THE EFFECTS OF POLYPROPYLENE FIBERS ON THE STRENGTH OF

CONCRETE

Presented By:AnjaliAnupam SinghHeenu ChaudharyLalitHarsh Lodhi

INTRODUCTION• Concrete is world’s most widely used construction material. Due to its low tensile strength and a low tensile strain limit it results in the development of microcracks in it. So in order reduce this effects polypropylene fibers can be used.

•Excessively wide cracks can also result in leakage in structures such as dams, tanks, and pools. In many of the cases this cracking is so significant that it may lead to failure of the structure. The deterioration of such structures is of great concern since the repairing and rehabilitation of these structures are time consuming and costly.

•By adding polypropylene fibers into the concrete, the plastic shrinkage cracks of concrete at the early age reduced and it can also reduce the surface bleeding and settlement of aggregate of fresh concrete, which can prevent the formation of settling cracks.

• In this study various mixtures of polypropylene fiber of volume fractions of 0.15, 0.20, 0.25, and 0.30 was used for concrete mixes. Each series consists of cubes as per IS standard. A series of tests were carried out to find out the compressive strength at the age of 28 days. At the age of 28 days each mixture were tested and analysed in order to find out the best efficient mixture in favouring of strength characteristics of concrete mix.

•Polypropylene fibers are cheap and abundantly available.

•Due to its low density (0.9 gm/cc), high crystalline, high stiffness and excellent chemical/bacterial resistance, is tactic PP is widely used in many industrial applications such as nonwovens, industrial ropes, packaging materials, furnishing products, etc.

NECESSITY

•Weight•Plastic Shrinkage Cracks•Cost •Permeability •Absorption of water, chemicals & dusting•Corrosion

INCREASES

DECREASES•Durability

•Anti-breaking capacity•Abrasion Resistance•Fire Resistance •Strength

OBJECTIVES OF PROJECT

To compute the effect on compressive strength of M30 mix concrete due to Polypropylene fibre.

To carry out experimental investigations for comparative study with varying Polypropylene fibre and water-cement ratio.

LITERATURE REVIEWAuthor’s Name Research Paper Experimental WorkT.Aly, J.G. Sanjayan, F. Collins

Effect of Polypropylene Fibers on Shrinkage and cracking of concretes

focused on the plastic shrinkage cracking performance of concrete incorporating PP fibers that are subjected to restrained conditions.

Rana A. Mtasher, Dr. Abdulnasser M. Abbas, Najaat H. Ne’ma

Strength Prediction of Polypropylene Fiber Reinforced Concrete

investigates on the study of effects of polypropylene fiber on the compressive and flexural strength of normal weight concrete.

J.A. Larbi and R.B. Polder

Effects of Polypropylene fibers in concrete: Microstructure after fire testing and chloride migration

revealed that the amount of explosive spalling and the extent of cracking can considerably be reduced by use of suitable amount of polypropylene fibers.

Alan Richardson and Urmil V. Dave

The Effect of Polypropylene fibers within concrete with regard to Fire Performance in Structures

examined the effect of various polypropylene fibers addition to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires.

K. Murahari and Rama Mohan Rao

Effects of Polypropylene fibers on the strength properties of fly ash based concrete

deals with the strength properties of concrete containing polypropylene fiber and class C fly ash. It was found that the compressive, flexural and split tensile strength increases gradually by the addition of polypropylene fibers.

METHODOLOGY

Preparation of Mix

Mixing of Materials

Addition of Water

Casting of Samples

Curing of Specimens

MATERIALS REQUIREDCEMENT

COARSE AGGREGATES

FINE AGGREGATES

POLYPROPYLENE FIBER

WATER

POLYPROPYLENE FIBER CONCRETE

CEMENT•The cement used was Ordinary Portland Cement of 53 Grade.•The cement has a specific gravity of 3.15.•The physical properties are confirming to IS: 12269-1987 is given in Table 1.

Table 1: Physical Requirements for OPC, 53 grades

Sl No.

Characteristics Requirements

1. Fineness, m²/kg, Min 225370 for 53-S grade

2. Setting Time:a) Initial, min, Min 30

60 for 53-S gradeb) Final, min , Min 600

3. Compressive Strength, MPaa) 72 ± 1h, Min 27b) 168 ± 2h, Min 37

37.5 for 53-S gradec) 672 ± 4h, Min 53

COARSE AGGREGATES

•Coarse aggregates used in this study are the crushed aggregates. The commercial stones are quarried, crushed and graded. These are mainly the crushed angular granite metal stones.

•The sizes of 20mm and 10mm are used.

•The specific gravity and water absorption is given in table 2 conforming IS 2386 (part iii)- 1963.

Table 2: Physical properties of Coarse Aggregates

Physical Property

20mm 10mm

Specific Gravity 2.883 2.878

Water Absorption

0.97 0.83

FINE AGGREGATES•Fine aggregate used in the study is river sand confirming to zone III (IS: 383 -1970).

•Specific gravity and water absorption value (IS: 2386 (Part-iii) 1963) of sand used was 2.605 and 1.23% of wt. respectively.

•Limits of grading zone III is given in Table 3.

Table 3: % passing for Fine Aggregates

IS Sieve Designation % passing for Grading Zone III

10mm 1004.75mm 90-1002.36mm 85-1001.18mm 75-100

600µ 60-79300µ 12-40150µ 0-10

POLYPROPYLENE FIBER

•The fibres used were fine polypropylene monofilaments .

•It is available in 3 different sizes i.e. 6mm, 12mm and 24 mm.

•In the present investigation 12mm fiber length is used . The physical properties are given in Table 4.

Table 4: Physical Properties Of Polypropylene Fibers

PARAMETERS SPECIFICATIONSSize 12 mmMelting point 170°CTensile Strength 390-590 MPaSpecific Gravity 0.91Water Absorption 0

WATER

Potable water is used for mixing and curing from the water supply network system as it was free from the suspended solids and organic material, which might have affected the properties of the fresh and hardened concrete

MIX DESIGN

• The Concrete mix design has been carried out for various proportions as per IS 10262: 2009.

•The ratio of water added to the cement was w/c = 0.42.

• 380kg/m³ • 1283kg/m³

• 711kg/m³• 160kg/m³

CEMENTCOARSE

AGGREGATES

FINE AGGREGA

TESWATER

Freshly prepared PP Fiber Concrete

MIX PROPORTION

The mix proportion was obtained for various percentages of polypropylene fiber i.e., 0.15%, 0.20%, 0.25%, and 0.30% replacement for Ordinary Portland Cement. In the first trial, water content was maintained constant. However in the second trial water /cement ratio was maintained constant. The mix proportions for various batches for trial I & II given in Table 5 & 6:

Table 5: Details of Mix Proportions- Trial I Table 6: Details of Mix Proportions- Trial IIPP Fibre content (%)

Cement (kg/m³)

Fine Aggregates (kg/m³)

Coarse Aggregates (kg/m³)

Water (kg/m³)

00.150.200.250.30

PP Fibre content (%)

Cement (kg/m³)

Fine Aggregates (kg/m³)

Coarse Aggregates (kg/m³)

Water (kg/m³)

00.150.200.250.30

TEST ON SPECIMENS

1. COMPRESSION TESTIn this investigation we use cubical moulds of size 15 cm x 15cm x 15 cm.

Concrete is poured in the

cast iron moulds

Compacted properly by tamping rod of standard size or by vibration

Stored at temperature (15° -25°) &

relative humidity of

90% is maintained

Demoulded after 24 hrs &

stored in water for

curing

After 7 & 28 days

specimens are tested by

CTM

Load at the failureCOMRESSIVE STRENGTH = Area of Specimen

Load should be applied gradually at the rate of 140 kg/cm² per minute till the specimens

fails

Compression Strength (MPa)PP Fiber Content (%)

7 Days 28 Days

00.150.200.250.30

Compression Strength (MPa)PP Fiber Content (%)

7 Days 28 Days

00.150.200.250.30

Table 7: Compressive Strength for Trail I

Table 8: Compressive Strength for Trail II

Compression Testing Machine

2. 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 mix is workable.

The slump cone is a metal mould in the

shape of the frustum of cone which is open at both ends with a base diameter of 203 mm (8 inches), a top diameter of 101 mm (4 inches),

and a height of 305mm (12 inches).

Fill the cone in 3 layers.

Each layer is tamped 25

times by rod

Remove excess

concrete from top of the cone

Immediately lift cone vertically

with slow and even motionInvert the

withdrawn cone & place

next to slumped concrete

Measure the amt. of

slump from bottom to top

of slumped cone

Rod dimension:610 mm long bullet nosed metal rod of 16 mm in diameter

PP Fiber Content (%)

Slump values (mm)

Slump Type

00.150.200.250.30

Types of Concrete Slump

Table 9: Slump Tests Values

3. UNIT WEIGHT OF CUBES

Tests to study the variation of unit weight of the cube were conducted. The table10 shows the details about the unit weight of the cube with the increase in the percentage of the polypropylene fibre content in concrete.

PP Fiber Content (%)

Wt of the Cube(kg)

Unit Wt of The Cube (kg/m3)

00.150.200.250.30

Table10: Unit Weight of Cubes

4. POROSITY TEST

Water absorption test or the porosity test was carried out the percentage water absorption was measured. The table11 shows the details about the water absorption test carried out.

PP Fiber Content

(%)

Avg. Dry wt(g)

Avg. wet wt(g)

Water Absorbed

(g)

Percentage Water

Absorption %

00.150.200.250.30

Table 11: Water Absorption by Cubes

•Pavements and guard rails of highways and expressways

•Airport runway and parking apron

•Sprayed concrete at the wall surface and top of tunnel and mine revetment

•Major structure of bridge and deck

•Composite floor in building constructions

•Waterproof layer, floor, inner & outer wall of industrial and civil constructions

APPLICATIONS

REFERENCES•IS 516: 1959 Method of test for strength of concrete

• IS 2386 (Part VIII): 1963Methods of Test for Aggregates for Concrete.

• IS 383:1970, Specification for coarse and fine aggregates from natural sources for concrete

• IS 10262:2009 Concrete Mix Proportioning- Guidelines.

• Aly T, Sanjayan J G and Collins F (2008),“Effect of Polypropylene Fibers on Shrinkage and Cracking of Concretes”, RILEM, Materials and Structures, Vol. 41, pp. 1741-1753, DOI 10.1617/s11527-008-9361-2.

• Rana A. Mtasher, Dr. Abdulnasser M. Abbas, Najaat H. Ne’ma (2011) “Strength Prediction of Polypropylene Fiber Reinforced Concrete”, Eng. & Tech. Journal, Vol. 29, No. 2, pp 305-311, 2011.

• J.A. Larbi and R.B. Polder “Effects of Polypropylene fibers in concrete: Microstructure after fire testing and chloride migration”, HERON Vol. 52, No. 4, pp 289-305, 2007.

• Google search for images.

 

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