CHAPTER- 7 DURABILITY STUDIES ON SELF COMPACTING CONCRETE WITH GGBS AND RHA

Transcription

1 270 CHAPTER- 7 DURABILITY STUDIES ON SELF COMPACTING CONCRETE WITH GGBS AND RHA 7.0 INTRODUCTION Self-compacting concrete cubes of 100 mm x 100 mm size are cast with eight selected mixes of concrete and are tested for compressive strength at the age of 28 are taken for durability studies. The durability studies are done on cubes immersed in H2SO4, Na2SO4 & HCl for 30, 45, 60, 75 and 90. The obtained results are presented in tables and the test results are also presented in the form of graphs for better study and analysis. 7.1 ACID ATTACK After 28 of curing, each cube is tested for weight and lengths. The cubes are subjected to 5% solutions of Sulphuric Acid (H2SO4), Sodium Sulphate (Na2SO4) and Hydrochloric acids (Hcl) individually. Cubes are continuously immersed in solution for 30, 45, 60, 75 and 90. The specimens are arranged in the plastic baths in such a way that the clearance around and above the specimen is not less than 30mm.The response of the specimens to the solution is evaluated through change in appearance, weight, compressive strength, thickness and solid diagonals. Three specimens from each group are used for testing after 30,

2 271 45, 60, 75 and 90 of immersion. Before testing, each specimen is removed from the baths, brushed with a soft nylon brush and rinsed in tap water. This process removes loose surface material from the specimens. For determining the resistance of concrete specimens to aggressive environment such as acid attack, the durability factors as proposed by the philosophy of ASTM ( ).The standard test method for resistance of concrete to rapid freezing and thawing and the durability factors are defined in terms of relative dynamic modulus of elasticity. In the present investigation, the Acid Durability Factors are derived directly in terms of relative strengths. The relative strengths are always compared with respect to the 28 value (i.e. at the start of the test) The Acid Durability Factors (ADF) can be calculated as follows. ADF = Sr N / M Where, Sr - Relative Strength at N, (%) N - Number of at which the durability factor is needed. M - Number of at which the exposure is to be terminated. So M is 90 in this case. The extent of deterioration at each corner of the struck face and the opposite face is measured in terms of the acid diagonals (in mm) for each of two cubes and the Acid Attack Factor (AAF) per face is calculated as follows.

3 272 AAF = (Loss in mm on eight corners of each of 2 cubes)/4. The results of the tested Acid Resistance Behaviour at 30,45, 60,75 and 90 for M20,M40 and M60 grades SCC is shown in Table to and the respective graphs are shown in Figs to Table Acid Durability and Acid Attack Factors for M20, M40 and M60 SCC mixes immersed in H2SO4 No. of Immersion in H2SO4 of M20 M20 GGBS M20 GGBS- RHA immersion Sr ADF AAF Sr ADF AAF Sr ADF AAF Acid Durability Factors -ADF, Acid Attack Factors - AAF, Sr - Relative Strength. No. of of immersion Immersion in H 2 SO 4 M40 M40 GGBS M40 GGBS- RHA Sr ADF AAF Sr ADF AAF Sr ADF AAF

4 273 No. of of immersion M60 Immersion in H 2 SO 4 M60 GGBS- RHA Sr ADF AAF Sr ADF AAF Fig Acid Durability, Acid Attack Factors and Days of immersion for M20 SCC mixes immersed in H2SO4 Fig Acid Durability, Acid Attack Factors and Days of immersion for M40 SCC mixes immersed in H2SO4

5 274 Days 30 Fig Acid Durability, Acid Attack Factors and Days of immersion for M60 SCC mixes immersed in H2SO4 Table Acid Durability and Acid Attack Factors for M20,M40 and M60SCC mixes immersed in HCl Immersion in HCl M20 M20 GGBS M20 GGBS- RHA Sr ADF AAF Sr ADF AAF Sr ADF AAF Days Immersion in HCl M40 M40 GGBS M40 GGBS- RHA Sr ADF AAF Sr ADF AAF Sr ADF AAF

6 275 Days M60 Immersion in HCl M60 GGBS- RHA Sr ADF AAF Sr ADF AAF Fig Acid Durability, Acid Attack Factors and Days of immersion for M20 SCC mixes immersed in HCl Fig Acid Durability, Acid Attack Factors and Days of immersion for M40 SCC mixes immersed in HCl

7 276 Fig Acid Durability, Acid Attack Factors and Days of immersion for M60 SCC mixes immersed in HCl Table Acid Durability and Acid Attack Factors for M20, M40 and M60SCC mixes immersed in Na2So4 Days Immersion in Na2So4 M20 M20 GGBS M20 GGBS- RHA Sr ADF AAF Sr ADF AAF Sr ADF AAF Days Immersion in Na2So4 M40 M40 GGBS M40 GGBS- RHA Sr ADF AAF Sr ADF AAF Sr ADF AAF

8 277 Immersion in Na2So4 Days M60 M60 GGBS- RHA Sr ADF AAF Sr ADF AAF Fig Acid Durability, Acid Attack Factors and Days of immersion for M20 SCC mixes immersed in Na2So4 Fig Acid Durability, Acid Attack Factors and Days of immersion for M40SCC mixes immersed in Na2So4

9 278 Fig Acid Durability, Acid Attack Factors and Days of immersion for M60 SCC mixes immersed in Na2So4 7.2 Weight Loss and Loss The weight and compressive strength of cubes immersed for 30, 45, 60, 75 and 90 in acids are noted down. The Weight Loss and Strength loss at 30, 45, 60, 75 and 90 for three grades are calculated. The Weight Loss and Strength loss at 30, 45, 60, 75 and 90 results of M20 grade SCC are shown in tables to (Weight in kg and in MPa).The figures to shows the graphs of weight loss, compressive strength loss and of immersion of three grades of SCC.

10 279 Table Weight Loss and Loss for M20 SCC mixes immersed in H2SO4 Type of mix M20 M20- GGBS M20- GGBS- RHA Weight Loss and compressive strength loss Weight before H2SO Weight after defined age % Weight loss before after defined age % loss Weight before Weight after defined age % Weight loss before after defined age % loss Weight before Weight after defined age % Weight loss before after defined age % loss

11 280 Table Weight Loss and Loss for M40 SCC mixes immersed in H2SO4 Type of mix M40 M40- GGBS M40- GGBS- RHA Weight Loss and compressive strength loss H2SO Weight before Weight after defined age % Weight loss Compressive Strength before Compressive Strength after defined age % Compressive Strength loss Weight before Weight after defined age % Weight loss Compressive Strength before Compressive Strength after defined age % Compressive Strength loss Weight before Weight after defined age % Weight loss Compressive Strength before Compressive Strength after defined age % Compressive Strength loss

12 281 Table Weight Loss and Loss for M60 SCC mixes immersed in H2SO4 Type of mix M60 M60- GGBS- RHA Weight Loss and H2SO4 Compressive Strength loss Weight before Weight after defined age % Weight loss before after defined age % loss Weight before Weight after defined age % Weight loss before after defined age % loss Fig Weight Loss, Loss and Days of immersion for M20 SCC mixes immersed in H2SO4

13 282 Fig Weight Loss, Loss and Days of Immersion for M40 SCC mixes immersed in H2SO4 Fig Weight Loss, Loss and Days of immersion for M60 SCC mixes immersed in H2SO4 Fig Weight Loss, Loss and Days of Immersion for M20 SCC mixes immersed in HCl

14 283 Fig Weight Loss, Loss and Days of immersion for M40 SCC mixes immersed in HCl Fig Weight Loss, Loss and Days of immersion for M60 SCC mixes immersed in HCl Fig Weight Loss, Loss and Days of immersion for M20 SCC mixes immersed in Na2So4

15 284 Fig Weight Loss, Loss and Days of immersion for M40 SCC mixes immersed in Na2So4 Fig Weight Loss, Loss and Days of immersion for M60 SCC mixes immersed in Na2So4