mechanical properties of gabbro aggregate concrete

International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 10, October 2018, pp. 176–181, Article ID: IJCIET_09_10_018 Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=10 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication

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MECHANICAL PROPERTIES OF GABBRO AGGREGATE CONCRETE Rasha Ali Al-Fatlawy Assistant Lecturer, M.Sc. Degree in Geotechnical Engineering, Civil Engineering Department, Faculty of Engineering, University of Kufa Waseem Al-Baghdadi Lecturer, M.Sc. Degree in Geotechnical Engineering, Civil Engineering Department, Faculty of Engineering, University of Kufa

Qusay A. Jabal Lecturer, M.Sc. Degree in Concrete Technology Civil Engineering Department, Faculty of Engineering, University of Kufa ABSTRACT A lot of materials could be used as an admixture or even as an essential part of concrete, the aim of this study is to use the Gabbro rocks as a fine and coarse aggregate in concrete. The used Gabbro in study is obtained from waste black granite (as it's locally named). Results showed a significant increase in compressive, tensile and flexural strength when using Gabbro as fine and coarse aggregates, comparing with normal aggregate concrete; compressive strength started to increase from 35.1 MPa for reference mixes up to 56.8 MPa for Gabbro concrete (GC) while flexural strength increased significantly from 3.2 MPa for reference mix to 10.3 MPa to GC concrete (221% increment). Keywords: gabbro concrete, fine aggregate, coarse aggregate, compressive strength, tensile, flexural Cite this Article: Rasha Ali Al-Fatlawy, Waseem Al-Baghdadi and Qusay A. Jabal, Mechanical Properties of Gabbro Aggregate Concrete, International Journal of Civil Engineering and Technology, 9(10), 2018, pp. 176–181. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=9&IType=10

1. INTRODUCTION Concrete is the most common construction material all over the world even when comparing with steel, for example, which is less durable, less fire resistance and more expensive. According to that, increasing the mechanical properties and enhancing the durability of the http://www.iaeme.com/IJCIET/index.asp

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Mechanical Properties of Gabbro Aggregate Concrete

concrete represents a highly priority for designers. Many researches were done to achieve these goals even by using new material as admixtures or by using these new materials as concrete aggregate itself. One of the most durable rocks is the Gabbro rock, the Gabbro rock is igneous rocks having a grey or black color, its durability and scratch resistance were very high. Moreover, the compressive strength was also very high (more than 280 MPa). The Gabbro rock was used, as it is, as facing for buildings, paving, flooring and decoration [1,2]. On the other hand, the chemical structure of Gabbro contains several melted minerals together forming very hard rock, it contains quartz, chromium, nickel, cobalt, gold, silver, platinum and iron. The priority of this investigation is to use the Gabbro as fine and coarse aggregate in study, since the Gabbro is expensive, the use of waste Gabbro from local markets or buildings reduce the overall cost of concrete.

2. EXPERIMENTAL WORK 2.1. MATERIALS Ordinary Portland cement was used in all mixes, sand was used as fine aggregate from An Najaf area / Iraq, and gravel with 16mm for maximum size were used in reference mixes, tables 1 and 2 show the sieve analysis of coarse and fine aggregates which confirming Indian standards IS-383 [3], The Gabbro rocks used as a replacement from fine and coarse aggregates, it crushed in laboratory to become a fine and coarse aggregate then used as aggregate replacement with different ratios (10%, 20%, 30%, 40%, 50% finally reaching to 100%). reference mix concrete ingredients shown in table 3, while figure 1 shows the gabbro fine and coarse aggregates used in study.

2.2. SPECIMENS and MOULDS Three specimens were used for each type of concrete mix to find the average value of all mechanical properties. Compressive strength was done by using steel molds with dimensions of 100×100×100mm. The fresh concrete was compacting using vibration table machine, the moulds were opened after 24 hours, the specimens were curing in water for 28 days. Figure 2 shows the cubic concrete specimen under testing.

2.3. TESTING Tensile strength test was done by using splitting tensile test for a steel cylinders with 100mm in diameter and 200mm in height. Figure 3 shows the cylindrical concrete specimen under testing. The value of tensile strength was calculated using equation no.1

Where: ft: tensile strength of cylinder P: maximum load (failure load) applied from machine D: diameter of cylinder, and L: height of cylinder

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The flexural strength test was performed by using third point loading for a beams with dimensions of 100×100×400mm. Figure 4 shows the concrete beam under testing for flexural strength. The flexural strength value obtained from equation 2 shown:

Where: fb: flexural strength of concrete P: maximum load from machine. L: length of beam. b; width of beam, and d: depth of beam

3. RESULTS AND DISCUSSIONS All the results of reference concrete (RC) and gabbro concrete (GC) with different ratio of replacement for compressive, tensile and flexural concrete were summarized in table 4. The compressive strength of was suddenly increased from 35.11 up to 40.39 MPa by just 10% of aggregate replacement, then it is gradually increased while increasing the replacement ratio until it finally reached to 56.82 MPa. this could be attributed to the strength of gabbro rocks which have a very high values of compressive strength that exceed 200 MPa, hardness equal to 7 and high durability [4,5], this high resistance properties were due to the existence of course crystal grains which generated by heating several metals that crystallized underground [6 ,7]. Both tensile strength and flexural strength were also significantly increased. The tensile strength was increased by 32% with 10% replacement while the increasing percentages were achieved more than 125% with 100% aggregate replacement ratio. Same pattern was noticed with the flexural strength, the increasing percentages were 26% and 215% with the same previously mentioned replacement ratios. The relationship between increasing percentages with the aggregate replacement ratio is shown in figure (5). This behavior could be attributed to two reasons; firstly, this type of aggregate gives, by its tough and rough texture, a very good bond with cement paste which lead to create higher strength. The second reason is the excellent properties of tensile and flexural strength of gabbro itself (as shown in table 5), it have about 15-30 MPa tensile strength, and have flexural strength of about 10-20 MPa [8]. Table 1 Sieve Analysis of Course Aggregates Used in Study Confirm IS-383 Sieve Size, mm 40 20 16 10 5

%passing by Weight 100 100 94.2 43.9 3.8

%Passing Spec. (IS-383) 100 100 90-100 30-70 0-10

Table 2 Sieve Analysis of Fine Aggregate Confirm Zone 2 Sieve size 10 MM 5 mm 2.36 1.18 600 mic

%passing spec. –IS-383-ZONE2 100 90-100 75-100 55-90 35-59

%passing 100 91.0 82.7 77.5 44.1


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300 mic 150 mic

17.8 4.2

8-30 0-10

Table 3 Reference Concrete Mix Ingredients for Each Cubic Meter of Concrete. ingredient Weight kg

cement 495

Fine agg. 745

Coarse agg. 935

water 218

Table 4 Mechanical Properties (MPa) of Concrete with different ratios of Gabbro Aggregate Replacement Ratio Reference mix (RC) (0%) 10% 20 % 30% 40% 50% 60% 70% 80% 90% 100%

Compressive strength 35.11 40.39 42.89 44.61 46.49 48.30 49.88 51. 43 52.80 54.72 56.82

Tensile strength 2.16 2.85 3.10 3.56 3.78 3.90 4.23 4.41 4.50 4.67 4.93

Flexural strength 3.25 4.10 5.16 5.93 6.71 7.23 8.00 8.77 9.34 10.02 10.34

Table 5 Some Mechanical and Physical Properties of Gabbro [8] Property

Color

Density (kg/m3)

Compressive strength (MPa)

Tensile strength (MPa)

Flexural strength (MPa)

Value

Dark grey to black

2810 – 3030

124 – 303

15 – 30

10 – 20

Figure 1 Gabbro Fine and Coarse Aggregates Figure 2 Compressive Strength Test for GabbroConcrete (GC)


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Figure 3 Tensile Strength Test for Gabbro-Concrete (GC)

Figure 4 Flexural Strength Test for Gabbro-Concrete (GC)

Figure 5 Relationship between Increasing Percentage and Aggregate Replacement Ratio


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REFFERENCE [1] [2] [3] [4] [5] [6] [7] [8]

https://en.wikipedia.org/wiki/gabbro “Gabbro”, wkipedia ,the free encyclopedia, page last edited on 6 November, 2017 www.Rocks.comparenature.com /en/granite-vs-gabbro/comparison-1-14-0 , “ compare rocks” ,copyright 2015-2018, A softUvista IS-383 ,”Indian Standards Specifications for Coarse and fine Aggregates from Natural Sources for Concrete”, 2002. WWW.ROCKS.COMPARENATURE.COM/en/properties-of-model-14-6 ,”properties of gabbro-physical ,thermal compare Rocks”,2018 http://www.ucl.ac.uk/earth.sciences/impact/rocks/igneous/gabbro ,”earth sciences-Gabbro “,university college, London ,2018. http://study.com/academy/lesson/gabbro-uese-facts.html “Gabbro: uses and facts”,2018. WWW.SOFTSCHOOLS.COM“Gabbro facts, http://www.softschools.com/facts/rocks /gabbro-facts www.matweb.com/search/datasheettext.aspx?bassnum=bmin04 ,”Gabbro Mechanical and physical properties “,2018.


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