Niewiadomski Paweł, Karolak Anna, Stefaniuk Damian, Królicka Aleksandra, Szymanowski Jacek, Sadowski Łukasz
Faculty of Civil Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
Civil and Environmental Engineering Department, Cullen College of Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA.
Materials (Basel). 2021 Nov 18;14(22):6970. doi: 10.3390/ma14226970.
Recently, the research of innovative building materials is focused on applying supplementary materials in the form of micro- and nanopowders in cementitious composites due to the growing insistence on sustainable development. Considering above, in paper, a research on the effect of microsilica and SiO nanoparticles addition to cement paste, designed with Andreasen and Andersen (AA) packing density model (PDM), in terms of its physical and mechanical properties was conducted. Density, porosity, compressive strength, hardness, and modulus of indentation were investigated and compared regarding different amount of additives used in cement paste mixes. Microstructure of the obtained pastes was analyzed. The possibility of negative influence of alkali-silica reaction (ASR) on the mechanical properties of the obtained composites was analyzed. The results of the conducted investigations were discussed, and conclusions, also practical, were presented. The obtained results confirmed that the applied PDM may be an effective tool in cement paste design, when low porosity of prepared composite is required. On the other hand, the application of AA model did not bring satisfactory results of mechanical performance as expected, what was related, as shown by SEM imaging, with inhomogeneous dispersion of microsilica, and creation of agglomerates acting as reactive aggregates, what as a consequence caused ASR reaction, crack occurrence and lowered mechanical properties. Finally, the study found that the use of about 7.5% wt. of microsilica is the optimum in regards to obtain low porosity, while, to achieve improved mechanical properties, the use of 4 wt. % of microsilica seems to be optimal, in the case of tested cement pastes.
近年来，由于对可持续发展的要求日益提高，创新建筑材料的研究集中在将微粉和纳米粉形式的辅助材料应用于水泥基复合材料中。考虑到上述情况，本文依据安德烈亚森和安德森（AA）堆积密度模型（PDM），对添加微硅粉和SiO纳米颗粒的水泥浆体的物理和力学性能进行了研究。研究并比较了水泥浆体混合物中使用不同添加量时的密度、孔隙率、抗压强度、硬度和压痕模量。分析了所得浆体的微观结构。分析了碱-硅反应（ASR）对所得复合材料力学性能产生负面影响的可能性。对所进行的研究结果进行了讨论，并给出了结论，包括实际应用方面的结论。所得结果证实，当需要制备低孔隙率的复合材料时，所应用的PDM可能是水泥浆体设计中的有效工具。另一方面，AA模型的应用并未带来预期的令人满意的力学性能结果，如扫描电子显微镜成像所示，这与微硅粉的不均匀分散以及形成作为活性集料的团聚体有关，结果导致了ASR反应、裂纹出现和力学性能下降。最后，研究发现，就获得低孔隙率而言，使用约7.5%重量的微硅粉是最佳的，而对于测试的水泥浆体，为了提高力学性能，使用4%重量的微硅粉似乎是最佳的。
