Effect of nano-silica on rheology and fresh properties of cement pastes and mortars |
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| Authors: | Luciano Senff João A Labrincha Victor M Ferreira Dachamir Hotza Wellington L Repette |
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| Affiliation: | 1. Materials Science and Engineering Graduate Program (PGMAT), Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil;2. Department of Ceramics and Glass Engineering (CICECO), University of Aveiro (UA), 3810-193 Aveiro, Portugal;3. Department of Civil Engineering (CICECO), University of Aveiro (UA), 3810-193 Aveiro, Portugal;4. Department of Chemical Engineering (EQA), Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil;5. Department of Civil Engineering (ECV), Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil |
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| Abstract: | Amorphous nano-silica (nS) particles (0–2.5 wt%) by cement were incorporated in cement pastes and mortars, and their effect on the fresh state behaviour was analysed. Rheological tests showed that after 75 min from the mixing start, the mortar having 2.5 wt% nS shows insufficient flowability to allow its continuous monitoring in a Viskomat PC viscometer. The influence of nS content was better observed on yield stress when compared with plastic viscosity values (the first increased about 66.5% while the latter just increased 3.6%). With nS addition, spread, setting time and the moment to reach the maximum temperature decreased 33%, 60% and 51.3%, respectively, when compared with samples without nS. X-ray diffraction showed presence of calcium hydroxide after 9 h in the sample with 2.5 wt% nS. The air content increased 79% and apparent density decreased 2.4% when nS was added. |
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