Abstract
The effects or high CaO fly ash and sulfate activator on cementless grouting material were investigated through Labiles Waterglass (LW) grouting applied at an actual construction field. Circulating fluidized bed combustion ash was used as CaO fly ash, and petro cokes desulfurization gypsum was used as sulfate activator. Cementless grouting material (CGM) could decrease the gel time by about 16.7% compared with ordinary Portland cement (OPC). This characteristic improved the average daily workload and construction period per meter by about 13.5% with CGM. Furthermore, when constructing 1000 holes of LW grouting, the construction time could be reduced by 19 days (20% of the total construction period of LW grouting). Meanwhile, CGM could increase the homogel strength by about 48.4% after 28 days compared with OPC. After X-ray diffraction analysis and scanning electron microscope analysis, CGM was found to produce cement hydrate by chemical reaction mechanism of high CaO fly ash and sulfate activator, even though cement was not used. The matrix structure properties of CGM and OPC specimens were similar, but CGM, with 134.3% fineness, exhibited higher compressive strength and lower air permeability than OPC. As a result, CGM could reduce the leakage length per square meter by 74.4% compared with OPC. Using CGM as a substitute for OPC in LW grouting in actual sites could be beneficial in terms of securing construction speed and durability, as well as reducing CO2 emissions due to reduction of OPC usage.
Highlights
The Labiles Waterglass (LW) grouting method is a type of chemical injection method developed to increase water resistance and strengthen grounds by mixing sodium silicate number 3 (SS (No 3))solution and ordinary Portland cement (OPC) suspension
In our previous study, we reviewed the engineering properties of cementless grouting material (CGM) that can replace the OPC, an existing binder type of the LW grouting method
As a result, when constructing 1000 holes of LW grouting, the construction time could be reduced by 19 days (20% of the total construction period of LW grouting)
Summary
The Labiles Waterglass (LW) grouting method is a type of chemical injection method developed to increase water resistance and strengthen grounds by mixing sodium silicate number 3 (SS (No 3))solution (liquid A) and ordinary Portland cement (OPC) suspension (liquid B). The use of admixture materials that can significantly reduce cement clinker production is effective for reducing CO2 emissions, because most of the CO2 emission generated during the manufacturing process of construction materials are known to occur during cement manufacturing [12,13,14]. They are rarely applied in the Materials 2019, 12, 3664; doi:10.3390/ma12223664 www.mdpi.com/journal/materials
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