Effect of flyash as cement replacement material and pore filling material in concrete

Author(s):  
B. Kameswara Rao ◽  
M. Achyutha Kumar Reddy ◽  
A. Venkateswara Rao
Geophysics ◽  
2011 ◽  
Vol 76 (3) ◽  
pp. E69-E79 ◽  
Author(s):  
Remy Agersborg ◽  
Tor Arne Johansen ◽  
Gary Mavko ◽  
Tiziana Vanorio

Compaction of siliciclastic sediments leads to an increase in their stiffness parameters and seismic velocities. Although mechanical compaction implies a reduction of porosity and closing of compliant pores, chemical compaction may alter the mineral properties, the cementing of grain contacts, and the pore volume. The ability of rock physics models to quantify such effects on seismic observables will aid hydrocarbon exploration. A framework was designed for modeling compaction effects by use of a so-called coated inclusion model that eliminates the need of using a hybrid approach through combining different theories. A basic feature of the model is that the inclusion is defined by a kernel representing the pore, which is surrounded by shells that may individually have different elastic properties from those of the pore-filling material and the background matrix. The modeling can be designed to explore seismic effects of various texture perturbations, including contact cementing and pore-filling processes. The numerical modelings seem to be consistent with the results obtained from other rock physics models. The model allows for the possibility of including small-scale heterogeneities within the rock texture and estimating frequency dispersion together with attenuation due to pore fluid flow. A basic weakness of the method is the relatively large number of parameters needed to describe a porous rock, which will always limit its practical usage. However, its basic physical foundation may provide a reference for understanding the qualitative and quantitative effects of various cementation scenarios on seismic parameters.


Geophysics ◽  
2007 ◽  
Vol 72 (6) ◽  
pp. A75-A79 ◽  
Author(s):  
Radim Ciz ◽  
Serge A. Shapiro

Gassmann equations predict effective elastic properties of an isotropic homogeneous bulk rock frame filled with a fluid. This theory has been generalized for an anisotropic porous frame by Brown and Korringa’s equations. Here, we develop a new model for effective elastic properties of porous rocks — a generalization of Brown and Korringa’s and Gassmann equations for a solid infill of the pore space. We derive the elastic tensor of a solid-saturated porous rock considering small deformations of the rock skeleton and the pore infill material upon loading them with the confining and pore-space stresses. In the case of isotropic material, the solution reduces to two generalized Gassmann equations for the bulk and shear moduli. The applicability of the new model is tested by independent numerical simulations performed on the microscale by finite-difference and finite-element methods. The results show very good agreement between the new theory and the numerical simulations. The generalized Gass-mann model introduces a new heuristic parameter, characterizing the elastic properties of average deformation of the pore-filling solid material. In many cases, these elastic moduli can be substituted by the elastic parameters of the infill grain material. They can also represent a proper viscoelastic model of the pore-filling material. Knowledge of the effective elastic properties for such a situation is required, for example, when predicting seismic velocities in some heavy oil reservoirs, where a highly viscous material fills the pores. The classical Gassmann fluid substitution is inapplicable for a configuration in which the fluid behaves as a quasi-solid.


2019 ◽  
Vol 8 (4) ◽  
pp. 1921-1926

Expansive soil implies low bearing capacity and high swelling property perhaps causes serious problems during construction includes low stability, non-uniform settlements and shear distribution. The soil stabilization is one such method to improve the process and it depends upon the soil condition and the nature of soil according to the desired requirements of footing. This study aims to increase the index and engineering properties of soil by addition of the natural fiber (sisal), lime and silica fume. Soil stabilization by lime involves the admixture in the form of calcium oxide or calcium hydroxide to the soil and silica fume as an industrial waste by product acts as a pore filling material. The project is economically viable because the stabilizing materials are easily available and less cost. This project is also analyzed by using the PLAXIS software.


Geophysics ◽  
1991 ◽  
Vol 56 (2) ◽  
pp. 225-230 ◽  
Author(s):  
D. Marion ◽  
A. Nur

A new method estimates the dependence of P and S velocities in rocks on elastic properties of the pore‐filling material by going beyond Gassmann’s relations and accounting for pore‐filling materials with nonzero shear stiffness. The resulting estimates are in good agreement with experimental data and Gassmann’s relations for values of velocity in water‐saturated rocks predicted from velocity measured on dry rocks. The method successfully predicts the temperature dependence of velocity: (1) in frozen rocks at the ice‐water phase transition, and (2) in rocks saturated with heavy hydrocarbon undergoing solid‐liquid phase transition.


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