20320140503037

181 views

Published on

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
181
On SlideShare
0
From Embeds
0
Number of Embeds
7
Actions
Shares
0
Downloads
2
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

20320140503037

  1. 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 317 RESIDUAL COMPRESSIVE STRENGTHS OF FLY ASH CONCRETES EXPOSED TO ONE YEAR OF ACCELERATED SULPHATE ATTACK Rajamane N. P.1 , Dattatreya J. K.2 , D. Sabitha3 1 Head, CACR, SRM University, Kattankulathur (Ex-SERC), 2 Professor, Dept. of Civil Engg, SIT, Tumkur (Ex-SERC), 3 Scientist, CSIR-NGRI, Hyderabad ABSTRACT The presence of sulphate ion causes deterioration of concrete structural components exposed to marine environments or placed in soils and groundwater contaminated with sulphate salts. This aspect of concrete deterioration is being studied for decades. Sulphate attack on concrete is a complex process involving many factors such as cement type, sulphate cation type, sulphate concentration and exposure period. The sulphate ions react with C3A and Ca (OH)2 , to produce expansive and/or softening types of deterioration. The sulphate attack in marine environment gives rise to expansive ettringite, gypsum, and brucite and sometimes is associated with calcite formation. The use of blended cements incorporating supplementary cementing materials and cements with low C3A content is becoming common to prevent the deterioration of concrete structures subjected to aggressive sulphate environments, even though it has been reported that the limitation on C3A content is not the general answer to the problem of sulphate attack. This paper presents the results of an investigation on the performance of fly ash blended cement (made in cement plants or on site) concrete mixtures with immersion period of up to 12 months in environments characterized by the presence of mixed magnesium-sodium sulphates. The concrete mixtures of basically, M25 grade, comprise one Portland cement (OPC) (with w/c=0.55), one Portland Pozzolana Cement (PPC) i.e. factory blended cement contacting fly ash (with w/c=0.55), and one on site fly ash based blended concretes (water-to-binder ratio of 0. 50). Deterioration of concrete due to mixed sulphate attack (sulphates of sodium and magnesium) was evaluated by assessing concrete visual inspection, weight loss and strength loss at periodic intervals throughout the immersion period of 12 months. The test data shows that sulphate attack cannot be prevented by only any one of three common factors: low w/c, low calcium hydroxide content, or low C3A content. Lowering w/c has a deleterious effect on the resistance of concrete exposed to magnesium sulphate, as at low values of w/c, there is limited pore space to accommodate the products of reactions with sulphate, namely, magnesium silicate INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME: www.iaeme.com/ijciet.asp Journal Impact Factor (2014): 7.9290 (Calculated by GISI) www.jifactor.com IJCIET ©IAEME
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 318 hydrate (which has no adhesive properties) and gypsum. The test data in the present paper shows that a reduction in the w/b from 0.55 of OPCC to 0.50 in FAC has not helped FAC which had 10% strength loss between 180 and 360 days as compared to 5% strength loss in OPCC. However, an increase of w/b ratio from 0.50 in FAC to 0.55 in PPCC, has indeed caused higher strength of loss of 30% between 180 and 360 day, but only 10% loss in FAC. Interestingly, during the period of 180 to 360 days, at w/b ratio of 0.55, the OPCC had performed favourably as against fly ash containing PPCC. Thus, adoption of one parameter alone among many such as w/c ratio, cement type, fly ash content etc may not be sufficient to ensure sulphate resistance. Any sulphate resistance study, longer period, say of one year is essential, to arrive at rational decisions on sulphate attack 1.0 INTRODUCTION Sulphates of sodium, potassium, magnesium and calcium which occur in soil or ground water may be carried into inner sections of concrete by either ionic diffusion or capillary absorption of their salt solutions and cause disruptive forces leading to cracking or spalling of concrete [Lawrence, 1990; Newmann, 1990; Mark Richardson, 2002; Neville, 1995]. They react with the hydration products of cement paste, viz. calcium hydroxide (CH), Calcium Alumino hydrate (CAH), and even calcium silicate hydrate (CSH). Sodium sulphate attacks CH in an acidic type reaction forming gypsum, NaOH and water. In flowing water, CH can be completely leached out. Sulphates also react with the C3A component of cement forming an expansive product called ettringite (3CaO.Al2O3.3CaSO4.32H2O), which results in cracking of concrete. MgSO4 attacks CSH as well as CH & CAH forming gypsum, Mg (OH)2 (brucite) and aqueous silica. Because of the very low solubility of Mg (OH)2, the reaction proceeds to completion, so that, under certain conditions, the attack by MgSO4 is more severe compared to other sulphates. The critical consequence of MgSO4 attack is the destruction of CSH. In addition to disruption and cracking, sulphate attack also leads to loss of strength due to reduced cohesion in Hydrated Cement Paste (HCP) and in the bond between HCP and aggregate. Concrete attacked by sulphate has typical whitish appearance. The attack usually starts at the edges and corners and is followed by progressive cracking and spalling, reducing the concrete to a friable mass. Sulphate attack occurs only when the sulphate ion concentration exceeds a certain threshold. It is about 0.5% for magnesium sulphate and 1% for sodium sulphate. A saturated solution of magnesium sulphate leads to severe deterioration, but for low water-cement ratio concretes, it takes 2-3 years for the usual appearance of distress. The three principal means for reducing sulphate attack are : (1) limiting C3A and C4AF content of cement (2) use of pozzolanic additions (3) prevention of ingress of sulphates by making dense, low-permeability concrete. It is now well accepted that limiting C3A and C4AF is not the ultimate answer to the problem of SO4 attack and blended cements may be preferable from this point of view [Mangat, 1992 and 1995; Neville, 1995; Lawrence, 1990; Osbome 1994; Torii, 1994]. The resistance of concrete to sulphate can be tested in the laboratory by storing the specimens in a solution of magnesium sulphate or sodium sulphate or in a mixture of the two. Alternate wetting and drying accelerate the damage due to crystallisation of salt in the pores of concrete. However there is no agreement on the choice of wetting and drying durations. The effect of expansion can be estimated in terms of loss in strength of specimen, change in dynamic modulus Edyn, magnitude of expansion, loss of mass and visually observed deterioration. ASTM C 1012 tests for 1:3 cement mortar immersed in 2.5% SO4 solution can be used to assess the effect of using various cementitious materials in the mix. However, the test is slow and since mortar and not concrete is tested, some typical effects of mineral fillers in the aggregates are not reflected. Other ASTM tests based on C 452-894 and C 1038-89 are also related to mortar and intend to identify the excessive sulphate content of an OPC rather than attack by expansive sulphate.
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 319 Some of the recent studies [Newmann, 1990; Al Amoudi 1995] on long term performance in extreme climates (combined attack of sodium and magnesium sulphate in extreme temperatures) indicate that the aluminate contents of cement and CRMs are both critical factors that control the performance and even dense concretes with low water-cement ratio could be affected in very adverse environments. This paper describes the test results of three types of mixes of M25 grade concretes with binders being OPC, OPC+25% FA, and factory produced fly ash containing Portland Pozzolana cement (PPC). The data is expected to show the influence of presence of fly ash on the sulphate resistance of concretes and residual compressive strength measured after the predetermined accelerated sulphate exposure time was taken as parameter to quantify the degree of the deterioration. 2.0 CONCRETE MIXTURES INVESTIGATED • Grade: M25 • Types of concretes mixtures: I. Ordinary Portland Cement Concrete (OPCC) Mixture, II. FA based Portland Cement Concrete (FACC) Mixture with FA (% by mass) contents in binder portions of the concretes being 25%. Class F fly ash from a coal based thermal plant near Chennai, admixed with OPC during preparation of concrete mixes in the laboratory. III. Portland Pozzolana Cement Concrete (PPCC) Mixture. Minimum slump of about 100 mm was maintained in the concrete mixes to facilitate easier compaction by a table vibrator. The curing period of the specimens before subjecting them to accelerated exposure test was 56 days (28 days water curing followed by 28 days of storage in ambient conditions in the laboratory). This period was expected to provide sufficient time to enable the pozzolanic reactions of FA within the concrete matrix so that there is a significant contribution from FA to the microstructure refinement of the concrete and realistic durability characteristics of fly ash based concretes could be assessed. The properties of cements and fly ash are described in Tables 1 (a) and 1 (b) respectively. Table 1 (a): Physical and Chemical Properties of OPC and PPC Nature of Tests Cement type 43 grade OPC PPC1 1. Chemical composition in percent by mass (IS:4032) (a) Silicon dioxide, SiO2 21.65 29.07 (b) Insoluble residue 1.08 28.87 (c) Iron Oxide, Fe2O3 4.77 3.10 (d) Total Calcium Oxide, CaO 62.48 47.84 (e) Aluminium Oxide, Al2O3 5.65 13.89 (f) Potassium Oxide, K2O 0.43 0.46 (g) Sodium Oxide, Na2O 0.20 0.30 (h) Magnesia, MgO 0.8 1.11 (i) Sulphur calculated as sulphuric anhydride, SO3 2.48 2.54 (j) Loss of Ignition 1.71 1.64 Specific surface,m2 /kg 333 362 3. Compressive Strength (IS:4031) (a) 3 days, MPa 32.7 29.0
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 320 Table 1 (b): Physical and Chemical Properties of Fly Ash The mix proportions including water-cement ratio (w/c) were selected based on exposure conditions stipulated in IS: 456 and guidelines for mix design of ACI Committee report 211 [ACI 211, 2005]. Based on the several trial mixes produced in the laboratory with the available materials strength and workability performance of these mixes, the proportions for OPC control mixture (OPCC) of M25 grade was finalised with water-cement ratios (w/c) of 0.55. The same water-cement ratios and mixture proportions were adopted for PPCC mixtures also. As most of the durability characteristics of concretes in general are more governed by water-cement ratio (or water-binder ratio) rather than by the strength, the selection of same water-binder ratios for OPCC and PPCC can be considered as rational. However, suitable modifications were made in the water-binder ratios (b) 7 days, MPa 36.3 35.5 (c) 28 days, MPa 52.3 57.3 4. Setting Time (IS:4031) (a) Initial 2hrs. 20min. 1hr. 20min. (b) Final 3hrs. 45min. 3hrs. 45min. 5. Soundness (a) Expansion after boiling 3 hr in Lechatlier’s Mould 0.5 0.5 (b) Expansion after Autoclave Test 0.02 Nil Drying Shrinkage, percent - 0.07 7. Water required for standard consistency, percent 26% 30.5% 8. Temperature during the period of testing 28°C 28°C 9. Relative humidity during the period of test 64% 64% S.No. NATURE OF TESTS Results Obtained 1. Chemical analysis Percent by mass 1.1 Silicon dioxide, (SiO2) + Aluminium Oxide,(Al2O3) +Iron Oxide, (Fe2O3) 94.84 1.2 Silicon dioxide, (SiO2) 60.39 1.3 Magnesium Oxide, MgO 1.85 1.4 Sulphur calculated as sulphuric anhydride, (SO3) 0.27 1.5 Sodium Oxide, (Na2O) 0.18 1.6 Loss of Ignition 1.12 1.7 Aluminium Oxide,(Al2O3) 33.71 1.8 Iron Oxide, (Fe2O3) 0.74 1.9 Calcium Oxide, (CaO) 1.06 1.10 Potassium Oxide, (K2O) 0.12 2. Fineness Specific surface,m2 /kg 300 3. Test for Lime Reactivity Average compressive strength, N/mm2 4.72 4. Test for Drying Shrinkage Average Drying Shrinkage, percent 0.02 5. Test for Soundness Soundness by Autoclave expansion, percent 0.01
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 321 (w/b) and mix proportions in case of FACC mixture taking into account their cementing efficiency at 28 days and their lower specific gravity in order to achieve required target strengths and workability. Details of the mixture proportions are presented in Tables 2 (a) and 2 (b). Table 2: Mixture Proportions for M25 Grade Concrete B = Binder = Cement + Fly Ash = C + FA Table 3: Strength Test Results 3.0 DETAILS OF EXPERIMENTAL INVESTIGATIONS 3.1 Strengths The test results given in Table 4 indicate that there is a negligible increase in compressive strength between 90 and 180 days and also between 180 and 360 days, as compared to that between Materials (kg/m3 ) OPCC, PPCC FACC Mix Id OA, P1A OAF25 Binder (B) 360 396 Cement (C) 360 297 Fly Ash (FA) - 99 Sand (S) 648 581 Coarse aggregate (CA) 1152 1152 Water (W) 198 198 w/b =W/B 0.55 0.50 Proportions (B:S:CA:W) 1:1.8:3.2:0.55 1:1.47:2.91:0.50 Mix ID OA OAF25 P1A w/b 0.55 0.5 0.55 Grade M25 M25 M25 Age (days) Compressive strength, MPa 3 18 18 26 7 23 25 31 28 32 33 42 56 41 41 49 90 42 46 51 180 42 48 53 360 43 52 54 Flexural strength, MPa 28 5.1 5.1 5.8 90 5.9 6.5 6.4 180 5.9 6.8 6.6 360 5.9 7.9 7.3 Split tensile strength, MPa 28 2.9 2.9 2.6 90 3 3.3 3.3 180 2.9 3.5 3.5 360 3 3.6 3.5
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 322 28 and 90 days and as expected the rate of increase in strength at longer age is very less, especially for OPCC specimens. FACC specimens registered slightly higher increase (Figures 1). Figure 1: Compressive Strength Development of Concrete Specimens with Age OPCC specimens had almost reached their maximum strength by the end of 90 days where as FACC specimens required a longer period of about 180 days to reach their maximum strengths. It may be noted here that after 28 days of water curing, no external curing by application of moisture or water was undertaken. The specimens gained their strength due to the water available within the matrix after the specimens were taken out of water at the end of 28 days of curing. After the specimens are exposed to ambient conditions, there is a gradual loss of water from the specimens and there could be a limit on the age up to which there is a continuous development of strength. In the present study, it was observed that the refinement of the concrete matrix due to the presence of fly ash slows down the drying process due to the tortuosity of the pores and thereby allows the strength development to proceed for longer duration than in the concretes without fly ash. The test results indicate that the required 28-d compressive strengths were achieved for both OPCC and FACC mixes. This is evident from the strengths of 32 to 34 MPa for M25 grade concretes. However in case of PPCC, in spite of using the maximum permissible water-cement ratio of 0.55 as per IS 456-2000, 28-d strength of 42 MPa was obtained and this strength could be taken as corresponding to M35 grade concrete. The test data shows that it is possible to achieve the required target strength at 28 day in case of M25 grade of concrete containing 25% fly ash. However, it is seen that for a given grade of concrete, the lower water-binder ratio should be used for FACC. Thus, at similar strength levels, OPCC would have comparatively higher water-cementitious material ratio than the corresponding FACC. In case of PPCC, the water-cement ratio to be adopted for given grade of concrete depends upon the nature of the PPC being considered. The compressive strengths at 360 day were marginally more than that at 180 day. The increase in compressive strength at 180 day relative to that 28 day was in the range of 10 % to 45% and this range increased to 24% to 65% at 360 days, depending upon the type of mix 3.2 Accelerated sulphate attack on concrete specimens In the present study, a combination of Na2SO4 and MgSO4 (each 5% solution) was used for investigating the response of test specimens. Since, there is no accepted duration of wetting and drying cycles, it was decided to expose the specimens continuously to sulphate solution. After 56
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 323 days of curing, the specimens were immersed in combined sulphate solution. The pH of solution was maintained in the range of 8.1 to 8.5. All the concrete test specimens were exposed continuously to sodium sulphate and magnesium sulphate solution (concentration of each salt was 5% by mass) after 56 days of curing. The physical deterioration of the specimens, pH of the solution and possible changes in visual nature of specimens were monitored at regular intervals of time. The concentration of the solutions was adjusted once in a month. Photo1 shows a view of specimens exposed to sulphate attack. The compressive strengths of the test specimens after desired period exposure were determined to know the deteriorating effects of sulphates on concrete (Table 4). Photo 1: A View of specimens exposed to sulphate attack Up to 180 days of exposure to sulphate solution, there was no perceptible (visible) physical deterioration. During combined sulphate attack, the changes in mass of test specimens were less than about 6% for all the mixtures investigated indicating only minor effect of sulphate exposure on external appearance of test specimens. With regards to compressive strength, following observations can be made: After 180 days of exposure, the OPCC specimen (mix OA) had about 20% reduction in compressive strength and in case of concrete mixes containing fly ash (both PPCC and FACC), the change of compressive strength was in the range of –2% to +5% (Table 4, Figure 2). The changes in concretes containing fly ash were almost negligible as this variation are well within practically acceptable limits for any concrete. Figure 2: %Change in Compressive Strength after Sulphate Attack
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 324 After 360 days of exposure, the following points were observed: • The OPCC specimen (mix OA) had about 23% reduction in compressive strength and in case of concrete mixes containing fly ash (both PPCC and FACC), the change of compressive strength was in the range of –7% to -34% (Table 4, Figure 2). • The changes in concrete containing fly ash are comparable to those of OPCC. Up to 25% fly ash content, the loss in compressive strength is less that of OPCC. The PPCC (P1A) has shown higher compressive strength loss. In case of sodium sulphate attack, ettringite may form due to sulphate and C3A present in the cement. This leads to expansion, and cracking which enables easy penetration of solution into the concrete and leads to further deterioration. In the present case, negligible expansion and cracking were observed indicating that all the concretes considered had high resistance to ettringite formation. C3A + sulphate + water C3A 3CS·H32 (Ettringite) However, sulphate attack on CH and CSH portions of cement, involves a different mechanism which may cause expansion and spalling. However, its most important feature is the loss of strength and adhesion of the cement paste due to decalcification of C-S-H which is primarily responsible for the binding capacity of the cement paste. Concrete forming gypsum under sulphate attack shows whitish patches on the surface and perceptible loss of strength (Photo 2). However, fly ash concretes could resist gypsum formation (or gypsum corrosion) better due reduction in free lime content of hydrated matrix. OA P1 A Photo 2: View of specimens deteriorated due to sulphate attack The attack on C-S-H by magnesium sulphate (Mg SO4) is not directly related to ettringite formation. In this type of attack, without the ettringite formation, there is loss of strength and adhesion of the cement paste due to decalcification of C-S-H The formation of brucite, which is not readily soluble worsens the situation. This process is suspected to have set in the present case as the sulphate penetration and build up within the concrete mass would have reached the level required (more than 1000 ppm) for the process of silica gel formation to initiate. Since fly ash concretes with higher fly ash content, which have lower free lime content, have shown higher loss in strength, it is evident that the deterioration should have been more by reaction of magnesium sulphate within C-S- H rather than with lime and calcium aluminate fractions. From the test results, it is seen that, performance of PPCC could be lower than that of FACC and the fly ash content of PPC seem to be critical in determining its resistance to sulphate attack.
  9. 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 325 Table 4: Compressive Strength after Exposure to Sulphate Solution of Magnesium and Sodium * Strength before start of exposure to sulphate solutions Based on the test results available, the following observations are made: I Compressive strength of concrete mixtures recorded only about 0 to 2 MPa growths between the ages 90 and 180 days. During this period, the split tensile and flexural tensile strengths showed marginal increase. Thus, there was only insignificant increase in strengths after 90 days. II Exposure of specimens to accelerated sulphate environment has shown that at 180 days, OPCC specimens had shown marginal reduction in compressive strength while FACC and PPCC specimens have not shown any apparent signs of deterioration. But, after 360 days of exposure, the fly ash based concretes seem to loose higher percentage of strength. Thus, it would become necessary to determine or know the content of fly ash in manufacturing PPC to know its level of sulphate resistance, since, a minimum amount Portland cement portion of PPC or any fly ash based concrete is important from sulphate resistance considerations. III The test data show that the measurable significant deterioration generating effect of sulphate exposure can be obtained very long period of accelerated test duration, say about a year and more. IV Even though parameters such as low w/b ratio, low C3A content, blending of cement with pozzolana (such as fly ash), are generally useful to reduce the sulphate attack, their explicit individual parameter alone cannot ensure sulphate resistance. In the present study, between 180 days and 360 days of exposure, a) At w/c ratio of 0.55, OPCC performed better than PPCC (presence of fly ash in PPCC could not contribute towards improved performance) b) In spite of lower w/b ratio of 0.50 in FAC, OPCC with higher w/c ratio of 0.55 was better c) Fly ash containing mixes, PPCC and FAC, had different resistances to sulphate attack V Literature study shows that as the type and degree of sulphate attack depends upon the type of cation in the sulphate (such as calcium, sodium, magnesium, ammonium, etc), it is necessary to identify different strategies for reducing ill-effects of sulphate and low C3A alone not ensure sulphate resistance of concrete. REFERENCES 1. AASHTO T-259, [2002], Standard Method of Test for Resistance of Concrete to Chloride Ion Penetration, American Association of State Highway and Transportation Officials, USA 2. AASHTO T-277, [2007], “Standard Method of Test for Rapid Determination of the Chloride Permeability of Concrete”, American Association of State Highway and Transportation Officials, USA 3. ACI 211, [2005], “Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete (ACI 211.1-91), American Concrete Institute, USA 4. Amoudi Al, S.B., Maslehuddin, M. And Saadi, M.M., [1995], “Effect of Magnesium Sulfate and Sodium sulfate on the Durability Performance of Plain and Blended Cements”, ACI Materials journal, Vol. 92, No. 1, pp 15-24 Mix IDs Strength after exposure % Change in strength 0* 90d 180d 360d 90d 180d 360d 0d&90d 90d &180d 180d & 360d OA 41 36 33 31 -12 -20 -23 -12 -7 -5 OAF25 41 45 43 35 10 5 -15 10 -5 -10 P1A 49 51 48 32 4 -2 -34 4 -6 -33
  10. 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 317-326 © IAEME 326 5. Dattatreya, J. K., Rajamane, N. P., Neelamegam, M., Annie Peter, J., and Gopalakrishnan, S., [2002], “Technical considerations for use of fly ash in structural concrete – a critical view,” New Building Materials and Construction World, Vol. 8, N0. 4, Oct, pp 56-71 6. Gopalakrishnan, S, Neelamegam, M, Rajamane, N.P., Jolly Annie Peter, and Dattatreya, J.K. [2001], “Effect of Partial Replacement of Cement with Fly Ash on the Strength and Durability Characteristics of High Performance Concrete”, Indian Concrete Journal, May 2001, 335-341. 7. Gopalakrishnan, S., Lakshmanan, N, Rajamane, N. P., Krishnamoorthy, T. S., Neelamegam, M., Annie Peter, J., Balasubramanian, K., Prabhakar, J., Bharatkumar, B. H., Dattatreya, J. K., and Sabitha, D., [2005], “Development of High Volume Fly ash Concrete for Structural Applications”, for Confederation of Indian Industries, Mumbai, GAP 2041, February 2005. 8. Malhotra, V.M., and Ramezanipour, A. A., [1994], “Fly ash in Concrete”, II ed., September, Ministry of Supply and Services, Canada, 307 p 9. Mangat, P.S., and Khatib, J.M., [1992], “Influence of Fly ash, Silica fume, and slag on the Sulphate Resistance of Concrete”, ACI Materials journal, Vol., No. 5, 1995, pp 542-552 10. Mangat, P.S., and Khatib, J.M., [1995], “Influence of Initial curing on Sulphate Resistance of Blended cement Concrete”, Cement and Concrete Research, Vo. 22, 1992, pp 1089-1100 11. Mark G. Richardson, [2002], “Fundamentals of Durable Reinforced Concrete”, Modern Concrete Technology Series, SPON PRESS 12. Neville, A.M., [1995], “Properties of Concrete”, Fourth Edition, Longman, 1995, 844 p. 13. Newman John and Ban Seng Choo (ed), [2003], “Advanced Concrete Technology”, Properties, Elsevier, Butter Worth Heiremann 14. Powers, T.C., [1968], “Properties of Fresh Concrete”, John Wiley & Sons 15. SERC, [2006a], Rajamane, N. P., Chellappan, A., Neelamegam, M., Annie Peter, J., Dattatreya, J.K., Prabhakar, J., Srinivasan, P., Bhaskar, S., Sabitha, D., Ambily, P.S., Harish, K.V., ‘Interim Report I on studies on evaluation of durability of cracked RC members using fly ash concrete subjected to accelerated corrosion and carbonation’, Grant-in-aid Project No. GAP 02541, July 2006 16. SERC, [2006b], Rajamane, N. P., Chellappan, A., Neelamegam, M., Annie Peter, J., Dattatreya, J.K., and et all ‘Interim Report II on studies on evaluation of durability of cracked RC members using fly ash concrete subjected to accelerated corrosion and carbonation’, Grant-in-aid Project No. GAP 02541, December 2006 17. SERC, [2006c], Rajamane, N. P., Chellappan, A., Neelamegam, M., Annie Peter, J., Dattatreya, J.K., and et all ‘Interim Report III on studies on evaluation of durability of cracked RC members using fly ash concrete subjected to accelerated corrosion and carbonation’, Grant-in-aid Project No. GAP 02541, March 2007 18. SERC, [2006d], Rajamane, N. P., Chellappan, A., Neelamegam, M., Annie Peter, J., Dattatreya, J.K., and et all, ‘Interim Report IV on studies on evaluation of durability of cracked RC members using fly ash concrete subjected to accelerated corrosion and carbonation’, Grant-in-aid Project No. GAP 02541, July 2007 19. SERC, [2008], Rajamane, N. P., Chellappan, A., Neelamegam, M., Annie Peter, J., Dattatreya, J.K., Prabhakar, J., Srinivasan, P., Bhaskar, S., Sabitha, D., Ambily, P.S., Harish, K.V., ‘Studies on evaluation of durability of cracked RC members using fly ash concrete subjected to accelerated corrosion and carbonation’, Grant-in-aid Project No. GAP 02541, Dec 2008. 20. Alok Verma, M. Shukla and A. K. Sahu, “Effect of Number of Classes in a Visual Rating for Sulphate Attack”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 1, 2013, pp. 165 - 181, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. 21. Behrouz Mohebimoghaddam and S.Hossein Dianat, “Evaluation of the Corrosion and Strength of Concrete Exposed to Sulfate Solution”, International Journal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 198 - 206, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

×