapse slump is an indication of too wet a mix. Only a true slump is of any use in the

test. A collapse slump will generally mean that the mix is too wet or that it is a high

workability mix, for which slump test is not appropriate.[1]:128[3] Very dry mixes; having

slump 0 – 25 mm are used in road making, low workability mixes; having slump 10 –

40 mm are used for foundations with light reinforcement, medium workability mixes; 50 -

90 for normal reinforced concrete placed with vibration, high workability concrete; >

100 mm.[4]:68

Collapse Shear True

In a collapse slump the concrete collapses completely.[3]

In a shear slump the top portion of the concrete shears off and slips sideways.[3]

In a true slump the concrete simply subsides, keeping more or less to shape.[3]

[edit]European classes of slump

According to European Standard EN 206-1:2000 five classes of slump have been

designated, as tabulated below.[4]:69

Slump classSlump in

mm

S1 10 - 40

S2 50 - 90

S3 100 - 150

S4 160-210

S5 ≥220

Limitations of the slump test

The slump test is suitable for slumps of medium to high workability, slump in the range

of 25 – 125 mm, the test fails to determine the difference in workability in stiff mixes

which have zero slump, or for wet mixes that give a collapse slump. It is limited to

concrete formed of aggregates of less than 38 mm (1 inch).

Differences in standards

The slump test is referred to in several testing and building codes, with minor

differences in the details of performing the test.

[edit]United States

In the United States, engineers use the ASTM standards and AASHTO specifications

when referring to the concrete slump test. The American standards explicitly state that

the slump cone should have a height of 12-in, a bottom diameter of 8-in and an upper

diameter of 4-in. The ASTM standards also state in the procedure that when the cone is

removed, it should be lifted up vertically, without any rotational movement at all.[5] The

concrete slump test is known as "Standard Test Method for Slump of Hydraulic-Cement

Concrete" and carries the code (ASTM C 143) or (AASHTO T 119).

[edit]United Kingdom and mainland Europe

In the United Kingdom, the standards specify a slump cone height of 300 mm, a bottom

diameter of 200 mm and a top diameter of 100 mm. The British Standards do not

explicitly specify that the cone should only be lifted vertically. The slump test in the

British standards was first (BS 1881–102) and is now replaced by the European

Standard (BS EN 12350-2).[6] The test should be carried out by filling the slump cone in

three equal layers with the mixture being tamped down 25 times for each layer.

[edit]Other tests

Numerous tests exist to evaluate concrete: a similar test is the K-Slump Test (ASTM C

1362). Other tests evaluating consistency are the

British compacting factor test (BS EN 12350-4), the

Vebe consistometer for roller-compacted concrete

(ASTM C 1170), and the flow table test (DIN 1048-

1).[7]

What is Flexural Strength?

It is the ability of a beam or slab to resist failure in bending. It is measured by loading un-reinforced 6x6 inch concrete beams with a span three times the depth (usually 18 in.). The flexural strength is expressed as “Modulus of Rupture” (MR) in psi.

Flexural MR is about 12 to 20 percent of compressive strength. However, the best correlation for specific materials is obtained by laboratory tests.

 

Why Test Flexural Strength?

Designers of pavements use a theory based on flexural strength. Therefore, laboratory mix design based on flexure may be required, or a cement content may be selected from past experience to yield the needed design MR. Some also use MR for field control and acceptance of pavements. Very few use flexural testing for structural concrete. Agencies not using flexural strength for field control generally find the use of compressive strength convenient and reliable to judge the quality of the concrete as delivered.1

 How to Use Flexural Strength

Beam specimens must be properly made in the field. Pavement concretes are stiff (1/2 to 2 ½ inch slump). Consolidate by vibration in accordance with ASTM C 31 and tap side to release bubbles. For higher slump, after rodding, tap the molds to release bubbles and spade along the sides to consolidate. Never allow the beam surfaces to dry at any time. Immerse in saturated lime water for at least 20 hours before testing.

Specifications and investigation of apparent low strengths should take into account the higher variability of flexural strength results. Standard deviation for projects with good control range from about 40 to 80 psi. Values over 100 psi indicate testing problems, and there is high likelihood that testing problems, or moisture differences within a beam, will cause low strength.

 

Where a correlation between flexural and compressive strength has been established, core strengths by ASTM C 42 can be used for compressive strength to check it against the desired value using the ACI 318 85 percent criteria. It is impractical to saw beams from a slab for flexural testing. Sawing beams will greatly reduce measured flexural strength and should not be done. Some use has been made of measuring indirect tensile strength of cores by ASTM C 496, but experience is lacking on how to apply the data.

Another procedure for in-place strength investigation uses compressive strength of cores calibrated by comparison with acceptable placements on either side of the concrete in question:

 What are the Problems with Flexure?

Flexural tests are extremely sensitive to specimen preparation, handling, and curing procedure. Beam specimens are very heavy, and allowing a beam to dry will yield lower strengths. Beams must be cured in a standard manner, and tested while wet.2A short period of drying can produce a sharp drop in flexural strength.

Many state highway agencies have used flexural strength but are now changing to compressive strength for job control on concrete paving. Cylinder strengths are also used for concrete structures.

“The data points to a need for a review of current testing procedures. They suggest also that, while the flexural strength test is a useful tool in research and in a laboratory evaluation of concrete ingredients and proportions, it is too sensitive to testing variations to be usable as a basis for the acceptance or rejections of concrete in the field.”3 The CSI Spec-Data Sheet by NRMCA, the Municipal Concrete Pavement Manual by ACPA, ACI 325, and ACI 330 on Concrete Pavements, all point to the use of compressive strength as more convenient and reliable. The Pennsylvania DOT uses compressive strength of cylinders; 3750 psi is specified with 3000 psi for opening a pavement to traffic.

The concrete industry and inspection agencies are much more familiar with traditional cylinder compression tests for control and acceptance of concrete. Flexure can be used for design purposed, but the corresponding compressive strength should be used to order and accept the concrete. Any time trial batches are made, both flexural and compressive tests should be made so that a correlation can be developed for field control.

Flexural Strength Tests of Concrete Using Simple Beams

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The test for flexural strength of concrete beams under third point loading utilizes a beam testing machine which permits the load to be applied normal to the loaded surface of the beam. The specimen is tested on its side with respect to its molded position. The beam is centered on the bearing supports. The dial indicator of the proving ring is placed at the zero reading. The load is applied at a uniform rate and in a way to avoid shock. The load required to cause specimen failure is obtained from the dial indicator's final reading and the proving ring calibration curve.

The Different Kinds of Filipino Folk Dances

By Sharon Bernhardt, eHow Contributor

There is a variety of forms of folk dancing in the Philippines.

Dancing is a key element of any culture. It is a form of expression used as a central component of festivals, ceremonies and rituals as well as entertainment. The nation of the Philippines has a rich history honored by the various dances. In addition to traditional dances, there are European influences due to colonization by Spain. Despite these influences, there are also strong connections to ethnic roots and each particular area has its own form of dance.Other People Are Reading

Basic Steps in a Filipino Folk Dance

The History of Filipino Folk Dance

Print this article 1. Tinikling

o Tinikling is the national dance of the Philippines. The word "tinikling" means "bamboo dance." Dancers perform graceful movements while hopping between bamboo poles that are tapped together by another pair of dancers. When the first set of dancers makes an error, the dancers change places. This dance is one of the oldest known dances in the Philippines and started in the Visayan Islands. The dance mimics the movements of the tikling bird.

Maglalatik

o Another exciting dance of the Philippines is the Maglalatik. This dance depicts a battle between the Christians and the Moros and has four parts. This battle was over "latik" which is the product after coconut meat is boiled. This dance involves two groups of men dressed as either Christians or Moros. They use the shells of coconuts throughout the dance. This dance began in Laguna and is often performed in tribute to the patron saint of farmers, San Isidro de Labrador.

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Binasuan

o The Binasuan dance takes a lot of skill. Originating in the Pangasinan province, "binasuan" means "with the use of drinking glasses." In this dance, a female dancer performs to music while balancing drinking glasses filled with water. The dancer holds a glass on each palm and a glass on her head. She performs a variety of graceful moves without ever spilling a drop of water from the glasses.

Pantomina

o The Pantomina folk dance is performed annually in the month of October during the Sorsogon Kasanggayahan Festival. This dance is also known as the "Dance of the Doves". It is a courtship dance which mimics the courtship rituals of the dove. This dance is mainly performed by elderly couples during the festival.

2.3.  4. footwork in Paso Doble is composed of forward steps with the heel leads.Paso Doble has

less hip action than other International Latin dances.Paso Doble uses music that is played at bullfights. The man plays therole of the matador while the lady plays the role of the matador's cape,the bull or a flamenco dancer.

5. Basic stepsLead Steps to the Basic6. With the dancers in a rigid and closed dance frame, lead's lefthand clasping the follow's

right held out from the body, and his righthand at her back, her left hand held at his bicep, the dancers need tokeep a rigid and close hold throughout the steps. The lead begins facing line of dance and steps forward with the left,letting the body rotate to the center of the dance floor as the right footsteps ahead. Remaining on the balls of the feet, beats 3-8 are stepped ina chasse. The next eight beats begin with one of the "cape" moves, as theman takes three steps in a tight, counterclockwise circle, finishing off thelast beats with side steps back against the line of dance.All of these moves should be sharp and quick, with the chest andhead held up and out epitomizing "pride and dignity."

7. Follow Steps to the Basic

8.  The follow basically mirrors the steps of the lead, movingbackwards in the tight circle, using the motion to lend the impression of a flowing cape to the traditionally long skirts worn by the woman for thepaso doble. The dance is very intensely connecting between the two, witheye contact and physical contact lending an urgent tension between thetwo dancers.

9. Rumba (Africa / Cuba)10.1711.  12.History13.Not only is the Rumba the most popular Latin slow dance inAmerica, it is also the #1

dance chosen by wedding couples. In addition,Rumba is the foundational dance of all the other Latin and American

14.18

15.16.  17.Rhythm dances. Cuban action (which makes Latin dances look Latin) isan important

characteristic of this dance. The basic rhythm of theRumba box is “slow—quick—quick.” The list of Latin dances from slow tofast is: Bolero, Rumba, Cha Cha, Mambo and lastly Jive.Rumba footwork consists of smooth toe-heel staccato action. Thisfootwork along with Cuban motion, gives Rumba its characteristic hipmoving action. The Cuban action develops naturally from alternatelybending and straightening the

knees. Posture in Rumba is more forwardtoward your partner than it is in the ballroom dances. In addition, strongLatin arm styling will give your Rumba a fantastic Latin flare.

18.Basic Steps19.Step1Stand up straight, take a deep breath, and face your partner. If  you are a woman,

hold up your right hand, and put your left hand lightlyon the man's right shoulder.If you are a man, grasp the woman's handlightly in your left hand, and put your right hand at the small of herback, above the waist.Step2Dance quickly. Rumba is danced in quick, light steps withmovement across the dance floor and tight turns. Its basic step is in theshape of a box, done half at a time, and counted slow-quick-quick, slow-quick-quick. If you are a woman, start your basic rumba box step bypicking up your right foot and moving it back only about four inches. Put your weight on your right foot. This is your first slow step.Pick up yourleft foot, pull it back to meet your right foot and then move it to your leftabout four inches. Put it down on the dance floor and shift your weightto it. Bring your right foot to meet your left foot. Those were your nextquick-quick steps.Step3Start your basic rumba box step by picking up your left foot andmoving it forward about four inches if you are the man. Put your weighton your left foot. This is your first slow step.Pick up your right foot, andpush it forward to meet your left foot and then move it to your rightabout four inches. Put it down on the dance floor and and shift your weight to it. Bring your left foot to meet your right foot. Those were yourquick-quick steps.Step4Start to complete your first box step in rumba by stepping forwardabout four inches with your left foot if you are the woman. This is yourfirst slow step.Pick up your right foot, push it forward to meet your leftfoot and then move it to your right about four inches. Put it down on thedance floor and shift your weight to it. Bring your left foot to meet yourright foot. Those were the second set of quick-quick steps to complete your rumba box.If you are a man, pick up your right foot and move itback about four inches. Put your weight on your right foot. This is yourslow step to complete your basic rumba box. Pick up your left foot, pull it

20.1921.  22.back to meet your right foot and then move it to your left about fourinches. Put it down

on the dance floor and shift your weight to it. Bring your right foot to your left foot. Those were the second set of quick-quicksteps to complete your basic rumba box.Step5Sway those hips! Remember, each time you take a sideways step,sway your hips just like a very fast pendulum. The more you can put your weight forward on your toes, and dance in a light, choppy fashion,the easier the hip movement will be, and the more

23.expressive the dance 

o

Types of DanceBy Treva Bedinghaus, About.com GuideSee More About:

dance styles beginner ballet folk dancing

Dance seems to be a lot like ice cream flavors...it's so hard to choose just one. If you are thinking of trying out a new dance style, there may be a few you haven't even considered. Check out this list of dance genres and see which one appeals to you. There are many fun types of dance, you may need to sample a few to find your favorite.

Ballet

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Ballet serves as a backbone for many other styles of dance, as many other dance genres are based on ballet. Ballet is based on techniques that have been developed over centuries. Ballet uses music and dance to tell stories. Ballet dancers have the ability to transport an audience to another world.

AdsWarsaw's best Strip Club www.playhouse.com.pl Voted no.1 Strip Club in Warsaw.Photography School www.NYFA.edu Students Get a Free DSLR Camera! Hands-On Intensive Courses.Create a Facebook Profile www.Facebook.com Find & Share A Wide Variety Of Facebook Applications. Sign Up Now!Jazz

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Jazz is a fun dance style that relies heavily on originality and improvisation. Many jazz dancers mix different styles into their dancing, incorporating their own expression. Jazz dancing often uses bold, dramatic body movements, including body isolations and contractions.

Tap

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Tap dancing is an exciting form of dance in which dancers wear special shoes equipped with metal taps. Tap dancers use their feet like drums to create rhythmic patterns and timely beats.

Hip-Hop

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Hip-hop is a dance style, usually danced to hip-hop music, that evolved from the hip-hop culture. Hip-hop includes various moves such as breaking, popping, locking and krumping, and even house dance. Improvisation and personal interpretation are essential to hip-hop dancing.

Modern

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Modern dance is a dance style that rejects many of the strict rules of classical ballet, focusing instead on the expression of inner feelings. Modern dance was created as a rebellion against classical ballet, emphasizing creativity in choreography and performance.

Swing

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Swing dance is a lively dance style in which couples swing, spin and jump together. Swing dancing is a general term that means dancing to swing music, or music that "swings." How can you tell if a song swings? Swing dancers know when a song swings because when they hear it, they can't stand still.

Contra Dance

Betty Ann Sather / Great Meadow Music

Contra dance is a form of American folk dance in which the dancers form two parallel lines and perform a sequence of dance movements with different partners down the length of the line. Contra dances are relaxed with family-like atmospheres. The dancing is excellent exercise, and dancers can set their own pace. Contra dancers are usually friendly, active people with a love of dance.

Country and Western

Michael Buckner / Getty Images

Country and western dance includes several dance forms, usually danced to country-western music. If you've ever been to a country and western club or tavern, you've probably seen a few cowboy boot-wearing dancers twirling around the dance floor with big smiles on their faces.

AdsComedy Props Tricks Books www.sillymagic.com For the kid show entertainer. From Silly Billy and David KayeKervansaray Turkish Night www.kervansarayistanbul.com Famous Belly Dancers Turkish & Int.CuisineBelly Dance

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Belly dance is a unique form of dance characterized by sharp, rolling movements of the hips and abdomen. The true origins of belly dancing are debated among enthusiasts.

Flamenco

Jess Alford / Getty Images

Flamenco dance is an expressive dance form that mixes percussive footwork with intricate hand, arm and body movements. Flamenco is a Spanish art consisting of three forms: Cante, the song, Baile, the dance, and Guitarra, guitar playing. .

Latin Dance

Stockbyte / Getty Images

Latin dance is a fast-paced, often sensual, partner dance characterized by sexy hip movements. However, hip movements are not intentional in any of the Latin dances. The hip motion is a natural consequence of changing weight from one foot to the other.

Folk Dance

Guang Niu / Getty Images

Folk dance refers to a variety of dances developed by groups or communities, as opposed to being made up by a choreographer. There are several types of folk dance including clogging, English country dance, international folk dance, Irish dance, Maypole dance, Morris dance, Nordic polska dance, square dance, and many more. Folk dances are often performed at social events.

Read more: The Different Kinds of Filipino Folk Dances | eHow.com http://www.ehow.com/info_8304990_different-kinds-filipino-folk-dances.html#ixzz29MEwwihN

ASTM C293 / C293M - 10 

ASTM C293 / C293M - 10 Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Center-Point Loading)

Active Standard ASTM C293 / C293M Developed by Subcommittee: C09.61 |Book of Standards Volume:04.02

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ASTM C293 / C293MSignificance and Use

This test method is used to determine the modulus of rupture of specimens prepared and cured in accordance

with Practices C31/C31Mor C192/C192M. The strength determined will vary where there are differences in specimen size, preparation, moisture condition, or curing.The results of this test method may be used to determine compliance with specifications or as a basis for proportioning, mixing and placement operations. This test method produces values of flexural strength significantly higher than Test Method .1. Scope1.1 This test method covers determination of the flexural strength of concrete specimens by the use of a simple beam with center-point loading. It is not an alternative to Test Method .1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) ASTM StandardsC31/C31M Practice for Making and Curing Concrete Test Specimens in the FieldC78/C78M Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)C192/C192M Practice for Making and Curing Concrete Test Specimens in the LaboratoryC617 Practice for Capping Cylindrical Concrete SpecimensC1077 Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing Agency EvaluationE4 Practices for Force Verification of Testing Machines

Keywords

beams; concrete; flexural strength testing; modulus of rupture; Center-point loading; Concrete test specimens;

Flexural testing--concrete;

The slump test is the most well-known and widely used test method to characterize the workability of fresh concrete. The inexpensive test, which measures consistency, is used on job sites to determine rapidly whether a concrete batch should be accepted or rejected. The test method is widely standardized throughout the world, including in ASTM C143 in the United States and EN 12350-2 in Europe.         The apparatus consists of a mold in the shape of a frustum of a cone with a base diameter of 8 inches, a top diameter of 4 inches, and a height of 12 inches. The mold is filled with concrete in three layers of equal volume. Each layer is compacted with 25 strokes of a tamping rod. The slump cone mold is lifted vertically upward and the change in height of the concrete is measured. Four types of slumps are commonly encountered, as shown in Figure 3. The only type of slump permissible under ASTM C143 is frequently referred to as the “true” slump, where the concrete remains intact and retains a symmetric shape. A zero slump and a collapsed slump are both outside the range of workability that can be measured with the slump test. Specifically, ASTM C143 advises caution in interpreting test results less than ½ inch and greater than 9 inches. If part of the concrete shears from the mass, the test must be repeated with a different sample of concrete. A concrete that exhibits a shear slump in a second test is not sufficiently cohesive and should be rejected.

       The slump test is not considered applicable for concretes with a maximum coarse aggregate size greater than 1.5 inches. For concrete with aggregate greater than 1.5 inches in size, such larger particles can be removed by wet sieving.         Additional qualitative information on the mobility of fresh concrete can be obtained after reading the slump measurement. Concretes with the same slump can exhibit different behavior when tapped with a tamping rod. A harsh concrete with few fines will tend to fall apart when tapped and be appropriate only for applications such as pavements or mass concrete. Alternatively, the concrete may be very cohesive when tapped, and thus be suitable for difficult placement conditions.

       Slump is influenced by both yield stress and plastic viscosity; however, for most cases the effect of plastic viscosity on slump is negligible. Equations have been developed for calculating yield stress in terms of slump, based on either analytical or experimental analyses. Since different  rheometers measure different absolute values for the yield stress of identical samples of concrete, the experimental equations are largely depended on the specific device used to measure yield stress. 

Advantages:   • The slump test is the most widely used device worldwide. In fact, the test is so well known that often the terms workability and slump are used interchangeably, even though they have different meanings. • Specifications are typically written in terms of slump. • The slump test is simple, rugged, and inexpensive to perform. Results are obtained immediately. • The results of the slump test can be converted to yield stress in fundamental units based on various analytical treatments and experimental studies of the slump test. • Compared to other commonly used concrete tests, such as for air content andcompressive strength, the slump test provides acceptable precision. Disadvantages: • The slump test does not give an indication of plastic viscosity. • The slump test is a static, not dynamic, test; therefore, results are influenced by concrete thixotropy. The test does not provide an indication of the ease with which concrete can be moved under dynamic placing conditions, such as vibration. • The slump test is less relevant for newer advanced concrete mixes than for more conventional mixes.

Flexural Strength Testing

Flexural testing is used to determine the flex or bending properties of a material. Sometimes referred to as a transverse beam test, it involves placing a sample between two points or supports and initiating a load using a third point or with two points which are respectively call 3 Point Bend and 4 Point Bend testing. 

Maximum stress and strain are calculated on the incremental load applied. Results are shown in a graphical format with tabular results including the flexural strength (for fractured samples) and the yield strength (samples that did not fracture). Typical materials tested are plastics, composites, metals, ceramics, and wood.

Tests on concrete

SAMPLING The first step is to take a test sample from the large batch of concrete. This should be done as soon as discharge of the concrete commences. The sample should be representative of the concrete supplied. The sampleis taken in one of two ways:

For purposes of accepting or rejecting the load: Sampling after 0.2 m3 of the load has been poured.

For routine quality checks: Sampling from three places in the load.

a) Concrete Slump Test

This test is performed to check the consistency of freshly made concrete. The slump test is done to make sure a concrete mixis workable. The measured slump must be within a set range, or tolerance, from the target slump.

Workability of concrete is mainly affected by consistency i.e. wetter mixes will be more workable than drier mixes, but concrete of the same consistency may vary in workability. It can also be defined as the relative plasticity of freshly mixed concrete as indicative of its workability.

Related Pages

Tools and apparatus used for slump test (equipment):

1. Standard slump cone (100 mm top diameter x 200 mm bottom diameter x 300 mm high)

2. Small scoop3. Bullet-nosed rod (600 mm long x 16 mm

diameter)4. Rule5. Slump plate (500 mm x 500 mm)

Flexural

Strength of

Concrete

High Strength

Concrete Mix

Rate of

Strength gain

of Concrete

Reinforced

Concrete

Design

Concrete

Types

Bitumen tests

Civil Lab tests

How to calculate the compressive

strength of concrete?

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guyrogueBest Answer - Chosen by Voters

Concrete specimens are tested using the ASTM39 Test Standard Test Method forCompressive Strength of Cylindrical Concrete Specimens by using two samples made from the same test at the same age, usually at strength of 28 days old.

Design engineers use the specified strength ƒ´c to design structural elements. This specified strength is incorporated in the job contract documents.

The concrete mixture is designed to produce an average strength (ƒ´cr) higher than the specified strength, such that the risk of not complying with the strength specification is minimized.

Cylindrical specimens for acceptance testing should be 6 x 12 inch (150 x 300 mm) size or 4 x 8 inch (100 x 200 mm) when specified. The Concrete strength is calculated by dividing the maximum load at failure by the average cross sectional area. 

Concrete compressive strength requirements can vary from 2500 psi (17 MPa) for residential concrete to 4000 psi (28

MPa) and higher in commercial structures. Higher strengths up to and exceeding 10,000 psi (70 MPa) are specified for certain applications.

Cylinders are placed in a Compression testing machine and loaded to failure from 20 to 50psi. The type of break should be recorded by a Certified Technician.

Example 1:For a concrete sample that is broken after 28 daysThe cylinder is 6” diameter, so it has an area of 3.14 x Diameter squared /4

A = 3.14 x 6 x 6/4A = 28.26 square inches

If the force required to

break the cylinder was 97,500 pounds 

Then the compressive strength is 97,500 pounds / 28.26 square inches = 3,450 psi.3,450psi needs to be compared to the Design strength determined by the Design Strength determined by the Design Engineer.

Example 2:Given: f 'c = 3000 psiConcrete test cylinders averaged 2800 psi.PSICore 1 =2900Core 2 =2850Core 3 =2450Average compressive strength of 3 cores = 2730 psi.Find: Is the concrete in the structure adequate under CDOT specifications?

Solution:Test Evaluation:f 'c = 3000 psiAverage compressive strength of 3 cores - 2730 psiDo any compressive strengths differ from the average by more than 10%?10% of Average compressive strength = 273 psiCore 1: 2900 - 2730 = 170 psi, < 273 therefore OKCore 2: 2850 - 2730 = 120 psi, < 273 therefore OKCore 3: 2730 - 2450 = 280 psi, > 273 therefore -discard core and re-compute average compressive strength using two remaining cores.New average compressive strength = 2875 psi

Procedure of slump test for concrete:

1. Clean the cone. Dampen with water and place on the slump plate. The slump plate should be clean, firm, level and non-absorbent. Collect a sample of concrete to perform the slum test.

2. Stand firmly on the footpieces and fill 1/3 the volume of the cone with the sample. Compact the concrete by 'rodding' 25 times. Rodding means to push a steel rod in and out of the concrete to compact it into the cylinder, or slump cone. Always rod in a definite pattern, working from outside into the middle.

3. Now fill to 2/3 and again rod 25 times, just into the top of the first layer.

4. Fill to overflowing, rodding again this time just into the top of the second layer. Top up the cone till it overflows.

5. Level off the surface with the steel rod using a rolling action. Clean any concrete from around the base and top of the cone, push down on the handles and step off the footpieces.

6. Carefully lift the cone straight up making sure not to move the sample.

7. Turn the cone upside down and place the rod across the up-turned cone.

8. Take several measurements and report the average distance to the top of the sample.If the sample fails by being outside the tolerance (ie the slump is too high or too low), another must be taken. If this also fails the remainder of the batch should be rejected.

b) The Compression Test

The compression test shows the compressive strength of hardened concrete. The compression test shows the best possible strength concrete can reach in perfect conditions. The compression test measures concrete strength in the hardened state. Testing should always be done carefully. Wrong test results can be costly.

The testing is done in a laboratory off-site. The only work done on-site is to make a concrete cylinder for the compression test. The strength is measured in Megapascals (MPa) and is commonly specified as a characteristic strength of concrete measured at 28 days after mixing. The compressive strength is a measure of the concrete’s ability to resist loads which tend to crush it.

Apparatus for compression test

Cylinders (100 mm diameter x 200 mm high or 150 mm diameter x 300

mm high) (The small cylinders are normally used for most testing due to their lighter weight)

1. Small scoop2. Bullet-nosed rod (600 mm x 16 mm)3. Steel float4. Steel plate

How to do a compression test?

Procedure for compression test of concrete

1. Clean the cylinder mould and coat the inside lightly with form oil, then place on a clean, level and firm surface, ie the steel plate. Collect a sample.

2. Fill 1/2 the volume of the mould with concrete then compact by rodding 25 times. Cylinders may also be compacted by vibrating using a vibrating table.

3. Fill the cone to overflowing and rod 25 times into the top of the first layer, then top up the mould till overflowing.

4. Level off the top with the steel float and clean any concrete from around the mould.

5. Cap, clearly tag the cylinder and put it in a cool dry place to set for at least 24 hours.

6. After the mould is removed the cylinder is sent to the laboratory where it is cured and crushed to test compressive strength

Compression Test

Select image to enlargeA compression test determines behavior of materials under crushing loads. The specimen is compressed and deformation at various loads is recorded. Compressive stress and strain are calculated and plotted as a stress-strain diagram which is used to determine elastic limit,proportional limit, yield point, yield strength and, for some materials, compressive strength.

Why Perform a Compression Test?

The ASM Handbook®, Volume 8, Mechanical Testing and Evaluation states: "Axial compression testing is a useful procedure for measuring the plastic flow behavior and ductile fracture limits of a material. Measuring the plastic flow behavior requires frictionless (homogenous compression) test conditions, while measuring ductile fracture limits takes advantage of the barrel formation and controlled stress and strain conditions at the equator of the barreled surface when compression is carried out with

friction.  Axial compression testing is also useful for measurement of elastic and compressive fracture properties of brittle materials or low-ductility materials. In any case, the use of specimens having large L/D ratios should be avoided to prevent buckling and shearing modes of deformation1."

The image at right shows variation of the strains during a compression test without friction (homogenous compression) and with progressively higher levels of friction and decreasing aspect ratioL/D (shown as h/d)1.

The figure to the right illustrates the modes of deformation in compression testing. (a) Buckling, when L/D > 5. (b) Shearing, when L/D > 2.5. (c) Double barreling, when L/D > 2.0 and friction is present at the contact surfaces. (d) Barreling, when L/D < 2.0 and friction is present at the contact surfaces. (e) Homogenous compression, when L/D< 2.0 and no friction is present at the contact surfaces. (f) Compressive instability due to work-softening material1.

Typical Materials

The following materials are typically subjected to a compression test.

Concrete

Metals Plastics Ceramics Composites Corrugated Cardboard

Workability of Fresh Concrete by Slump Test

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WORKABILITY

Slump test is used to determine the workability of fresh concrete. Slump test

as per IS: 1199 – 1959 is followed.The apparatus used for doing slump test

are Slump cone and Tamping rod.

Procedure to determine workability of fresh concrete by slump test.

i) The internal surface of the mould is thoroughly cleaned and applied with a

light coat of oil.

ii) The mould is placed on a smooth, horizontal, rigid and nonabsorbent

surface.

iii) The mould is then filled in four layers with freshly mixed concrete, each

approximately to one-fourth of the height of the mould.

iv) Each layer is tamped 25 times by the rounded end of the tamping rod

(strokes are distributed evenly over the cross section).

v) After the top layer is rodded, the concrete is struck off the level with a

trowel.

vi) The mould is removed from the concrete immediately by raising it slowly

in the vertical direction.

vii) The difference in level between the height of the mould and that of the

highest point of the subsided concrete is measured.

viii) This difference in height in mm is the slump of the concrete.

Reporting of Results

The slump measured should be recorded in mm of subsidence of the

specimen during the test. Any slump specimen, which collapses or shears off

laterally gives incorrect result and if this occurs, the test should be repeated

with another sample. If, in the repeat test also, the specimen shears, the

slump should be measured and the fact that the specimen sheared, should

be recorded.

Typical Questions

Ques 1. What is the ideal value of slump?

Answer 1 In case of a dry sample, slump will be in the range of 25-50 mm

that is 1-2 inches. But in case of a wet concrete, the slump may vary from

150-175 mm or say 6-7 inches. So the value of slump is specifically

mentioned along the mix design and thus it should be checked as per your

location.

Slump depends on many factors like properties of concrete ingredients –

aggregates etc. Also temperature has its effect on slump value. So all these

parameters should be kept in mind when deciding the ideal slump

Ques 2. How does a superplasticizer effect the slump of concrete?

Answer 2 Value of Slump can be increased by the addition of chemical

admixtures like mid-range or high-range water reducing agents (super-

plasticizers) without changing the water/cement ratio.

Ques 3. How much time one should take to raise the cone?

Answer 3 Once the cone is filled and topped off [ excessive concrete from

top is cleared ] raise the cone within 5-10 seconds.

Ques 4. What are the dimensions of the cone used in Slump Test?

Answer 3 The dimensions are

Top Diameter – 10cm

Bottom Diameter – 20cm

Height – 30cm

What is a "slump test" for concrete?

Answer:

This is a frequently asked question. The purpose and process of a slump test may be the best way to answer the question. The purpose of a slump test is to determine the consistency or texture of fresh concrete and to check its uniformity. Uniformity or consistency of concrete is important to a successful concrete project. The "slump" test is based on American Society for Testing and Materials C 143 "Standard Test Method for Slump of Portland Cement Concrete."

The visual part of a slump test should be part of this answer. There is a sturdy metal cone, the cone is open at the top and bottom. Cone is a good description for this equipment, because the top is more narrow in diameter than the bottom. The entire cone is twelve inches high. There are simple handles on the sides of the cone. The handles allow the tester to hold the cone down or lift it up with ease.

The hollow metal cone is filled with fresh concrete in a very precise set of steps. In general the cone is filled in three lifts and each lift is rodded 25 times to consolidate the lifts of concrete. All this is done while the cone is held firmly against a flat firm surface. The term rodding refers to a stabbing motion performed with a long metal rod, twenty-four inches in length and 5/8" in diameter. The use of a chunk of rebar rod is not considered proper.

The cone is full of compacted or rodded concrete and now begins the delicate part of the "slump" test. The person performing the slump test must lift the cone off the fresh concrete in a manner not to disturb the concrete.

Anyone that has used a drinking cup to mold a mound of damp sand knows the cup or cone must be lifted straight up and avoid bumping the molded sand. The same care is required in lifting the slump cone up off the fresh concrete.

Slump is then observed by the person performing the test. The top of the fresh concrete "slumps" down towards the ground and the slump cone is placed next to the pile of concrete. The slump cone is used as pedestal or support for a straight edge to bridge over the pile of fresh concrete. A ruler is extended down from the straight edge to the original top and center of the concrete pile. The distance between the bottom of the straight edge and the top of the concrete is reported to the nearest one-quarter inch. The term "a four inch slump" means the distance between the bottom of the straight edge and the top of the original center of the pile of concrete is 4 inches.

Since the metal cone is twelve inches tall the slump could never be more than twelve inches. Typical slumps are three inches, four inches, to as much as nine inches for concrete with special additives to make it very plastic in "slump."

Thus, slump is used to give a person a reference to the consistency of the concrete, terms like wet, dry, runny, etc., are not precise enough, slump is a much better way to describe the consistency of the concrete.

Slump testDescription The slump test is a means of assessing the consistency of fresh

concrete. It is used, indirectly, as a means of checking that the correct amount of water has been added to the mix. The test is carried out in accordance with BS EN 12350-2, Testing fresh concrete. Slump test. This replaces BS 1881: Part 102.

The steel slump cone is placed on a solid, impermeable, level base and filled with the fresh concrete in three equal layers. Each layer is rodded 25 times to ensure compaction. The third layer is finished off level with the top of the cone. The cone is carefully lifted up, leaving a heap of concrete that settles or ‘slumps’ slightly. The upturned slump cone is placed on the base to act as a reference, and the difference in level between its top and the top of the concrete is measured and recorded to the nearest 5 mm to give the slump of the concrete.

When the cone is removed, the slump may take one of three forms. In a true slump the concrete simply subsides, keeping more or less to shape. In a shear slump the top portion of the concrete shears off and slips sideways. In a collapse slump the concrete collapses

completely. Only a true slump is of any use in the test. If a shear or collapse slump is achieved, a fresh sample should be taken and the test repeated. A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which the flow test (see separate entry) is more appropriate.