Concrete Technology

UNIVERSIDAD SAN IGNACIO DE LOYOLA

FACULTY OF ENGINEERING AND ARCHITECTURE

CONCRETE TECHNOLOGY

Professor:

Sotil Chvez, Andrs

Section:

FC-PREING05A1T

Members:

Wong Rodrguez, Eduardo San

Snchez Ramos, Adolfo

Ramirez, Raul

Chvez Cruzado, Daniel

Topic:

Laboratory Building Materials Concrete Tests

Delivery Date:

18/11/2014

Lima Per

2014-2

TABLE OF CONTENTS

Introduction

2

Definitions

2

Apparatus and tools

3

Materials

4

Procedure

4

Calculations and results

6

Recommendations

11

Conclusions

11

References

12

I. INTRODUCTION

Compressive Strength Test.

This laboratory report is intended to present some tests: Compressive strength (with software) and Flexural strength (mechanical form). These tests had been applied in different samples of concrete (cylinder and beams samples). Furthermore, any process is detailing; materials, tools and machinery required and used in this activity. Finally, the calculations and results (Breaking strain, type of failure and compression), recommendations, conclusion and a photographic section are detailing.

II. DEFINITIONS

Compressive Strength Test

Concrete mixtures can be designed to provide a wide range of mechanical and durability properties to meet the design requirements of a structure. The compressive strength of concrete is the most common performance measure by the engineer in designing buildings and other structures. The compressive strength is measured by breaking cylindrical concrete specimens in a compression-testing machine. The compressive strength is calculated from the failure load divided by the cross-sectional area resisting the load and reported in units of pound-force per square inch (psi) in US Customary units or mega pascals (MPa) in SI units.

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.

Flexural Strength Test

Flexural strength is one measure of the tensile strength of concrete. It is a measure an unreinforced concrete beam or slab to resist failure in bending. It is measured by loading 6 x 6-inch (150 x 150-mm) concrete beams with a span length at least three times the depth. The flexural strength is expressed as Modulus of Rupture (MR) in psi (MPa) and is determined by standard test methods ASTM C 78 or ASTM C 293.

Flexural MR is about 10 to 20 percent of compressive strength depending on the type, size and volume of coarse aggregate used. However, the best correlation for specific materials is obtained by laboratory tests for given materials and mix design.

III. APPARATUS AND TOOLS

APPARATUS

DESCRIPTION

IMAGE - PHOTO

Compressive Strength Machine

(a)

Standard test method for compressive strength of cylindrical concrete specimens ASTM C39 (NTP 339.034 - 2008).

Providence: Germany.

Capacity: 3000 kN.

Year: 2012.

Works with software and sensors.

Flexural Strength Machine

Hydraulic machine that generates a load on two points, to obtain the tensile strength of concrete beam.

Compressive Strength Machine (b)

This is an hydraulic machine, which does not have sensors or software for obtaining more accurate data.

IV. MATERIALS

MATERIAL

DESCRIPTION

IMAGE - PHOTO

Cylindrical Concrete Sample

Samples made fourteen days ago, which have been made to the required design.

Concrete Beam Sample

V. PROCEDURE

Compressive Strength Test

1. Measure the height and diameter of the sample.

2. Enter sample data, such as diameter, date of collection and testing.

3. Verify that the load cell is clean. Place the specimen (or sample) in the load cell correctly centered on the plates.

4. Starting the application of the load at a constant speed form the norm.

5. The maximum supported load is recorded (a break is appreciated).

6. Review of results and preparation of report.

7. Presentation of results and archive

8. End of test.

Be careful when handling specimens and machine.

Flexural Strength Test

1. Measure the concrete beam.

2. Using a marker make marks. It is marked 2.5 cm from the outer edge; the remainder is divided by three. This will help to establish the correct beam under each load point.

3. Apply the load at a uniform rate. Stops when a break in the concrete beam occurs.

4. The beam is removed carefully, and the fault produced is studied.

5. Procedure to calculate the MR:

6. End of test.

Be carefulwhenhandlingspecimens and machine.

VI. CALCULATION AND RESULTS

Compressive Strength Test

N

DATE

DIAMETER (cm)

HEIGHT (cm)

LOAD (kg)

TYPE OF FAILURE

PHOTO

OBT

TEST

1

30/10/14

13/11/14

15.27

30

38772

214

I

2

15.25

38829

213

I

3

15.22

41346

227

I

4

15.22

32315

178

I

5

15.23

91270

501

I

6

15.28

94180

514

IV

7

15.21

85702

470

I

8

15.25

40279

221

I

9

15.20

39634

218

I

10

15.26

38818

211

II

Remarks:

The sample number 4 is not a part of the samples prepared by the class.

The sample number 3 had mold in it. There can be two possibilities: the aggregates were organic presence or water.

Taking averages of compressive strength:

Sample N 1, 2 and 3:

Sample N 5, 6 and 7:

Sample N 8, 9 and 10:

Flexural Strength Test

N

TIME (DAYS)

DIST. BETWEEN SUPPORTS (cm)

DIMENSIONS (cm)

LOAD (Kg)

FLEXURAL STRENGTH )

PHOTO

LONG

WIDTH

HEIGHT

1

14

2.5

51

15

15

2800

38.16

2

14

2.5

50

14.5

13.3

3300

57.90

3

14

2.5

52.5

15

15

2550

35.89

Is calculated the MR of each concrete beam:

End of test.

Particular test case. A concrete simple cylinder is placed in the compression strength machine, where the sample is placed horizontally to find another type of failure.

VII. RECOMMENDATIONS

The concrete tests should be performed using carefully the guidelines otherwise we can get false results.

A constant addition of load during the test is necessary because otherwise we can get higher resistances resulted from loading weight onto the cylinder too fast.

You shouldnt retest a cylinder whose test stopped without finishing because most likely some of it will be weaker in some parts.

VIII. CONCLUSION

In conclusion we can say that depending on how the concrete cylinder breaks we can know if the proportions of aggregates and water are correct.

If we have an adequate quality control on each step of the concrete mix we can know if the problems of the concrete are caused by human error or by bad materials in the mix.

Standard deviation can affect the test results if the results are too disperse.

For every questions and/or situation there is the standard regulation inside the ntps.

Modern machines for concrete tests are more precise than the old ones.

The minimum fc needed depends on the type of construction.

IX. REFERENCES

Concrete in practice. What, Why and How? NRMCA CIP 16: Flexural Strength Concrete.

Concrete in practice. What, Why and How? NRMCA CIP35:Testing Compressive Strength of Concrete.

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