Pozzolanic activity and compressive strength of concrete incorporated nano micro Silica

Abstract EN

This paper aims to give a recommendation about the suitable nano silica proportion and curing method for testing its strength pozzolonic activity, in addition to suggest a mixing or batching procedure of this material with other concrete ingredients.

The influence of nano and micro silica on concrete compressive strength is also studied.

Three proportions of nano silica (0.5, 5, &10%) , two curing methods (accelerated in oven and normal in water) and two tested ages are used in pozzolonic activity test of nano silica.

For compressive strength test, eleven mixes are considered: without-adding (two mixes), three micro silica (M) mixes with replacement ratios of 5, 10 & 15%, four nano silica (N) mixes with replacement ratios of 0.5, 1.5, 3 & 5%, and three micro plus nano silica mixes (0.5N+9.5M, 1.5N+8.5M and 3N+7M%) are adopted.

Results of pozzolanic activity test denoted that nano silica has remarkable pozzolanic activity for all tested replacements.

However, it is suggest using 5% nano silica for performing this test by using either accelerated or water curing.

Additionally, it was found that nano silica had more impact on compressive strength of concrete than micro silica for all tested ages.

Where, maximum enhancement ratios of compressive strength were about 33% and 27% for 3% nano silica mix at 7 and 90 days age respectively, and 22% for 5% nano silica mix at 28 days age.

For micro silica mixes, higher improvement ratios were found in 15% micro silica mix: 2%,5% &7% at 7,28 &90 days age respectively.