Steric stabilization of graphene oxide in alkaline cementitious solutions: Mechanical enhancement of cement composite
Steric stabilization of graphene oxide in alkaline cementitious solutions: Mechanical enhancement of cement composite
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DOI：
10.1016/j.matdes.2017.04.083
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发表时间：
2017-08-05
影响因子：
8.4
通讯作者：
Li, Zongjin
中科院分区：
文献类型：
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作者：
Lu, Zeyu;Hanif, Asad;Li, Zongjin
氧化石墨烯（GO）具有优异的性能，被认为是一种很好的增强胶凝材料的候选材料。由于GO具有多种含氧官能团，在水溶液中分散性好，但在碱性胶凝溶液中不稳定，限制了GO在胶凝材料力学性能增强中的充分利用。在本研究中，通过预加入聚羧酸酯-醚（PCE）共聚物，在与水泥混合之前获得稳定的GO水溶液。实验结果表明，由于PCE具有较强的空间位阻和氢键作用，可以显著提高GO在碱性胶凝溶液中的分散性和稳定性。然而，GO突然团聚时，它首先与水泥混合通过快速的物理和化学相互作用，和后加入的PCE有微不足道的帮助去絮凝GO。在机械性能方面，水泥浆与稳定的GO-PCE相比，由于更好地分散在硬化水泥基体中的GO，没有PCE表现出更高的抗折强度和抗压强度。因此，通过预掺PCE，保证GO在碱性胶凝溶液中的良好分散，是提高GO对水泥浆体力学性能增强作用的前提。
Graphene oxide (GO) with extraordinary properties has been regarded as a good candidate to reinforce cementitious materials. Due to a variety of oxygen functionalities, GO can be well dispersed in aqueous solutions but unstable in the presence of alkaline cementitious solutions, which restricts the fully utilization of GO to the mechanical enhancement of cementitious materials. In this study, a stabilized GO aqueous solution by pre adding polycarboxylate-ether (PCE) copolymer was obtained before mixing with cement. The experimental results indicated that PCE can significantly improve the dispersion and stability of GO in alkaline cementitious solutions due to the stronger steric repulsion and hydrogen bonding. However, GO suddenly agglomerated when it was firstly mixed with cement by a rapid physical and chemical interaction, and post-addition of PCE has negligible helps to de-flocculate the GO. In terms of mechanical properties, cement paste with the stabilized GO-PCE showed higher flexural and compressive strength in comparison to that without PCE due to the better dispersion of GO in the hardened cement matrix. In conclusion, the prerequisite to make GO contribute more to the mechanical enhancement of cement paste is to ensure the good dispersion of GO in alkaline cementitious solutions achieved by pre-adding PCE.