Influence of waste alumina powder on self-compacting concrete resistance under elevated temperature

Influence of Nano-Alumina (NA) powder prepared from damaged alumina rollers that are waste objects from the production line in a tile and ceramic factory on Self-Compacting Concrete (SCC) under elevated temperature are investigated in this study. Three mix designs including without NA, with 1%NA, and 2%NA, that were replaced for cement, were investigated under temperatures of 27 degrees C, 100 degrees C, 200 degrees C, 300 degrees C, 450 degrees C, and 600 degrees C. To evaluate compressive strength and modulus of elasticity (E-value) of each mix design, 7-day and 28-day samples were tested before or after heating for ten or 60 min. For each mix design, cured samples experiencing only the ambient temperature of about 27 degrees C were also tested as reference samples. Results show that using NA decreases compressive strength of 7-day samples in the ambient temperature, but improves their compressive strength after 10 min heating under the target temperature of up to 200 degrees C. Nano-alumina improves compressive strength of 28day SCC samples by its pozzolanic activity for the ambient temperature and under 100 degrees C. For the higher target temperatures at both ages, NA particles are effective to reduce strength degradation due to heating. Compared to the samples without NA, compressive strength of the 28-day samples with 1%NA and 2%NA, after experience of 10 min heating, were 11.7% and 16.2% higher, respectively. These values for the samples experiencing 60 min heating were 22.4% and 26.5%. Results of E-value tests on 28-day samples exhibit positive influence of NA under ambient temperature and these nanoparticles are able to slow down degradation of E-value after an experience of ten or 60 min under the target temperatures. However, almost different from previous literature, the 2%NA has a higher influence to reduce SCC strength degradation than 1%NA. This may be attributed to the NA resource that is from waste materials containing some impurities.