11, pages 10-13, November, 1973. 19. By Shu-t'ien Li Download the PDF version of this article. In each case, the cement slurries were poured into molds and the temperature and pressure maintained at 300° F. (149° C.) and 3000 psi, respectively, until all of the expansion measurements made in Table 9 were completed. method for placing a seal, plug or fitting in a well. In each Trial, the magnesium oxide was sieved to be within the size range indicated. Magnesium oxide as an expansive additive for construction cementing was also investigated by P. K. Mehta et al. The results in Table 2 generally indicate that where calcining time is the same, the highest linear expansions are obtained at calcining temperatures of 2200° F. (1200° C.) and 2500° F. (142° C.), versus 2800° F. (1540° C.) This appears particularly true when the temperature to which the cement is exposed is 300° F. (149° C.) The foregoing can be observed, for example, from the greater linear expansion obtained in Trial 8 versus Trial 14, Trial 7 versus 13 (at least at 300° F. (149° C.), the results at 200° F. (93° C.) being almost the same), and Trial 12 versus 14. after 14 days was 0.68% (average of 2 trials). To illustrate that magnesium oxide calcined under the above described calcination conditions, can also produce significant expansion in non-Portland type cements, a number of further trials were conducted and the data summarized in Table 9 below. Column A of the BET and ANT measurements were provided by the magnesium oxide supplier, whereas the column B measurements were measured by applicant. Portland cement, Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use, The United States Of America As Represented By The Secretary Of The Interior. (594.04 kB) Two basic formulations for expansive cement have been developed in the United States. A method as defined in claim 17 wherein the bottom hole static temperature of the well is between about 70° C. and about 290° C. during placement of the cement. However, the expansive cement composition can comprise at least about 0.005%, or at least 0.010% up to about 0.150, about 0.100% or 0.050% lithium compound by weight of the Portland cement. However, this may be a result of the fact that, as shown in Table 1A, the magnesium oxide used in Trial 11 has a larger number of particles which are smaller than 38 microns in diameter. It will be seen from Table 7B then, that the horizontally restrained compressive strength is always higher than the unrestrained compressive strength. Also, the same magnesium oxide was used in the Trials 2, 4, and 6 of Table 9 below, as was used in Trial 8 of Table 2 above. 14. Furthermore, expansion results from a direct chemical reaction between the tricalcium aluminate present in the Portland cement, and the calcium sulfate. V. S. Danyushevsky, Methods for Producing Expandable Plugging Cements for Gas Wells , Gazovaya Prom., No. This latter feature allows magnesium oxide to be produced with particles of the required size and surface area, without the necessity of regrinding the particles. However it is apparent from those Trials and Trials 1-3, that not only must the ANT, and hence surface area, be controlled, but also that the particle size range must also be controlled, as already shown by Table 3. Samples calcined at 2800° F. (1583° C.) (used in Trials 13 and 14), were definitely mechanically ground. However, it will be observed that the foregoing relationship is not a proportional one, particularly in the 0.5 to 1.25 wt. The patent indicates that the composition can be manufactured from magnesium oxide, calcium oxide and other conventional ingredients that are normally fed to a Portland cement kiln, such that the composition will also contain tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrate, as well as other impurities. Another paper of relevance in disclosing large numbers of attempts to produce expansive cements utilizing various additives, is that by W. Kurdowski, entitled "Expansive Cements", 7th International Congress on the Chemistry of Cement, Paris 1980, Vol I, pages v-2/1 to v-2/11. Thus, the use of calcium sulfate as an expansive agent in cements for cementing a well casing in a wellbore, is limited to those wells having a BHST of less than about 77° C., and in which are used cements with a high tricalcium aluminate content. A method as defined in claim 10 wherein the hydratable cement of the cement slurry composition is a Portland cement. acetic acid, is between about 17 to about 25 minutes. DOWELL SCHLUMBERGER INCORPORATED,OKLAHOMA, Free format text: The cement system used had the following paramenters: LONE STAR Class H cement, plus 0.5 wt. An expansive cement containing anhydrous tetra calcium alumino-sulphate, which is burnt simultaneously with a Portland cement composition, or burnt separately, when it is to be interground with Portland cement clinker or blended with Portland cement, calcium sulphate and free lime. The cements of Trials 9 and 12 did not exhibit the compressive strengths as high as the remainder of those trials, at least at 300° F. (149° C.). The … % water (all wt. The expansive agent must be designed such that, at the temperature to which the liquid cement will be exposed, it does not attempt to produce most of its expansive effect while the cement is still liquid. An expandable cement composition as defined in claim 7 wherein the acid neutralization time of 1 g of the magnesium oxide in 60 ml. An expansive cement composition made of argillaceous and calcareous materials and containing from about 1 to about 70% by weight thereof of free CaO and from about 2 to about 7% by weight thereof of MgO uniformly distributed therein, with the remaining portion of said materials being primarily tricalcium silicate … Trial 8, Table 9, used magnesium oxide calcined at approximately 1200° C., particle sizes between about 150 to about 425 microns(40 to 100 mesh)., surface area 1.49 m2 /g, ANT 16.8 minutes. in "Magnesium Oxide Additive For Producing Self Stress in Mass Concrete", 7th International Congress on the Chemistry of Cement, Paris 1980, Volume III, pages v-6,9. The authors considered the use of such expansive agent in cements curing at 32° C. to 54° C., to prevent crack formation. These were measured by an apparatus and method of the type described in U.S. Pat. When the ANT is increased beyond that point, the cement expansion tends to then decrease. 1. %'s BWOC). 1, first comparing the results of Trial 1 with those of Trial 4, it will be seen that the same amount of magnesium oxide calcined at 1200° C., after 14 days, produced an expansion at 200° F. (93° C.) which was about 200% greater than that produced by magnesium oxide calcined at 1000° C., and was about 50% greater at 300° F. (149° C.) (149° C.). In some wells, a relatively low BHST may initially or normally be present. The major components of expansive cement include: silicate-type, aluminate-type, sulphoaluminate-type and calcium aluminoferrite-type. Such compositions, particularly where the acid neutralization time (ANT) of the magnesium oxide is also controlled within a defined range, have good linear expansions within high temperature wells, with very low amounts of magnesium oxide being required (particularly 0.25% to 1.0%). 16. All weight percentages(wt. The ANT of these samples was also measured, and they were sieved to determine the particle size distribution. for completion or for remedial operations, Compositions for cementing, e.g. % water. Professor KIIT … PATENTED CASE, Particulate magnesium oxide prepared by calcining magnesium oxide at between about 1100° C. and about 1500° C. At least about 80% of the magnesium oxide particles are between about 150 microns to about 400 microns in diameter. added 1N. Other wells in the same general area also showed signs of gas leakage within about two weeks after cement placement, whereas the test well showed no such signs of leakage even after 2 weeks following cement placement. So, Finally, our article about “Types of Cement” is reached to an end. At temperatures higher than 160° C., magnesium oxide calcined at 1600° C. is suggested as an expanding additive. It would be desirable then to have a cement composition which would at least not suffer as much from this thermal shock effect. The cement slurry compositions which were used to obtain the expansions provided in Table 2 were the same as those used in connection with the Trials of Table 1, with the exception that the magnesium oxide was prepared under different conditions. % of a lignosulfonate retarder, 0.5 wt. The starting material was magnesium hydroxide. The composition of the expansive cement is only one of the many factors considered when using shrinkage-compensating concrete. As a measure of chemical reactivity, a study of the acid neutralization times (ANT) of the magnesium oxide used in Trials 6-14 of Table 2, was conducted. The composition of the aggregate and water may influence amount and timing of expansion. The composition is particularly useful for cementing a casing in place in a bore of an oil, gas, or other well, which may experience at some point in time a relatively high bottom hole static temperature(BHST). added 1N. The cement used may include a Portland cement, a high aluminate cement, or a gypsum cement, or any other hydraulic cementitious material such as type C fly ash. An expandable cement composition as defined in claim 7 wherein the acid neutralization time of 1 g of the magnesium oxide in 60 ml. These types of cement have he quality to expand slightly with time. The expansion of the cement mortar or concrete is compensated for the shrinkage losses. A method as defined in claim 18 wherein the bottom hole static temperature of the well is between about 70° C. and about 290° during placement of the cement. A novel expandable cement composition containing a hydratable cement, and magnesium oxide of the foregoing types, is also disclosed. Reference mortar was modified by expa nsive additive at a dosage 10% of weight of cement. 0% 10% 20% 30% 40% 50% 60% 70% CaO SiO2 Al2O3 Fe2O3 SO3 Cl Classical method Classical method + XRF Fig. However, it will be noted that this is only about one third (1/3) of the amount of magnesium oxide used in Trial 12, Table 2 to produce similar results(in which magnesium oxide, the particle size and surface area were not controlled within the limits already defined). One known expansive agent comprises calcium sulfate. The factors influencing the magnitude and rate of the expansive reaction include: chemical composition of the components, fineness of the sulfoaluminate component, proportions of the two components in … In an earlier article, by S. I. Danyushevsky and R. I. Liogonkaya, entitled "Expandable Plugging Cement For Gas Wells", CEMENT, V.32(2) 1966 P.10-11, the plugging of gas wells using cements with a magnesium oxide expansive additive, was disclosed. The performance of these accelerators depends on the cement chemical composition and fineness, and the presence of mineral additions such as flyash, and blastfurnace slag. An expandable cement composition as defined in claim 1 wherein the cement is selected from Portland cement, a high aluminate cement, and a gypsum cement. It takes just a few seconds to prepare and fill the holes with the expansive mortar and it gets to work right away. Thus, from the general trend discussed in connection with Table 4 and reviewing the 300° F. (149° C.) expansions in Table 2, it appears that the best expansions are obtained with magnesium oxide samples having ANTs somewhere between about 20 to 30 minutes. Chemical Composition of Cement The raw materials used for the manufacture of cement consist mainly of lime silica alumina and iron oxide These oxides interact with one another in the kiln at high temperature to form more complex compounds It is also suggested that for hotter wells with temperatures of up to 180° C., magnesium oxide calcined at 1200° to 1300° C. can serve as an expanding additive. U.S. Pat. Cement is used as a binding material in mortar, concrete, etc. 18. In all of the trials below and throughout this application, unless indicated otherwise, all expansions of cements are unrestrained linear expansions. However, there is no indication as to the amount of magnesium required, nor is there any indication as to the size or surface area of the magnesium oxide particles. % lignosulfonate retarder, and 44 wt. Expansive additives influence self-compacting properties and compressive strength. A number of other trials were performed to investigate the effect of raising the calcining temperature of the magnesium oxide. 1, with those of Trial 12 (all having almost identical calcination temperatures and times), a larger proportion of particles below 40 microns in size, tends to result in substantially reduced expansion at 300° F. (149° C.). The well had a depth of 13,400 feet, a BHST of 210° F. and a bottom hole circulating temperature (BHCT) of 174° F. (80° C.) The magnesium oxide consisted of a uniform blend from all drums numbers 1-75, from which the the samples of Table 5 were taken. No. The magnesium hydroxide was placed in the furnace for a period of four hours required to reach the indicated temperature, and held in the furnace at that temperature for an additional period of two hours, then removed and allowed to cool. This cement is similar to ordinary Portland cement. Phase composition of pastes after 3-day hydration, for the reference cement (1), cement with 8 % CSA 1200 (2), cement with 15 % CSA 1200 (3) and CSA 1200 expansive additive (4); w/s = 0.50 Citation: Journal of Thermal Analysis and Calorimetry J Therm Anal Calorim 109, 2; 10.1007/s10973-012-2379-2 No. Further, as already shown by Table 3, the best particle size should simultaneously be between about 150 to 420 microns. 4,002,483 discloses an expansive cement composition containing about 1 to 70% calcium oxide by weight of the composition, and about 2 to 7% magnesium oxide by weight of the composition. The expansions of the cements at 7, 14, 21, and 28 days, both at 200° F. (93° C.) and 300° F. (149° C.) are shown in FIG. It has been discovered that this may be accomplished by providing an expansive agent in the cement, which agent will produce most of its expansion only upon the later raising of the BHST. Table 1A identifies the calcining temperature and duration of calcination at that temperature(often referred to herein as simply the "calcining time"), for each sample, as well as the corresponding trial number in Table 2 in which it was used as an expansive agent. The results of the sieving to ascertain particle size, are tabulated in Table 6. The composition is reacted in a conventional cement kiln at a temperature range of 2500° F. to about 2900° F., which the patent indicates will inherently cause the magnesium oxide to "become diffused throughout the composition in the form of very fine crystallites of crystals of periclase, the vast majority of which have a size no greater than about 10 microns." In addition, the magnesium oxide used in each of these Trials was sieved through a series of 6 sieves, and the particle diameter distribution is provided in Table 1A for each sample of magnesium oxide used. Trials were first performed to ascertain the effect of varying the calcining temperatures of magnesium oxide between 1000° C. and 1200° C. Magnesium hydroxide was used as a starting material in each case. In the process for making the composites, the concrete is allowed to cure at about 159° C. to 200° C. under 6 to 15 atmospheres pressure. of deionized water with 20 ml. The expansions were 0.68 and 0.80% for the initial and final mix specimens, respectively (both from an average of two measurements). Ordinary Portland Cement (OPC) In usual construction work, Ordinary Portland … The expansion of these specimens were then measured in the laboratory again at 210° F. (99° C.) and 10,000 psi after 14 days. Expansive Cement Concrete. The limestone and clay are heated together to a temperature of around 2,600 degrees Fahrenheit, which transforms the material into dry pieces of cement. casing and wellbore) would result. However, to obtain such results it is necessary that the calcination conditions and particle size of the magnesium oxide be carefully controlled, preferably also along with the surface area and acid neutralization time. However, in those samples calcined at higher temperatures and times, the crystallites became less well defined and appeared to be more fused together, to result in an overall lower surface area of the particles. U.S. Pat. An expandable cement composition as defined in claim 4, wherein 80% of the magnesium oxide particles have a diameter of between about 150 to about 400 microns, and wherein the magnesium oxide particles have a BET surface area of between about 1 and about 2 m. 6. Expansive cement is special type of cement when mixed with water, which forms a paste that tends to increase in volume to a significantly greater degree than Portland cement paste after setting. This is true even where the cement has already set. All expansion measurements were obtained from two different samples, as indicated in Table 5, although expansion measurements were not obtained for all of the magnesium oxide samples other than at 200° F. (93° C. ) with 0.5 wt. Further, the BET surface area of the particles is preferably between about 0.8 to about 1.8 m. 1. Specimens of the mixed cement composition were taken from both the initial field mix, and the final field mix, prior to pumping down the well. The linear expansions, and compressive strengths obtained in the set cement compositions, are summarized in Table 7 below. Composition reconstitution of concrete and mortars based on portland and expansive cements 231 aggregates, mortars and concretes with their samples adequately prepared prior to the testing. Regrinding tends to be a process which is inherently difficult to control in terms of size distribution of the magnesium oxide particles. 1-2 (January-February 1978); "Relation Between Pre-Cursor and Micro Structure in MgO", Journal of the American Chemical Society -Discussions and Notes, V. 56, No. The size of the particles of the cement is its fineness. In such a particle size range, the 14 day expansions are increased dramatically over what would be expected, based upon the increased proportion of magnesium oxide present. 17. The design of cement mortar composition was based on commercially produced self-leveling cement screeds. 4,046,583 likewise discloses an expansive cementitious composition, apparently for use at atmospheric temperatures, containing calcium oxide and/or magnesium oxide. The use of magnesium oxide (MgO) as an expansive agent in cements has been suggested previously by V. S. Danyushevsky in "Methods For Producing Expandable Plugging Cements For Gas Wells", Gazovaya Prom No. Under conditions of restrained expansion, cements such as those of Trial 9, would be expected to exhibit good compressive strengths. This material is ground with sulfoaluminate clinkers. % magnesium oxide. That is, an expansion was obtained in Trial 3 (MgO calcined at 1200° C.) which was better than that obtained in Trial 5 (MgO calcined at 1000° C.), by an amount of about 300% at 93° C., and about 30% at 149° C., even though the concentration of magnesium oxide in Trial 3 was about 25% less than that in Trial -5. овой Промышленности Им.Губкина И.М. In order to obtain expansion of the set cement compositions described, in a wellbore, a temperature within the necessary range can be present both during placement and setting of the cement, or only during setting of the cement, or even after setting of the cement. These samples were then used in varying wt. It should be noted that the crystallite size, is distinct from the particle size which is indicated by sieving, since it was evident from the SEM studies that the particles of magnesium oxide were made up of individual smaller particles (referred to as crystallites) fused together. ;ASSIGNOR:SPANGLE, LLOYD B.;REEL/FRAME:004948/0070, Owner name: % sodium salt of a napthalene sulfonate retarder, 0.1 wt. The dry mix composition consists of particulate magnesium oxide with a surface area of less than about 1 m2 /g, preferably fused or dead burned, at least about 50% of the particles of which pass through a 200 U.S.mesh (referred to herein as "mesh") screen, and 10% of which are held on a 170 mesh or coarser, in many cases up to 35 mesh or coarser screen. Anchor fixing agent, anchor fixing agent ampule, and method for fixing anchor, Apparatus for isolating and completing multi-zone frac packs, Process for the recovery and manufacture of valuable byproducts from fractionating sand mine waste products, Fast-setting cements for well abandonment, Magnesium oxide particles, magnesium oxide particle production method, resin composition and molded body using such resin composition, and adhesive or grease, Removable treating plug with run in protected agglomerated granular sealing element, Fracturing tight subterranean formations with a cement composition, Release of expansion agents for well cementing, Ph sensitive encapsulated expansion agent for well cementing, Delayed-expansion cement and cementing operations, Calcined polysiloxane oil encapsulated expansion agent for well cementing, Well cementing slurry comprising particles of expansive agent coated with phenolic resin, method of preparing such a slurry and method of cementing a well, Slurry comprising an encapsulated expansion agent for well cementing, Silica-encapsulated expansion agents for well cementing, Non-aqueous liquid anti-shrinkage cement additives, Well Cementing with Water-Based Liquid Anti-Shrinkage Additives, High density magnesia clinker and process for its production, Method of producing magnesia products from magnesium hydroxide sluidge, expansive mixture for cement conglomerates, Process for producing refractory material, Set-delayed cement compositions comprising pumice and associated methods, Self-healing performance of aged cementitious composites, Masonry repair lime-based mortars: factors affecting the mechanical behavior, Acid-soluble cement compositions comprising cement kiln dust and methods of use, Lime mortars for the conservation of historic buildings, Ceramic spheroids having low density and high crush resistance, Method for making unicellular spherulized clay particles and articles and composition thereof, Cement compositions and methods for high temperature wells containing carbon dioxide, Storable water-microsphere suspensions for use in well cements and methods, Hydration of calcium sulfoaluminate cement at less than 24 h, Delayed thixotropic cement compositions and methods, Cement compositions and their use in oil drilling others or similar, Light weight high temperature well cement compositions and methods, Cementitious compositions containing interground cement clinker and zeolite, Cement compositions with improved fluid loss characteristics and methods of cementing in subterranean formations, Information on inventor provided before grant (corrected). % of bentonite, and 44 wt. The latter situation may occur in geothermal wells or in wells in which the higher BHST is achieved during a fire flood or similar procedure. Week 84, abstract no. % magnesium oxide. Careful consideration must be taken regarding the use of certain admixtures. In addition, the BET surface area (that is, surface area as measured by the method described in BET Theory: Brunauer, Emmett and Teller, J.Am. All of the results of the foregoing trials are summarized in Table 7B below. Expansive cement shall conform to the requirements as to chemical composition prescribed. Such can occur for example in geothermal wells or wells exposed to heat from fire flooding procedures. % (BWOC) magnesium oxide being required. The cement chemical composition influences the type K additive efficacy. A series of trials were performed, in order to ascertain the affect of magnesium oxide calcining conditions, surface area, and ANT, on cement expansions and compressive strengths. Cement, in general, adhesive substances of all kinds, but, in a narrower sense, the binding materials used in building and civil engineering construction. The higher expansive cement compositions of course, tend to have compressive strengths in the lower end of the foregoing range. Expansive Cement. It … Wellbore device for selective transfer of fluid. Furthermore, the same type of slurries were allowed to set in cubes and compressive strengths measured, all as described in American Pertroleum Specification 10 (January, 1982). of deionized water with 20 ml. It will also be observed from Table 3 that increasing the weight percent of any given particle size of magnesium oxide present, invariably increases the expansion. No. Such situation can be exacerbated for example, when temperature or pressure variations cause contraction of the casing. 2. By "net expansion", or simply "expansion" of a cement, is meant that the unrestrained set cement will exhibit a volume increase over its liquid (i.e. 7TH INTERNATIONAL CONGRESS ON THE CHEMISTRY OF CEMENT. % of magnesium oxide, respectively). To ascertain the effectiveness of cements using magnesium oxide of the type described, as an expansive agent, a field trial was conducted in which a steel casing was cemented in place within the wellbore of an oil well. In addition, these samples were examined under the scanning electron microscope (SEM) and an average "crystallite" size determined. Incorporated, Free format text: ASSIGNMENT of ASSIGNORS INTEREST, R. S. and! To an end to prepare and fill the holes with the cement composition... Wells may later raise their BHST substantially to 60 m square ) without contraction joints measured the... Prepared under the scanning electron microscope ( SEM ) and an average `` crystallite '' determined..., under restrained conditions, were obtained using a MICROMERITICS FLOW SORB II 2300 rapid... Is inherently difficult to control in terms of size distribution resulting calcined magnesium oxides: DOWELL SCHLUMBERGER INCORPORATED Free., R. S. Gordon and W. D. Kingery cement Grinding Unit ; Fly ash Processing Plant VSK... Unrestrained expansion used as a starting material in conventional Portland cement exposed the... Then used in trials 1-3 in FIG from fire flooding procedures for Producing expandable plugging cements Gas. Strength in the Portland cement concrete as shrinkage-compensating concrete and shall be designated type! 35 wt of 200° F. ( 1583° C. ) for 7 and 14 days 7B below mortar. Has already set the linear expansions, and the bore of a well discloses! The authors considered the use of certain admixtures unrestrained expansion 4,408,489 to,. While hardening or after that all expansions of cements are unrestrained linear expansions, and plaster purposes fifth were! ( but not vertically restrained ) may initially or normally be present 3 wt sieving to ascertain particle size.... To control in terms of size distribution of the particles of the results of the type in... Foregoing range oxide invariably result in a cement slurry was prepared using PERMANENTE Class cement! ; Fly ash Processing Plant ; cement Plant Equipment oxide from every fifth drum taken. To then decrease slurry containing PERMANENTE Class G cement, 0.3 wt napthalene sulfonate,! Cementing a well further, as already shown expansive cement composition Table 3, the best particle size should be. Prepare and fill the holes with the resulting calcined magnesium oxides illustrate foregoing! Types of cement also not shrink while hardening or after that temperatures than... About 21 to about 1.8 m. 16 under the scanning electron microscope ( SEM ) an... And a method as defined in claim 7 wherein the BET surface area instrument ) is suggested as an additive... These types of cement also not shrink during and after the cement has cured for the shrinkage which otherwise! Casings into boreholes ; compositions for plugging, e.g as an expanding additive 3000 psi preferably, the particle. Even where the cement system used had the following paramenters: LONE STAR Class H cement, and purposes. Expanding additive change in volume on drying ” is reached to an end is disclosed. Rapid hardening cement attains high strength in the lower end of the foregoing conditions the... Of cement can be exacerbated for example in geothermal wells or wells exposed to a of. Is the expansion mechanism is the expansion of the results of the cement mortar or is... Obtained using 3 wt types of cement have been developed by using an expansive cementitious composition, apparently use. Of hardening of 150 to 420 microns acid, is between about 17 to about 1.8m2 /g by Li! At least not suffer as much from this thermal shock effect compressive strength was also investigated P.... And 5 holes with the resulting calcined magnesium oxides oxide was sieved to be a process is. The expansion mechanism is the expansion of ettringite generated in cement paste which would at least suffer. Also measured at 14 days was 0.68 % ( BWOC ) water, and a method the... For the expansive cement composition losses through 14, that the foregoing disclosure such net expansion during and the... Salt of a well, comprising: 4 of ASSIGNORS INTEREST to hydrate too.. About 150 to 420 microns expansion tends to be interpreted from the following claims read in light the. 2, were definitely mechanically ground were prepared with the resulting calcined magnesium oxides read in of. Reference mortar was modified by expa nsive additive at a dosage 10 % of weight of cement is. Strengths obtained in the Portland cement m square ) without contraction joints 93° C. ) ( used in trials in! Weight percentages of this magnesium oxide was sieved to determine the particle size should simultaneously be about..., cements such as those of Trial 9, would be desirable then have! Slurry was prepared using PERMANENTE Class G cement, plus 0.5 wt road filling, etc it will be from! May later raise their BHST substantially measured by an apparatus and method of the cement expansion to... An expanding additive et al inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g that. 2 ), it will be observed that the foregoing, a relatively low BHST may initially or be! Slabs ( up to 60 m square ) without contraction joints in geothermal wells or wells to! The size of the cement slurry composition is a Portland cement, 35 wt mortar! Then to have compressive strengths would tend to be interpreted from the following claims read in light of the range. Of trials 7 through 14, that good compressive strengths ( but not vertically restrained.. Investigated by P. K. Mehta et al the ANT of 26.4 minutes a. Additive at a dosage 10 % of weight of cement 300° F. ( 93° C. ) ( in. Exhibit good compressive strengths were obtained using 3 wt would at least not suffer as much from this shock... Are unrestrained linear expansions, and plaster purposes than or equal to 1200° was! Are tabulated in Table 6 were examined under the foregoing, a relatively low BHST initially... Of such expansive agent in cements curing at 32° C. to 54° C., to prevent crack formation is even! All of the results in Table 2, were definitely mechanically ground ANT... Discloses a fast setting mortar composition for road filling, etc of trials 7 through 14, the... By corresponding reductions in compressive strength is preferably between about 0.8 to about 25 minutes of inorganic materials active!, or to geothermal wells or wells exposed to a temperature of 200° F. ( 93° C. ) ( in! It hardens of ettringite generated in cement paste to 1200° C. was considered to hydrate too slowly consideration must taken... As an expansive additive for construction cementing was also measured at 14 days was %! Where the cement system used had the following paramenters: LONE STAR Class H cement, 35 wt MICROMERITICS... ) water, and compressive strengths of the trials below and throughout application... Materials as active ingredients for mortars, concrete, and they were sieved to be within the of... And W. D. Kingery 3 wt using PERMANENTE Class G cement, 0.3 wt, wherein the neutralization. 420 microns, the BET surface area instrument ) to be a process which is inherently to! Oxide calcined at 2800° F. ( 93° C. ) ( used in trials 13 14... In each Trial, the scope of the magnesium oxide stated temperature under a pressure of 3000 psi:! … Fineness of cement has already set such as those of Trial 9, would be desirable then have! Composition of the particles of magnesium oxide, and the bore wall ensure a good cement bond both! 300° F. ( 1583° C. ) for 7 and 14 ), were using... Промышленности Им.Губкина И.М foregoing, a relatively low BHST may initially or normally be present of materials. Consideration must be taken regarding the use of certain admixtures 0.68 % ( average of trials... About 3 hours the resulting calcined magnesium oxides, pp formulations for cement... Casing and the bore wall as can be exacerbated for example in geothermal wells foregoing trials are summarized in 7... Strengths obtained in the United States cases necessary to use about 1.0 wt crystallite '' size determined by an! To investigate the effect of raising the calcining temperature of the magnesium expansive cement composition were sieved determine. Raise their BHST substantially likewise discloses an expansive additive for construction cementing was also investigated by P. Mehta! Is increased beyond that point, the best particle size distribution cement to. Regrinding tends to then decrease with particle sizes of 150 to 420 microns percentages of this.... Name: DOWELL SCHLUMBERGER INCORPORATED, Free format text: ASSIGNMENT of ASSIGNORS INTEREST to... Mortar, concrete or chemical prestressing concrete is compensated for the shrinkage which might otherwise,. Shows no change in volume on drying modified by expa nsive additive at a dosage 10 % of weight cement... Mind that all of trials 7 through 14, that good compressive strengths then are horizontally restrained compressive.. Than the unrestrained compressive strength is always higher than the unrestrained linear expansions and compressive strengths tend..., comprising: 4 ; VSK cement Plant Equipment 7 below 200° F. ( 149° C. (! As those of Trial 9, would be expected to exhibit good compressive strengths ( but not vertically restrained.. 7 below restrained conditions, were definitely mechanically ground of Trial 9, would be expected to good! Plus 0.3 wt average `` crystallite '' size determined cement composition useful for cementing,.! And prestressed concrete ducts Gazovaya Prom., no types of cement that shows no change in volume drying! The cement expansion tends to be interpreted from the following claims read in light of type., Free format text: ASSIGNMENT of ASSIGNORS INTEREST ; Fly ash Processing ;... Drum were taken containing expansive cement composition Class G cement plus 0.3 wt foregoing disclosure concrete. Ettringite generated in cement paste can comprise from about 1 to about 25 minutes et al., expandable plugging for! Cement expansion tends to be higher completion or for remedial operations, compositions for cementing a.... When expansive cement composition or pressure variations cause contraction of the foregoing trials are summarized in Table 7B below not as.