ACCELERATING ADMIXTURE RAPIDITE -ITS EFFECT ON PROPERTIES OF CONCRETE

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET Volume 6, Issue 12, Dec 215, pp , Article ID: IJCIET_6_12_6 Available online at ISSN Print: and ISSN Online: IAEME Publication ACCELERATING ADMIXTURE RAPIDITE -ITS EFFECT ON PROPERTIES OF CONCRETE Dr. Javed Ahmed Naqash Associate Professor, National Institute of Technology Srinagar, J&K, India Ifrah Habib Lone, Amir Majid, Bisma Gayas, Itret Hussaini, Mubashir Hassan Department of Civil Engineering, University of Kashmir, J&K India ABSTRACT This paper aims to investigate the effect of use of in cold weather concreting. In order to illustrate such effect, a series of laboratory tests were conducted. Workability tests, compressive strength tests, flexural tests and split tensile strength tests were carried out on concrete specimens having different percentage of and the results thus obtained were compared those of normal concrete. The results indicated that all the three strength parameters viz, compressive strength, split tensile strength and flexural tensile strength of concrete increase when compared plain one. The increase in strength reaches the maximum value at the percentage of 1.5%, beyond which it starts decreasing. The increase in 7 day strength is much higher than increase in 28 day strength. Further adding Rapidte has shown increase in the workability of mix respect to the plain mix. Key words:, Workability, Compressive, Flexural and Split Tensile. Cite this Article: Dr. Javed Ahmed Naqash, Ifrah Habib Lone, Amir Majid, Bisma Gayas, Itret Hussaini and Mubashir Hassan, Accelerating Admixture -Its Effect on Properties of Concrete. International Journal of Civil Engineering and Technology, 6(12, 215, pp INTRODUCTION is a specially developed Concrete Set Accelerator, a ready-to-use, liquid admixture. It accelerates initial setting time (cement-water chemical reaction HYDRATION of normal mortar and concrete and acts as anti-freeze in cement concrete. It improves workability and strength while fastening the hydration of cement. It makes the mix easier to place and speeds construction by shortening the initial set and curing time. Time and labor are saved, because forms and other protection can be removed earlier and finishing can be started. is 58 editor@iaeme.com

2 Accelerating Admixture -Its Effect on Properties of Concrete recommended for use during cool and cold weather to accelerate the set time and reduce the risk of frozen mortar and concrete mixes. Winter has some peculiarities that affect construction in general and concreting in particular. Its duration is different in different parts of globe, but cold weather white frosts may also happen in spring and autumn not just in winter only. In India certain regions experience sub-zero temperatures in winter. Concrete structures in such regions undergo cycles of freezing and thawing and their durability is affected due to frost action. Fresh concrete contains considerable quantity of fresh water which gets converted into ice lenses at freezing temperature. The ice formation in fresh concrete results in about 9% rise in volume and causes permanent damage to concrete and structural integrity cannot be recovered even if the concrete is made to harden later at high temperature. Thus, in winters, especially in Kashmir where the temperatures are below zero degree in winters some admixtures need to be added to nullify the effects of cold temperature on the strength of concrete. Rapidte is a commonly used admixture in Kashmir during winter to accelerate the strength gain of concrete. 2. MATERIALS USED Cement Ordinary Portland Cement (OPC 43 Grade (Khyber cement confining to IS: 431[4] has been used for this Work. The properties of the used cement are shown; Fineness % Aggregates: Fine aggregates used throughout the work comprised of clean river sand maximum size of 4.75mm conforming to zone III as per IS: [5] Coarse aggregates used consisted of machine crushed stone angular in shape passing through 2mm I S sieve and retained on 4.75mm I S sieve. Standard Consistency (% Initial Setting Time Properties Color- Lemon-Orange Appearance-Clear bright Liquid Relative Density (g/ml-1g/ml Final Setting Time Soundness (mm Compressive strength(n/mm hr. 22 min 6 hrs.1 min EXPERIMENTAL PROGRAM Mix Used: Nominal mix M2 (1:1.5: 3 water to cement ratio of.5. In total five castings were done at the percentage of.75, 1.25, 1.5, 1.75 and editor@iaeme.com

3 Dr. Javed Ahmed Naqash, Ifrah Habib Lone, Amir Majid, Bisma Gayas, Itret Hussaini and Mubashir Hassan First Casting Average Temp: 1.3 C Percentage of by weight of cement =.75% Compressive (σ c 7 Days 28 Days Average Split Tensile (σ t and Flexural (σ b Average (σ t (σ b Compaction (N/mm 2 Slump factor PCC mm.72 CC mm.77 Second Casting Average Temp: 2 C Percentage of by weight of cement = 1.25% Compressive (σ c 7 Days 28 Days Average Split Tensile (σ t and Flexural (σ b Average Split tensile Flexural strength Compaction strength (N/mm 2 Slump factor PCC mm.74 CC mm.81 Third Casting Average Temp: 1.5 C Percentage of by weight of cement = 1.5% 6 editor@iaeme.com

4 Accelerating Admixture -Its Effect on Properties of Concrete Compressive (σ c 7 Days 28 Days Average Split Tensile (σ t and Flexural (σ b σ t σ b Average Compaction (N/mm 2 Slump factor PCC mm.77 CC mm.86 Fourth Casting Average Temp:-1 C Percentage of by weight of cement = 1.75 % Compressive (σ c 7 Days 28 Days Average (N/mm Split Tensile (σ t and Flexural (σ b σ t σ b Average Slump Compaction factor PCC mm.75 CC mm.88 Fifth Casting Average Temp:-1.2 C Percentage of by weight of cement = 2 % 61 editor@iaeme.com

5 Dr. Javed Ahmed Naqash, Ifrah Habib Lone, Amir Majid, Bisma Gayas, Itret Hussaini and Mubashir Hassan Compressive (σ c 7 Days 28 Days Average (N/mm Split Tensile (σ t and Flexural (σ b σ t σ b Average Slump Compaction factor PCC mm.73 CC mm DISCUSSION In order to study the rate of variation of strength respect to the percentage, a comparative study of the test results achieved at different percentage is performed. Following Variations are studied Variation of increase in 7 day strength % Variation of Increase in 28 day strength % Variation of split and flexural tensile strength % Comparison of Avg. Increase in 7 and 28 day strength for mm Comparison of Avg. Increase in 7 and 28 day strength for 1mm Variation of compaction factor on adding. Average increase in 7 days and 28days strength (%age Average % increase 7 days Average % increase in 28 strength days strength Percentage of 1mm 1mm mm mm editor@iaeme.com

6 Compressive Compressive Accelerating Admixture -Its Effect on Properties of Concrete G1: Variation of 7 day strength % %age of Avg 7 day strength of OF 1mm Avg 7 day strength of rapidite OF 1mm Avg 7 day strength of OF mm G2: Variation of 28 day strength % The increase in 7 day strength is much higher than increase in 28 day strength, in case of mm s former is 18% more increase and in case of 1mm s former shows 214% more increase. Thus increase in early strength is more significant than increase in lateral strength Average increase in Split tensile strength (σ t and Flexural strength (σ b Percentage of G2:Variation of 28 day strength % %age of Average percentage increase in Split tensile strength Average percentage increase in Flexural strength Avg 28 day strength of OF 1mm Avg 28 day strength of rapidite OF 1mm Avg 28 day strength of OF mm Avg 28 day strength of rapidite OF mm 63 editor@iaeme.com

7 Dr. Javed Ahmed Naqash, Ifrah Habib Lone, Amir Majid, Bisma Gayas, Itret Hussaini and Mubashir Hassan G3: Variation of split tensile strength % Avg %age increase in split tensile strength G4: Variation of Flexural strength % Avg %age increase in flexural strength There is an increase in both split and flexural tensile strengths up to the 1.5% of rapidite, beyond this value the strength decreases in both the cases. G5: Variation of Compaction factor % The compaction factor always increases when compared the plain concrete, thus workability increases by the addition of rapidite editor@iaeme.com

8 Accelerating Admixture -Its Effect on Properties of Concrete 5. CONCLUSION The use of admixture increases the compressive, flexural and split tensile strength of concrete compared to plain concrete. The increase in strength reaches the maximum value at the percentage of 1.5%, beyond which it starts decreasing. The increase in 7 day strength is much higher than increase in 28 day strength, in case of mm s former is 18% more increase and in case of 1mm s former shows 214% more increase. Thus increase in early strength is more significant than increase in lateral strength There was no freezing of water as there is increase in early strength of concrete so whole water was available for complete hydration of cement. The admixture used is an anti freezing agent which depressed the freezing point of water mixed and protected the concrete from freezing in early age. The compaction factor always increases when compared the plain concrete, thus workability increases by the addition of. REFERENCES [1] Cold weather concreting, reported by ACI committee 36, Nicholas J. Carino, Chairman, p. 36 R-1. [2] Annual book of ASTM Standards (1979, part 13, ASTM C : Standard test method for time of setting of hydraulic cement. ASTM RaceSt. Philadelphia,pa [3] Concrete Technology, A. M. Neville and J. J. Brooks. [4] 43 Grade Ordinary Portland Cement Specification. IS 8112:1989, Bureau of Indian Standards, New Delhi. [5] Specification for Coarse and Fine Aggregates from Natural Sources for Concrete. IS: , Bureau of Indian Standards, New Delhi. [6] Recommended Guidelines for Concrete Mix Design. IS: , Bureau of Indian Standards, New Delhi. [7] Sameer Ul Bashir, Younis Majid and Ubair Muzzaffer Rather, Effect of on of Concrete in Warm Climates. International Journal of Civil Engineering and Technology, 4(6, 213, pp [8] Concrete Technology, A. M. Neville and J. J. Brooks. [9] Concrete Technology, A. M. Neville and J. J. Brooks, p. 166 [1] Methods of Sampling and Analysis of Concrete. IS: , Bureau of Indian Standards, New Delhi. [11] Methods of Tests for of Concrete. IS: , Bureau of Indian Standards, New Delhi. [12] Methods of Tests for of Concrete. IS: , Bureau of Indian Standards, New Delhi. [13] Sameer Ul Bashir, Shabbir Ahmad Parray and Syed Rizwan Shah, Harmful Effects of on of Concrete. International Journal of Civil Engineering and Technology, 4(6, 213, pp [14] Splitting Tensile of concrete Methods of test. IS 5816:1999. [15] Methods of Tests for of Concrete. IS: , Bureau of Indian Standards, New Delhi editor@iaeme.com