Long-Term Mechanical Behavior of Nano Silica Sol Grouting.

Dongjiang Pan,Nong Zhang,Changliang Han,Deyu Qian,Sen Yang,Chenghao Zhang

doi:10.3390/nano8010046

Abstract

The longevity of grouting has a significant effect on the safe and sustainable operation of many engineering projects. A 500-day experiment was carried out to study the long-term mechanical behavior of nano silica sol grouting. The nano silica sol was activated with different proportions of a NaCl catalyst and cured under fluctuating temperature and humidity conditions. The mechanical parameters of the grout samples were tested using an electrohydraulic uniaxial compression tester and an improved Vicat instrument. Scanning electron microscope, X-ray diffraction, and ultrasonic velocity tests were carried out to analyze the strength change micro-mechanism. Tests showed that as the catalyst dosage in the grout mix is decreased, the curves on the graphs showing changes in the weight and geometric parameters of the samples over time could be divided into three stages, a shrinkage stage, a stable stage, and a second shrinkage stage. The catalyst improved the stability of the samples and reduced moisture loss. Temperature rise was also a driving force for moisture loss. Uniaxial compressive stress-strain curves for all of the samples were elastoplastic. The curves for uniaxial compression strength and secant modulus plotted against time could be divided into three stages. Sample brittleness increased with time and the brittleness index increased with higher catalyst dosages in the latter part of the curing time. Plastic strength-time curves exhibit allometric scaling. Curing conditions mainly affect the compactness, and then affect the strength.

Highlights

Nano silica sol is a kind of grouting material made up of nanometer particles that is highly transmissive [1]; it has been used in the geotechnical field in recent years [2]
Graphs The in Figure show that the catalyst the stability of the decrease approximately catalyst can apparently decrease theenhances shrinkage rate and prolong samples and reduces moisture loss
Axelsson’s 180-day experiments showed that the greater the relative humidity, the less the drying shrinkage and that shrinkage tended to stabilize by day 180

Summary

Introduction

Nano silica sol is a kind of grouting material made up of nanometer particles that is highly transmissive [1]; it has been used in the geotechnical field in recent years [2]. Studied permanent barrier systems formed by colloidal silica and polysiloxane for contaminant isolation. Saito et al [5] proposed the use of silica sol to maintain overburden stability during shield tunneling. Butron et al [6,7] tested the mechanical properties and failure of silica sol used for rock grouting for periods of up to half a year. Funehag et al [8,9,10] designed a grouting procedure for a tunnel using silica sol. McCartney et al [11] evaluated the formation of hydraulic barriers for secondary containment through the permeation of colloidal silica grout. Gallagher et al [12] studied a passive site stabilization technique for nondisruptive mitigation of liquefaction risk using colloidal

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