Polymer-modified mortar with a gradient polymer distribution: Preparation, permeability, and mechanical behaviour

A technology that produces a gradient polymer distribution in polymer-modified mortar (PMM) was developed to minimize the polymer addition in PMM without losing the improved properties. The mortar was modified using a magnetic responsive polymer latex and was subjected to a magnetic field during moulding. Driven by magnetic force, the added polymer particles were enriched in the superficial region of the PMM, and a dense protective layer with much higher polymer content was generated in the hardened mortar, which increased the impermeability of the material. The gradient polymer distribution was confirmed by thermogravimetric analysis and X-ray diffraction analysis. The chloride permeability test according to ASTM-C1202 and alternative current impedance spectroscopy measurement were carried out to compare the permeability of PMM with the gradient and homogenous polymer distributions with the same polymer addition. The results from the bending test revealed that the gradient polymer distribution led to a higher flexural strength when the polymer-rich side was placed downwards during the test.