Journal
CEMENT & CONCRETE COMPOSITES
Volume 128, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.cemconcomp.2022.104419
Keywords
Enhanced autogenous healing; Mechanical property; Fluid loss agent; Oil well cement; Hydrophobic surface
Funding
- National Natural Science Foundation of China [51874210]
- China Postdoctoral Science Foundation [2020TQ0221]
- Key Technology Research Project of China National Petroleum Corporation [2020A-3913]
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Enhanced autogenous healing using a cement-polymer composite additive (CPCA) was found to improve the durability and sustainability of cementitious materials. The addition of CPCA-4 improved the compressive strength of hardened cement and enhanced the autogenous healing effectiveness of the matrix.
Enhanced autogenous healing is a desirable solution to improve the long-time durability and sustainability of cementitious materials. Herein, a self-healing agent, also is called cement-polymer composite additive (CPCA), was prepared by pretreatment of cement grains with polymer to accelerate the autogenous self-healing process. The polymer used in CPCA is the siloxane (vinyltrimethoxysilane) modified fluid loss agent (FLA-V), which can greatly reduce the fluid loss from the cement slurry to formation. Water contact angle test showed that the hydrophobic group in the FLA-V endowed CPCAs with different degrees of hydrophobicity, and CPCA-4 had better hydrophobicity. Results of hydration kinetics showed that the addition of CPCA-4 formed the graded hydration system, which densified the micro-structure and further improved the compressive strength of hardened cement. The compressive strength at 7 days was approximately 32.71% higher than that of plain cement. Furthermore, the strength recovery and crack width visualization test indicated that the addition of CPCA-4 enhanced the autogenous healing effectivity of the matrix. The compressive strength of the specimens with 5% CPCA-4 recovered 101.26% of its initial compressive strength after curing for 21 days. The micro-cracks measuring approximately 150 mu m were completely sealed after healing for 28 days. The comprehensive measurements of the healed area indicated that the self-healing products mainly consisted of CaCO3, CH, and C-S-H.
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