The development of cracks inside concrete is harmful to the structural durability of seawater coral aggregate concrete (CAC) subjected to an aggressive marine environment. Thus, three-point bending (TPB) tests were performed on the notched beams to determine the fracture properties of cement-based CAC and slag-based alkali-activated CAC (AACAC) at different initial crack-depth ratios (a₀/H = 0.2, 0.3, 0.4, and 0.5) and alkaline contents (Na₂O-to-binder ratios of 3%, 4%, and 6% by mass). The initial fracture toughness ($K_{\mathrm{I}\mathrm{C}}^{\mathrm{i}\mathrm{n}\mathrm{i}}$), critical effective crack length (a_c), and unstable fracture toughness ($K_{\mathrm{I}\mathrm{C}}^{\mathrm{u}\mathrm{n}}$) of the CAC and AACAC were calculated and analyzed based on the double-K fracture criterion. Then, the fracture energy (G_F) and characteristic length (l_ch) were introduced to analyze the energy consumption and brittleness of concrete. It was found that increasing the a₀/H ratio reduced the initial cracking load (P_ini), peak load (P_max), a_c, G_F, and l_ch, but increased the P_ini/P_max ratio, $K_{\mathrm{I}\mathrm{C}}^{\mathrm{i}\mathrm{n}\mathrm{i}}$, $K_{\mathrm{I}\mathrm{C}}^{\mathrm{u}\mathrm{n}}$, and $K_{\mathrm{I}\mathrm{C}}^{\mathrm{i}\mathrm{n}\mathrm{i}}/K_{\mathrm{I}\mathrm{C}}^{\mathrm{u}\mathrm{n}}$ ratio, implying that a higher a₀/H ratio had a detrimental effect on the crack propagation and increased the brittleness of the AACAC. Additionally, a higher alkaline content, i.e., a greater compressive strength of concrete, upgraded the values of P_ini, P_max, $K_{\mathrm{I}\mathrm{C}}^{\mathrm{i}\mathrm{n}\mathrm{i}}$, $K_{\mathrm{I}\mathrm{C}}^{\mathrm{u}\mathrm{n}}$, and G_F due to better mechanical interaction at paste-aggregate interfaces. However, the P_ini/P_max ratio, a_c, and l_ch were steadily lowered with increasing concrete strength, justified by an increase in brittleness. Moreover, the notched AACAC beams contained higher a_c (approximately 12.2% increase) and lower $K_{\mathrm{I}\mathrm{C}}^{\mathrm{i}\mathrm{n}\mathrm{i}}/K_{\mathrm{I}\mathrm{C}}^{\mathrm{u}\mathrm{n}}$ (approximately 4.6% decrease) than those of the notched CAC beams, demonstrating that the existence of alkali-activated materials (AAMs) was beneficial to crack propagation due to improved interfacial transition zone (ITZ) between the paste matrix and aggregates.

混凝土内部裂缝的发展对海水珊瑚骨料混凝土 (CAC) 在侵蚀性海洋环境中的结构耐久性有害。因此，对缺口梁进行了三点弯曲（TPB）试验，以确定水泥基 CAC 和矿渣基碱活化 CAC（AACAC）在不同初始裂纹深度比（a ₀ / H  = 0.2、0.3、0.4 和 0.5) 和碱含量（Na ₂ O 与粘合剂的质量比为 3%、4% 和 6%）。初始断裂韧性（${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{一世}\mathrm{n}\mathrm{一世}}$)、临界有效裂纹长度 ( a _c ) 和不稳定断裂韧性 (${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{你}\mathrm{n}}$) 的 CAC 和 AACAC 基于双 K 断裂准则进行计算和分析。然后，断裂能（G ^ _˚F）和特征长度（升_CH）引入到分析混凝土的能量消耗和脆性。据发现，增加一个₀ / ħ比率降低了初始开裂荷载（P _INI），峰值负荷（P_最大），一个_Ç，ģ _˚F，和升_CH，反而增加了P _INI / P_最大比率，${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{一世}\mathrm{n}\mathrm{一世}}$, ${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{你}\mathrm{n}}$， 和 ${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{一世}\mathrm{n}\mathrm{一世}}/{钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{你}\mathrm{n}}$比率，这意味着较高的₀ / H比率对裂纹扩展产生不利影响并增加了 AACAC 的脆性。此外，较高的碱含量，即混凝土的较大抗压强度，提高了P _ini、P _max、${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{一世}\mathrm{n}\mathrm{一世}}$, ${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{你}\mathrm{n}}$, 和G _F由于在膏体-聚集体界面更好的机械相互作用。然而，随着混凝土强度的增加，P _ini / P _max比值a _c和l _ch稳步降低，这是由脆性增加证明的。此外，缺口 AACAC 光束包含更高的a _c（大约增加 12.2%）和更低的${钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{一世}\mathrm{n}\mathrm{一世}}/{钾}_{\mathrm{一世}\mathrm{C}}^{\mathrm{你}\mathrm{n}}$ （减少约 4.6%）比缺口 CAC 梁的那些，表明碱激活材料 (AAM) 的存在有利于裂纹扩展，因为改善了糊状基质和聚集体之间的界面过渡区 (ITZ)。