Miñano Isabel, Benito Francisco J, Valcuende Manuel, Rodríguez Carlos, Parra Carlos J
Department of Architecture and Building Technologies, Technical/Polytechnic University of Cartagena, Paseo Alfonso XIII, 30203 Cartagena, Spain.
Department of Architecture Constructions, Polythenic University of Valencia, Camí de Vera, 46022 Valencia, Spain.
Materials (Basel). 2019 Apr 9;12(7):1147. doi: 10.3390/ma12071147.
The objective of the experimental work is to study the mechanical properties in self-compacting concretes (SCC) in which part of the limestone aggregate has been replaced by granulated blast furnace slag (GBFS) in different percentages ranging from 0% to 60%. The results show that at early ages the SCC with the largest content in slag tend to have lower compressive strengths due to the poor compacting of the aggregates, although in the long-term their strength increases due to the reactivity of the slag. In fact, at the age of 365 days, the mortars made with the substitution of 50% of cement by ground GBFS reach compressive strength similar to that of the mortar made with 100% of cement. The consumption of calcium hydroxide during the hydration of the GBFS and the formation of hydrated calcium silicate (CSH) improve the mechanical properties of the slag-paste interface. The new compounds formed by the hydration of anhydrous oxides of the GBFS improve the aggregate-paste transition zone. The chemical interaction between the dissolution of the cement pore and the GBFS ends up generating new compounds on its surface. The increasing hydration of the GBFS produces a greater amount of silica gel that polymerises, densifying the matrix and reducing the porosity, which improves the mechanical properties of the concrete and perhaps its durability. The topography of the particles and their interface are analysed with atomic force microscopy techniques to assess the morphology depending on the aggregate used. On the other hand, a study was carried out of the aggregate-paste interface with scanning electronic microscope at different ages. It can be seen that in the contours of the hydrated GBFS particles, a band or ring forms with the new reaction products. The results obtained strengthen the previous conclusions. The new hydrated compounds fill the reaction ring, introducing chemical bonds between the aggregate and the interface, occupying part of the original pores or substituting spaces occupied originally by large portlandite crystals, of lesser mechanical strength and easily leached. For all this, the benefit is twofold. On the one hand, use is made of industrial by-products and, on the other hand, part of the destruction of natural quarries to obtain the necessary raw materials is avoided.
实验工作的目的是研究自密实混凝土（SCC）的力学性能，其中部分石灰石骨料已被粒化高炉矿渣（GBFS）以0%至60%的不同比例替代。结果表明，在早期，矿渣含量最高的自密实混凝土由于骨料压实不良，抗压强度往往较低，尽管从长期来看，由于矿渣的反应性，其强度会增加。事实上，在365天时，用磨细的GBFS替代50%水泥制成的砂浆的抗压强度与用100%水泥制成的砂浆相似。GBFS水化过程中氢氧化钙的消耗以及水化硅酸钙（CSH）的形成改善了矿渣-浆体界面的力学性能。GBFS无水氧化物水化形成的新化合物改善了骨料-浆体过渡区。水泥孔隙溶解与GBFS之间的化学相互作用最终在其表面产生新的化合物。GBFS水化的增加产生了更多聚合的硅胶，使基体致密并降低了孔隙率，从而改善了混凝土的力学性能及其耐久性。使用原子力显微镜技术分析颗粒及其界面的形貌，以评估取决于所用骨料的形态。另一方面，在不同龄期用扫描电子显微镜对骨料-浆体界面进行了研究。可以看出，在水化GBFS颗粒的轮廓上，会形成一个带有新反应产物的带或环。获得的结果强化了先前的结论。新的水合化合物填充反应环，在骨料和界面之间引入化学键，占据部分原始孔隙或替代原本由大的氢氧化钙晶体占据的空间，这些晶体的机械强度较低且容易被浸出。综上所述，好处是双重的。一方面，利用了工业副产品，另一方面，避免了为获取必要原材料而对天然采石场的部分破坏。
