Experimental Investigations on Mechanical Properties of High Strength Concrete by using Supplementary Cementing Materials

 

M. Vijaya Sekhar Reddy¹*, Dr. I.V. Ramana Reddy², K. Madan Mohan Reddy¹,

N. Krishna Murthy³, P. Ramesh⁴

¹Department of Civil Engineering, Srikalahasteeswara  Institute of Technology, Srikalahasti, AP, India,

²Department of Civil Engineering, Sri Venkateswara University College of Engineering, Tirupati, AP, India,

³Engineering Department, Yogi Vemana University, Kadapa, AP

⁴Department of Civil Engineering, Sri Vidyanikethan Engineering College, Rangampeta, Tirupati, AP,

*Corresponding Author: skitce.hod@gmail.com

 

ABSTRACT:

Portland cement has been a very satisfactory hydraulic binder for structural applications for a long time now. However there are many new issues stemming from its ever increasing use. Sustainable development today demands development of new concrete technologies, which use less natural resources and energy, and generate less CO₂, without compromising on strength and durability properties. Supplementary Cementing Materials (SCMs) such as Flyash, Blast Furnace Slag, Silica Fume and Metakaoline etc., either in singly or in combination, in development of alternate binder systems is thus of economic and ecological significance. In the recent years, use of High Performance Concrete (HPC) in the construction industry as got momentum. For designing HPC, both SCMs and Superplasticizers are essential for the improvement of Workability and Mechanical Properties. The paper presents experimental studies conducted on two grades of HPC mixes of M₅₀ and M₆₀ using mineral and chemical admixtures in various proportions. Overall, the paper highlights the usage of admixtures to achieve high strength concrete mixes and from the experimental investigation it is clear that mineral admixtures contribute effectively a lot not only for achieving durability, also high strength.

 

 

INTRODUCTION:

Conventional concrete in India is often produced with four components namely, cement and water together they act as binder the crushed or uncrushed stone, natural sand or stone dust. The stones and sand those together form the main skeleton of the matrix are called aggregates. In addition to the above ingredients one or two additional chemicals are also added to the recipe of concrete in order to enhance certain properties quite often such chemical are called chemical admixtures. Certain materials of mineral origin are also added to concrete to enhance their strength and durability properties of concrete and are referred to as mineral admixture.

 

The SCMs such as flyash, Blast furnace slag, silica fume and metakiolin which are generally very fine, may be finer than cement, when added to concrete in right proportion can improve the strength and durability of concrete drastically and high strength and high performance concrete is obtained in this manner. One major concern about the concrete is its sustainability. Every tone of cement produces equal amount CO₂ through consumption of fuel in burning and decomposition of CaCO₃ thus control of Green House gas emission is major issue in the context of sustainable concrete. Use of SCM, especially other industrial by-product such as blast furnace slag, flyash in concrete to reduce OPC clinker consumption is currently being considered as a major step towards achieving sustainability of concrete. Composite cements containing more than one SCM can be used where ever appropriate [1].

Application of the method of the simplex-lattice design for predicting the properties of cement-based composites. On the basis of the compressive Strength, its use was demonstrated on ternary paste systems composed of cement, silica fume and fly ash with constant water to binder ratio and a mass fraction of mineral admixtures not exceeding 30% [2].

 

The use of High–Volume Flyash system for sustainable development resulting in production of such concrete with reasonable cost with the lowest possible environmental impacts. In view of the global sustainable development, it is imperative that SCM be used to replace large propor­tion- of cement in the concrete industry, and the most available SCM world-wide is Flyash [3].

 

An experimental investigation on the strength characteristics of high performance concrete (HPC). The strengths of HPC mix 1:1.2:3.4:0.34 are measured by compression test, split tensile test and modulus of rupture test (Two point loading). Test results are compared with the existing models and checked. The relationship between split tensile strength and compressive strength, modulus of rupture and compressive strength are studied [4].

 

An experimental investigation on the effect SCMs on strength and durability of concrete cured for a short period of time—14 days. This work primarily deals with the characteristics of these materials, including strength, durability, and resistance to wet and dry and freeze and thaw environments [5].

 

Materials used in the present study:

Cement:

Ordinary Portland cement Zuari-53 grade conforming to IS: 12269-1987 [6] were used in concrete. The physical properties of the cement are listed in Table 1.

Aggregates:

A crushed granite rock with a maximum size of 20mm and 12mm with specific gravity of 2.60 was used as a coarse aggregate. Natural sand from Swarnamukhi River in Srikalahasthi with specific gravity of 2.60 was used as fine aggregate conforming to zone- II of IS 383-1970 [7]. The individual aggregates were blended to get the desired combined grading.

 

Water:

Potable water was used for mixing and curing of concrete cubes.

 

Supplementary Cementing Materials:

Flyash:

Fly ash was obtained directly from the M/s Ennore Thermal Power Station, Tamilnadu, India. The physicochemical analysis of sample was presented in Table 2.

 

Silica Fume:

The silica fume used in the experimentation was obtained from Elkem Laboratory, Navi Mumbai. The chemical composition of Silica Fume is shown in Table 3.

 

Metakaoline:

The Metakaoline was obtained from M/s. 20 Microns Limited, Baroda, India. The chemical composition of Metakaoline is shown in Table 4.

 

Blast Furnace Slag:

The blast furnace slag was obtained from Sesa Goa Limited. Goa. The chemical composition of Blast Furnace Slag is shown in Table 5.

 

 

 

Table 1. Physical Properties of Zuari-53 Grade Cement

 

Table 2 . Physicochemical properties of Flyash sample.

Sample	Specific Gravity	Specific Surface Area (m2/g)		Moisture Content (%)			Wet density (gram/cc)		Turbidity (NTU)			pH
Flyash	2.20	1.24		0.20			1.75		459			7.3
	Chemical Composition, Elements (weight %)
	SiO2	Al2O3	Fe2O3		CaO	K2O		TiO2		Na2O3	MgO
	56.77	31.83	2.82		0.78	1.96		2.77		0.68	2.39

 

 

Table 3. Chemical composition of Silica Fume.

 

Table 4. Chemical composition of Metakaoline

Chemical Composition	SiO2	Al2O3	Fe2O3	TiO2	CaO	MgO	SO3	Na2O	K2O	LOI
Mass Percentage	52 to 54%	42 to 44%	< 1 to 1.4%	< 3.0%	0.1%	< 0.1%	< 0.1%	< 0.05%	< 0.4%	< 1.0%

 

 

Table 5. Chemical composition of Blast Furnace Slag.

 

Super Plasticizer:

VARAPLAST PC100: A high performance concrete superplasticizer based on modified polycarboxilic ether, supplied from M/s Akarsh specialities, Chennai.

 

RESULTS AND DISCUSSIONS:

In the present work, proportions for high strength concrete mix design of M₅₀ and M₆₀ were carried out according to IS:10262-2009 [8] recommendations. The mix proportions are presented in Table 6 and Table 7.

 

The tests were carried out as per IS: 516-1959 [9] and IS: 5816-1999 [10]. The 150mm cubes and cylindrical specimens (15mm dia and 300mm height) of various concrete mixtures were cast to test compressive strength and split tensile strength. The cubes and cylindrical specimens after de-moulding were stored in curing tanks and on removal of cubes and cylinders from water the compressive strength and split tensile strength were conducted at 7days, 28days, 90 days and 180 days. The test results were compared with individual percentage replacements and combinations of admixtures for two grades of concrete (M₅₀ & M₆₀). Results of compressive strength and split tensile strength for M₅₀ & M₆₀ were shown in Figure 1, Figure 2 and Figure 3, Figure 4 respectively.

 

Fig 1. Shows the Compressive Strength results of M₅₀ mix.

Fig 2. Shows the Compressive Strength results of M₆₀ mix.

 

Fig 3. Shows the Split Tensile Strength results of M₅₀ mix.

 

Fig 4. Shows the Split Tensile Strength results of M₆₀ mix.

 

 

Table 6. Mix Proportion for M₅₀ Concrete.

 

Table 7. Mix Proportion for M₆₀ Concrete

CONCLUSIONS:

1.      In high performance concrete mix design as water/cement ratio adopted is low, super plasticizers are necessary to maintain required workability. As the percentage of mineral admixtures is increased in the mix, the percentage of super plasticizer should also be increased, for thorough mixing and for obtaining the desired strength.

2.      In M₅₀ and M₆₀ grades of concrete as the water-cement ratios of 0.397and 0.341 are insufficient to provide the good workability, hence super plasticizer is necessary for making high strength concrete.

3.      In case of individual percentage replacement of mineral admixtures the maximum compressive strength achieved in M₅₀ grade concrete is 61.20 Mpa with replacement of 10 % Metakaoline.

4.      In case of combination percentage replacement of mineral admixtures the maximum compressive strength achieved in M₅₀ grade concrete is 59.10 Mpa with replacement of 20% flyash and 10 % Metakaoline.

5.      In case of individual percentage replacement of mineral admixtures the maximum compressive strength achieved in M₆₀ grade concrete is 72.10 Mpa with replacement of 10 % Metakaoline.

6.      In case of combination percentage replacement of mineral admixtures the maximum compressive strength achieved in M₆₀ grade concrete is 69.30 Mpa with replacement of 20% flyash and 10 % Silica Fume.

7.      In case of individual percentage replacement of mineral admixtures the maximum Split tensile strength achieved in M₅₀ grade concrete is 4.82 Mpa with replacement of 10 % of Metakaoline.

8.      In case of combination percentage replacement of mineral admixtures the maximum Split tensile strength achieved in M₅₀ grade concrete is 4.65 Mpa with replacement of 20% Flyash and 10 % of Metakaoline.

9.      In case of individual percentage replacement of mineral admixtures the maximum Split tensile strength achieved in M₆₀ grade concrete is 4.52 Mpa with replacement of 10 % of Metakaoline.

10.    In case of combination percentage replacement of mineral admixtures the maximum Split tensile strength achieved in M₆₀ grade concrete is 4.49 Mpa with replacement of 20% Flyash and 10 % of Metakaoline.

11.    The scope for using high strength concrete in our constructional activities are more such as precast, prestressed bridges, multi-storied buildings, bridges and structures on coastal areas. To affect this change, we will have to revive the designing of structures by encouraging use of high strength concrete mixes.

 

 

REFERENCES:

 [1]    Bhattacharjee B, Misra A, Rai HS. Specifications for High Performance Concrete in India. In proceedings of the International UKIERI Concrete Congress, New Delhi, India, 8-10 March 2011.

 [2]    Chen HS,  Sun W and  Stroeven P. Prediction of compressive strength and optimization of mixture proportioning in ternary cementitious systems. Materials and Structures, 36; 2003: 396-401.

 [3]    Alain Bilodeau and Mohan Malhotra V. High-volume fly ash system: sustainable development, ACI Materials Journal, 97(1); 2000:.41-48.

 [4]    Natesan SC, Ananda Kumar S and Venkatesh Babu DL. Effect of pulverized fuel ash (PFA) and condensed silica fume (CSF) on the strength of high performance concrete (HPC), Proceedings of International Conference on Civil Engineering, Bangalore, 2001: 89-95.

 [5]    Toutanj H, Delatte N, Aggoun S, Duval R and Danson A. Effect of supplementary cementations materials on the compressive strength and durability of short-term cured concrete, Cement and Concrete Research, 34; 2004: 311-319.

 [6]    IS: 12269-1987, Specification for 53 Grade Ordinary Portland Cement, Bureau of Indian Standards, New Delhi, India, 1989.

 [7]    IS: 383-1970: specifications for Coarse and Fine Aggregates for natural sources of concrete, Bureau of Indian standards, New Delhi.

 [8]    IS: 10262-2009: Concrete Mix Proportioning-guidelines, Bureau of Indian Standards, New Delhi.

 [9]    IS: 516-1959: Methods of tests for strength of concrete, Bureau of Indian standards, New Delhi.

[10]  IS: 5816-1999: Methods of tests for Splitting tensile strength concrete, Bureau of Indian standards, New Delhi..

 

 

Received on 08.11.2012                             Accepted on 23.12.2012        

©A&V Publications all right reserved