CONCRETE FOR PIPE COATING

TECHNICAL FIELD

[0001] This disclosure relates to concrete coating, particularly concrete coating for pipes.

BACKGROUND OF THE INVENTION

[0002] Concrete coated steel pipes for oil and gas application, particularly, for subsea pipelines, are known and typically comprise an external coating of concrete comprising water, cement, sand, gravel/iron ore and steel reinforcement. Concrete coatings are desirable to add weight, and/or to protect the pipes from detrimental environment, for example, submarine or wet conditions. This includes mechanical protection including falling objects, trawling, and handling of the pipe during the laying process. Adding weight from the concrete helps stabilization of the pipeline on the sea bed and helps prevent the moving around of the pipe due to negative buoyancy of the pipeline.

[0003] Concrete coatings for pipelines have a wide range of compositions and properties. In certain embodiments, a known concrete pipeline coating has a density of about 3040 kg/m ³ , a void percentage (i.e. air) of about 10%, and a composition of about 15.5% cement, 62.7% iron ore, 16.7% sand, and 5.1% water by weight.

[0004] Conventional concrete-coated pipes are prone to damage during handling, for example, when the pipes are handled on the lay barge. Pipes are also sometimes damaged during storage in the yard when stacked with point contact.

[0005] Also, spalling of conventional concrete occurs on some concrete coated pipes during bending or laying process, particularly on small sections of cutback areas where no reinforcement exists. This occurs specifically when a steel cage is used as reinforcement. Conventional concrete also experiences crushing when gripped by jaws of tensioner during the laying process on the lay barge vessel. [0006] To mitigate such damages, it is desirable to improve the flexibility and toughness of the concrete coating. This would result in improved strain

resistance/toughness of the concrete coated pipes which would decrease damage to the concrete coating specifically during storage, handling, and installation.

[0007] It is also desirable to improve workability of conventional concrete during application to improve compactability of final product, ideally resulting in reduced void percentage and enhanced compressive strength. This may also result in reduced cost for producing the concrete or higher density at a same coating thickness.

BRIEF SUMMARY OF THE INVENTION

[0008] According to one aspect of the present invention is provided a concrete composition for coating pipes, the composition comprising: water, cement, iron ore, sand, and further comprising fiber and/or water-reducing admixture.

[0009] In certain embodiments, the composition comprises water, cement, iron ore, sand, and fiber.

[0010] In certain embodiments, the concrete composition comprises, by volume in liters in one cubic meter of concrete: water: 150-180, preferably about 164.5; cement: 125-175, preferably about 149.6; iron ore: 375-425, preferably about 405.4; sand : 170-220, preferably about 190.8; fiber: 3.0 - 7.0, preferably about 5.0; and the balance being air.

[0011] In certain embodiments, the fiber is one or more of polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber, or glass fiber. In certain embodiments, the fiber is combined with or substituted with other additives / fillers, for example Wollastonite or silica fume.

[0012] In certain embodiments, the fiber is polyvinyl alcohol fiber.

[0013] In certain embodiments, the PVA fiber is about 19 mm in length.

[0014] In certain embodiments, the fiber is polypropylene fiber. [0015] In certain embodiments, the composition comprises water, cement, water, cement, iron ore, sand, fiber, and water-reducing admixture.

[0016] In certain embodiments, the composition comprises, by mass percentage: water: 4.8 - 5.4, preferably about 5.1; concrete: 13.8 - 18.1, preferably about 15.5; iron ore: 50.11 - 80.2, preferably about 62.7; sand : 1.2 - 29.8, preferably about 16.7; wherein the water-reducing admixture is in a range of 130 - 975, preferably about 500 mL/100 kg cement, the fiber is in a range of 3.0 - 7.0, preferably about 5.0 liters per one cubic meter of the concrete composition, and the balance is air.

[0017] In certain embodiments, the water-reducing admixture complies with ASTM C 494 requirements for Type A or F admixture.

[0018] In certain embodiments, the water-reducing admixture is one or more of BASF MasterCast 900, Quantec PL450, Sikamix BF3, and BASF MasterGlenium 7925.

[0019] In certain embodiments, the fiber is one or more of polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber, or glass fiber. In certain embodiments, the fiber is combined with or substituted with Wollastonite or silica fume.

[0020] In certain embodiments, the fiber is polyvinyl alcohol fiber.

[0021] In certain embodiments, the PVA fiber is about 19 mm in length.

[0022] In certain embodiments, the fiber is polypropylene fiber.

[0023] In certain embodiments, the concrete composition comprises water, cement, water, cement, iron ore, sand, and water-reducing admixture.

[0024] In certain embodiments, the composition comprises, by mass percentage: water: 4.8 - 5.4, preferably about 5.1; concrete: 13.8 - 18.1, preferably about 15.5; iron ore: 50.11 - 80.2, preferably about 62.7; sand : 1.2 - 29.8, preferably about 16.7; wherein the water-reducing admixture is in a range of 130 - 975, preferably about 500 mL/100 kg cement, and the balance is air. [0025] In certain embodiments, the water-reducing admixture complies with ASTM C 494 requirements for Type A or F admixture.

[0026] In certain embodiments, the water-reducing admixture is one or more of BASF MasterCast 900, Quantec PL450, Sikamix BF3, and BASF MasterGlenium 7925.

[0027] According to yet another aspect of the present invention is provided a method for preparing a concrete composition, comprising: mixing a water-reducing admixture with the concrete composition.

[0028] In certain embodiments, the method comprises: mixing sand and iron ore with water to form a first mixture; mixing the first mixture with cement to form a second mixture; mixing the water-reducing admixture with the second mixture.

[0029] In certain embodiments, the sand, the iron ore, and the water are mixed for 30 seconds to form the first mixture; the first mixture is mixed with cement for 1 minute to form the second mixture; and the water-reducing admixture is mixed with the second mixture for 30 seconds.

[0030] In certain embodiments, the water-reducing admixture complies with ASTM C 494 requirements for Type A or F admixture.

[0031] In certain embodiments, the water-reducing admixture is one or more of BASF MasterCast 900, Quantec PL450, Sikamix BF3, and BASF MasterGlenium 7925.

[0032] According to yet a further aspect of the present invention is provided a method for preparing a concrete composition, comprising: mixing sand, iron ore, water, and cement to form a first mixture; adding a water reducing admixture to this first mixture and mixing the admixture into the first mixture to form a second mixture; adding fibers to the second mixture to mix into a final mixture.

[0033] In certain embodiments, mixing the fiber and the second mixture is for a duration of 30 seconds to 1 minute. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which :

[0035] Figure 1 shows the ASTM C496 Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens.

[0036] Figure 2 shows the step for impact testing.

[0037] Figure 3 shows the proposed locations for adding fibers to the concrete in a plant setting.

[0038] Figure 4 shows fiber distribution in freshly mixed concrete.

[0039] Figure 5 shows fiber distribution in hardened concrete.

[0040] Figure 6 shows concrete surface after hardening.

[0041] Figure 7 shows the void content at different dosages of the

admixtures.

[0042] Figure 8 shows locations in a plant setting for adding the admixture.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0043] In various examples, the present disclosure describes concrete compositions for improving the properties of the concrete, methods for making, testing, and applying such compositions. Although the present disclosure provides examples, the disclosed compositions and methods may be suitable for other purposes, with modification as appropriate.

[0044] In this disclosure, "Wrap" refers to compression wrap mix designs and "Impingement" refers to the impingement mix designs. 'Wrap" mix designs were the same in all cases apart from fiber type and addition rates.

[0045] In some embodiments, the following "wrap" mix design was used : 470 kg/m ³ cement, 10% voids, 3040 kg/m ³ target density, 0.33 w/c (water-to-cement ratio). In some embodiments, the impingement mix designs were: 550 kg/m ³ cement, 10% voids, 3040 kg/m ³ target density, 0.30 w/c.

[0046] In some embodiments, Type I/II cement was used in the

compositions. In some embodiments, the cement used is St. Mary's cement. The cement was mixed with iron ore, for example, iron ore produced by LKAB, and sand, preferably meeting ASTM C33 gradation requirements. Iron ore and sand may be collectively referred to as "aggregates."

[0047] (A) Addition of Chopped Fibers

[0048] It was found that incorporating short polymer fibers can improve the toughness of the concrete coating on the pipeline, including increasing its flexural strength, its impact resistance, and its load bearing capacity. Surprisingly, contrary to short polymer fiber addition in other applications and industries, the addition of a relatively small amount of such fibers was sufficient to provide significant increase in toughness in the pipeline coating setting.

[0049] It was found that short polymer fibers could be added to the concrete coating utilizing the conventional, continuous manufacturing process. Normally, concrete made to coat pipes is made with shorter mix time and a different integration approach than is recommended when utilizing such fibers in other applications and industries. It has been found that certain fibers, of certain properties are more advantageous than others for use in such a continuous manufacturing process due to the small window for mixing material; preferably, the short continuous fibers should separate and disperse within the concrete mix quickly and evenly.

[0050] In one embodiment, we found that a 36 to 44 denier PVA

monofilament bundle having cut lengths of about 15mm to 30 mm, a melting point of 200-250 degrees Celsius, a tensile strength of 900 MPa to 1100 MPa, a flexural strength of 26 GPa to 32 GPa, and a specific gravity of 1.0 to 1.5 was particularly advantageous. In particular, we found surprisingly good improvement in concrete strength from use of NYCON PVA RFS400 (Nycon, USA) fiber products, which are a 40 denier, PVA monofilament bundle having cut lengths of 19mm, a specific gravity of 1.3, a melting point of 225 degrees Celsius, a tensile strength of 1000 MPa, and a flexural strength of 29 GPa. Surprisingly, and despite the manufacture

instructions to the contrary (which require mixing at high speed for a minimum of 5 minutes, and which recommend use of at least wt 1% of the Nycon PVA RFS400 in the concrete mixture in order to obtain relevant results), we have found that the short continuous fibers could be used in a near instantaneous mixing process currently used when formulating and applying standard concrete weight coating onto pipeline, and that a significant and desirable increase in toughness of the concrete pipeline coating was obtained in concentrations as low as 0.2% by volume.

[0051] An exemplary composition of the concrete composition is shown in

Table 1 : 0.35% to 0.7% Fibers in Wrap Mix Design

Table 1

[0052] Although the RFS 400 fibers as described above and utilized in the specific embodiment described in Table 1 were particularly advantageous, the short polymer fibers can be selected from a number of suitable materials. They may be polyvinyl alcohol (PVA) fibers, for example, grades RFS400 and RECS15 produced by Nycon. The fibers can also be polypropylene (PP) fibers, for example, grades HP and PPM produced by Sika. The fibers can also be glass fibers, for example, grade 19PH901X produced by NEG. The fiber used in the composition can also be a combination of two or more of the fibers listed above. In certain cases, the fibers may be combined with, or substituted by, fillers, for example Wollastonite or silica fume.

[0053] The fibers are mixed in the composition. In some embodiment, the fibers were added as a continuous flow into the concrete mix, for example, by using compressed air to blow the fibers into the concrete mix. In a plant setting, the fibers may be added on the belt conveyor transporting dry concrete mix, in the concrete mixer/applicator, or in the fall-through area, for example, as shown in Figure 3. The resultant content of the fibers in the dry concrete composition was between 0.10 - 0.40 % by volume, for example between 0.20-0.40% by volume or about 0.35% by volume. It is preferable that the fibers are dry and not exposed to moisture before loading into the mix.

[0054] Concrete slabs made of the concrete composition as described above in Table 1 were subject to impact testing as shown in Figure 2, to determine their impact resistance property.

[0055] Because concrete coated pipes experience multi directional forces during handling/laying, a test that indicates whether toughness has improved is flexural and tensile strength testing. Since tensile testing is difficult to perform on concrete, an indirect method, the "Splitting Tensile Test", was used, where the cylinder is split in two by a force applied along its length. The force required to split the cylinder is related to the tensile strength of concrete. The flexural strength is done on beams in a four point bending also known as third point loading test (since forces are applied at 1/3 and 2/3 points on the beam). The test results are shown below in the Examples.

[0056] The method for testing Splitting Tensile Strength of Cylindrical

Concrete Specimens is shown in Figure 1, in accordance with standard ASTM C496. The cylindrical concrete specimens were cured in a moisture room for 28 days, then air dried for two days, and then subject to testing.

[0057] Compressive strength was performed on proctor cylinders and also on cores. [0058] A pipe coating trial was conducted to prove the concept of fiber addition, coating of pipe with concrete using fibers and later testing the concrete collected from the pipe for tensile, flexural and impact resistance, density, water absorption, permeable void and compressive strength.

[0059] B - Water Reducing Concrete Admixture

[0060] It was also found that toughness of the concrete can be improved by reducing void content in the hardened concrete, for example, by making the concrete more compactible. This can be achieved by using water-reducing admixtures, for example, admixtures in accordance with ASTM C 494 requirements for Type A and F admixtures, preferably F admixtures. We have found that using water reducing admixtures can also improve the workability of the concrete. The improved workability of concrete also helps to improve compaction which results into lower void concrete. By reducing the void content, a mix design using less cement and iron ore, and more sand, may advantageously be used. This reduces the cost of the concrete mix overall as cement and iron ore are usually approx. 10 times more expensive than sand per metric tonne. Using the water reducing admixtures may also reduce the stickiness of the concrete mix, thus improving workability and reducing downtime and providing better product consistency. It is understood that the void percentage is more relevant to the concrete's strength, and toughness, rather than just the density of the concrete. To achieve good results using water reducing admixtures, sufficient mixing was preferred. It was found that the water reducing admixtures were effective for cement content in the range of 430-550 kg per one cubic meter of concrete. The other components could be adjusted accordingly.

[0061] For example, the water reducing admixtures may be added to the concrete via the conveyor belt transporting the aggregates to a feeding hopper. The water reducing admixtures can also be added at the end of the raw materials belt right at the fall through area. The testing results show that it is advantageous to add the water reducing admixtures to the aggregates when it is being transported on the conveyor belt before the cement and water are added. Without being limited to a particular theory, it is hypothesized that adding the water reducing admixtures to the aggregates results in better properties because sand typically contains more moisture and these materials undergo some mixing effect before reaching to the mixing auger.

[0062] It is expected that by using both fibers and water reducing

admixtures, compliant with ASTM C 494 requirements for type A and/or F, in the concrete composition, both the toughness and strength of the concrete can be improved while reducing the cost of overall mix.

[0063] Several water reducing admixtures were found to work well. For example, MasterGlenium 7925 (BASF, U.S.), with a low cement mix design, allowed for a reduction of ore content to about 10-11%, a reduction of cement of about 1- 2%, and a reduction of air content from 10% to about 5%, resulting in a much greater percentage of sand being used, typically an increase of about 11-12%. This reduced costs significantly - currently about 9.4% at present cost rates - both by reducing the percentage of voids (~5 v. 10%) and the cost of materials. Another water reducing admixture, MasterCast 900 (BASF, U.S.), also performed well. One study estimated a cost savings of about 3.4 million dollars, on 187 million liters of total concrete made for a recent major project, or 9.4%.

[0064] Example 1: Impact testing results for concrete compositions containing fiber.

[0065] Impact testing as shown in Figure 2 was applied to concrete slabs made of the concrete compositions of Table 1 with different fibers and without fibers as a reference. The samples were prepared without steel reinforcement. The test results were compared against the reference.

[0066] Before testing, the concrete slabs were cured in a moisture room with continuous mist for 28 days, and then air-dried for 2 days. The test was done by using a concrete slab that was compacted in two layers in a mold using a metal plate and two vibrating motors. By controlling the amount of concrete going into the mold and weighing out the correct mass, a target density could be achieved. In these particular tests, a pneumatic impact tester with a manual pressure control and a digital readout of the speed of impact was used. A 4.3 kg piston was accelerated to a speed of about 5 m/s by setting the pressure. The piston struck a round tip that delivered the impact to the concrete slabs. Every blow would result in slightly different speed, which was recorded. The speed was used for energy

calculations using the formula E _x — mv , in which £ _x =kinetic energy of object,

m= mass of object, and v=speed of object.

[0067] Three concrete slabs were made from each composition, and the results for the three slabs were averaged. The results are shown in the following tables. In the tables, J to 1 ^st crack means the energy (joule) required for the first crack to appear and J to failure means the energy (joule) required to reach failure of the slabs. At times this first crack could appear at the same blow as failure occurs.

[0068] The test results for the reference composition is shown in Table 2:

Table 2

[0069] The test results for concrete slabs made of the concrete composition of Table 1, in which the fiber is PVA fiber of the grade RFS400, were shown in Table 3 :

Table 3 [0070] The test results for concrete slabs made of the concrete composition of Table 1, in which the fiber was PVA fiber of the grade RECS15, are shown in Table 4:

Table 4

[0071] The test results for concrete slabs made of the concrete composition of Table 1, in which the fiber was PP fiber of the grade HP and was at 0.13% by volume, are shown in Table 5:

Table 5

[0072] The test results for concrete slabs made of the concrete composition of Table 1, in which the fiber was a combination of PVA fiber of the grade RFS400 and Silica Fume (SF), of just SF with no fiber, are shown in Table 6:

Table 6

For slab 2, the SF fiber was at 10% in volume in the composition.

[0073] As can be seen from these comparisons, the resistance of the concrete slabs to impact improved significantly in the fiber-containing concrete composition. [0074] Example 2: Flexural strength testing results for concrete compositions containing fiber

[0075] Flexural beams made of the concrete compositions disclosed above were subject to flexural strength tests in accordance with ASTM C78 or C1609, selected depending on whether fiber is incorporated in the composition. Before testing, the flexural beams were cured for 28 days in the moisture room. They were tested in moist condition, as required under the standard.

[0076] For concrete composition of Table 1 without fibers, which is used as control for comparison, the deflection is not measured, only peak load is recorded. The testing apparatus for the concrete compositions of Table 1 was fitted with deflection measuring instruments, such that both load and deflection are recorded. Testing proceeds until 3mm deflection is achieved. One control beam and three beams made of the concrete compositions of Table 1 were tested for flexural strength. The beams were prepared without steel wire reinforcement. The test results are shown in Table 7:

Table 7

[0077] The average peak strength was 4.19 MPa, which is about 26% weaker than the peak strength of the beam without fiber in it.

[0078] Fiber reinforced beams had the peak load at a deflection of 0.046—

0.111mm. However, fiber reinforced specimens were able to deflect without falling apart due to presence of fiber reinforcement, to test completion, which is 3mm. Thus, much greater flexibility was achieved by adding fiber reinforcement.

[0079] Example 3: Splitting Tensile Strength Testing Results for Fiber

Reinforced Concrete Compositions

[0080] Concrete cylinders were made of the concrete compositions of Table 1. Concrete cylinders were also made of the concrete compositions of Table 1 without the fibers as a reference. The test results are shown in Table 8:

Table 8

As shown in Table 8, for the concrete compositions with fibers, there is on average an 8%-28% improvement in the strength as compared to concrete compositions without fibers. Surprisingly, it was noted that shorter mixing time resulted in higher strength.

[0081] Example 4: Preparation of concrete specimens with reduced void content and testing of compaction

[0082] The concrete compositions were formulated with a target density of 3040 kg/m ³ . The reference composition, in which void is not reduced, was formulated to target a 10% void by volume in the total volume of the concrete, and in which the water-to-cement ratio is about 0.33. The reference composition was shown in Table 9 below:

Table 9

[0083] Four water reducing admixtures, that comply with ASTM C 494 Type A and F admixture classes, were separately used for reducing the void content of the concrete. The admixtures include MasterCast 900 (BASF, U.S.), Quantec PL450 (Gcp Applied Technologies), Sikamix BF3 (Sika Corporation), and MasterGlenium 7925 (BASF), all of them were selected based on their use for dry/zero slump concrete. BASF MasterCast 900 may be added in the concrete composition at a dosage in a range from 130 to 780 mLyiOO kg of cement, and preferably at 400 ml_ / 100 kg of cement. Quantec PL450 may be added at a dosage in a range from 130 to 325 mLy 100 kg of cement, and preferably at 325 ml_ / 100 kg of cement.

Sikamix BF3 is added at a dosage in the concrete composition in a range from 130- 520 ml_ / 100 kg of cement, and preferably at 500 ml_ / 100 kg of cement. BASF MasterGlenium 7925 is added at a dosage in the concrete composition in a range from 130-975 ml_ / 100 kg cement, and preferably at 500 ml_ / 100 kg of cement.

[0084] The concrete mixtures were made into cylinders having a diameter of

100 mm and a height of 116.0 mm, which equates a volume of about 911 ml_ and a mass of about 2769 g. 12 cylinders were made for each composition. Compaction of the cylinders were tested using Pine Testing Equipment Gyratory Compactor. The angle of gyration is set at 1.16°, pressure is set at 150 kPa. 21 gyrations for the density of 3040 kg/m ³ . The degree of compaction was determined by recording the height of the cylinder after 21 gyrations indicated on the screen. This height was then used to evaluate the density of the cylinder since there was a known mass that was put into the machine to be compacted. This calculated density was then used to determine the void content which was always lower than the typical 10% voids.

[0085] The void contents at different dosages of the admixtures are shown in Figure 7. In the figure, the volumes indicated at the bottom of bar graphs are the volumes of the admixtures added, the numbers at the top of bar graphs are the densities of the concrete cylinders, and the percentages shown on the bar graphs are the amounts of void in the cylinders.

[0086] Example 5: Compressive Strength Test Results for cylinders made in Example 4

[0087] The cylinders made in Example 4 with the water reducing admixtures added at the preferable dosages were cured in the moisture room and tested for compressive strength at 1, 7 and 28 days. These results were compared against the compressive strength of the reference composition, also made into cylinder in Example 4. The results are shown in Table 10:

[0088] Example 6: Effects of Mixing Time on Compaction

[0089] Different mixing times were used for mixing the compositions disclosed in Example 4 and went through the compaction test disclosed in Example 4. The results for the reference composition and compositions with recommended dosage of the admixtures were shown in Table 11 :

Table 11

[0090] There were two scenarios tested, one denoted 15/15/15 and the other denoted 30/lm/30. The first number represents the number of seconds the aggregates (iron ore and sand) and water will be mixed for. The second number represents the number of minutes the cement will be mixed with the already mixed aggregate and water, and the third number represents the minutes the concrete would be mixed for after adding the water reducing admixture.

[0091] It can be seen from the Table 11 that the 15/15/15 mixing results in lower densities of the concrete. However, extending the mixing time to 30/1/30 results in about the same densities as in the normal procedure.

[0092] Example 7: Test Results for Reducing Cement Usage [0093] Concrete compositions of Example 4 were modified to reduce the cement usage from 470 kg/m ³ to 450 kg/m ³ when water reducing admixtures of the preferred dosages were added, and to increase the water-to-cement ratio to about 0.36. The other components were adjusted accordingly. The compositions were shown in Tables 12 and 13:

Table 12

Table 13

[0094] The same tests as in Examples 4-6 were conducted and the results were compared to the results for the reference composition of Example 4. The results are shown in Table 14:

Table 14

[0095] It can be seen that when the water reducing admixtures were used, the compressive strengths were improved even though less cement and more water were incorporated in the composition. Despite this, water reducing admixtures provided higher concrete density.

[0096] The concrete compositions with water reducing admixtures were adjusted so that the densities are about the same as the base mix. The

compositions are shown in Tables 15 and 16:

Table 15

Table 16

[0097] The results are shown in Table 17:

Table 17

[0098] The concrete compositions were further adjusted to reduce cement use. The compositions and test results are shown in Table 18 below:

Table 18

[0099] These results show that even with a lower amount of cement, higher strength was found, due to lower void content.

[00100] Example 8: Admixture Addition Points testing results

[00101] The properties of concrete specimens with water reducing admixtures added to the concrete in a belt conveyor transporting the sand to a feeding hopper, and to the concrete at the end of the raw materials belt at a fall through hopper, were studied. BASF MasterGlenium 7920 was used for this test, which is added to the concrete at an amount of 500 mL/100 kg of cement. The addition was implemented by using compressed air attached to a flowmeter to dispense the admixture at a rate of 129.7 g/15 seconds.

[00102] Concrete proctor cylinders were made using the method according to standard as discussed earlier. Concrete composition without admixtures or fibers was used as reference ("Ref concrete," i.e., reference concrete). The curing and testing procedures of Example 5 were applied. The concrete compositions were also applied as coatings to pipes. The test results are shown in Table 19:

ID Density Density MC Strength Strength Strength

Pipe Number

Number (kg/m3) pcf (%) 1 D 7 D 28 D

Ref concrete 3030 ^* 189 5.2 Avg % admix a 1 3122 195 38.57

admix a 2 3132 195 Admixture 39.76

admix a 3 3166 198 4.9

added to belt. 44.43 0.88

5.1

admix a 4 3202 200 129.7 g/15 sec

4.8 47.03 0.68 admi flow 0.58 x a 5 3232 202 0.41 admix a 6 3190 199 0.35 admix b 1 7 3149 197 5.66 36.33

admix b 2 8 3139 196 Admixture g 2 34.02

added on top. _c ^‘

admix b 3 9 3064 191 5.60 34.68 1.69

129.6 g/15 sec

admix b 2 10 3139 196 flow 1.04 1.25 admix b 2 1 1 3137 196 1.01

On-Pipe Proctors Avg Proctor Strength Strength Strength

Pipe # Density PCF Comments

Made Density 1 D 7 D 28 D

3775 3093 193.1 1 3060 Ref (Stripped)

3775 31 18 194.6 6 3174 39.2 45.73 Adm, added to belt Admix A

5 3126 35.2 34.68 Adm, added on top Admix B

Table 19

In the table, "pcf" means "pounds per cubic foot." The term "admix a" refers to concrete in which the water reducing admixtures were added at a belt conveyor transporting the sand to a feeding hopper. The term "admix b" refers to concrete in which the water reducing admixtures were added at a fall through hopper. MC refers to the moisture content. Strength ID, 7D, and 28D refer to strength at 1, 7, and 28 days. The term WA refers to the water absorption test results for the hardened concrete. The term "Ref" means "reference" and refers to the reference concrete.

[00103] As can be seen from the table, the concrete showed higher strength when the water reducing admixtures were added at a belt conveyor transporting the sand to a feeding hopper, but both addition methods provided stronger concrete than reference concrete containing no water reducing admixture. In addition, the density of the concrete increased compared to the concrete without the water reducing admixture. [00104] Example 9: Test Results for High Cement Content and Low Water-to- Cement Ratio

[00105] Tests were also done on concrete compositions having high cement content and low water-to-cement ratio. In this experiment, the target density of the concrete was still 3040 kg/m ³ . However, 550 kg/m ³ of cement was used, and the w/c was at 0.30. The tests were conducted by the same method as disclosed in other experiments. The test results are shown in Table 20:

Table 20

[00106] As shown in Table 20, by using the water reducing admixtures, the voids were reduced, and compressive strength was improved.

[00107] Further tests were conducted to investigate the result of reducing the cement and iron ore contents and increasing the w/c ratio and sand content. The test results are shown in Table 21 :

[00108] This result again confirms that using the water reducing admixtures can improve compressive strength of the concrete even if the amount of cement and iron ore were reduce and water and sand content were increased.

[00109] Example 10: Test Results for Concrete with Higher Density

[00110] Tests were conducted to investigate the effects of using water reducing admixture in improving the density of concrete weight coating. In this experiment, the density of the concrete was configured to be 3400 kg/m ³ . The same test procedures as disclosed above were used, and the results are shown in Table 22:

Table 22

[00111] This result confirmed that the water reducing admixtures are also effective when the density of concrete is higher, i.e., at 3400 kg/m ³ , as compared to other examples.

[00112] Example 11: Adding both Fibers and Water Reducing Admixtures

[00113] In this example, the proposed concrete compositions are as shown in Table 22:

Table 22

[00114] The composition containing both the fiber and water reducing admixture compliant with ASTM C 494 requirements for type A and F admixtures provides both improved toughness and strength. The improvements in toughness and strength may be synergistic when compared to either use of fiber or water reducing admixture on their own.

[00115] Example 12: Admixture Trial on Full Size Pipe [00116] Tests were done to determine the ability to apply concrete comprising admixture to full size pipes in a standard impingement process, to determine whether there would be improvements on compaction on impige concrete mix by utilizing an admixture. BASF MasterGlenium ACE 8580, at 500-550 ml/lOOkg of cement was added to either Type II cement or to Portland Composite cement, to determine pipe compressive strength and concrete density.

[00117] Concrete composition was prepared as shown in Tables 23 and 24 (two different mixtures, each with or without admixture). Admixture, when added, was added via an application nozzle inside the mixer.

TABLE 23

TABLE 24

The compositions were applied to 18" and 36" pipe. In all cases, the admixture - containing weight coatings had significantly higher compression and density.

Compression testing resulted in higher average pipe density, higher average proctor density, higher 1 and 7 day compressive strength, and higher 28 day compressive strength for the admixture - containing concrete coatings.

[00118] The embodiments of the present disclosure described above are intended to be examples only. The present disclosure may be embodied in other specific forms. Alterations, modifications and variations to the disclosure may be made without departing from the intended scope of the present disclosure. While the system, devices and processes disclosed and shown herein may comprise a specific number of elements/components, the systems, devices and assemblies could be modified to include addition or fewer of such elements/components. For example, while any of the elements/components disclosed may be referenced as being singular, the embodiments disclosed herein could be modified to include a plurality of such elements/components. Selected features from one or more of the above-described embodiments may be combined to create alternative embodiments not explicitly described. All values and sub-ranges within disclosed ranges are also disclosed. The subject matter described herein intends to cover and embrace all suitable changes in technology. All references mentioned are hereby incorporated by reference in their entirety.