Mechanical Properties Evaluation of Polymer-Binding C-S-H Structure from Nanoscale to Macroscale: Hydroxyl-Terminated Polydimethylsiloxane (PDMS) Modified C-S-H

Abstract

Exploring and modifying the C-S-H structure at a micro–nano level is an effective solution to improve the performance of Portland cement. Compared with organics inserting C-S-H, the research on the performance of a polymer-binding C-S-H structure from nanoscale to macroscale is limited. In this work, the mechanical properties of a modified C-S-H, using hydroxyl-terminated polydimethylsiloxane (PDMS) as the binders, are evaluated. The PDMS-modified C-S-H structures are introduced into macro-defect-free cement to obtain stress–strain curves changes at a macro scale. The AFM–FM was adopted to measure the morphology and elastic modulus of C-S-H at a nano scale. The molecular dynamics (MD) simulation was performed to assess the toughness, tensile properties, and failure mechanism. The results show that the PDMS-modified C-S-H powders change the break process and enhance ductility of MDF cement. The elastic modulus of PDMS-modified C-S-H is lower than pure C-S-H. When PDMS molecules are located between the stacking crystal units, it can enhance the toughness of C-S-H aggregates. The PDMS-modified C-S-H stacking structure has better plasticity, and its tensile strains are higher than the pure C-S-H. PDMS molecules hinder the initial crack expansion, leading to the branching of the initial crack. In addition, the measurement of AFM–FM can identify and obtain the mechanical properties of basic units of C-S-H. This paper enhances the understanding of cement strength sources and modification methods.

Recombinant SARS-CoV-2 Spike Protein Stimulates Secretion of Chymase, Tryptase, and IL-1β from Human Mast Cells, Augmented by IL-33

“…This result is of clinical relevance as blood IL-1β levels are increased in patients with COVID-19 [53,54], and administration of the IL-1 receptor antagonist Anakinra improved outcomes of severe COVID-19 patients [54]. IL-33 has been implicated in severe COVID-19 [55][56][57][58][59][60][61][62]. Moreover, IL-33 was reported to increase the expression of ACE2 [63].…”

Frustrated π-stacking

“…8,63,64 The introduction of bulky substituents on the rigid p-scaffolds is best suited to achieve the slipped arrangement of J-aggregates. [65][66][67][68][69] The exceptional planarity of 4,4-difluoro-4-bora-3a,4a-diaza-sindacene (BODIPY) fluorophores makes them particularly prone to p-p stacking, a phenomenon widely recognized for its tendency to diminish emission efficiency in most instances. By judiciously introducing 'spheroidal' bulky substituents such as adamantyl groups, 70 [2,2]paracyclophane, 71 or triphenylamine 72 at the BODIPY core, face-to-face molecular packing mode between the indacene planes is discouraged, resulting in J-aggregates with a slipping angle.…”

State of Charge Estimation for Lithium‑Ion Batteries Based on Extended Kalman Particle Filter and Orthogonal Optimized Battery Model

“…However, the HPPC experiment has no fixed experimental content. [27][28][29][30] Wang et al [31] investigated the effects of different pulse times, current multiples, and shelving times on battery modeling accuracy in the HPPC experiment. They found that the three factors can significantly affect the accuracy of parameter identification.…”