TECHNICAL FIELD

[0001] The present disclosure relates to cementitious compositions, and in particular to cementitious compositions for making anti-tamper concrete (ATC) coatings and coated pipes made therefrom.

BACKGROUND

[0002] The theft of pipeline contents, such as petroleum products, from onshore pipelines is a problem in some parts of the world. Pipelines may also be subject to attack from terrorism in some parts of the world. Accordingly, there is a need for protective coatings for pipelines to delay access to the steel wall and tapping of the pipeline.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0003] The present disclosure provides ATC coatings for pipelines and cementitious compositions for making anti-tamper concrete coatings. The ATC coatings are designed to be resistant to physical attack (e.g., from drilling, sawing and/or impact forces), chemicals and/or high temperatures depending on the composition selected. For example, the ATC coatings may be designed to be resistant to drilling with tungsten carbide masonry bits, sawing with fused aluminum oxide (FAO) concrete cutting blades, and/or impact forces from sledge hammers, chisels and the like. The ATC coatings may also be designed to be resistant to strong mineral acids such as hydrochloric, sulphuric and nitric acids, which attack the alkaline constituents of hydrated Portland cement (i.e., calcium silicate hydrate, and a by-product of Portland cement hydration, calcium

hydroxide). The ATC coatings may also be designed to be resistant to high temperatures caused, for example, by fires or torches.

[0004] The ATC coating of the present disclosure may be used to increase the time required to expose the underlying pipe compared to conventional concrete coatings. The ATC coating may also serve to discourage tampering with the pipeline because of the time and cost required to access the underlying pipe. The ATC coating in combination with tamper detection technologies, such as fiber optic sensors, may be used to increase the amount of time available to respond to and prevent access or damage to the pipeline. The ATC coatings may, in some embodiments, increase the time required to expose the steel by up to 15 times the time required for conventional concrete coatings.

[0005] In accordance with one embodiment of the present disclosure, there is provided a cementitious composition, comprising : a cement (also known as a binder), an aggregate or mixture of aggregates, and water. The cement may be a Portland cement, a calcium aluminate cement or a geopolymer cement. In some examples, the aggregate consists of approximately 80 vol. % FAO and

approximately 20 vol. % fine siliceous concrete sand of the total composition by volume. In other examples, the aggregate consists of approximately 50 vol. % FAO, approximately 30 vol. % emery, and approximately 20 vol. % fine siliceous concrete sand of the total composition by volume. The size and hardness of the aggregate may be selected to provide resistance to physical attack such as that from drilling and sawing. In some examples, the aggregate includes a hard aggregate having a Mohs hardness of 8 or more. In some examples, the hard aggregate has an average particle size of between 0.5 to 2 mm, preferably an average particle size of 1 mm.

[0006] In some examples, the cementitious composition may include reinforcing materials to provide resistance to physical attack such as impact resistance. The reinforcing materials may provide impact resistance by increasing the flexural and tensile of the resultant concrete.

[0007] In some examples, the cementitious composition may include one or more additives, such as a friction reducing additive which reduces the friction between tools and the resultant concrete, a high range water reducer which reduces the water content, an additive which improves tensile and/or impact resistance of the resultant concrete, or any combination thereof. [0008] In accordance with another embodiment of the present disclosure, there is provided a coated pipe, comprising : a length of pipe; an ATC coating formed from a cementitious composition in accordance with the present disclosure, the ATC coating being applied to at least a portion of the exterior surface of the pipe.

[0009] In some examples, when the cement is Portland cement or calcium aluminate, the consistency of the concrete formed ranges from very stiff, with a slump less than approximately 0 mm, to very fluid, having a slump greater than approximately 180 mm . In some examples, when the cement is a geopolymer cement, the consistency of the concrete formed ranges from very stiff, with a slump less than approximately 0, to a slump less than approximately 150 mm .

[0010] In some examples, the cementitious composition has a total binder content greater than 350 kg/m ³ and a water/cement ratio less than 0.50.

[0011] In some examples, the concrete has a void content less than

approximately 15% by volume, preferably less than approximately 10% by volume, and more preferably less than approximately 5% by volume.

[0012] In some examples, the concrete has a compressive strength of approximately 30 MPa or more, preferably approximately 60 MPa or more.

[0013] In accordance with a further embodiment of the present disclosure, there is provided a pipeline comprising at least one section of coated pipe in accordance with the present disclosure.

[0014] Portland cement is made by heating a source of calcium carbonate (such as limestone) with small quantities of an aluminosilicate such as clay or similar material at a sintering temperature (typically about 1450 °C) in a kiln in a process known as calcination. During calcination a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide which is blended with the secondary materials. The resulting hard substance, called "clinker", is ground with a small amount of gypsum (calcium sulfate dihydrate) and/or anhydrite into a powder. Portland cement reacts with water to form primarily calcium silicate hydrate. The strength of the resultant concrete results from a hydration reaction between the silicate phases of Portland cement and water to form calcium aluminate hydrate Ca ₃ Si ₂ 0iiH ₈ (3 CaO ^■ 2 Si0 ₂ ^■ 4 H ₂ 0, or C ₃ S ₂ H ₄ in Cement chemist notation (CCN)) and calcium hydroxide (lime) as a by-product. Portland cement-based ATC coatings may be manufactured with Portland cement meeting the requirements of ASTM C150 Type I, II, I/I I, III, IV or V or equivalent standard specifications.

[0015] Supplementary cementitious materials (also known as secondary mineral components) may be partially substituted for Portland cement to improve the durability and ultimate strength of the resultant concrete, react with calcium hydroxide, a by-product of Portland cement hydration to form additional binder which further increases durability and ultimate strength, reduce material costs, and provide resistance to acids which may be used to attack the alkaline constituents of hydrated Portland cement. Supplementary cementitious materials also improve the resistance of concrete to chemical attack from soluble sulphate in soild and ground water. The supplementary cementitious materials are silicate or

aluminosilicate materials which exhibits pozzolanic properties. The supplementary cementitious materials may include one or any combination of ground granulated blast furnace slag (GGBFS) (ASTM C989), coal combustion ash (ASTM C618), silica fume (ASTM C1240), rice husk ash or any fine silicate or aluminosilicate material which exhibits pozzolanic properties. Fine silicate or aluminosilicate materials typically haave an average particle size of less than 15 microns. ATC coatings based on Portland cement may be manufactured with or without supplementary cementitious materials. When supplementary cementitious materials are used, the substitution range of Portland cement with the various supplementary cementitious materials will typically range between 5 and 70% by weight, preferably between 5 and 50% by weight to reduce the impact of lower strengths of caused by higher levels of supplementary cementitious materials and reduce the time before coated ATC pipes can be handled.

[0016] Calcium aluminate cements are hydraulic cements made primarily from limestone and bauxite. The active ingredients are monocalcium aluminate CaAI ₂ 0 ₄ (CaO ^■ Al ₂ 0 ₃ or "CA" in CCN) and mayenite Cai ₂ Ali ₄ 0 ₃₃ (12 CaO ^■ 7 Al ₂ 0 ₃ , or C12A7 in CCN). Strength of the resultant concrete results from hydration to calcium aluminate hydrates. Calcium aluminate cements are well-adapted for use in refractory (high-temperature resistant) concretes, such as in furnace linings.

Calcium aluminate cement-based ATC coatings typically have an Al ₂ 0 ₃ content between 39 and 80%.

[0017] Supplementary cementitious materials may also be added or partially substituted for Calcium aluminate cement to increase the durability and ultimate strength of the resultant concrete by reducing or preventing conversion (a change in the internal structure of the resultant concrete). The supplementary

cementitious materials may include one or any combination of fly ash, silica fume or possibly slag (e.g., GGBFS). Hydrated calcium aluminate cements are resistant to sulfate attack and therefore may be suitable when the soils that the pipeline is in contact with contain high levels of naturally occurring soluble sulfates. Calcium aluminate cements, which are used to manufacture refractories, are heat resistant up to temperatures between about 950°C and about 1540°C, depending on the particular concrete composition. Therefore, calcium aluminate cements may be used in the ATC coating when heat resistance is required. When supplementary cementitious materials are used, the substitution range of Calcium aluminate cement with the various supplementary cementitious materials is estimated to range between 5 and 15%.

[0018] Geopolymer cements are generally formed by reaction of an

aluminosilicate powder with an alkali solution and alkaline silicate solution at ambient conditions and up to 80°C. The supplementary cementitious materials, described above, are the main or primary constituents of geopolymer cements and are blended to achieve a specific rates of reaction and strength. Metakaolin is an aluminosilicate powder generated by thermal activation of kaolinite clay which is commonly used in geopolymer cements. Geopolymer cements can also be made from natural sources of pozzolanic materials such as lava or fly ash from coal. Geopolymer cements-based ATC coatings may comprise a binder system including metakaolin which is calcined at a sintering temperature (typically about 750°C). Geopolymer cements manufactured without metakoalin may alternatively be used; however, the strength may be lower and may be slower to develop.

[0019] The silicate and aluminosilicate materials may include one or any combination of GGBFS, silica fume, fly ash (ASTM Class C or F), rice hull (husk) ash, cracking catalyst (an aluminosilicate used to process petroleum products) or natural pozzolan (trass or pumice). The particular geopolymer composition will vary depending on the composition and reactivities of the raw materials used. The composition and reactivity of metakaolin is generally uniform but the compositions and reactivities of an aluminosilicate material such as GGBFS and fly ash can vary widely. There is a substantial body of published patent and non-patent literature describing the types and properties of metakaolin and the aluminosilicate materials described above. Sodium and/or potassium silicate predominantly in the

orthosilicate form may be added as a solution to the metakaolin and supplementary cementitious materials, typically in powder form, to produce the geopolymer cement. The particular amount of sodium and/or potassium silicate will vary depending on the raw materials used. Through a process of alkaline hydrolysis and condensation a strong and heat resistant cementitious binder may be formed.

Thus, geopolymer cements may be used for the ATC coating instead of calcium aluminate cements when heat resistance is required.

[0020] Calcium aluminate cements and geopolymer cements also provide resistance to attack by strong mineral acids, such as hydrochloric, sulphuric and nitric acids which attack the alkaline constituents (i.e., calcium silicate hydrate and lime) of hydrated Portland cement which are susceptible to attack by organic and mineral acids which degrade the concrete rapidly. Calcium aluminate cements and geopolymer cements do not include lime or large amounts of other alkalis which may react with acid applied or otherwise exposed to the concrete. Therefore, calcium aluminate and geopolymer cements may be used for the ATC coating when acid resistance is required. Aggregates

[0021] The aggregate includes a hard aggregate having a Mohs hardness of 8 or more (based on Mohs scale of mineral hardness). The hard aggregate may be made from natural rock and/or artificial materials. Examples of suitable hard aggregates include abrasives such as emery, corundum, fused aluminum oxide (FAO) and calcined bauxite. The hard aggregate system may comprise emery, corundum, FAO or calcined bauxite, or a mixture of any two or more of emery, corundum, FAO or calcined bauxite in any proportion.

[0022] The aggregate may also include an aggregate having a Mohs hardness of less than 8. The lower hardness aggregate may be sand (such as quartz or silica sand), concrete sand and/or pea gravel. The low hardness aggregate may be added up to a maximum of 50% of the total aggregate by volume to optimize the particle size distribution and to improve particle packing of the aggregate mixture and reduce cost.

[0023] Sieve analysis of example lower hardness aggregates is given in the following Table 1 below:

Table 1 : Aggregate Sieve Analysis

[0024] Fine siliceous concrete sand having the above-noted size distribution may be described as a sand which is substantially retained on the 0.075 mm sieve and passing the 0.600 mm sieve (or +0.75 - 0.060 mm).

[0025] The aggregate properties, including compressive strength, Mohs hardness and modulus of elasticity, are given in Table 2 below. The aggregate properties may vary somewhat according to the source from which the aggregate is extracted or acquired; however, the aggregate properties are generally similar between sources.

Table 2 : Aggregate Properties

¹ Source : "Knoop Hardness Numbers for 127 Opaque Minerals", F. Roberston, GSA Bulletin, V. 72 (4), pp. 621 - 637 (April 1961)

² Source: http://www.matweb.com

³ Emery has a variable composition

[0026] The compressive strength and moduli of the hard aggregates, such as FAO, are significantly higher than the soft aggregates as shown in Table 2. The compressive strengths of concretes prepared with hard aggregates also exhibit significantly higher compressive strengths relative to concrete prepared with soft aggregates. Particle morphology and surface texture also play a role in the development of higher compressive strengths. Hard aggregates are generally angular because of the crushing process used to manufacture them. Siliceous sands used to manufacture conventional concrete are generally rounded due to

weathering. Concrete prepared with angular aggregates typically exhibit higher compressive strengths due to their higher surface areas and the greater ability to mechanically interlock under compressive stresses. The chemical nature of the aggregate surface may also affect the strength of the bond between the cement paste and the aggregate.

[0027] When resistance to high temperatures is desired, the hard aggregate is FAO, calcined bauxite or emery or a mixture of any two or more of FAO, calcined bauxite or emery in any proportion. The linear coefficient of thermal expansion of FAO, calcined bauxite and emery are given in Table 3.

Table 3 : Linear Coefficient of Thermal Expansion of Aggregates

American Society for Testing and Materials (ASTM) STP169C, entitled "Significance of Tests and Properties of Concrete and Concrete-Making Materials".

[0028] FAO is a refractory material and has a linear coefficient of thermal expansion which is significantly less than siliceous sands (e.g., fine sand and quartz) as shown in Table 3. At a temperature of 572.7°C, FAO expands 0.85% as described in American Society for Testing and Materials (ASTM) STP169C, entitled "Significance of Tests and Properties of Concrete and Concrete-Making Materials". FAO expands and contracts considerable less in response to high temperatures than siliceous sands. Excessive expansion of the aggregate degrades the structural integrity of the concrete due to the development of high internal tensile stresses in the concrete. Therefore, the use of FAO as an aggregate provides a measure of heat resistance to the concrete in which it is carried compared with concretes containing only siliceous sands.

[0029] The hard aggregate provides resistance to physical attack from drilling and sawing. Experimentation has shown that an average particle size of between 0.5 to 2 mm for the hard aggregate provides relatively effective resistance to physical attack from drilling and sawing, preferably an average particle size of 1 mm. This particle size provides protection against drilling and sawing by concrete and masonry drill bits and saw blades, such as carbide-tipped masonry bits and blades.

Reinforcement

[0030] The cementitious composition may also include reinforcing materials for reinforcement of the concrete in some embodiments. The reinforcing materials provide resistance to impact by increasing the flexural and tensile strength of the concrete. Reinforcement increases the amount of energy required to cause rupture and complete failure. Reinforcing materials may be added to any of the cement compositions described herein. The reinforcing materials provide strength when cracks form in the concrete as a result of sustained impacts. When a crack forms in the concrete, the reinforcing materials bridge the void created by the crack and allow the concrete to deform in a ductile manner.

[0031] The reinforcing material may comprise one or any combination of steel rebar, wire mesh, steel fibers, polypropylene fibers, nylon fibers or polyvinyl alcohol fibers. In some embodiments, the total content of the reinforcing material is between 0.25% and 2% of the cementitious composition by volume (of concrete), preferably between 0.6% and 2% of the cementitious composition by volume, and preferably 1% to 2% of the cementitious composition by volume. In some example embodiments, the reinforcing material comprises one or any combination of wire mesh, steel fibers or polyvinyl alcohol fibers. Properties of suitable wire mesh, steel fibers or polyvinyl alcohol fibers are described in Table 4 below.

Table 4: Reinforcing Material Properties

* Nominal, 1 in x 2.75 in., (center to center of wire) [0032] When resistance to high temperatures is desired, polypropylene fibers and/or polyvinyl alcohol fibers may be used as the reinforcing material . When exposed to high temperatures, the polypropylene fibers and/or polyvinyl alcohol fibers melt and decompose, opening channels in the concrete. The channels allow water vapour (e.g., steam), which is generated from the decomposition of hydrated cements to escape from the concrete, reducing and/or preventing the cracking and spalling of concrete due to generation of high internal tensile forces.

Additives

[0033] Friction reducing additives may be added to the cementitious composition to reduce the friction between tools (e.g., drill bits, saw blades, etc.) and the concrete. Friction reducing additives increase drilling time and may increase sawing time. The friction reducing additives may comprise one or any combination of granulated polyethylene (such as Ultra-High Molecular Weight Polyethylene (UHMWPE)), graphite or Teflon®. Properties of friction reducing additives are described in Table 5 below.

Table 5 : Friction Reducing Additives Properties

[0034] A high range water reducer may be added to the cementitious compositions. Typically, use of a high range water reducer is limited to a Portland cement or calcium aluminate cement. A water reducer reduces the water content (e.g., the water/cement ratio), decreases the concrete porosity, increases the concrete strength as less water is required for the concrete mixture to remain workable, increases the workability (assuming the amount of free water remains constant), reduces the water permeability (due to a reduction in connected porosity), and reduces the diffusivity of aggressive agents in the concrete and thereby improves the durability of the concrete. A high range water reducer is an admixture which has the ability to reduce the water/cement of concrete over a wide range, for example 5 to 15% as per ASTM C494, compared with conventional water reducers are typically limited to 5 to 8%. The high range water reducer may be, but is not limited to, a polycarboxylate superplasticizer or other material which is functionally equivalent and meets ASTM C494, Type F and G requirements.

[0035] Other additives may be added to the cementitious composition to modify the properties of the concrete, such as acrylic or styrene butadiene latex, or emulsified epoxy to improve tensile and impact resistance. Typically, use of styrene butadiene latex is limited to a Portland cement or calcium aluminate cement. For example, Wollastonite, a processed fiberous calcium inosilicate mineral (CaSi0 ₃ ) having an aspect ratio of 9 : 1 to 15 : 1 (length to diameter) may be added as a component in the geopolymer cement to improve the tensile and flexural properties of the resultant concrete (i.e., as a form of micro-reinforcement) and as a secondary source of calcium ions for the geopolymer binder system.

Cement Properties

[0036] Cementitious compositions in accordance with the present disclosure may have a total binder content between 350 kg/m ³ and 550 kg/m ³ and a water/cement ratio between 0.5 and 0.25. Cementitious compositions having these properties are believes, based on limited testing, to achieve an effective balance between concrete strength and drill/impact resistance. As the amount of the binder content is reduced, the strength of the ultimate concrete is reduced. As the amount of the binder content is increased, the volume of aggregate will be lower and drill resistance will be impacted of the ultimate concrete is reduced.

[0037] When Portland cement is used, supplementary cementitious materials may be partially substituted for Portland cement between 5% and 50% by weight. When a Portland or calcium aluminate cement are used, the consistency of concrete formed is expected to range from very stiff, with a slump less than 0 mm, to very fluid, having a slump greater than 180 mm . When a geopolymer cement is used, the consistency of the concrete formed is expected to range from very stiff, with a slump less than 0, to a slump less than 150 mm . The void content of the concrete is preferably less than 15% by volume, more preferably less than 10% by volume, and more preferably less than 5% by volume. The compressive strength of the concrete is at least 30 MPa, preferably 60 MPa or greater. The compressive strength up to approximately 120 MPa are possible but very expensive and difficult to manufacture consistently. Accordingly, a compressive strength of approximately 80-90 MPa may be the practical upper limit for ATC coatings.

Application to pipe

[0038] The ATC coating may be bonded to an anti-corrosion coating (e.g., fusion bonded epoxy, polyethylene or polypropylene) of the steel pipe with an epoxy-based or latex-modified cement slurry adhesive. The bonding of the ATC coating to the steel pipe creates a composite and increases the impact resistance of the ATC coating. The adhesive further makes it difficult to remove the ATC coating from the steel pipe, which makes attaching connections to the steel pipe, such as nipples, more difficult and time consuming. Alternatively, the ATC coating may be applied to bare steel pipe.

[0039] Two processes are contemplated for use in the manufacture of the ATC coating although other processes may be used : (1) a (compression) wrapping process and (2) a form and pour/pump process. The wrapping process uses concrete which is relatively dry (similar to damp sand which holds together when compressed by hand pressure). The form and pour/pump process uses concrete which is fluid. The concrete used in the wrapping process will likely have a void content between approximately 10 and 25% and the concrete used in the form and pour/pump process will likely have a void between approximately 2 to 4%.

Generally, for every 1% increase in void content approximately 3 MPa in strength is lost. Therefore, the void content of the concrete significantly affects its strength. Cement content can be low if the void content are low and vice versa.

Performance of ATC Coatings

[0040] Table 6 below shows the relative penetration resistance of ATC coatings relative to conventional Portland cement concrete with a compressive strength of 30-50 MPa. The impact drill resistance results are presented as relative resistance and are based on the rate of penetration with a 25 mm tungsten carbide bit in mm/second using a proprietary testing method. The saw resistance results are presented as relative resistance and are based on rate of penetration in mm/second with a 229 mm diameter FAO masonry blade using a proprietary testing method. Impact resistance is a relative resistance based on Joules required to penetrate 50 mm using proprietary testing method, and time to penetrate 50 mm with an electric impact hammer using a proprietary testing method.

Temperature resistance is based on published literature rather than experimental data. The predicted acid resistance is based on published literature and the binder chemistry rather than experimental data.

Table 6 : Relative Resistance to Attack

[0041] Experimental data has shown that ATC coated pipe sections coated with low and high strength concrete coatings with 1-2 vol. % steel fibres, and concrete coatings without steel fibres, exhibit high current densities when tested according to a proprietary method which exceeded the minimum current density for maintaining cathodic protection in at least some applications. Testing showed that ATC coated pipe sections coated with low and high strength concrete coatings with 1-2 vol . % steel fibres, and concrete coatings without steel fibres, exhibited current densities of at least is 3 mA/ft ² . Thus, the ATC coatings of the present disclosure appear to be compatible with applications which require the use cathodic protection systems for underlying steel pipelines. The inclusion of steel fibres increases current density, and increasing the content of steel fibres from 1 vol . % to 2 vo. % increases the current density significantly. Concrete mixtures containing 430 kg/m ³ cement with dry or plastic consistencies exhibited low electrical resistivities; however, high strength concrete mixtures having 500 or 550 kg/m ³ cement (e.g., Portland cement) exhibited higher electrical resistivities. Steel fibres significantly reduce resistivity by providing low resistance pathways through the concrete coating. Generally, the electrical resistivity is lowered as the content of steel fibres increases.

Portland cement compositions

[0042] Table 7 illustrates Portland cement mixture range and properties based in accordance with examples of the present disclosure. Steel fibers and wire mesh are provided for reinforcement in the examples in Table 7. Polyvinyl alcohol or other suitable reinforcing materials (such as those described above) may be used in addition, or instead of steel fibers and wire mesh in other examples. Some of the examples in Table 6 include friction reducing additives, which may include one or any combination of Teflon, UHMWPE or graphite in the proportions specified. The Examples identified as Type 1-2 and Type 1-3 show improved heat resistance owing, at least in part, to the inclusion of FAO as a hard aggregate and its refractory properties.

Table 7 : Portland concrete mixture range and properties

Example Portland cement compositions

[0043] Examples of Portland cement compositions for use in forming the ATC coatings of the present disclosure are provided in Tables 8 to 12 shown below. The compositions in Table 8 below include reinforcement and aggregate in the form of fine and coarse siliceous concrete aggregate. No hard aggregates are present. Cements formed using the compositions in Table 8 were found to have low drill and saw resistance, moderate impact resistance, and are expected to have low

resistance to high temperatures and low resistance to acid attack.

Table 8

[0044] The compositions in Table 9 below include no reinforcement but include aggregates in the form of FAO, emery and fine siliceous concrete sand. FAO and emery are considered hard aggregates; however, fine siliceous concrete sand is considered a low hardness aggregate based on Mohs Hardness, as described above. Cements formed using the compositions in Table 9 were found to have high drill and saw resistance, low impact resistance, and a predicted moderate resistance to high temperatures and low resistance to acid. Table 9

[0045] The compositions in Table 10 below include no reinforcement but include aggregates in the form of FAO and fine siliceous concrete sand. Cements formed using the compositions in Table 10 were found to have high drill and saw resistance, low impact resistance, and are predicted to have a moderate resistance to high temperatures and low resistance to acid attack.

Table 10

[0046] The compositions in Table 11 include steel reinforcement but include aggregates in the form of FAO, emery and fine siliceous concrete sand. FAO and emery are considered hard aggregates but fine concrete sand is considered a soft aggregate based on Mohs hardness, as described above. Cements formed using the compositions in Table 11 were found to have high drill and saw resistance, high impact resistance, moderate resistance to high temperatures and low resistance to acid attack.

Table 11

[0047] The compositions in Table 12 below include no reinforcement but include aggregates in the form of FAO and fine siliceous concrete sand. Cements formed using the compositions in Table 12 were found to have high drill and saw resistance, high impact resistance, and predicted moderate resistance to high temperatures and low resistance to acid attack. Table 12

[0048] Table 13 shown below, provides a comparison of the example Portland cement compositions in Tables 7 through 11 in terms of various types of anti- tamper resistance.

Table 13 : Comparison

Calcium aluminate cement compositions

[0049] Table 14 illustrates calcium aluminate cement mixture ranges and properties based in accordance with examples of the present disclosure. Steel fibers and wire mesh are provided for reinforcement in the examples in Table 14. Polyvinyl alcohol or other suitable reinforcing materials (such as those described above) may be used in addition, or instead of steel fibers and wire mesh in other examples. Some of the examples in Table 14 include friction reducing additives, which may include one or any combination of Teflon, UHMWPE or graphite in the proportions specified.

[0050] The calcium aluminate cements in Table 14 show improved heat and acid resistance owing, at least in part, to the refractory properties of the calcium aluminate binder. The calcium aluminate binder allows even further improved heat and acid resistance compared to Portland cement mixtures which utilize refractory aggregates.

Table 14: Calcium aluminate concrete mixture range and properties

Geopolymer cement compositions

[0051] Table 15 illustrates geopolymer cement mixture range and properties based in accordance with examples of the present disclosure. Steel fibers and wire mesh are provided for reinforcement in the examples in Table 15. Polyvinyl alcohol or other suitable reinforcing materials (such as those described above) may be used in addition, or instead of steel fibers and wire mesh in other examples. Some of the examples in Table 15 include friction reducing additives, which may include one or any combination of Teflon, UHMWPE or graphite in the proportions specified.

[0052] The geopolymer cements in Table 15 show improved heat and acid resistance owing, at least in part, to the refractory properties of the geopolymer binder. The geopolymer binder allows even further improved heat and acid resistance compared to Portland cement mixtures which utilize refractory aggregates.

Table 15 : Geopolymer concrete mixture range and properties

[0053] Each of the documents mentioned herein is incorporated by reference herein it is entirety.

[0054] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects as being only illustrative and not restrictive. The present disclosure intends to cover and embrace all suitable changes in technology. The scope of the present disclosure is, therefore, described by the appended claims rather than by the foregoing description . All changes that come within the meaning and range of equivalency of the claims are intended to be embraced within their scope.