Diagnostics and regulation of rheological characteristics for injection mortars by electromechanical sensors

A comparative study of the fracture features, strength and deformation properties of pseudo strain-hardening composites based on alkali-activated slag and Portland cement matrices with polypropylene microfiber was carried out. Correlations between their compositions and characteristics of stress–strain diagrams under tension in bending with an additional determination of acoustic emission parameters were determined. An average strength alkali-activated slag matrix with compressive strength of 40 MPa and a high-strength Portland cement matrix with compressive strength of 70 MPa were used. The matrix compositions were selected for high filling the composites with polypropylene microfiber in the amount of 5%-vol. and 3.5%-vol. ensuring the workability at the low water-to-binder ratios of 0.22 and 0.3 for Portland cement and alkali-activated slag matrices, respectively. Deformation diagrams were obtained for all studied compositions. Peaks in the number of acoustic signals in alkali-activated slag composites were observed only in the strain-softening zone. Graphs of dependence of the rate of acoustic events occurrence in samples from the start of the test experimentally prove that this method of non-destructive testing can be used to monitor structures based on strain-hardening composites.

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“…The main advantages when using the fiber-reinforced spray concrete for walling the mine workings are as follows [83][84][85][86][87][88]:…”

Section: Discussionmentioning

confidence: 99%

Strain Hardening of Polypropylene Microfiber Reinforced Composite Based on Alkali-Activated Slag Matrix

Smirnova

Pidal²,

Alekseev³

et al. 2022

Materials

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“…Створення [22,23] ці моделі застосовано для розроблення автоматизованої системи регулювання складу розчину безпосередньо під час його ін'єктування у міжтрубний зазор у разі ремонту каналізаційних колекторів методом вставок.…”

Section: Abstract the Natural And Technological Factors Influencing On The Depth Of Injection Cement Mortars Penetration Into The Crackedunclassified

Injection Model of Cement Mortar Penetration Into Cracked Rocks Behind Walling

Plugin¹,

Kalinin²,

Miroshnichenko³

et al. 2021

ЗНПУДУЗТ

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The natural and technological factors influencing on the depth of injection cement mortars penetration into the cracked rocks and emptiness under the lining of mountain tunnels have been studied. There are the width of cracks in rocks and groundwater pressure in them, the dynamic viscosity of the solution, which is determined by the content of additives-superplasticizer and watercement ratio W/C, the magnitude and duration of pressure during the projection (crimping). Thesefacts were established after the analytical of literature sources and the analysis of features, design and a technical condition of real tunnel, geological structure of processing rocks under their lining. Based on the fundamental rheological equation - Newton's law in viscous flow models of dependences of depth of penetration on factors mentioned above are developed. Because of research of these models the sizes of technological factors, including dynamic viscosity of the mortar, providing the required penetration of cement mortars were received. To ensure the penetration of the solution to a depth of 10 m in cracks with a width of 10 mm, the dynamic viscosity should not exceed over 0.05 Pa·s, and in cracks of 1 mm – 0.01 Pa·s. To ensure the penetration of the solution to a depth of 2 m in cracks with a width of 1 mm, the dynamic viscosity should be in the range of 0.03–0.1 Pa·s, and in cracks of 0.1 mm – 0.0025–0, 01 Pa·s. Superplasticizers allows reducing the dynamic viscosity ofsolutions to such values and effectively increasing the depth of their penetration into cracks and, as a result increasing the water resistance and load-bearing capacity of the fractured rock. The technology of injecting cement mortars with superplasticizer additives has been improved and developed for: the reconstruction of underground structures and massive artificial structures; the designing of a spherical bearing between galvanized concrete without a bald spot and the exposedmetal beams. The technology is recommended to be used for waterproofing and increasing the bearing capacity of tunnel, piers, bridges, and for the device of a laying layer between а withoutballast reinforced concrete bridge plate and longitudinal beams of metal bridges.

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