Adding Fly Ash as a Cement Replacement Material

(1)

82

Analysis of the Pressure Strength and Drying Time of Concrete Using an Integral Waterproof Mixture and

Adding Fly Ash as a Cement Replacement Material

Syafwandi, Habie Ramadhan, Agung Sumarno, Resi Aseanto

Civil Engineering department, Faculty of Engineering, Mercu Buana University [email protected], [email protected]

Abstract

The growth of technology, infrastructure and needs along with the time in the construction world that continues to find new ideas and innovations such as structural dimensions, working methods or materials in the formation of a concrete. The most common form of concrete is Portland cement concrete made from aggregate, cement and water. During the making of concrete, it is constantly changing with the mix of materials that are expected to produce concrete of the desired quality. When performing concreting in the field, the quality of the material, the mixing process, the casting process and the compaction must be taken into account. This determines the final result of the concrete work. The aim of this study was to determine compressive strength, initial curing time and permeability by replacing integral waterproofing and fly ash. The more use is made of integral waterproofing substitution (Damdex), the lower the compressive strength, the largest change is in the 1.5% integral waterproofing (Damdex), the more fly ash substitution the compressive strength decreases. initial curing time of integral waterproofing replacement (damdex) can affect the drying time of concrete, while fly ash replacement cannot speed up the drying time of concrete, the fastest initial curing time in integral wat erproofing (damdex) is 0.5%, 1% and 1.5% while initially is the longest curing time on the integral waterproofing + fly ash replacement.

The effect of the permeability of concrete, concrete with integral waterproofing substitution (Damdex) can reduce the pores or density of the concrete, in a mixture of 0.5%, 1% and 1.5% integral waterproofing, will prevent concrete seepage reduce impermeability while for fly ash no pore sealing or concrete impermeability occurs.

Keyword:

Compressive Strength, Concrete Permeability, Fly Ash, High Strength Concrete, Integral Waterproofing (Damdex), Initial Curing Time.

1. Introduction

Concrete is a construction material commonly used for buildings, bridges, roads and others. Concrete is a homogeneous unit. This concrete is obtained by mixing fine aggregate (sand), coarse aggregate (gravel) or other aggregates and water with Portland cement or other hydraulic cement, sometimes with the addition of chemical or physical additives in certain proportions. it becomes a homogeneous whole. The mixture will harden like stone, hardening takes place through a chemical reaction between cement and water.

Hardened concrete can also be called artificial rock, where the cavities between the large grains (coarse aggregate or crushed stone) and filled with small rock (fine aggregate or sand), and the pores between the fine aggregates are filled with cement and water (cement paste) . Cement paste also acts as a glue or binder in the curing process, so that the aggregate granules are firmly bonded together into a solid and durable unit.

Making concrete is actually not easy, just mixing the basic ingredients into a plastic mixture as we often see when making simple buildings. But if you want to make good concrete, in the sense of meeting stricter requirements due to higher demands, you have to consider how to get a fresh concrete mixture and also good hard concrete. Good fresh concrete is fresh concrete that can be mixed, transported, poured, compacted, there is no tendency to separate gravel from the mortar or to separate water and cement from the mortar. Good hard concrete is concrete that is strong, durable, water-repellent, wear-resistant and low shrinkage. (Tjokrodimuljo, 1996) (Maiti

& Bidinger, 1981).

1.1. Formulation of the Problem

1. What is the effect of compressive strength on the addition of integral waterproofing and fly ash to concrete?

2. How does the addition of integral waterproofing and fly ash affect the initial curing time of the concrete?

3. How is the effect of concrete mixed with integral waterproofing on the permeability of concrete?

(2)

83 1.2. Research Goals and Objectives

1. Find out the results of the compressive strength of concrete with the addition of integral waterproofing and fly ash?

2. To find out the effect of adding integral waterproofing and fly ash to the initial curing time of concrete?

3. Determine the effect of concrete mixed with integral waterproofing on the permeability of concrete?

2. Material and Methods

2.1. Material

The materials used in this study are:

c. Cement: When testing the material, namely cement, the first thing to consider is the physical condition, whether the cement has a smooth texture or not, such as clumping or hardening, so that when making fresh concrete, the quality of the cement does not deteriorate, whether the cement used is such as OPC (ordinary) type cement (Portland cement).

d. Coarse aggregate: Coarse aggregate used in this study is crushed stone with a size of 10-25 mm.

e. Fine aggregate: The fine aggregate used in this study is sand (ex. Jambi & M sand, ex. Cariu) f. Water: The water used in this study must be clean, free of mud, oil and salt.

g. Integral waterproofing: The integral waterproofing used in this study is the Damdex brand.

h. Fly Ash: The fly ash used is type C fly ash from PLTU Paiton, East Java.

2.2. Research Methods

In this study using an experimental method by mixing integral waterproofing with fly ash as cement substitute, which aims to determine the value of compressive strength and drying time of the concrete mixture performed in this study to obtain the data and results of this study. To refer to this study, this study uses an approximation method by collecting data from previous research (Secondary data) with related issues.

Research variable is an object in research observation. Basically, in research there is something that becomes the target, namely variables. A variable is a phenomenon that becomes something that is observed or measured. In the case of this study, the independent variable (X1) is the addition of integral waterproofing to the concrete mixture, the independent variable (X2) is the addition of fly ash as cement replacement, the independent variable (X3) is the addition of integral waterproofing and fly ash to the concrete mix, the variable related (Y) the value of compressive strength and drying time of concrete.

The following is a diagram of the flow of research that will be discussed in this study:

(3)

84

Figure 1 diagram of the flow of research Start

Preparation Of Tools and Materials Material Test

Cement Aggregate Water

Mix Design

Slump Test

Concrete Treatment (Curing)

Strong Test 3,7,14 And 28 Days

Data Management

Integral Waterproofing Additives 0%, 0.5%, 1%, 1.5% And Fly Ash 0%,

10%, 15%

Discussion and Conclusion

Finish Setting Time

28 Days Permeability Test

(4)

85 2.3 Calculation mix design 1 m³

Table 1. Mix Design Control f`c 30, D-0,5%,D-1%,D-1,5%

Mix Design Code

Unit

Control f`c 30

Damdex 0,5%

Damdex 1%

Damdex 1,5%

Implementation date 15 June

2021

8 June 2020

10 June 2020

Compressive Strength Target (f'c) MPa 30 30 30 30

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

OPC Cement Type I Gresik Kg/m³ 375 375 375 375

Fly Ash (C) Ex. Paiton Kg/m³ - - - -

Fine Aggregate Ex. Jambi Kg/m³ 382 396 399 400

Fine Aggregate M Sand Ex. Cariu Kg/m³ 391 405 408 409

Coarse Aggregate Ex. Rumpin 10-25 mm Kg/m³ 1004 979 977 979

Additive (Damdex) Ltr/m³ - 0,90 1,80 2,70

Water Ltr/m³ 180 179,1 178,2 177,3

(Source : Author Data, 2021)

Table 2. Mix Design FA-10%, FA-15%, D-0,5%+FA-10%, D-1%+FA-10%

Mix Design Code

Unit

Fly Ash 10%

Fly Ash 15%

D - 0,5%

FA - 10%

D - 1%

FA - 10%

2021

12 June 2020

14 June 2020

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

Fly Ash (C) Ex. Paiton Kg/m³ 38 56 38 38

Additive (Damdex) Ltr/m³ - - 0,90 1,80

Water Ltr/m³ 180 180 179,1 179,2

(Source: Author Data, 2021)

(5)

86

Table 3 Mix Design D-1,5%+FA-10%, D-0,5%+FA-15%, D-1%+FA-15%, D-1,5%+FA-15%

Mix Design Code

Unit

D - 1,5%

FA - 10%

D - 0,5%

FA - 15%

D - 1%

FA - 15%

D - 1,5%

FA - 15%

2021

14 June 2020

15 June 2020

11 June 2020

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

Fly Ash (C) Ex. Paiton Kg/m³ 38 56 56 56

Additive (Damdex) Ltr/m³ 2,70 0,90 1,80 2,70

Water Ltr/m³ 177,3 179,2 178,2 177,3

2.4 Calculation trial mix design, setting time, and permeability

Table 4. Mix Design Control f`c 30, D-0,5%, D-1%,D-1,5%

Mix Design Code

Unit

Control f`c 30

Damdex 0,5%

Damdex 1%

Damdex 1,5%

2021

8 June 2020

10 June 2020

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

OPC Cement Type I Gresik Kg/m³ 29,62 29,62 29,62 29,62

Fly Ash (C) Ex. Paiton Kg/m³ - - - -

Fine Aggregate Ex. Jambi Kg/m³ 30,18 31,28 31,52 31,60 Fine Aggregate M Sand Ex. Cariu Kg/m³ 30,91 32,03 32,22 32,33 Coarse Aggregate Ex. Rumpin 10-25 mm Kg/m³ 79,32 77,34 77,18 77,10

Additive (Damdex) Ltr/m³ - 0,07 0,14 0,21

Water Ltr/m³ 14,22 14,15 14,08 14,01

Table 5. Mix Design FA-10%, FA-15%, D-0,5%+FA-10%, D-1%+FA-10%

Mix Design Code

Unit

Fly Ash 10%

Fly Ash 15%

D - 0,5%

FA - 10%

D - 1%

FA - 10%

2021

12 June 2020

14 June 2020

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

Fly Ash (C) Ex. Paiton Kg/m³ 3,00 4,42 3,00 3,00

Fine Aggregate Ex. Jambi Kg/m³ 30,34 29,94 30,49 30,57

Fine Aggregate M Sand Ex. Cariu Kg/m³ 31,07 30,65 31,19 31,30 Coarse Aggregate Ex. Rumpin 10-25 mm Kg/m³ 77,81 78,05 77,81 77,74

Additive (Damdex) Ltr/m³ - - 0,07 0,14

Water Ltr/m³ 14,22 14,22 14,15 14,08

(6)

87

Table 6. Mix Design D-1,5%+FA-10%, D-0,5%+FA-15%, D-1%+FA-15%, D-1,5%+FA-15%

Mix Design Code

Unit

D - 1,5%

FA - 10%

D - 0,5%

FA - 15%

D - 1%

FA - 15%

D - 1,5%

FA - 15%

Implementation date 14 Junie

2021

14 June 2020

15 June 2020

11 June 2020

Slump Target Cm 12±2 12±2 12±2 12±2

FAS (w/c) 0,480 0,480 0,480 0,480

Fly Ash (C) Ex. Paiton Kg/m³ 3,00 4,42 4,42 4,42

Fine Aggregate Ex. Jambi Kg/m³ 30,73 30,10 29,47 30,34

Fine Aggregate M Sand Ex. Cariu Kg/m³ 31,48 30,83 30,16 31,06 Coarse Aggregate Ex. Rumpin 10-25 mm Kg/m³ 77,58 73,86 79,32 77,81

Additive (Damdex) Ltr/m³ 0,21 0,07 0,14 0,21

Water Ltr/m³ 14,01 14,15 14,08 14,01

2.5 The place and Time of Research

Place: PT. Waskita Beton Precast Tbk Laboratory, West Java, Indonesia.

Time: The time of the research will be carried out in June 2021 until it is completed.

3. Results and Discussion

3.1 Slump Test

Following are the results of the slump values obtained in this study:

Figure 2 Slump Test Results (Source: Author Data, 2021)

3.2 Result of Setting Time

Following are the results of the initial setup time values obtained in this study:

Figure 3 Results of Setting time (Source: Author Data, 2021)

(7)

88 3.3 Compressive Stregh Results

The following are the results of the compressive strength values obtained in this study:

Figure 3. Compressive Strength Results 3 Day, 7 Day, 14 Day and 28 Day (Source: Author Data, 2021)

3.4 Permeability result

The following are the results of the permeability values obtained in this study:

Figure 4. Permeability Result 28 Days (Source : Author Data, 2021)

Based on the table chart of the above numbers, the higher the chart, the better the results.

4. Conclusion

Based on the results of the research conducted, the following conclusions can be drawn:

1. Based on the results of the initial curing time test, the less integral waterproofing (Damdex), it will accelerate the concrete drying time (initial curing time) results. A good damdex measure used for concrete drying time is 0.5%-1.5%. the results of testing the initial setting time of concrete with fly ash replacement did not affect the accelerated drying time of concrete (initial setting time), the results of drying control concrete and replacing concrete with 10% fly ash ranged from 3 hours 38 minutes - 3 hours 40 minutes, the difference in concrete time control and concrete replaced by 10% fly ash, that is 2 minutes, while the concrete replaced by 15% fly ash leads to the initial curing time being far from dry from the control concrete. The use of integral waterproofing (Damdex) mixed with fly ash cannot affect the acceleration of concrete drying, concrete replacing integral waterproofing (Damdex) + fly ash will result in an initial curing time that is far from the results of control concrete or concrete with damdex mixture only.

2. Based on the results of testing the compressive strength of concrete, concrete added with integral waterproofing (Damdex) will negatively affect the concrete. The average results for normal concrete are Fc = 30.07 MPa, while for integrally waterproof concrete (Damdex) Fc = 29.07 MPa (0.5%), 29.77 MPa (1%) and 24.70 (1. 5%), as well as replacing concrete with fly ash also had a negative effect, fly ash replacing concrete Fc = 26.96 MPa (10%), 24.32 MPa (15%). The concrete added with integral

(8)

89

waterproofing (Damdex) + fly ash also has a negative influence on the concrete. The average result of integral waterproofing (Damdex) + fly ash Fc = 27.21 MPa (0.5% + 10%), 27.95 MPa (1% + 10%), 22.83 MPa (1.5% + 10 %) and Fc = 27.88 MPa (0.5%+15%), 20.23 MPa (1%+15%), 25.28 MPa (1.5%+15%).

3. Based on the permeability test of concrete, concrete substituted for integral waterproofing (Damdex) can reduce the pores or density of the concrete. The ratio of permeability between normal concrete and integral waterproof concrete (Damdex) is approximately 18.7 mm (Normal) and 15.8 mm (Damdex), 15.2 mm (Damdex) and 15.4 mm (Damdex). Meanwhile, the permeability test of concrete with fly ash substitution was far from normal concrete results, which was about 18.7mm (normal) and fly ash = 27.3mm (10%) and 29.7mm (15%). The results of the test for permeability of integral waterproof concrete (Damdex) + fly ash, seepage ranges from 22.9 mm – 24.4 mm.

Refrences

Maiti, R. K., & Bidinger, F. R. (1981). Growth and development of the pearl millet plant (Research Bulletin 6).

ICRISAT. http://oar.icrisat.org/6060/

Tjokrodimuljo, K. (1996). Teknologi Beton. Nafiri.

Biographies

Syafwandi, born in Jakarta on October 13, 1956. he is a Directory professor with a Professor Degree, hestudied Bachelor’s degree at the University of Indonesia (1983), Doctor randes University of Muhammadiyah Jakarta (1984), Master in Technology Institute of Bandung (1988). And Earned a Doctorate at Satyagama University Jakarta (2005). In the world of education, he teaches Science at Mercu Buana University, STKIP Albana, Menara Siswa School of Administrative Sciences, Jakarta High School of Technology. He also teaches in the field of Civil Engineering on Building Structures and others.

Habie Ramadhan, born in Jakarta, December 26, 1998. Habie Ramadhan is a student of Civil Engineering Study Program, Faculty of Engineering, Mercu Buana University in 2017 - 2021. He studied at High School 16 Bekasi majoring in Social Sciences (IPS) in 2013 – 2016 During the university, Habie Ramadhan was active in various activities on and off campus, Habie Ramadhan was a committee or chairman of the exhibition at the 2019 civil expo event, the 2018 intimacy night committee and seminar events held by the civil engineering study program.

The off-campus activities in which he participated are study excursions to 3 countries (Malaysia, Thailand and Singapore) in 2018, habie ramadhan did 3 months hands-on work at the Anami-1 Tower B Apartment Klapa Village Project.