THE INFLUENCE OF FLY ASH ADDITION ON THE COMPRESSIVE STRENGTH OF CONCRETE CONTAINING RECYCLE CONCRETE AGGREGATES

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1 Advanced Materials Research Online: ISSN: , Vol. 626, pp doi: / Trans Tech Publications, Switzerland THE INFLUENCE OF FLY ASH ADDITION ON THE COMPRESSIVE STRENGTH OF CONCRETE CONTAINING RECYCLE CONCRETE AGGREGATES Rosyid Kholilur Rohman 1,a, Setiyo Daru Cahyono 2,b A.R. Hanung Triyono,c 1 Lecturer of Civil Engineering Department of Merdeka University of Madiun, Indonesia. 2 Lecturer of Civil Engineering Department of Merdeka University of Madiun, Indonesia 3 PhD students at Environment Science Postgraduate Program Sebelas Maret University, Surakarta, Indonesia a kangroko@yahoo.co.id, b cahyono.ds@gmail.com, c hanungtri@yahoo.com Keywords: recycle aggregate, fly ash, concrete, compressive strength Abstract The rapid economy growth in Indonesia encourages the developments in all fields. One of them is the development of infrastructure on housings, transportations, and irrigation. Constructions of concrete building are used on the road, bridges, buildings, housing, and water buildings. A concrete is a material structure of building that made from mix of sand, gravel, cement and water as adhesive. All the materials of the concrete were derived from the nature. To avoid the excessive exploration of nature resource the method of recycling of used concrete to become new one were needed. The used concrete was used for coarse aggregate. To improve the quality of concrete from the used one, additional material was required, that is, fly ash. The test material were formed of cube of 15x15x15 cm in size. From the result of research, the analysis can be done in order to find the relationship between quantity of fly ash to be added and the quality of concrete can be formulated as y = x x , in which y is compressive strength and x is the percentage of fly ash. Thus, for maximum addition of fly ash of 16.4 %, it obtains the maximum compressive strength of concrete of 26.4 MPa and the age of concrete is 28 days. The method of recycling of used concrete and the use of fly ash to become the material of new concrete are safe environmentally, which can overcome the nature filthy especially from the waste of used concrete and coal. Therefore, this is in line with the principal of nature preservation, those are Reduce, Reuse dan Recycle. Introduction Infrastructure development in all areas is required to support society economic growth. Infrastructures that become priority are housings, buildings, roads, irrigation and bridge. All the infrastructure developments are always use concrete construction. For this reason, accomplishment of the concrete material requirement will be very much. Concrete is a material structure made from sand mixture, gravel, cement and water as the adhesive. All concrete materials are taken from nature. Because requirement of concrete materials is quite a lot, it is necessary to have a research about recycling of used concrete as the effort to decrease natural resource exploration for the very much concrete material. Recycling used concrete as coarse aggregate for new concrete frequently has smaller strength depress of concrete compared to one from aggregate newly from nature. Therefore it needs additional material. One of additional material is fly ash. The fly ash is the result of combustion process of coal from combustion stove, despite the residue of combustion of coal that left at the base of stove is called Bottom Ash. Fly Ash is the waste of coal which in Indonesia is very abundance so that very compatible to be employed as an additional aggregate of concrete. Moreover, it can prevent environmental pollution from coal waste. Fly Ash is expected to be able to improve the strength depress concrete resulted from recycling the used concrete. The method of recycling the used concrete and the employing of the fly ash for the new concrete material is more environmentally; because it can overcome environmental contamination problems especially by using concrete material dismissal and prevents environment contamination from coal All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (# , Pennsylvania State University, University Park, USA-12/09/16,10:48:57)

2 392 Advanced Materials Engineering and Technology fly ash. This matter is deal with the principles of preservation of environment, reduce, reuse and recycle. The problem formula taken in this research is how the influence of the fly ash toward the new resulting concrete especially about the compressive strength. Method In this research, the method used was experimental laboratory to collect data to investigate the correlation among examined variables. This research was conducted in Structure Laboratory of Civil Engineering Department of Merdeka University, Madiun, Indonesia. The purpose of this research is to know the influences of adding the coal fly ash and the used concrete to produce the new concrete. It is expected that the new concrete has the strength to be equal to the concrete made from the natural materials. Literature References Concrete represents construction of building coming from sand mixture, gravel, crushed stone and other substance and also mixture of pasta from cement and water. In making of concrete can be enhanced with substance of additive to yield certain characteristics like amenity in workmanship, durability and also time of ossification of concrete construction. [1] Aggregate is item of mineral of nature which is used for substance of filler in concrete mixture. In a concrete construction, the sum up aggregate must be equal to 70% - 75% from total of concrete volume. The quality of aggregate influences the quality of concrete. The used concrete can be recycled to become new concrete that is taken for the coarse aggregate of new concrete. [2] To make concrete having certain character can be given by a substance addition. The substance addition is substance of non water, non aggregate and or the cement enhanced in mixture of concrete so that the concrete able for the certain work or to quicken work and also more economic. [3]. One of substance addition is fly ash. Fly ash is ash of rest of combustion petrify of coal in the form of light and smooth item, it is not porous and have the character of pozzolanic. Fly ash has the nature of fastener, it is the same as cement, but has to be added water irrigate and the smooth particle. Oxidize silica which consisting in fly ash will react chemically with calcium of hydroxide which is formed by process of hydration cement and yields material owning ability of strengthening. [4] Compressive strength is obtainable by the examination test to depress hydraulic concrete mechanically fall to pieces later; then it is conducted by record-keeping of level of tension that happened later; then a calculation is done and packed into the following equation [5]: P f c = (1) A where : f c = value of Compressive Strength Test (MPa) P = Maximum force (N) A = width of pressed surface of tested material (mm 2 ) Concrete porosity is definitely stated in terms of percentage by volume of concrete. The strength and durability of concrete are also influenced by its porosity characteristic [6]. Many researchers have same opinion that porosity of concrete can be reduced using pozzolan or supplementary cementing material. The porosity of concrete can be calculated using the formula (20): B C P = 100% B A where : P = the total porosity (%) B = the weight of saturated samples measured in the air (g) A = the weight of saturated samples measured in water (g) C = the weight of oven dried samples measured in the air (g) (2)

3 Advanced Materials Research Vol Results and Discussion The conducted research is made by making sample of test concrete. The samples used the aggregate from used concrete and enhanced with the coal fly ash. For the coarse aggregate picture from the used concrete and the coal fly ash shown on picture 1 and 2. Picture 1. Coarse aggregate from the used concrete Picture 2. Coal fly ash The mix design for the object test concrete in this research shown at table 1. Table 1. Mix design for the sample test Code Volume Weight % Cement Water Sand Gravel Fly ash (m 3 ) Used Fly ash (Kg) (Kg) (Kg) (Kg) (Kg) 0% % % % % % % % % % Amount The test material is in the form of cube of 15x15x15 cm in size. After object of test is made then the object test is kept and conducted with a treatment till it reaches age 28 days. Then it is conducted a compressive strength test, shown at picture 3

4 394 Advanced Materials Engineering and Technology Picture 3. Compressive strength test The result of compressive strength test as at Tables 2 and Picture 3 Tables 2. Compressive strength test of concrete Code Weight Weight/Unit Maximum Force Average Compressive (gram) Volume (Kg/m 3 ) (KN) Sample 1 Sample 2 Sample 3 Force (KN) Strength (MPa) 0% % % % % ,0 Compressive Strength (MPa) 26,5 26,0 25,5 25,0 24,5 25,3 26,5 26,4 25,5 y = -34,921x ,45x + 25,465 R 2 = 0, ,6 24,0 0% 10% 20% 30% 40% Percentage of Fly Ash (%) Picture 3. Graph of Result of compressive strength From the research result, the quantity of the coal fly ash which can be added to obtain the maximum strength depress concrete is 16.4 % and the maximum compressive strength is 26.4 MPa. Hence, it can be formulated y = x x where y is compressive strength and x is percentage of fly ash. The result obtained from porosity test of the concrete shown in Picture 4. It shows that only 10 % of fly ash will give a better performance of concrete porosity and more than 10 % leads to the increasing

5 Advanced Materials Research Vol of porosity. Percentage of fly ash more than 10 % to the concrete mixture absorbsed water in large amount and will cause the mixture drying, so that the percentage of fly ash must be limited up to 10%. Porositas (%) % 10% 20% 30% 40% Percentage of fly ash Picture 4. Graph of Result of Porosity Test Summary The recycled aggregate of the used concrete and the coal fly ash can be used as materials for the new concrete. In this research shown that addition of the fly ash influences the compressive strength of concrete and is obtained the correlation of y =-34,921x x where y is compressive strength and x is percentage of fly ash. So that, the maximum coal fly ash which can be added is 16.4 % to get the maximum quality concrete to be equal to 26.4 MPa. Acknowledgements The writer would like to thank to the lectures of Civil Engineering Department of Engineering Faculty of Merdeka University of Madiun, Indonesia and also lecturers of Magister of Civil Engineering Department of Sebelas Maret University, Surakarta, Indonesia for the contributions related to this research so it is completed well. References [1] Mc. Cormac, J.C, Design of Reinforced Concrete (Fifth edition) (translate), Jakarta: Erlangga. (2003) [2] Rohman, Rosyid K, Pemanfaatan Agregat Beton Bekas sebagai Agregat kasar Beton Baru, Jurnal Agritek, Volume 9 No 2, Merdeka University of Madiun (2005) [3] Nawy, E.G, Reinforcement Concrete a Fundamental Approach (Third Edition), Preintice Hall, Upper Saddle River, New Jersey (1996) [4] Krisbiyantoro, Bambang, Tinjauan Permeabilitas dan Shrinkage Beton Mutu Tinggi dengan Bahan Tambah Mineral Metakaolin dan Superplasticizer, Final Project : The Department of Civil Enginerring, Sebelas Maret University of Surakarta (2005) [5] Dipohusodo, Istimawan, Struktur Beton Bertulang, Jakarta: PT Gramedia (1990) [6] Nugroho, Eko, Analisis Porositas dan Permeabilitas Beton dengan Bahan Tambah Fly Ash untuk Perkerasan Kaku (Rigid Pavement). Final Project. The Department of Civil Enginerring, Sebelas Maret University of Surakarta (2010)