Use of enhanced pre-mixed self-hardening grout for an emergency cut-off wall intervention in west africa-Paper

Paper

Pdf Summary

Buyo Dam in Côte d’Ivoire experienced sharply increased seepage and localized ground depressions along its right bank, raising concerns about embankment stability. Investigations identified an erodible, relatively permeable micaceous clayey silt layer beneath the dam as the likely seepage path.<br /><br />To intercept the flow, a 400 m long, 800 mm thick cut-off wall was installed from the dam crest while the reservoir remained near its normal operating level. The wall extended through the critical soil layer and into underlying weathered schist. Because bentonite was unavailable locally and the schedule was urgent, the contractor imported a factory-produced, pre-blended self-hardening grout. This approach enabled rapid mix qualification and consistent material quality; site crews mixed the powder with water and monitored the fresh grout.<br /><br />Construction began less than two months after contract award and took 103 calendar days. Primary and secondary panels were excavated using a hydraulic grab, with their overlaps designed to maintain wall continuity. The work proceeded without major operational problems or movement of the dam.<br /><br />Routine testing monitored fresh-grout properties and hardened samples. Independent laboratory results met the specified strength, deformability, and permeability requirements; measured hydraulic conductivity ranged from 10⁻⁸ to 10⁻¹⁰ m/s. Core drilling and water tests at panel joints also confirmed the wall’s integrity and acceptable permeability.<br /><br />The project demonstrates that pre-blended self-hardening grout can be an effective solution when rapid construction and dependable material quality are essential, particularly where suitable raw materials or local production expertise are lacking.

Keywords

Buyo Dam

Côte d’Ivoire

seepage control

cut-off wall

embankment stability

self-hardening grout

micaceous clayey silt

hydraulic conductivity

grout wall construction

dam rehabilitation