Abstract
Elastic modulus is an important mechanical index for the cement-based materials, which has a significant effect on the static and dynamic response of the concrete structure. To investigate the compressive behavior of nano metakaolin cement mortar, the effects of dispersion conditions, water to binder ratios, and mineral admixtures on the compressive strength of nano metakaolin cement mortar were examined. The elastic modulus of nano metakaolin cement mortar under different water to binder ratios and mineral admixtures was obtained. Based on the theory of micromechanics of composite materials, a theoretical model was deduced to calculate elastic modulus of nano metakaolin cement mortar. Based on the experimental results, an influence coefficient was introduced into simplified model to estimate the elastic modulus of nano metakaolin cement mortar. The results demonstrate that the application of ultrasonic dispersion and long-duration dispersion time (no more than 15 min) can effectively improve the compressive strength of nano metakaolin cement mortar. Compressive strength of nano metakaolin cement mortar mixed with ground granulated blast furnace slag, fly ash, and attapulgite clay is 33.38%, 17.65%, and 6.45% higher than that of the ordinary mortar, respectively. Compared with the experimental results, the calculated error of theoretical model is no more than 5%, while the calculated error of the simplified model is no more than 10%.
Highlights
With the development of nanotechnology, nanomaterials have been used in many industries extensively
Based on the experimental results, an influence coefficient is introduced into simplified model to estimate the elastic modulus of nano metakaolin cement mortar (NKCM)
Compared with the ordinary mortar, the compressive strength of NKCM at 28 days was increased by 7.76% and 10.81%, respectively, when the mechanical dispersion and ultrasonic dispersion were used for 10 min
Summary
With the development of nanotechnology, nanomaterials have been used in many industries extensively. It has been reported that nanomaterials can improve the mechanical properties,[1] chloride ion impermeability,[2] and frost resistance[3] of cementitious materials. The incorporation of nanomaterials in cementitious materials can promote the hydration degree of cement, while do not generate new hydration products. Nanomaterials with small size effects can fill the internal voids in the cementitious materials, which increase the density of cementitious materials.[4] Nano metakaolin (NMK) has a high volcanic ash activity, which caused widespread concerns in the civil engineering. The compressive behavior of nano metakaolin cement mortar (NKCM) is one of the most important indices for its Institute of Road and Bridge Engineering, Dalian Maritime University, Dalian, China
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