Experimental Investigation of the Influence of Cellulose Ether on the Floating of Rubber Particles in Mortar

As a kind of hyperelastic material, rubber can be mixed into mortar (or concrete) to improve the anticracking ability and ductility of concrete. The mixture of rubber can change the internal structure of concrete through physical interaction, without changing the chemical properties of each component in the mortar (or concrete). But since the apparent density of rubber is far less than the density of cement-based materials, rubber particles are likely to separate from cement-based materials in the mixture of rubber and mortar, and consequently, rubber particles will float upward. This study proposes a new method to restrain the rubber particles from floating upward: add cellulose ether in the mortar with a water-cement ratio of 0.45 so as to improve the mobility of mixture. Meanwhile, this study employs the method of quadratic orthogonal rotation combination experiment to carry out research on the influence of the mixing amount of cellulose ether (0∼5.43 kg/m3) and the ratio of rubber substituting for mortar (0∼0.5) on the degree of uniformity, consistency, and 28-day (28 d) strength of crumb rubber mortar, and it also studies the inhibiting effect of cellulose ether on the floating of rubber. The results show that cellulose ether mixed into the mortar can significantly improve the mobility of the mixture and restrain the floating of rubber. But with the increase of the mixing amount of cellulose ether, the 28 d strength of the mortar shows an obvious decreasing trend. This study has a guiding role in the practical application of crumb rubber mortar, crumb rubber concrete, and other lightweight aggregate concrete.