Shrinkage Of Cement Research Articles

The effect of sodium aluminate on the properties of the composite cements

The effect of sodium aluminate activator on properties of the Portland-composite cement (clinker factor 65 %) was studied and the results are being discussed. It is shown that the introduction of sodium aluminate (Na[Al(OH)4]) leads to an increase in the water demand of cement and a decrease in its strength. The results showed that the sodium aluminate and polycarboxylate ether (PCE) admixtures ensure the production of higher strength cements. It has been found that the addition of Na[Al(OH)4] – PCE significantly increases the compressive strength of cement mortar, particularly at 10–48 h of hydration. XRD and SEM measurements confirm that the hydration of composite cement with the addition of Na[Al(OH)4] – PCE is greatly accelerated by the way of formation of intense lines ettringite. It has been shown that the introduction of a sodium aluminate into the cement mortars allows to accelerate hardening and increase early strength and using of composite cement will provide improved performance and suitability. The results have shown that alkaline accelerator and polycarboxylate were effective for decrease shrinkage of composite cements.

Mechanical properties, durability characteristics and shrinkage of plain cement and fly ash concretes subjected to accelerated carbonation curing

The paper presents an experimental study on assessment of the effect of accelerated carbonation curing (ACC) on the performance of two concrete mixtures having the same mixture proportions but different cementitious materials (plain-cement and fly-ash-blended-cement). Different sets of specimens were cast utilising both concrete mixtures and were then subjected to ACC for ten hours at a constant pressure of 414 kPa (60 psi). After exposing the specimens to ACC, they were tested for weight gain, carbonation depth, compressive and tensile strengths, modulus of elasticity, water penetration depth, rapid chloride permeability, shrinkage, SEM and XRD. ACC of the concrete specimens for ten hours resulted in a significant weight gain with less than 2 mm of carbonation depth. Both mixtures gained compressive strength above 20 MPa after ten hours of ACC. The strength increased further when ACC-treated specimens were exposed to air, with a significant increase up to seven days for plain-cement concrete and up to 28 days for fly-ash-blended-cement concrete. Compared to reference moist-cured concretes, the ACC-treated concretes were found to exhibit a slightly lower long-term strength (15% for plain-cement and 5% for fly-ash-concrete). However, the overall performance of the ACC-treated concrete mixtures was comparable with the respective moist-cured concrete mixtures.

Effect of Nano-Materials on Autogenous Shrinkage Properties of Cement Based Materials

This paper presents an experimental investigation on the effect of nano-montmorillonite, carbon nanotubes, and nano calcium carbonate on autogenous shrinkage of cement based materials. Cement paste with different nano-montmorillonite dosage (1.0 wt.%, 2.0 wt.%, 3.0 wt.%), carbon nanotubes dosage (0.1 wt.%, 0.2 wt.%, 0.3 wt.%), and nano calcium carbonate dosage (1.0 wt.%, 2.0 wt.%, 3.0 wt.%) were compared with the reference group to assess the effects of nano-materials on cement paste. Results show that autogenous shrinkage of cement based materials containing nano-materials mainly occurs in the first 72 h. Nano-materials decrease the autogenous shrinkage of the investigated cement based materials at all ages. Compared with that of the reference group at the age of 168 h, the autogenous shrinkage of NM-modified cement based composites containing 3.0 wt.% NM decreased by as much as 57.4%; the autogenous shrinkage of CNTs-modified cement based composites containing 0.3 wt.% CNTs decreased by as much as 19.4%; the autogenous shrinkage of NC-modified cement based composites containing 2.0 wt.% NC decreased by as much as 17.1%. Electrochemical AC (Alternating Current) impedance spectroscopy results show that the resistance of the pore solution electrolyte of specimens containing nano-materials increases with age, and is less than that of specimens without nano-materials, which illustrates that the pore size of nano-modified cement based material is finer and autogenous shrinkage is smaller. Scanning electron microscope results show that the structure of cement matrix is denser with more hydration products by adding nano-materials. Nano-montmorillonite releases water to reduce self-drying effect during the process of hydration for its well water swelling. Carbon nanotubes have the nanometer filling effect and form a continuous network to restrain the early autogenous shrinkage of cement paste. Nano calcium carbonate not only decreases the porosity of the cement paste, but also reacts with tricalcium aluminate to generate the expanded product calcium carboaluminate for compensating autogenous shrinkage of cement paste.

Estimation of Conventional Pcc Strength And Durability with Partial Replacement of Cement using Aluminium Powder and Rice Husk Ash

Bond is generally noted to be most costly constituents of cement. The whole development industry is looking for an appropriate and viable the waste item that would extensively limit the utilization of concretes and at last lessens the development cost. Rice husk slag (RHA) which has the pozzolanic properties is a route forward. A relative report on impacts of solid properties when OPC of differing evaluations was mostly supplanted by RHA is examined in this paper. Rate supplanting of OPC with RHA was 0, 10, 20, 30 and 40% individually. The compressive quality, water ingestion, shrinkage and solidness of cement were for the most part considered. The examination recommends that up to 20% supplanting of OPC with RHA can possibly be utilized as halfway concrete substitution, having great compressive quality execution and durability. Percentage supplanting of OPC with Aluminum powder (Al) is 0.5% which is kept steady. We are utilizing M sand rather than typical sand to diminish the expense of development and builds quality and sturdiness concrete. The examination proposes the supplanting of concrete with RHA and Aluminum powder expands the compressive quality, solidness, and diminishes the expense of development.

AUTOGENOUS SHRINKAGE OF COMPOSITES BASED ON PORTLAND CEMENT

Autogenous shrinkage of cement based composites is important property influencing number of their engineering application. Its ultimate value is predominantly determined by mineralogical composition of cement and its particle size distribution. Present paper introduces experimental study focused on the evaluation of various cements of grade CEM I 42.5 produced in Czech Republic in terms of shrinkage under autogenous conditions. Selected cement type is currently the most frequently used cement. Conducted study confirmed essential differences in ultimate values of shrinkage, which is partially determined by its specific surface area. Accompanying tests of mechanical properties indicate the influence of particle size distribution, which controls initial phases of cement hydration.

Measuring and modeling hydration kinetics of well cements under elevated temperature and pressure using chemical shrinkage test method

Well cements hydrate under challenging conditions of elevated temperature and pressure. A standard and readily accessible experimental method to follow the hydration kinetics of well cements under these conditions is lacking. In this study, we present a new method to measure the chemical shrinkage of cements, using an ultrasonic cement analyzer coupled with an external pump — two common equipment in well cements research laboratories. The method measures chemical shrinkage by following the flux of water into the sample to maintain constant pressure. Various experimental parameters such as leakage and sample geometry are carefully examined. Chemical shrinkage results on Class G and Class H cements are in good agreement with various sources, including reported chemical shrinkage, reported activation constants, hydration kinetics measured by alternative methods, and phase assemblage measurements on hardened paste. The method offers a promising new technique to help advance our fundamental knowledge on the hydration of well cements.

Effect of Shrinkage Reducing Admixture on Shrinkage and Crack Properties of Cement Based Materials

In order to improve the dimensional stability of cement based materials, the effects of shrinkage reducing admixture (SRA) dosage on the shrinkage and crack properties of cement based materials were investigated. The hydration process of the cement pastes was tracked and monitored by hydration calorimeter and adiabatic temperature rise apparatus respectively. The action mechanism of SRA on hydration process of the cement based materials was characterized by differential scanning calorimeter (DSC). The shrinkage and crack results show that the ability of resist cracking of concrete can be effectively improved by SRA. The results of hydration calorimeter and adiabatic temperature rise indicate that the appear time of hydration temperature peak at early age was delayed and the development of hydration heat changed gently at later period by doped SRA. The results of DSC show that the release amount of hydration heat and the production of early calcium hydroxide can be delayed by SRA, however, there has no effects of SRA on the formation of cement hydration products like calcium hydroxide at the later period.

Full‐Life‐Cycle Analysis of Cement Sheath Integrity

This paper addresses evaluating the evolution of stress inside the casing‐cement sheath‐formation system during the cement injection, setting, completion, and production stages of hydrocarbon recovery. This full‐life‐cycle analysis of cement sheath integrity gives rise to assessment of potential failure mode (i.e., tensile mode, shear mode, and microannulus) in different stages, and the prevention measures can be proposed accordingly. Considering the loading history, two regimes should be distinguished. Before the accomplishment of cementation, as the cement slurry can merely withstand its hydraulic pressure, the in situ stress and the wellbore pressure are withstood by the rock and the casing, respectively. Once the cementation process is completed, the stress increment (e.g., hydraulic fracturing pressure) is withstood by the casing‐cement sheath‐formation system. The autogenous shrinkage of cement adversely affects the resistance of the system to all types of failure, whereas a moderate swelling of cement is favorable to the cement sheath integrity. In addition, the cement sheath integrity is strongly influenced by the depth: the failure is encountered more easily at the shallow layer. Both the hydraulic fracturing pressure in the completion stage and the increase in casing temperature in the production stage may lead to tensile circumferential stress, and the hydraulic fracturing is the most critical stage for the integrity of cement sheath.

Dimensional Changes of Glass Ionomers and a Giomer during the Setting Time.

ObjectivesThe aim of this study was to evaluate dimensional changes of conventional glass ionomer cements, resin-modified glass-ionomer cement, and a giomer during the setting time using digital laser interferometry. Additionally, the influence of different curing modes (“high”, “soft”, and “low”) of a light-emitting diode (LED) curing unit on dimensional changes was evaluated.Materials and methodsLinear curing shrinkage of conventional glass ionomer cements (CGICs): Fuji IX Extra (F9E), Fuji IX Fast (F9F), Ketac Molar Aplicap (KM), Ketac Molar Quick Aplicap (KMQ), resin-modified glass ionomer cement (RM GIC): Fuji II LC (F2LC) and giomer: Beautifil II (B2) was analyzed. All tested materials were of shade A3, while all of the GIC were encapsulated. Discoid specimens (n=10, d=10 mm, h=0.85 mm) were prepared for each tested material and each curing mode (for light-curable materials) according to the manufacturer’s instructions. Light-curable specimens were cured with LED curing unit (Bluephase G2, Ivoclar-Vivadent, and Schaan, Liechtenstein). Dimensional changes during curing were recorded in real-time. The results were analyzed by ANOVA, and Tukey post hoc test was used for multiple comparisons (α˂ 1%).ResultsAll tested materials showed an initial setting expansion and a subsequent setting shrinkage. KM and KMQ had significantly lower setting shrinkage than RM GIC polymerized using any of the three curing modes. B2 showed lower shrinkage compared to F2LC.ConclusionsThe extent of curing shrinkage in RM GIC measured in this study can affect longevity of restorations.

Shrinkage properties of plain and recycled steel–fibre-reinforced rapid hardening mortars for repairs

This article investigates the time dependent transport properties and shrinkage performance of rapid hardening plain and fibre reinforced mortars for repair applications. Two plain and two SFRC mixes with 45 kg/m3 of recycled clean steel fibres made with rapid hardening cements (CSA – calcium sulfoaluminate cement and RSC – calcium aluminate cement) are studied. It is found that mixes with CSA cement have much lower shrinkage values (around 220 and 365 microstrains) compared to mixes with RSC cement (around 2690 and 2530 microstrains), but most of the shrinkage in these mixes is autogenous. Nonetheless, fibres reduce the drying shrinkage of RSC cement mixes by approximately 12%. Model code 2010 and ACI equations can be used to estimate the shrinkage development with time for these mixes provided suitable parameters for each cement type are adopted. Inverse analysis using finite element method is successfully employed to determine the moisture diffusivity and the hygral contraction coefficient of each mix. A comparison is made between the values of shrinkage strain predicted by the numerical models over time, for different depths, and code equations. A simple analytical procedure is used to assess cracking and/or delamination risks due to restrained shrinkage for these materials in overlay applications.

Simulation of wellbore construction in offshore unconsolidated methane hydrate-bearing formation

The unconsolidated nature of offshore methane hydrate-bearing formation poses challenges to sustainable methane gas production as the weak formation is susceptible to disturbance during wellbore construction. This could contribute to loss of well integrity which could manifest as sand production and error in the interpretation of downhole tests such as mini-frac tests. In this study, a simulation methodology of wellbore construction process is proposed. A finite element model adopting this methodology is developed in order to assess the effect of wellbore construction process on the integrity of the unconsolidated methane hydrate-bearing formation in the Nankai Trough, Japan. The main objectives are (i) to develop a modelling methodology of well construction process for numerical simulations, (ii) to assess the zone and magnitude of well construction-induced stress/strain disturbance in the formation and (iii) to evaluate relative impact of each well construction stage on the integrity of the formation. The results from this study show that the zone of horizontal stress disturbance from the geostatic state due to wellbore construction could extend to more than three times the radius of the wellbore. Following the wellbore construction, the deviator stress is concentrated in the hydrate reservoir sublayers with high hydrate saturation while plastic deviatoric strain has accumulated in the sublayers with low hydrate saturation. The results also show that modelling of cement shrinkage process is crucial in predicting the concentration of deviator stress in the high hydrate saturation layers.

Push-out test: Why bother?

Bonding between cement and steel is currently believed to be of key importance in well integrity since it prevents the development of microannulus. Push-out test is often used to quantify the bonding strength between cement and steel in laboratory. Our experiments reveal a strong size-dependency of the push-out strength measured in these tests: the strength decreases with pipe diameter. This means that the push-out strength is not an intrinsic material parameter ("bonding strength") and therefore cannot be applied to field conditions before a proper correction is introduced. Such correction should take into account the large difference in diameter between the casing and the pipes typically used in laboratory tests. Finite-element simulations show that the experimentally-observed size-dependency could be, at least partially, explained by cement shrinkage that creates initial normal stress at the interface. The observed push-out strength is then not an intrinsic property of the interface between two materials (which would be an adhesive shear strength) but rather a result of interfacial friction. As the pipe diameter increases, the shrinkage-induced normal stress at the interface decreases, the frictional resistance decreases, and thus the measured push-out strength decreases, too, as observed in the lab tests. Simulations show, however, that shrinkage-induced decrease in push-out strength cannot fully explain the size-dependency since the decrease is much larger in the experiments than in the simulations. Another mechanism that could be at play is the common size effect: interfaces become weaker as their size increases because it is more likely that a larger interface contains an initial flaw of a given size. The decrease of push-out strength with pipe diameter has at least two practical implications: (i) the concept of bonding strength is misleading (unless it is specified explicitly that this parameter refers to frictional resistance at the interface rather than to an inherent adhesive strength) and (ii) the results of push-out tests can be used in well design only if a proper correction for the pipe diameter is introduced.

Ternary mix design of grout material for structural repair using statistical tools

Repair is an indispensable part of the maintenance of structures over their lifetimes. Structural grouting is a widely used remediation technique for concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. A structural grout system should be injectable in narrow spaces and hence include ingredients with finer particles. Ultrafine cements are ideal for these type of demanding grouts due to their superior properties compared to that of the less-expensive, but coarser ordinary Portland cement (OPC). Supplementary cementitious materials (SCMs) are often used to replace OPC clinker based binder in order to modify certain properties and to reduce costs. The most commonly used SCMs are fly ash (FA), and ground granulated blast furnace slag (GGBS). For various special applications microsilica (MS), and metakaolin (MK) are also used. Identifying the optimum replacement contents of OPC by SCMs are a challenge during the design of such grouts. The aim of this experimental study is to investigate the effect of the selected SCMs (FA, MS and MK) on the slump flow, time of efflux, viscosity, shrinkage, and compressive and flexural strength of ultrafine cement based grouts with constant water-binder ratio and superplasticizer content. The test program was formulated using Box-Behnken design principles. Maximum percentages of replacement with ultrafine cement was 6% by volume of cement for MS and 16% for FA, and MK. The results suggest that most investigated grouts have the potential to be used for structural applications. The appropriate quadratic models are then formulated through statistical tools and presented as response surfaces. The trends indicate that fly ash improves the rheological properties, whereas microsilica and metakaolin positively affect shrinkage and mechanical properties to some extent. Based on the influence of SCMs and priorities among the properties, Decision Matrix Analysis (DMA) is carried out to select the most suitable ones among the SCMs. The analysis suggests that microsilica and fly ash are more suitable as SCMs than metakaolin without affecting the properties.

Influence of Ambient Temperature and Light-curing Moment on Polymerization Shrinkage and Strength of Resin Composite Cements.

The purpose of this study was to establish a clinically appropriate light-curing moment for resin composite cements while achieving the highest indirect tensile strength and lowest polymerization shrinkage. Polymerization shrinkage of seven resin composite cements (Multilink Automix, Multilink Speed Cem, RelyX Ultimate, RelyX Unicem 2 Automix, Panavia V5, Panavia SA plus, VITA Adiva F-Cem) was measured at ambient temperatures of 23°C and 37°C. Testing was done for autopolymerized and light-cured specimens after light application at either 1, 5, or 10 minutes after mixing. Indirect tensile strength of all cements was measured after 24 hours of storage at temperatures of 23°C and 37°C, for autopolymerized and light-cured specimens after light application 1, 5, or 10 minutes after mixing. To illustrate filler size and microstructures, SEM images of all cements were captured. Statistical analysis was performed with one-way ANOVA followed by post hoc Fisher LSD test ( α=0.05). Final polymerization shrinkage of the resin composite cements ranged from 3.2% to 7.0%. An increase in temperature from 23°C to 37°C as well as the light-curing moment resulted in material dependent effects on the polymerization shrinkage and indirect tensile strength of the cements. Polymerization shrinkage of the cements did not correlate with the indirect tensile strength of the cement in the respective groups. Highest indirect tensile strengths were observed for the materials containing a homogeneous distribution of fillers with a size of about 1 μm (Multilink Automix, Panavia V5, VITA Adiva F-Cem). The magnitude of the effect of light-curing moment and temperature increase on polymerization shrinkage and indirect tensile strength of resin composite cements is material dependent and cannot be generalized.

Water absorption and shrinkage behaviour of early-age cement in wellbore annulus

Controlling cement shrinkage in a wellbore is important in maintaining its integrity. Although numerous laboratory experiments on the water absorption and shrinkage behaviour of oil well cement have been reported in the past, such behaviour in the wellbore annulus with consideration of pore water migration from the surrounding formation has seldom been examined. In this study, using a cement shrinkage model calibrated against available experimental data, a coupled hydromechanical finite element analysis of a cement-formation model is conducted to simulate the water migration, absorption and shrinkage behaviour of early-age cement placed in the annulus of a wellbore. The objectives of this study are (i) to identify the threshold permeability value of the formation above which there is no longer a bottleneck for pore water to flow into the cement and (ii) to estimate a reasonable range of cement bulk shrinkage volume in wellbore annulus geometry. Results show that the threshold permeability of the formation would be around 0.1 mD for three different types of cement examined in this study: Class G cement, rapid setting (RS) cement and Schlumberger optimized particle size distribution (OPSD) technology cement. The bulk shrinkage volume varies from 0.01% to 2.4% depending on cement type and formation permeability (1 mD to 0.1 μD). The proposed methodology facilitates the simulation of water migration/absorption and shrinkage behaviour of well cement in different formations.

Behavior of organic compounds in the pore solution of cement—experimental and molecular dynamics study

AbstractThis study summarizes molecular dynamics (MD) simulations and experiments using four ester‐based cement shrinkage reducing agents in pure water and simulated cement pore solution. The esters were found to completely dissociate in the alkaline pore solution to form acid and alcohol analogue compounds. The alcohol analogues were further found to be entirely responsible for the surface tension reduction capacity of the parent compounds. In addition, the surface tension reduction capacity of the alcohol analogues are not affected by relevant counterions present in the pore solution. The MD‐based analysis show that water molecules form stable hydrogen bonds with head groups of the alcohol analogues and that relevant dissolved ions, K+ and Na+, have virtually no effect on hydrogen bond stability. Furthermore, the higher the self‐diffusion coefficient of water molecules in the neighborhood of the head groups the lower the resulting surface tension at the air‐water interface.

Shrinkage and strength development of alkali-activated fly ash-slag binary cements

This paper evaluates the effect of fly ash and slag proportions and the type of activating solution on shrinkage and strength development of alkali-activated binary fly ash-slag mixtures (mortar and paste), cured at room temperature. Three different volumetric ratios of slag/fly ash were considered: 10%, 15%, and 20%. Two activators with different pH and modulus, n=(SiO2/Na2O)mol were utilized. The liquid to solid volume ratio of all binders was maintained at 0.75. The results showed that while the addition of slag significantly shortens the time of setting (up to 178min), and increases the compressive strength (up to 93%) and bulk modulus (up to 43%), it also results in higher autogenous shrinkage, but smaller mass loss during drying. Measured drying shrinkage of mixtures with various slag contents was similar, likely due to counteracting effects of binder stiffness and degree of saturation. Fly ash-slag binders activated at higher pH exhibited larger chemical shrinkage, but lower autogenous (up to 21%) and drying shrinkage (up to 47%) magnitude.

Application of Powers’ model to modern portland and portland limestone cement pastes

AbstractPowers’ model is a simple approach for estimating the relative volumes of hydration products, porosity, and chemical shrinkage present in portland cement paste as a function of its starting water‐to‐cement ratio (w/c) and current degree of hydration. It forms an important link between cement composition, microstructure, and performance, necessary for modeling cement‐based systems. Previous researchers have adapted Powers’ model for inert fillers to illustrate their effects on the hydration, porosity, and chemical shrinkage of blended cements; however, it is well‐documented that limestone is not, in fact, an inert filler, but rather participates in cement hydration through both chemical and physical processes. This research experimentally investigates the applicability of Powers’ model to modern portland cements containing up to 15% by mass finely divided limestone. The results demonstrate that the modified Powers’ model is insufficient for predicting the influence of finely divided limestone additions on the chemical shrinkage of both ordinary portland cement pastes and portland limestone cement pastes. Possible explanations for the discrepancy are discussed and a plausible source is proposed.

Effect of microannulus on ultrasonic pulse-echo resonance, flexural, and extensional Lamb-wave cement-evaluation measurements

Subterranean wells are usually constructed by cementing steel tubes, called casings, inside the borehole. The cement quality is typically verified through ultrasonic measurements deployed from inside the casing. Environmental effects such as cement shrinkage or changes in static pressure can alter the bonding properties between casing and cement with significant effects on the acoustic measurement response. The cement may detach from the casing, opening a gap, called a microannulus. This microannulus is sized from submicrometer to hundreds of micrometers and filled with either gas or liquid. The subwavelength nature of the microannuli does not allow a direct, unambiguous characterization through an ultrasonic measurement. We studied the measurement signature of ultrasonic-pulse-echo resonance, and flexural and extensional Lamb waves for air- and liquid-filled microannuli for various annulus materials and steel-casing thicknesses. This characterization allows statistically linking measured results to microannulus widths. The highest-precision measurements used in-situ laser interferometry through transparent annulus samples to characterize the microannulus thickness.

Real-Time Monitoring of Piezoresistive Smart Cement To Verify Operations

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 27060, “Field Test for Real-Time Monitoring of Piezoresistive Smart Cement To Verify Cementing Operations,” by C. Vipulanandan, M. Ali, B. Basirat, A. Reddy, N. Amin, and A. Mohammed, University of Houston; S. Dighe, SPE, Baker Hughes; and H. Farzam, Cemex, prepared for the 2016 Offshore Technology Conference, Houston, 2–5 May. The paper has not been peer reviewed. Copyright 2016 Offshore Technology Conference. Reproduced by permission. A field well was designed, built, and used to demonstrate the concept of real-time monitoring of the flow of drilling mud and smart cement and the hardening of the cement in place. A new method has been developed to measure the electrical resistivity of the materials with the two-probe method. Using the new concept, it has been proved that resistivity dominated the behavior of drilling fluid and smart cement. Introduction With reported failures and growing interest in environmental and economic concerns in the oil and gas industry, integrity of the cement sheath is of major importance. Oilwell cement serves many purposes in cemented oil and gas wells. Foremost among these is to form a sealing layer between the well casing and the geological formation. In order to characterize the cement and cement concrete in various applications, electrical-resistivity measurement has been used by many researchers. Studies have also examined the piezo-resistive behavior of modified cement-based and polymer composites. One conclusion is that the change in resistivity has the potential to be used to determine the integrity of the materials. Smart Oilwell Cement Cement-slurry flow and stability are the major requirements in well cementing. Oil- and gas-well cements are usually made from Portland cement clinker or from blended hydraulic cements. When admixtures are used with cement, tensile and flexural properties are modified. Also, admixtures will have an effect on the rheology, corrosion resistance, shrinkage, thermal conductivity, specific heat, electrical conductivity, and absorption (heat and energy) properties of cement. A smart cement has been developed that can sense any changes going on inside the borehole during cementing and during curing after the cementing job. The smart cement can sense the changes in the water/cement ratio, different additives, and any pressure applied to the cement sheath in terms of piezo resistivity. The failure compressive strain for the smart cement was 0.2% at peak compressive stress, and the resistivity change is on the order of several hundreds, making it more than 500 times more sensitive. Theory and Concept Impedance Model. Equivalent Circuit. It is important to identify the most appropriate equivalent circuit to represent the electrical properties of a material to characterize its performance with time. In this study, different possible equivalent circuits were analyzed to find an appropriate equivalent circuit to represent smart cement and drilling fluid.