Abstract
For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder) and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.
Highlights
With the rapid development of high-rise building and longspan concrete bridges in China, demands of high strengths and high toughness of concrete materials are more and more highlighted in the latest decade
An electronic mechanical testing machine was employed for this purpose
In order to evaluate the toughness of concrete through polymers and waste rubber powder, the integral area enclosed by 4-point bending load and max middle displacement curves was defined as the bending toughness of concrete without precut notch according to the Chinese Standard GB/T 50081-2002
Summary
With the rapid development of high-rise building and longspan concrete bridges in China, demands of high strengths and high toughness of concrete materials are more and more highlighted in the latest decade. That means the optimized cost-effective methodologies for toughness improvement of concrete is a big challenge so far. Many scientists (Dry [1], Ye [2], Guneyisi et al [3], etc.) have done many researches to decrease porosity, homogenize microstructure, enhance bond strength between aggregate and hardened cement paste, and decelerate crack growth through fiber reinforcement, polymer toughening, and nanoparticles. Polymers and reactive industry waste particles or powder could be better choice even though a slight decrease of concrete strength occurs. The present research employed two types of watersoluble polymers (such as dispersible latex powder and polyvinyl alcohol powder) and waste tire-rubber powders as constituents for toughness improvement. Primary strengths, bending toughness, and fatigue performance of concrete with polymers or/and waste tire-rubber powders were evaluated. The related nano-micromacro-multiscale mechanisms of these concretes were comprehensively investigated
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