Development of microfine cement grouts by pulverizing ordinary cements
TL;DR: In this article, three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum grain sizes of 40, 20 and 10μm.
Abstract: Three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0%, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum grain sizes of 40, 20 and 10 μm. Cements with the two finer gradations are classified as “microfine” cements. Suspension properties, groutability and effectiveness of all cements were evaluated for water-to-cement ratios (W/C) of 1, 2 and 3 by weight. A superplasticizer was used to optimize rheological properties. The properties and performance of all suspensions tested are affected primarily by W/C ratio and cement fineness. All microfine cement suspensions have acceptable apparent viscosity, behave as Bingham fluids, are stable for W/C = 1, have reasonable setting times for field applications, have mostly predictable groutability and provide satisfactory strength to grouted sands. The finer gradations of II/B-M cement exhibited the best overall behavior and are considered as the most promising compared to similar gradations of the other two cements.
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TL;DR: In this paper, the authors developed high-performance microfine cementitious grout (HPMCG) for high performance microfine Portland cement clinker (MPCC) + flue gas desulfurizing gypsum (MFGDG) + calcium carbonate (MCC) matrix.
Abstract: To develop high-performance microfine cementitious grout (HPMCG), the matrix [microfine Portland cement clinker (MPCC) + flue gas desulfurizing gypsum (MFGDG) + calcium carbonate (MCC)], mi...
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3 citations
01 Jul 2018
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05 Nov 2018
TL;DR: In this article, the effects of different w/b ratios, curing ages, limes and SiO2 on the compressive strength of the new grouting material were investigated.
Abstract: The new grouting material with advantages of early strength, strong liquidity, better expansibility and environmental protection can be applied to underground structure engineering. The effects of different w/b ratios, curing ages, limes and SiO2 on the compressive strength of the new grouting material were investigated. By SEM and TGA-DSC analysis, its microscopic morphology and hydration products are explored. The results show that the early strength of the new grouting material develops rapidly, and the 3d compressive strength can reach 80% of the 28d compressive strength. Under the condition that the w/b ratio is 1.0, the compressive strength increases with CaO content in lime increasing. The addition of micron-SiO2 can improve compressive strength by about 5% when the formulation is reasonable. The main hydration products of SEM-EDS are needle-like ettringite, spherical aluminum gel and amorphous C-S-H(C-A-S-H) gel, corresponding to three endothermic peaks appearing in TGA-DSC at around 90°C, 230°C and 660 °C, respectively.
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Book•
01 Jan 1983
TL;DR: In this article, the authors discuss the application and extension of established rheological techniques to the measurement of workability in place of ''ad hoc' empirical methods, and show that cement pastes behave according to the Bingham model at low shear rates.
Abstract: This book provides information on the workability of fresh concrete. The authors discuss the application and extension of established rheological techniques to the measurement of workability in place of `ad hoc' empirical methods. They show that cement pastes behave according to the Bingham model at low shear rates. This fact combined with the fact that shear rates involved in the handling and placing of concrete are considerably less than those in the mixing process, is the probable reason why concrete itself also conforms closely to the Bingham model. On this basis the authors, drawing on practical experience, develop a practical method of measurement and control. (TRRL)
512 citations
Book•
01 Dec 1989
TL;DR: Mechanical modification hydraulic modification physical and chemical modification modification by inclusions and confinement.
Abstract: Mechanical modification hydraulic modification physical and chemical modification modification by inclusions and confinement.
390 citations
TL;DR: In this paper, the authors reviewed the different aspects of the yield stress phenomenon and tried a synthesis of knowledge and concluded that the choice of observation time or shear rate to use should be related to the characteristic time of the flow process to which the result is to be applied.
Abstract: This paper reviews the different aspects of the yield stress phenomenon and attempts a synthesis of knowledge. Yield stress can be probed using constant shear stress or shear rate. The magnitude of the result depends on the time allowed to determine whether the sample has developed continuous flow or has ceased flowing. It is closely associated with creep, stress growth and thixotropic breakdown and recovery, and the characteristic times of these transient responses play a part in yield stress measurement. In thixotropic fluids, yield stress is a function of structure and hence of time. In simple thixotropy, the yield stress derived from the equilibrium flow curve is the same as that for the fully built-up structure. But in many materials, the static yield stress obtained after prolonged rest is much higher than the dynamic yield stress from the equilibrium flow curve. This is associated with the phenomenon in which the equilibrium flow curve bends upwards as the shear rate is reduced to very low values. The paper also reviews the many methods that can be used to measure yield stress. It is pointed out that the choice of observation time or shear rate to use should be related to the characteristic time of the flow process to which the result is to be applied. Examples discussed are solids suspension capability of fluids, levelling and sagging, pipeline flow and start-up power requirement of mixers.
330 citations
TL;DR: In this article, a scheme for systematizing the handling of viscometric data through use of the variables apparent fluidity φa and shearing stress F is proposed.
Abstract: A scheme is proposed for systematizing the handling of viscometric data through use of the variables apparent fluidity φa and shearing stress F. The rate of shear g(F) is obtained from the relation: g(F)/F =φa[1+Δ(F)]. Methods are presented for obtaining the correction term Δ(F) from capillary and concentric‐cylinder viscometric data. Use of the proposed scheme is illustrated.
138 citations
TL;DR: The possibilities of sealing structures are of great importance from both an economical and environmental point of view as discussed by the authors, and Grouting as a method of strengthening and sealing rock, soil and concrete is widely used.
121 citations