Collaborative enhancement in "strength-toughness-elastic modulus" of calcium-silicate-hydrate (C-S-H) based organic-inorganic composites: Chemical bonding and cracking path optimization

Strength and toughness are destined conflicts in traditional inorganic materials. Herein, we prepared a highperformance calcium-silicate-hydrate (C-S-H) based organic-inorganic composites, with a trace of sodium alginate (about 8 wt%). A 1.9-fold increase in flexural strength and a nearly 6.8-fold enhancement for work of fracture are achieved in the composites, and importantly, the elastic modulus is increased by 22.2 %. Here, flawless C-S-H gel devoid of obvious interphase boundary was formulated attributed to the intercalation of sodium alginate into the C-S-H layer, creating a hybrid bonding network of hydrogen bonds together with the ion complexation effect. Concurrently, sodium alginate is to establish an organic plasticizing zone, aiding in the mitigation of stress within cracks. Hence, our study overcomes the challenge of achieving a harmonious balance between strength and toughness, offering innovative pathways for advancing the development of highperformance organic-inorganic composite materials. Besides, the improvement mechanism proposed in this research provides a pristine and feasible methodology for strengthening and toughening of Portland cementbased materials.