An Experimental Study on No Fines Concrete with Partially Replacement of Cement by Silica Fume

An Experimental Study on No Fines Concrete with Partially Replacement of Cement by Silica Fume

K. Rubini1,

1Assistant Professor, Department of Civil Engineering, Karpagam University, Coimbatore,

Tamil Nadu

1. Sampathkumar2, Santhosh. D. C3, M. Ramprasath4

   2,3,4, UG Students, Department of Civil Engineering, Karpagam University, Coimbatore,

   Tamil Nadu

   Abstract: The mechanical characteristics of no fines concrete with or without silica fumes are investigated. The effect on mix proportions on compressive strength, tensile strength has to be presented. Along with the mix proportions and water content to have sufficient bond between the aggregate particles. The different combinations of cement, silica fume, water and coarse aggregate with different w/c ratio adopted for trial mixes. The w/c ratio as 0..34 and 0.36 are taken. Then the coarse aggregate of nominal size 20mm passed and 10mm retained. Cement is partly replaced with 20% and 25% of silica fume and with a cement to coarse aggregate ratio of 1:6.

   1. INTRODUCTION

      No fines concrete is a form of light weight concrete obtained when fine aggregate is omitted, i.e. consisting of cement, water and coarse aggregate only. No fines concrete is thus an agglomeration of coarse particles, each surmounted by a coating of cement paste up to about 1.3mm thick. There exist therefore, large voids within the body of the concrete which are responsible for its low strength, but their large size means that no capillary movement of water can take place.

      The usual size of aggregate is 10 to 20mm; 5 percent oversize and 10% undersize are allowed, but no particles should be smaller than 5 mm. Flaky or elongated particles should be avoided. The use of sharp edged crushed aggregate is not recommended as local crushing can take place under load.

      The main use of no-fines concrete is in load bearing walls in domestic buildings and in-filling in framed structure.

   2. OBJECTIVES

      The objective of the present study is to check the performance of No Fines concrete on various mixes of aggregates.

      Due to the absence of fine aggregate in no fines concrete, there is a high percentage of void space which results in high permeability.

   3. SCOPE

The scope of the present study is to carry out a detailed analysis of the following sub systems for the prescribed conditions:

1. Cement: concrete mix by volume is taken as 1:6.

2. Ordinary Portland cement of 53 grade.

3. Replacement of cement by 20 and 25% of silica fume.

4. Aggregates of sizes 20mm passing and 10mm retained are taken.

5. Water/cement ratios are limited to 0.34 and 0.36.

6. Testing of specimens at the ages of 7,14 and 28 days.

7. Determining the compressive strength of M20 grade mix.

   1. METHODOLOGY

      The methodology adopted and material characterization and design mix is created out is presented in the form of flow chart and parameters studied. Also the sequential activities involved in this study or presented in graphical form. Details of experimental study in materials are presented in sub sequent headings.

      Fig.1 Methodology

   2. MATERIALS

1. Cement

   Cement is very important part of the concrete because its the cement which gives the concrete its strength. OPC grade-53 cement is selected for our purpose (conforming ti IS 12269- 1987). This is used as the main binder in the mixes. There are currently more than eight types of cement that are used under specific conditions. Cement is a very important part of the concrete because it is the cement, which gives the concrete its strengths. The reaction is also exothermic, where heat is released in the chemical reactions.

2. Aggregate

Aggregates are broken down into two main categories, which are coarse and fine aggregates. The economic part of concrete is to use as little cement as possible and still obtain the required strength. Thus, when concrete is formed, the coarse aggregates with its large volume would make up a large position of the concrete. The fine aggregates would fill in the voids created between the coarse aggregates and reduce the amount of cement required. If only coarse aggregates are used then there would be voids between the particles and the voids created would be filled with cement paste. Oven dry aggregates would absorb water to fill its own internal voids and in doing so would reduce the water cement ratio. If this course occurs, then the hydration process is not permitted to continue and the strength of the concrete mix would be reduced by a considerable amount. Air dry aggregates would absorb some water but not to an extraneous degree like the oven dry aggregates.

6.2 Compacting and Curing

Rodding was adopted for the compacting of no-fines concrete. The concrete samples were tamped 25 times and split into three layer. This procedure ensures sufficient compacting has been produced.

The curing process starts with the moulds being left in place for 2 or 3 days to allow sufficient bonding between the aggregate particles. After the specimens were removed from the mould they were placed was used to ensure the time of testing. This process was used to ensure that optimum curing was achieved.

1. WORKABILITY TEST ON SAMPLES

   No-fines concrete is said to have self compacting properties. The will be tested with the compacting factor test. The slump and VEBE tests are not good for testing no-fines concrete due to the low cohesive between the aggregate particles.

   7.1 Compacting Factors Test

   The compacting factor test is used to determine the extent with which the fresh concrete compacts itself when allowed to fall without the application of any external compaction. The compaction obtained from the free falling is compaction with the sane sample under standard compaction practices Compaction factor = (m1)/(m2)

   M1= partially compacted concrete (kg) M2= fully compacted concrete (kg)

   5.3 Silica Fume

   Fig.2 Coarse Aggregate

2. COMPRESSIVE STRENGTH OF CONCRETE

The compressive strength tests are conducted to ensure a minimum strength is achieved by the particular mix. Cylinder and cube testing are the methods of determining the

Silica fume is a byproduct of producing silicon metal or

ferrosilicon alloys. One of the most beneficial uses for silica fume is in concrete. Because of its chemical and physical properties, it is a very reactive pozzolan. Concrete containing silica fume can have very high strength and can be very durable. Silica fume is available from suppliers of concrete admixtures and, when specified, is simply added during concrete production. Placing, finishing, and curing silica- fume concrete require special attention on the part of the concrete contractor.

6. PREPARATION OF SAMPLES

1. Mixing Process

   1. Weight aggregate, cement, GGBS and water for the mix.

   2. Moisten the working surface of the wheelbarrow to prevent the materials from sticking to the sides.

   3. Add the aggregate to the wheelbarrow and add approximately half the water and mix until all the aggregate is wet.

   4. Spread the cement and water uniformly over the surface aggregate.

   5. Mix the concrete until the aggregate is evenly covered with cement paste.

      compressive strength. The cube test, due to the method which it is implemented, should give a more stable test specimen that the cylinders. This test will determne the strength of the sample along the entire length of the sample and eliminated problems encountered with the edge aggregate dislodging and failing.

      Compressive strength = force/ area

      1. Conventional Concrete

         Conventional concrete was also manifested as normal concrete, After seven days of curing, the development of conventional concrete starts. On reaching 28 days almost 75- 80 % the total strength is obtained.

         Table 1 Test result for conventional concrete for 0.34% w.c

         Tests	Curing days	Strength(N/mm2)
         Compressive test	7	5.82
         	14	10.65
         	28	22.62
         Split tensile test	7	0.75
         	14	1.04
         	28	1.31

         25

         Compressive strength

         Split tensile strength

         20

         15

         10

         5

         0

1. DAYS 14 DAYS 28 DAYS

   Chart 1.Result of compression and split tensile test

   1. Designed concrete for various mixes

   The designed concrete for various mix is used to produce a special concrete having desired work ability, durability, compressive strength and split tensile test for 28 days for a specified grade of concrete. The availability materials for producing concrete can be used economically with comparatively low cost.

   Mix	Age of concrete	Compressive strength (N/mm2)	Split tensile strength (N/mm2)
   M1	7	6.13	0.88
   M2	7	6.01	0.82
   M3	7	5.72	0.81
   M4	7	5.63	0.76

   Table 3. Test result for 7 days

   From the observation and the graph shown above the result obtained for compressive strength is traced to be 22.62 N/mm2 and split tensile strength is 1.31 N/mm2. These inferences are used for further empirical studies.

   Table 2. Test result for conventional concrete for 0.36% w.c

   6.2

   6.1

   6

   5.9

   5.8

   5.7

   5.6

   5.5

   5.4

   5.3

   Compressive strength

   M1 M2 M3 M4

   Tests	Curing days	Strength(N/mm2)
   Compressive test	7	4.93
   	14	9.87
   	28	21.41
   Split tensile test	7	0.82
   	14	0.96
   	28	1.20

   Chart 3.Compression test results for various mixes of 7 days

   25

   Compressive strength

   Split tensile strength

   20

   15

   10

   5

   0

   7 DAYS 14 28

   0.9

   0.85

   0.8

   0.75

   0.7

   Split tensile test

   M1 M2 M3 M4

   DAYS

   DAYS

   Chart 4.Split tensile test results for various mixes of 7 days

   Chart 2.Result of compression and split tensile test

   From the observation and the graph shown above the result obtained for compressive strength is traced to be 21.41 N/mm2 and split tensile strength is 1.20 N/mm2. These inferences are used for further empirical studies.

   The result obtained for seven days compressive strength and split tensile strength was used to analysis the gain early strength and is calculated to about a certain percentage than that 28 days strength.

   Table 4. Test result for 14 days

   Mix	Age of concrete	Compressive strength (N/mm2)	Split tensile strength (N/mm2)
   M1	14	10.9	1.02
   M2	14	10.67	0.96
   M3	14	10.31	0.99
   M4	14	10.19	0.89

   11

   10.8

   10.6

   10.4

   10.2

   10

   9.8

   9.6

   Compressive strength

   M1 M2 M3 M4

   1.24

   1.22

   1.2

   1.18

   1.16

   1.14

   1.12

   Split tensile strength

   M1 M2 M3 M4

   Chart 5.Compression test results for various mixes of 14 days Chart 8.Split tensile test results for various mixes of 28 days

   1.05

   1

   0.95

   0.9

   0.85

   0.8

   Split tensile test

   M1 M2 M3 M4

   The result obtained for twenty eight days compressive strength and split tensile strength was used to analyze the gain early strength and is calculated to about a certain percentage than that 28 days strength.

   1. CONCLUSION

      The test results for conventional and designed concrete were compared in order to obtain the strength aspects of the concrete .The values are tabulated by the testing of cubes and cylinders for 7,14 and 28 days. The result indicate that the maximum compressive and split tensile strength was obtained for a partially replacement of cement by 20% of silica fume

      Chart 6.Split tensile test results for various mixes of 14 days

      The result obtained for fourteen days compressive strength and split tensile strength was used to analyze the gain early strength and is calculated to about a certain percentage than that 28 days strength.

      Table 5. Test result for 28 days

      Mix	Age of concrete	Compressive strength (N/mm2)	Split tensile strength (N/mm2)
      M1	28	23.5	1.24
      M2	28	23.26	1.20
      M3	28	23.08	1.17
      M4	28	22.87	1.16

      23.6

      23.4

      23.2

      Compressive strength

      23

      22.8

      22.6

      22.4

      M1 M2 M3 M4

      Chart 7.Compression test results for various mixes of 28 days

      in both w/c ratio. For 20% replacement the compressive strength was increased about 10% and the split tensile strength shows an decrement about 5% than that of conventional concrete. Further it depicts that the strength was decreased for 25% replacement, the strength of concrete is reduced and was lower than of control.

      • The material that has potential to replace the use of traditional concrete, such as car parks, residential streets, drive ways.

      • The varying compressive strength obtained from the different aggregate samples shows the shape of the aggregate particles used can dramatically affect the strength of concrete.

      • No-fines concrete has many positive attributes that make it use beneficial to the society.

      • However it is in nearly states of in development and requires more research before it is readily available and used extensively.

   2. REFERENCE

1. High Strength Permeable Pavement Using No Fines Concete By Dr.M.Mageswari,M.E,Ph.D (Ssrg International Journal Of Civil Engineering Volume 3 Issue 3)

2. Investigation Of Mechanical And Physical Poperties Of No Fines Concrete By Amjad A.Yasin (International Journal Of Engineering Innoation & Resarch Volume 4,6, Ssn;2277- 5668).

3. Sustainable And Durable No Fines Concrete For Vertical Applications By Francesca Tittrarelli (International Journal Of Chemical, Environmental And Biological Science (Ijcebs), Volume1,Issue5).

4. No Fines Concrete As A Road Pavement By Govindravish,Er.V.K.Ahuja (International Journal Of Engineering Trends And Techonolgy (Ijett)-Volume 24,Number4).

5. Experimental Study On Properties Of No Fines Concrete By Md.Abidalam,Shaguftanaz (International Journal Of Informative And Futuristic Research).

6. Investigation Of No Fines Concrete In Building Blocks By K.Satham Ushane,K.J.Pradeep Kumar (International Jounal Of Structure And Civil Engineering Research Volume 3,Number4)

7. No Fines Concrete In The Uk Social Housing Stock;50 Years OnBy James Sommerville Nigel Caig (Structural Survey, Volume 29,Number 4.

8. High Strength Concrete Using Silica FumeBy Mohd Khaja Moinuddin(Imperial Journal Of Interdisciplinary Research).

9. Effects Of Partial Replecement Of Cement By Silica Fume On Work Ability & Compressive Strength On High Performance Concret1e Volume:3By Dr.Indrajit N. Patel.

10. Labatory Investigation Of Compacted No Fines Concrete For Paving Materials By Nader Ghafoori, Member,Asce

11. Effect Of Silica Fume On Strength And Durability Parameters Of Concrete By N.K.Amudhavalli , (International Journal Of Engineering Sciences And Emerging Technologies).

12. Properties Of Concrete Incorporation Silica Fume By Davoud Tavakoli

13. Peffect Of Micro Silica On The Strength Of Concrete With Ordarniary Port Land Cement Volume 1(3) Sep (2012)

14. No Fines Concrete Its Application And Properties By Malhotra .V. M.(Journal Of American Concrete Institute)

15. The Silica Fume Association Www.Silicafume .Org

16. An Experimental Study On Crushed Glass Material For The Partially Replacement Of Natural Sand In Concrete By K.Rubini