Characterizing the Compressive Durability of Cement Grouts Up to Four Years-Paper

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The study examined the setting behavior and long-term compressive properties of Type I Portland cement grouts with water-to-cement ratios (w/c) of 0.6 and 1.0, with and without 10% metakaolin clay. Tests were conducted after 7 and 1,461 days of curing.<br /><br />Higher w/c ratios increased initial and final setting times and reduced compressive strength and modulus. Adding 10% clay shortened setting times and improved strength and stiffness. After four years, the strongest grout—w/c 0.6 with clay—reached 30.6 MPa. At that age, clay increased strength by about 81% at w/c 0.6 and 85% at w/c 1.0 compared with the corresponding clay-free grouts. For clay-modified grouts, strength also increased substantially between 7 days and four years: 99% at w/c 0.6 and 135% at w/c 1.0.<br /><br />All mixes displayed strain-softening behavior. The Vipulanandan p-q model predicted their compressive stress–strain response accurately, with R² values generally around 0.98–0.99. Its parameters were affected by w/c ratio, curing time, and clay content. Nonlinear models were also developed to relate these variables to stress–strain parameters, while a property-correlation model described strength variation with clay content and curing time.<br /><br />The results show that metakaolin can improve the long-term strength and stiffness of cement grout, while higher water content generally weakens performance. These findings support assessing grout properties over extended curing periods for infrastructure and well applications.

Keywords

Portland cement grout

setting time

compressive strength

metakaolin clay

water-to-cement ratio

long-term curing

stress-strain behavior

strain-softening

Vipulanandan p-q model

grout properties