Research on the performance of MXMCCC materials for gas leakage sealing

Abstract

Abstract To address the issues of poor strength and low efficiency in traditional clay-cement composite gas-sealing materials (CCC), a method was proposed to prepare a new type of sealing material by utilizing multi-walled carbon nanotubes (MWCNTs) along with xanthan gum (XG) and magnesium oxide (MgO) to modify CCC. Through controlled experiments of water extraction rate testing, the optimal water-to-solid ratio for the multi-component system material has been determined to be 0.6. Mechanical performance testing reveals that when 1.5% xanthan gum, 5% magnesium oxide, and 1.39% multi-walled carbon nanotubes are added, the compressive strength of the multi-walled carbon nanotube-xanthan gum-magnesium oxide-clay-cement composite (MXM-CCC) reaches 18.60 MPa, with a flexural strength of 3.89 MPa. Pore integration analysis reveals that MXM-CCC has a porosity of 17.29%, with pore sizes ranging from 2.00 nm to 50 nm accounting for 71.46% of the total. The proportion of larger pores has decreased, resulting in a more optimal distribution of pore sizes. The formation mechanism and sealing mechanism of MXM-CCC were explored using characterization techniques such as XRD, FTIR, SEM, and thermogravimetric analysis. The hydroxyl and carboxyl groups in konjac gum undergo chelation with Ca²⁺ in CCC, forming a chelate structure. This causes the hydration products of the clay and cement to adhere together, improving the pore structure and mechanical properties of MXM-CCC. The addition of multi-walled carbon nanotubes accelerates the hydration reaction, increasing the content of substances such as C-(A)-S-H gel, ettringite, and Mg(OH)2 in the MXM-CCC. These chemicals act as a framework, providing support within the pores and inhibiting the shrinkage of MXM-CCC, and improving the adhesion between various hydration products. Additionally, multi-walled carbon nanotubes perform a nano-filling role, filling the pores and improving the density of the multi-component material, thereby enhancing its mechanical properties.