富水环境对水泥基抗分散注浆材料水化产物黏附体系的影响

Influence of water-rich environment on the adhesion system of hydration products of cement-based anti-dispersion grouting materials

  • 摘要: 在煤炭开采过程中,矿井巷道在穿过富水且构造发育的地层时,容易揭露导水通道进而引发突水事故。为提升水泥基注浆材料在富水环境中的工作性能,使用聚丙烯酰胺(PAM)与水玻璃作为外加剂对普通硅酸盐水泥进行改性。并采用分子动力学模拟的方法,构建水泥与外加剂混合产物的界面模型,通过调整层间水分子数量用以模拟水化产物所处的不同含水量环境。进一步地,采用多种微观表征实验对模拟结果进行了论证。结果表明:PAM–水玻璃结构展现出良好的亲水性,较强的亲水性使其与C–S–H的结合具有较强的黏附性,能够更好的适应富水环境;水泥−水−PAM−水玻璃界面脱黏功的变化具有无规律性,在含水量为6%时,水泥−水−PAM−水玻璃界面脱黏功达到最大临界点为37 465.715 mJ/m2,在更高含水量下,水分子透过孔隙结构与材料内部发生更深层次的水合反应,增强了界面稳定性;XRD图谱中的衍射峰与计算模拟中预测的C–S–H和PAM–水玻璃的存在形式相吻合,证实了聚丙烯酰胺和水玻璃会与水泥水化过程中产生的Ca2+和Si4+发生反应;SEM图像显示,水泥–聚丙烯酰胺和水玻璃界面上存在大量水化颗粒和微孔隙,包括针状和球状结晶,这些水化颗粒可能是聚丙烯酰胺和水玻璃参与水泥水化过程形成的增强界面黏附性的水化产物,而微孔隙的存在是导致模拟中出现相互作用能和脱黏功的变化主要原因。通过分子动力学模拟与实验结果的可以证明PAM与水玻璃形成的絮体结构具有良好的亲水性。相较于传统水泥注浆材料,PAM–水玻璃改性水泥浆液中絮体结构与水泥水化产物C–S–H的黏附性能更强,这有效锁住了水化产物层间水分,从而提高了富水环境中浆液的稳定性。

     

    Abstract: In the process of coal mining, when the mine roadways pass through water rich and structurally developed strata, it is easy to expose water channels and cause water inrush hazards. In order to improve the working performance of cement-based grouting materials in water rich environments, this paper used polyacrylamide (PAM) and water glass as additives to modify ordinary Portland cement. Also, using the molecular dynamics simulation method, an interface model of cement and admixture mixed products was constructed, and the number of interlayer water molecules was adjusted to simulate the different water content environments of hydration products. Furthermore, various microscopic characterization experiments were used to verify the simulation results. The results show that the PAM water glass structure exhibits a good hydrophilicity, and the strong hydrophilicity enables its binding with C–S–H to have strong adhesion, which can better adapt to water rich environments. The variation of debonding energy at the interface of cement − water − PAM − water glass exhibits irregularity. At a moisture content of 6%, the debonding energy at the interface of cement − water − PAM − water glass reaches the maximum critical point of 37 465.715 mJ/m2. At higher moisture contents, water molecules penetrate the pore structure and undergo deeper hydration reactions with the interior of the material, enhancing interface stability. The diffraction peaks in the XRD pattern are consistent with the predicted forms of C–S–H and PAM water glass in the computational simulation, confirming that polyacrylamide and water glass will react with Ca2+ and Si4+ generated during the cement hydration process. The SEM images show that there are a large number of hydration particles and micropores, including needle shaped and spherical crystals, at the interface between cement polyacrylamide and water glass. These hydration particles may be hydration products that enhance the interfacial adhesion formed by polyacrylamide and water glass participating in the cement hydration process. The presence of micropores is the main reason for the changes in interaction energy and debonding work observed in the simulation. Through molecular dynamics simulation and experimental results, it can be proved that the floc structure formed by PAM and water glass has good hydrophilicity. Compared with the traditional cement grouting materials, the floc structure in the PAM-water glass modified cement slurry has stronger adhesion properties with the cement hydration products C–S–H, which effectively locks the water between the layers of hydration products, thus improving the stability of the slurry in the water-rich environment.

     

/

返回文章
返回