EXPERIMENTAL STUDY ON ADDING POLYPROPYLENE FIBER TO COMPRESSIVE STRENGTH AND FLEXURAL STRENGTH OF CONCRETE

Concrete is one of the most frequently used materials in the construction world, concrete is generally composed of a mixture of fine aggregate composition. Coarse aggregate, water and cement. However, concrete has a weakness to the ability to withstand the flexural force, today concrete has experienced a lot of innovations, one of which is fiber concrete. Polypropylene fiber is a type of fiber that can be used as an added material in concrete. This research was conducted to determine the effect of adding polypropylene fiber on compressive strength and flexural strength of concrete. Tests in this study were carried out according to SNI (Indonesian national standard) and ASTM (American standard testing and material), from the results of the experiment of adding polypropylene fiber with variations of 0%, 1%, 1.2%, and 1.4% known to have an effect to the compressive strength and flexural strength of concrete. The highest compressive strength and flexure obtained in concrete variations of 1%. By using cylindrical and beam test specimens.


INTRODUCTION
The construction world always experiences development from time to time, since the past until now Concrete is one of the most frequently used materials (commonly) in the construction process of construction other than wood and steel. Concrete is a mixture of cement, coarse aggregate, fine aggregate, and water with or without additives forming a solid mass (SK SNI T-15-1990-03: 01). Good concrete has strong, durable, waterproof, wear-resistant, and small shrinkage properties (Tjokrodimulyo, 1996: 2). Homogeneous mixture will harden as the chemical reaction that occurs between water and cement. Concrete is also known to have the ability to resist corrosion, environmental decay is also able to withstand the compressive force well. The use of CFRP (Carbon Fiber Reinforced Polymer) and GFRP (Glass Fiber Reinforced Polymer) on beams dimensions of 15 x 20 x 120 cm with reinforcing steel diameters 6 and 10 which results in a flexural strength increase of 31.885% with CFRP and 13.736% with GFRP (Nurlina, et al , 2016). The use of polyerta additive polymers and Fiber Polypropylene as a concrete added material (Hanafi, 2018). The use of Polypropylene Fiber which affects the compressive strength of concrete at a variation of 0.4 kg / m ^ 3 of 35.65 MPa or 18.13% greater than concrete without polypropylene fiber Polypropylene fiber is one of the added ingredients used in concrete mixtures. The use of Polypropylene fibers in concrete building materials is one of the ways used to improve and improve the structural properties of concrete (ACI Committee 544, 1982), namely ductility VOLUME 19 │ NUMBER 02 │ JANUARY 2020 https://ejournal.worldconference.id/index.php/neutron E-ISSN: 2685-3272 | P-ISSN 1412-0860 related to the ability of concrete to absorb energy, resistance to shock loads, and resistance to wear and tear. , and shrinkage effects.
RESEARCH METHODOLOGY This research will use an experimental method in a concrete laboratory using a mixture of Fiber Polypropylene which is used as an added material in the preparation of concrete with several variations used. All testing procedures in this study were carried out with reference to SNI (Indonesian National Standard) and ASTM (American Society for Testing and Materials).

Source : Research Data
Preparation of tools and materials, as well as material testing that will be used in research. Refers to SNI and ASTM. In this study the constituent materials in the concrete mixture are as follows: a) Cement used type 1from PT Semen Indonesia b) Coarse Aggregate used originates from Kusumo and the fine aggregate used Bangka. c) The water used comes from PDAM d) Admixture materials used in concrete are Pozzolith and Glenium from BASF e) Polypropylene fiber -Barchip48 from Barchip.

Place and Time of Research
Where: This research will be conducted at PT Waskita Beton Precast Laboratory.

RESULT AND DISCUSSION Material Inspection Results
The material used in this study has been through a series of tests in the laboratory to determine the nature and characteristics of the materials used, both fine aggregate and coarse aggregate, including:

Fine Agregate
Testing of fine aggregate material aims to determine the feasibility of the constituent materials that will be used in this study. So that obtained good results. Following testing of fine aggregate material.

a. Sieve Analys Of Fine Agregate
From the results of sieving analysis on the sand of the fart, obtained the results of Fine Modulus 2.59. These results are in accordance with the standard used which refers to The results of testing the absorption of water in fine aggregate obtained an absorption value of 0.98 gr / cm3.

e. Washing Loss
The results of sludge content testing on fine aggregate obtained sludge value of 2.3%. Referring to SNI S-04-1989-F the value is still within the allowable limit of <5%.

Coarse Agregate
Testing of coarse aggregate material aims to determine the suitability of the constituent materials that will be used in this study. So that obtained good results. Next is the testing of coarse aggregate material.

a. Sieve Analys Of Fine Agregate
From the test results of coarse aggregate sifter analysis, data such as the graph above obtained where the material passed in the 9.5mm sieve was 11.91%, the 12.5mm sieve was 35.74%, the 19.1mm sieve was 91.8, and the sieve was 25 , 4mm equal to 100. The aggregate used has a maximum size of 3cm.

b. Density Of Coarse Agregate
From the testing of coarse aggregate weight we get coarse aggregate values of 1,634 gr.

c. Specific Gravity (SSD)
From the test results obtained the value of specific gravity SSD (saturated surfce dry) of 2,671 grams. Referring to SNI 03-1750-1990, the value obtained is still within the allowable limit of 2.0-2.7 grams.

d. Water Absorbtion
From the absorption test results in the coarse aggregate values of 1.021% were obtained.

e. Roughness Coarse Agregate
From the results of tests on aggregates performed using Los Angeles machines, the aggregate wear value was 23.45%. Referring to SNI 03-2417-1991, this value is still within the allowable limit because the part that must not be destroyed in the wear test should not be more than 40%.

Workabilty.
Slump testing (workability) is needed to determine the level of fresh concrete permeability.
The higher the value of the slump, the concrete is thinner and easier to do, and vice versa. In this study the researchers planned a slump valueof 50 ± 2 cm.

Source : Research Data
Concrete Water Absorbtion Test.

Source : Research Data
Water Absorption Testing can find out what percentage of concrete can absorb water, for normal concrete conditions a smaller percentage of water absorption is better because the concrete can be waterproof so that if applied to the structure it can prevent water from entering so the reinforcing iron is not exposed to water making the structure durable and strong.

Concrete Compressive Strenght Test
Concrete compressive strength test was carried out on SNI 1974-2011, using cylindrical specimens with a size of 15 x 30 cm. For testing conducted when the sample has reached the age of 7, 28 days. With the following results :