Abstract
In this investigation, sodium silicate (SS) was mixed into rich-water (RW) materials consisting of Portland cement, calcium aluminate cement and gypsum for improved mechanical properties. The RW materials containing different amounts of SS were characterized by the compression test, mercury intrusion porosity, scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The results demonstrated that with the increase of SS additions, the early strength of the RW materials increases, and the long-term strength retrogression of the RW materials can be inhibited when the SS content is above 3%. Pore structures of the RW materials are improved significantly due to the filling effect of the calcium silicate hydration (C–S–H) gel from a reaction between silicate ions and Ca(OH)2, thus increasing the early strength of the RW materials. For the RW materials containing SS and cured for 0 to 14 days, there are more hexagonal hydrates including CaO·Al2O3·10H2O (CAH10) and 2CaO·Al2O3·8H2O (C2AH8), more C–S–H gel and less ettringite crystals, which is of benefit to the strength of the material. The strength retrogression can be attributed to phase conversions from hexagonal hydrates (CAH10 and C2AH8) to cubic ones (3CaO·Al2O3·6H2O) with lower intercrystal bonding forces. Furthermore, this phase conversion is inhibited effectively by the chemical reaction of silicate ions and CAH10 (or C2AH8), improving the long-term strength of the RW materials.
Highlights
Advanced materials that have properties of high water–solid ratio (W/S), low cost, good strength and durability, are required in the elds of mining engineering, tunnel engineering and oil– gas development
The compressive strength increases until 14 day, and the strength of the RW materials containing sodium silicate (SS) is likewise higher than that of the RW without SS. It indicates that the early strength of the RW materials is improved by blending SS
Combining with X-ray diffraction (XRD) and FTIR results, for the RW materials with SS, the hydration rate of CAx is inhibited to cause a decrease in the formation of AFt;[32,34] the hydration reaction of CSx and the reaction between SS and calcium hydroxide (CH) are both accelerated to produce much more calcium silicate hydration (C–S–H) to improve the early strength of the material.[15]
Summary
Advanced materials that have properties of high water–solid ratio (W/S), low cost, good strength and durability, are required in the elds of mining engineering, tunnel engineering and oil– gas development. High water materials consisting of sulphoaluminate cement (or its clinker), gypsum and lime have been applied to these engineering elds as lling media.[1,2] The compressive strength of the high water materials is very low at a high value of W/S, and the strength decreases over time due to water-loss.[3] To improve the mechanical property of the high water materials, calcium aluminate cement (CAC) was added to sulphoaluminate cement to obtain a novel high water material composed of sulphoaluminate cement, CAC, gypsum, lime and other additives.[4] when stirring water, sulphoaluminate cement, gypsum and lime together by a single-liquid grouting method, the setting time of the high water material pastes is excessively short, which cannot meet the requirements of eld-scale applications. To avoid the rapid setting, the high water materials should be divided into two parts for stirring, and the pastes a er stirring are grouted via a common pipe
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
