Alkali Pozzolan cement (APC) comprises a high volume of fly ash, lime, ordinary Portland cement (OPC), and a dry Na2SO4 activator. APC can be stored in dry form and only requires water to create a cementitious binder. Mechanical and microstructural properties of APC were investigated to determine the compressive strength and hydration products of different APC pastes. Air-cured APC pastes (w/b = 0.3) were found to gain 65–77% of the strength of similar OPC pastes at 28 days, while being 75% greater than that of corresponding high-volume fly ash ones. Microstructural properties studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermal analysis were able to explain the observed mechanical properties. The attacking of the smooth fly ash spheres (observed via SEM) by Ca(OH)2, evidenced by a reduction in the latter (observed through thermogravimetry) over a period of 112 days, could be linked to the strength gain of APC over that period. This strength gain could also be associated with the formation of ‘broad humps’, at the relevant 2θ values (around 29° and 32°) in XRD curves, which became more pronounced with time. Strength could also be correlated to the percentage of hydrate bound water, with the differing amounts of lime consumption by fly ash partly responsible for scatter.

中文翻译：

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碱火山灰水泥 (APC) 的机械和微观结构特性

碱性火山灰水泥 (APC) 包含大量粉煤灰、石灰、普通波特兰水泥 (OPC) 和干燥的 Na2SO4 活化剂。APC 可以干燥形式储存，只需要水就可以形成水泥粘合剂。研究了 APC 的机械和微观结构特性，以确定不同 APC 糊剂的抗压强度和水合产物。发现空气固化的 APC 浆料（w/b = 0.3）在 28 天时获得了类似 OPC 浆料的 65-77% 的强度，同时比相应的高容量飞灰浆料的强度高 75%。使用 X 射线衍射、扫描电子显微镜、能量色散 X 射线光谱和热分析研究的微观结构特性能够解释观察到的机械性能。Ca(OH)2 对光滑粉煤灰球体的侵蚀（通过 SEM 观察），后者（通过热重法观察）在 112 天内的减少证明了这一点，这可能与 APC 在此期间的强度增加有关。这种强度增加也可能与 XRD 曲线中相关 2θ 值（约 29° 和 32°）处“宽峰”的形成有关，随着时间的推移变得更加明显。强度也可能与水合物结合水的百分比相关，飞灰消耗的石灰量不同，部分原因是分散。