Cement, Energy and Environment

52 Table-5 Volume Stability of Nanomaterials through Autoclaving Tests Type of Cements Original Length of Sample(mm) [Typical] Expanded Length of Sample(mm) after Autoclaving [Avg.] Average Expansion(%) after Autoclaving Resistivity to Volume Expansion (in %) OPC 282 282.138 0.0490% -- OPC+ 0.75% ns 282 282.085 0.030% 38.78% OPC+ 0.02%CNT 282 282.021 0.0074% 84.90% OPC+ 1.0%TiO 2 282 282.042 0.0150% 69.39% Table-6 Properties of concrete and geopolymer concrete in presence of nanomaterials Type of Concrete Fresh Property (Slump) Geopolymer Concrete(nS = 0% by wt. of FlyAsh) 100 mm Geopolymer Concrete(nS = 0.75% by wt. of FlyAsh) 130mm (30% increase) The Test Results shows that:- 1. The mortar compressive strength as shown in Table 4 & determined as per IS: 4031 shows a 32.55% increase in strength at 0.75% nS addition at 28 days, with the rate of strength gain increasing up to 59.8% at 90 days but then falling by 8.4% at 180 days at same optimization.However, for long terms the 1% nS addition showed an 8 % increase. For CNTs the gain in strength was 38.7% at 28 days but falling to 15.48% at 90 days & 10% at 180 days. But 0.1% CNT shows a strength increase of 69% at 1 year. So, for long term for nS and CNT it is observed that slight increased dosages from the previous optimized @ 28days gave increased strength. Even Geopolymer concrete which is conventionally believed to be viscous in nature had a desired workability (more than 25% when compared to controlled concrete) when treated with the same optimized dosage of nanomaterials (as per Table 6). Conclusion 1. The results showed that the optimizations for nanomaterials in OPC mortar are nS=0.75%, CNT=0.02% and TiO 2 =1.0% for cement mortar up to 28 days. In the long-term strength, some contradictions were noticed for which the reasons are not clear. 2. It is seen that with the increased addition of nano materials like nano-silica (1% by cement wt.) and carbon nanotubes (0.1% by cement wt.) in OPC mortar the long term strength gain increases appreciably. 3. The optimum percentages based on cement mortar when used in geopolymer concrete produced good results for fresh properties (workability) of geopolymer concrete. Reference 1. G.Xu and D.J.Hannant, Cem.Concr.Compos .,1991,Vol 3,pp 95-106. 2. S.Marikunte,C.Aldea and S.P.Shah, Adv.Cem.Based Mater., 1997,Vol 5,pp 100-108. 3. E.M.Bezerra,A.P.Joaquim Jr,H.Savastano,V.M.John and V.M.Agopyan, Cem.Concr.Compos .,2006,Vol28,pp 555-563. 4. F.Sanchez and C.Ince, Compos.Sci.Technol., 2009,Vol 69, pp 1310- 1318. 5. S.Musso,J.M.Tulliani,G.Ferro and A.Tagliaferro ,Compos.Sci.Technol., 2009.Vol 69,pp 1985-1990. 6. M.S.Morsy,S.H.Alsayed and M.Aquel, Construct. Build.Mater .,2011,Vol 25, pp 145-149. 7. R.K.Abu Al-Rub,A.I.Ashour and B.M.Tyson, Construct.Build.Mater., 2012,Vol 35,pp 647-655. 8. J.P.Won,B.T.Hong,T.J.Choi,S.J.Lee and J.W.Kang, Compos.Struct .,2012,Vol 94,pp 1443-1449. 9. Kumar S. et al. Effect of multiwalled carbon nanotubes on mechanical strength of cement paste. Journal of Materials in Civil Engineering . 2012; 24(1): 84–91.5p.