Fly Ash Lab Report

CONCLUSION AND SCOPE OF THE FUTURE WORK
7.1 CONCLUSION
1. Addition of increased percentage of fly ash results in decrease of compressive strength gradually but workability parameters are within limits. By adding 20%, 25%, 30% and 35% fly ash we observed that the slump flow obtained at 30 minutes was 675mm, 685mm, 695mm and 665mm. All the results were within the recommended limit are 650-800mm.
2. The results obtained from the V-Funnel test were quite good. With 20%, 25%, 30% and 35% fly ash T0 time were 12 sec, 10 sec, 12 sec, 12sec and T5 time was 14 sec, 12sec, 13 sec, 13 sec. The recommended value are 8-12 sec for T0 and 11-15 sec for T5.
3. The L-Box test results addressed that blocking ratio for 20%, 25%, 30% and 35% fly ash were 0.8, 0.9, 0.7

The 28 days cube compressive strength decreased from 40 MPa to 35 MPa by increasing the percentage of fly ash from 20% to 35%. The decrease was almost 16%. Thereafter all the above tests were carried out by adding micro silica and metakaolin, both separately taking 35% fly ash as base mix.
5. The addition of micro silica was done at 4%, 6% and 8% by taking 35% of fly ash as base. The slump flow for 4%, 6% and 8% micro silica was found to be 710mm, 690mm and 655mm respectively. This implies that it increased by 8% on an average and hence better flow

Finally reviewing all the results it was concluded that concrete mixes with 6% micro silica and 8% metakaolin over 35% fly ash as base were the better mixes among all because compressive strength which is one of the key property of concrete obtained in these two mixes for M-30 grade concrete were close to or rather slightly higher than 30MPa. More over filling ability, passing ability and blocking ratio as obtained on other mixes were also well within the limits but were slightly on a higher side which may give rise to problem of segregation which is undesirable. Therefore studying all the test results we conclude the above two trials as the better amongst