One of the effective ways to reduce the risk of concrete cracking is the reduction of drying shrinkage by adding shrinkage-reducing admixture (SRA), which is generally based on the mechanism of reducing surface tension. According to Young-Laplace equation, the mechanism of increasing contact angle should also be very effective. However, the increase of hydrophobicity of admixture would inevitably lead to the decrease of compatibility and effectiveness, which still has been unsolved. This study aims to provide a novel approach for decreasing capillary pressure to reduce the shrinkage of cement-based materials by designing a new admixture with pH-responsive characteristics, which can spontaneously achieve the hydrophilic to hydrophobic transformation through the alkaline environment of cement pore solution. Excellent pH-response and shrinkage reduction in cement mortars were shown. Most importantly, this novel approach was proved to be effective, which had great potential in inhibiting the shrinkage and cracking of cement-based materials.

中文翻译：

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一种减少水泥基材料收缩的新方法：从亲水到疏水转变的 pH 响应外加剂

降低混凝土开裂风险的有效方法之一是通过添加减少收缩外加剂 （SRA） 来减少干燥收缩，这通常基于降低表面张力的机制。根据 Young-Laplace 方程，增加接触角的机制也应该非常有效。然而，外加剂疏水性的增加必然会导致相容性和有效性的降低，目前仍未解决。本研究旨在通过设计一种具有 pH 响应特性的新型外加剂来提供一种降低毛细管压力以减少水泥基材料收缩的新方法，该外加剂可以通过水泥孔隙溶液的碱性环境自发地实现亲水到疏水的转变。水泥砂浆表现出优异的 pH 响应和收缩降低。最重要的是，这种新方法被证明是有效的，在抑制水泥基材料的收缩和开裂方面具有巨大潜力。