Abstract
The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S) hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP) measurements, pore-size distribution (PSD), total porosity and critical pore diameter also confirmed such results.
Highlights
The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied
According to Haruehansapong et al [7], a nano-SiO2 particle size of 40 nm gives higher compressive strength compared with mortars with nano-SiO2 particle sizes of 12 and 20 nm, with it arguably being due to an agglomeration of small particles
Flexural and compressive strength tests were performed in 40x40x160mm mortars at two, seven and 28 days according to the European Standard EN 196-1: 2016 [23]
Summary
The standard mortar composition involves use of the sulphate-resistant Portland cement. A commercial nano-SiO2 Levasil 200/40%, distributed by Obermeier and a commercial Iron III oxide nano-particles (nano-Fe2O3) supplied by Tecnología Navarra de Nanoproductos S.L. A modified polycarboxylate-based superplasticizer or high-range water-reducing additive (HRWRA) according to EN 934-2 [24], Sika ViscoCrete®-5720 (pH = 4; density = 1.09 kg/l and 36% solid content) was employed with a relatively low dosage of 0.15– 0.3% per cement weight (Table 2). Combined effect of nano-SiO2 and nano-Fe2O3 on compressive strength, flexural strength 3. The particle size of the commercial nano-SiO2 Levasil was 10-20 nm (this value was supplied by the producer). The specific surface area of the commercial Iron III oxide 55.9 m2/g, and the nano-particles mean particle (nano-Fe2O3) was size 1.95 μm, with both being experimentally measured
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