Lightweight cement-based composites with high specific strength and low thermal conductivity are highly sought in the energy and construction industries. These characteristics are important in designing cement liners for high-temperature, high-pressure (HTHP) wells, in addition to those operating in permafrost. Similar attributes are also desirable in designing cementitious composites for energy efficient building envelopes. This work reports the results of an experimental campaign focused on engineering lightweight cementitious composites with hollow glass microspheres. It is demonstrated that the chemical stability of microspheres at HTHP conditions can be directly controlled by modulating the specific surface area and dissolution rate constant of supplementary siliceous additives. In addition to the stabilizing effect, such additives lead to the pore structure refinement and the enhancement of interfacial transition zone (ITZ). Introduced lightweight composites are capable of delivering significant load bearing capacity when normally cured, which is greatly increased by hydrothermal curing. Such high specific strength composites possess thermal conductivity below 0.3 W/mK at the oven dry density <1000 kg/m³ and cement dosage <400 kg/m³. This class of cementitious composites bears potential to enhance zonal insulation and well integrity, as well as increasing energy efficiency of building envelopes.

具有高比强度和低热导率的轻质水泥基复合材料在能源和建筑行业中得到了广泛的应用。除了在多年冻土中作业的那些之外，这些特性对于设计用于高温高压（HTHP）井的水泥衬里也很重要。在设计用于节能建筑外墙的水泥复合材料时，也需要类似的属性。这项工作报告了一项针对以中空玻璃微球体工程化轻质水泥复合材料为重点的实验活动的结果。结果表明，通过调节补充硅质添加剂的比表面积和溶解速率常数，可以直接控制HTHP条件下微球的化学稳定性。除了稳定作用 这类添加剂可改善孔隙结构并增强界面过渡区（ITZ）。引入的轻质复合材料在正常固化时能够提供显着的承载能力，而水热固化大大提高了承载能力。此类高比强度复合材料在烘箱干密度<1000 kg / m时具有低于0.3 W / mK的导热率³和水泥用量<400 kg / m ³。这类水泥复合材料具有增强区域隔热和井眼完整性以及提高建筑围护结构的能源效率的潜力。