Studies on Durability Factors of Self Compacting Concrete

 

Dr Seshadri Sekhar Tirumala

Prof and Dean National Institute of Construction Management and Research, Hyderabad.

*Corresponding Author E-mail: ss.tirumala@gmail.com

 

ABSTRACT:

The demand for high strength self compacting concrete is growing up today due to the increase of high rise structures across the globe because of its durability and ease of its place ability. It is very important to study its durability properties as it effects on economy, serviceability and maintenance. it is well known that the properties of concrete are affected by cementitious matrix, aggregate and the transition zone between the two phases. Reducing water powder ratio and addition of pozollona admixtures like Fly ash and Microsilica are often used to modify the micro structure of the matrix and to optimize the transition zone. An attempt was made to study the durability factors of High Strength Self Compacting Concrete Mixes. Durability properties have been established by exposing the concrete to Acidic and Suplhate medium.

 

KEYWORDS: Self Compacting Concrete, Acid Attack, Sulphate Attack, Durability factors.

 

INTRODUCTION:

In the current arena, infrastructure development holds the key for the development of every nation. Concrete is one of the most utilized materials by the construction industry which is a homogeneous material prepared of heterogeneous materials like Cement, sand and aggregate. However rapid urbanization has created a huge demand for natural sand hence made it even more expensive. Due to the high volume consumption all the natural resources are facing depletion. Industrial waste products are accumulating to an alarming level which makes the safe disposal of the industrial wastes a herculean task . High strength concrete is needed to build high rise structures. Due to high strength, we can reduce the column sizes of high rise structures there by increasing the available space.

 

Research significance:

Studies on durability aspect is the need of the hour in present day construction to buildup confidence among the engineers and builders and other end users. There are limited studies on durability aspects . So to fill the gap the an attempt had been made to study the durability parameters of high strength self compacting concrete.

 

Materials:

Cement:

53 grade Portland cement with specific gravity of 3.02 and fineness of 3200cm2/gm was used .

 

Coarse Aggregate:

10 mm sized crushed angular granite with specific gravity of 2.65 and fineness modulus 6.05 was used .

 

Fine Aggregate:

River sand with specific gravity of 2.55 and fineness modulus 2.77 was used .

 

Viscosity Modifying Agent:

A Viscosity modified admixture with Specific of gravity 1.01+0.01 @ 250C , pH value as 8+1 and Chloride Content nil was used.

 

Admixture:

The Modified Poly-carboxylated Ether based super with Relative density 1.10+0.01 at 25oC, pH >6 and Chloride Ion content <0.2% was used .

 

Fly Ash:

Type-II fly ash confirming to I.S. 3812 – 2003 part I and part II was used .

 

Micro Silica:

The Micro silica with specific gravity 2.2 was used.

 

Test Specimens:

The Trail Mixes for Mix 10 were carried out by verifying the fresh state properties with EFNARC guidelines. Test specimens of size 100 * 100* 100 mm were casted and tested as per IS 516 and 1199. Average dry density is observed to be 2503 Kg/cm3 and Average wet density is 2682 Kg/cm3

 

Testing Procedure:

The casted specimens after immersion in water for 28 days is exposed to Acidic and Sulphate medium for 28, 56, 90, 180, 270 and 360 days and tested for the compressive strength. The Durability factors were calculated for 28, 56, 90, 180, 270, and 360 days.

 

Table 1.0 Fresh Concrete properties of High Strength Self Compacting Concrete Mix M 10

Tests conducted

Mix 10

Permissible limits as per

EFNARC Guidelines

Compressive Strength (N/mm2)

Min

Max

7 days

28 days

V-Funnel

11 sec

6 sec

12 sec

96

118

Abrams slump flow

660 mm

650mm

800mm

T 50cm slump flow

40 sec

2 sec

5 sec

 L-Box

H2/H1

0 .80

1.0

0.90

T 20

1sec

2 sec

1sec

T40

2sec

3sec

2 sec

V-Funnel at T 5 min

13 sec

11 sec

15 sec

 

 

Fig 1.0.Graph Showing the Trail Mix Propoertions

 

Fig 2.0 Durability Factors of High Strength Self Compacting, Mix  10 subjected to Acidic and Sulphate Medium 

 

Discussion of Results:

Fresh State properties of high strength self compacting concrete mixes

Table 1.0 gives for Mix 10. The Mix Proportions are given in Fig 1.0.

 

Durability factors of specimens:

Fig 2.0 shows the behavior of durability factors on Mix 10 when exposed at different ages. The percentage loss of compressive strength in acid medium is more and durability factors are also increasing.

 

Conclusions:

The percentage loss of compressive strength of high strength self compacting concrete mixes after immersing in acids are increasing corresponding to the time. The percentage loss in compressive strength of high strength self compacting concrete mixes after immersing in sulphates are nil. This shows that Sulphate solution indirectly helping in curing the specimens. . Higher the Durability factor higher will be the resistance to the acids and sulphate attacks.

 

References:

1.      Ganesan.N , Indira.P.V& SanthoshKumar.P.T “Durability aspects of steel fibre- reinforced SCC”, The Indian Concrete Journal, May 2006 , PP 31-37.

2.      T.Seshadri Sekhar et.al “ durability Studies on Glass Fibre Compacted Concrete” , Indian concrete Journal Vol 83 , October 2009 , No 10 , PP 44-52

3.      T.Seshadri Sekhar et.al High Strength Self Compacting concrete using mineral admixtures” , Indian concrete Journal March 2013 , No 3 , PP 42-48.

4.      Sandeep Dhiman,Arvind Dewangan, Er. Lakhan Nagpal, Sumit Kumar “Permeability Behavior of Self Compacting Concrete” International Journal of Innovative Technology and Exploring Engineering (IJITEE)ISSN: 2278-3075,Volume-2, Issue-6, May 2013105

5.      P. M. Salim , T. Seshadri Sekhar “An Investigation on Optimum usage of Foundry Sand as Fine Aggregate in Foundry Sand Admixed Concrete “January 2016 , Research Journal of Applied Sciences, Engineering and Technology.

6.      D.Audinarayana, P.sarika, Dr.Seshadri Sekhar.T, Dr.Srinivasa Rao, Dr P Sravana G.Apparao “Studies on Compressive Strength Of Ternary Blended Concretes At Different Water Binder Ratios” American Journal of Engineering Research 2320-0936Volume-02, Issue-09, pp-37- 45.

7.      EFNARK, “Specifications and guidelines for self compacting concrete”, www.efnarc.org

 

 

 

Received on 23.04.2021   Accepted on 06.05.2021              

©A&V Publications all right reserved

Research J. Engineering and Tech. 2021;12(2):29-31.

DOI: 10.52711/2321-581X.2021.00005