Abstract
Adding an expansive agent to ordinary grout can cause an expansion in volume, but also reduces its strength. In order to improve the strength of expansive grout, quartz sand is used as the strength enhancement additive. In this study, the expansion behavior and mechanical properties of the expansive grout with quartz sand are explored, through expansion development monitoring, uniaxial compression strength (UCS), acoustic emission (AE), SEM and XRD test methods. The results showed that: (1) The final expansion ratio and expansion development of the samples are related to the use of an expansive agent, but not affected by quartz sand. With the increase in expansion agent content, the average expansion ratios of the samples are 0.03%, 0.16%, 0.67%, 1.06% and 1.48%; (2) The UCS of the samples decreases with the increase in expansive agent content but increases with the increase in quartz sand content. Compared with no quartz sand, and with the increase in quartz sand content, the average strength of the samples increased by 10.51%, 29.88%, and 37.92%; (3) Quartz sand does not effectively participate in the hydration reaction, but it can effectively enhance the strength of the expansive grout without affecting its volume expansion, which makes it an ideal expansive grout strength enhancement additive.
Highlights
During the construction of underground roadways, fractured rock masses are often encountered, and the stability of the fractured rock masses becomes an obstacle to the tunnel support engineering [1,2]
Under the condition of different expansive agent contents, compared with the uniaxial compression strength (UCS) of the sample with no quartz sand, when the quartz sand contents were 5%, 10%, 15%, the UCS increased by 10.51%, 29.88%, and 37.92% on average, respectively
In order to effectively improve the strength of the expansive grout, ultrafine quartz sand is used as the added aggregate
Summary
During the construction of underground roadways, fractured rock masses are often encountered, and the stability of the fractured rock masses becomes an obstacle to the tunnel support engineering [1,2]. Because the grout is usually an ordinary cement material, its shrinkage may affect the grouting effect [11,12] In response to this problem, an expansive grout using an expansive agent has been developed. Quartz sand is low cost and widely available, and possesses stable chemical properties, effectively not reacting with cement components It may be the most suitable strength-enhancing material for expansive grout [26,27]. SEM and XRD tests are conducted to analyze the morphological characteristics and phase composition of the expansive grout, and the expansion and mechanical performance of samples with different contents of expansive agent and quartz sand on a microscopic level are explained. As a mineral admixture, is introduced to improve the hydration degree of cement, increase the density of cement by filling the voids created by Ca(OH) crystals, and increase the strength of the grout
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