Printability, Thermal and Compressive Strength Properties of Cementitious Materials: A Comparative Study with Silica Fume and Limestone

Abstract

Over the past decade, 3D printing in the construction industry has received worldwide attention and developed rapidly. The research and development of cement and concrete products has also become quite well-established over the years, while other sustainable materials receive considerably lower attention in comparison. This study aims to investigate the influence of the two most commonly used sustainable cementitious materials i.e., silica fume and limestone powder, on printability, thermal and mechanical properties of fly ash–Portland cement blends. Ternary blends containing Portland cement, fly ash and silica fume or limestone powder are prepared, whereas phase change material (PCM) is introduced to improve the thermal behavior. Based on the rheological properties and concurrent 3D concrete printing, improved buildability of the modified mixtures is linked to their static yield stress. Anisotropic mechanical properties are observed for 3D printed specimens, while cast specimens exhibit a maximum 41% higher compressive strength due to better material compaction. It is clear from the results that addition of silica fume and limestone powder ranged from 5% to 10%, reducing the anisotropic mechanical properties (maximum 71% and 68% reduction in anisotropic factor, respectively) in the printed specimens. The PCM addition ranged from 5% to 10% and improved thermal performance of the mixtures, as measured by a decrease in thermal conductivity (9% and 13%) and an increase in volumetric heat capacity (9% and 10%), respectively. However, the PCM-containing mixtures show around 29% reduction in compressive strength, compared to the control specimen, which necessitates new material design considering matrix strengthening methods.

Study of Microstructure, Crystallographic Phases and Setting Time Evolution over Time of Portland Cement, Coarse Silica Fume, and Limestone (PC-SF-LS) Ternary Portland Cements

“…Srinivas et al [11] manufactured ternary cements by mixing Portland cement, coal fly ash, and silica fume or limestone powder to assess their rheological properties, and they found that their enhanced buildability was linked to their static yield stress. Therefore, silica fume and limestone, ranging from 5% to 10% with higher static yield stress, enhanced the buildability and reduced the anisotropic mechanical properties.…”

Effect of Silica Fume Utilization on Structural Build-Up, Mechanical and Dimensional Stability Performance of Fiber-Reinforced 3D Printable Concrete

“…The highest increase in thixotropic behavior compared to the control mixture was obtained in the SF-6% and SF-9% mixture and the A thix method. In a similar study involving SF by [ 55 ], it was reported that SF has an optimum usage rate on its rheological properties. It was declared by the authors that substituting up to 10% of cement with SF increases the buildability of 3D printable concrete mixtures by providing higher SYS without affecting their extrudability.…”

“…It was reported that the use of SF significantly increases the height change caused by DS at the early ages [ 73 ]. In a study conducted by [ 55 ], the effect of changing the SF usage rate on the CS of 3D printable concrete mixtures was examined. It was determined that the CS values of mixtures containing 5% and 10% SF were lower than the control mixture.…”

Machine Learning-Based Predictive Model for Tensile and Flexural Strength of 3D-Printed Concrete

“…It can also reduce the heat of hydration and mitigate the risk of thermal cracking. However, its use may require adjustments to the mix design and printing parameters [67,175].…”

“…This can cause tearing defects in the final printed layer [59]. The literature shows that the addition of cement content, nano clay [60,61], fiber content [62][63][64][65], silica fume [66,67], and fly ash [68][69][70][71] increases the yield strength of the concrete mix for printing purposes. Still, at the same time, they decrease the extrudability of the printable mix.…”