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1. Abstract
This report reviews the literature related to the fresh and hardened properties of sustainable 3D printable cementitious material. Besides having the in depth studies regarding the properties of 3D printable material, conclusion of the possibility of the 3D printing to be used in the industry will be included. 3D printing (using 3D printable cementitious material) is an Additive Manufacturing (AM) that can be control digitally to build or print building and architectural components. Numerous advantages can be list from the use of 3D printing in industry compared to the conventional construction method. Cementitious material make use of the advantages present on self-compacting concrete and sprayed concrete to optimise the mix proportion to suit the process. The effects of the 3D printing of concrete on the workability, compressive/tensile strength, and continuity of the cementitious material will be investigated together with other variables throughout the process
2. Introduction: 3D printing and Its Mechanisms
3D printing, which also commonly known as Additive Manufacturing (AM), is a new form of technology that could build a three-dimensional structure with complex shape and size. This can be done with the helped of Computer-Aided Design (CAD) model without any help of tools or human intervention. In general, the prototypes of that specific structure could be drawn directly from Computer-Aided Design (CAD) and the structure would be printed as of the prototypes.
In the 3D printing process, structures or components are designed and build using a 3D modelling software. Structures would be represented as a series of two-dimensional layers. These data are exported to a printing machine. The printing machine would print the structural components, as of the data, layer by layer by a controlled extrusion of the machine. The rheology of the concrete must be allowed to be extruded through the nozzle, a component that incorporated with the printing head, to form concrete filament. As the layers of concrete filament are extruded out of the nozzle, the concrete filament would bond together to build 3D components or structures that is desired
Extrusion is mechanical process that required high pressure. As a result, the mechanical properties such as the strength and stiffness of the concrete composite are altered. A clear relevance can be seen between extrusion and 3D printing, which also known as Additive Manufacturing (AM). This method has been used extensively in the construction industry. For example, the pre-fabrication of structural element from decorative element to larger structural element.
Mechanism of extrusion:

3. Literature Review
3.1 3D Printing in Building and Construction (B&C) industry
3D printing have been successfully implemented in numerous area, such as manufacturing industry, medical applications and food preparation. The use of 3D printing may change the way things are produce or manufacture in the future. The technology use in 3D printing can meet all the expectation of diversification and industrialisation for construction, bringing in the possibility of building a complex structure or components by printing. Currently, materials, such as sand, cement, plastic and powdered ceramic & metal, can be used to print structures by 3D printing. As the concept of 3D printing has been rapidly develop, more and more material can be used in 3D printing process. Not only more material can be used in 3D printing, the rapid development of 3D printing has also increase the size of the printer. Using a 3D printer of a much larger in size, building or printing a bigger and more complex structures could be done near future.
Example of 3D printer use in industrial experiment:

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In the recent years, problems, such as lack of skilled labour, automation and safety issues, have arises. Due to these problems occurring, the demands have not been met or more of difficult to keep up with the demands. The possible solution to these problems would be the introduction of the 3D printing to the industry. 3D printing would be a promising technology that can be used to print or build a complex three-dimensional structure such as a building. This process can be done without any form of manual labour work or external work. Hence, this would help to overcome problem like the lack of skilled labour in the Building and Construction (B&C) industry. Apart from providing the solution to the problem on lack of skilled labour, the use of 3D printing in the industry help to mitigate other problem such as the safety issues that workers face in the precarious environment. The cost of building a complex structure, such as a building, would be reduced. Cost of building a building includes the cost of labour, transportation, energy consumption and emissions. Beside these, the cost to manufacture a building and overall life cycle should be included. In general, the reduction of long construction time and high cost of production are the main emphasis and lead to the in depth research on the possibility of 3D printing in Building and Construction (B&C).
3.2 Mix Proportion of Cement
Controlling the amount of water used in concrete is one of the important factors in the properties of concrete. Strength of the concrete is mainly affected by the water to cement mass ratio (w/c). In current modern day concrete industry, addition of chemical additives, like Superplasticiser (SP) and viscosity modifying repellence, are commonly included in concrete. Adding chemical additives to the concrete mixtures help to improve the workability. These polymers act as a dispersants to prevent particle segregation and improve the flow of the particles. Besides that, the addition of chemical additives to concrete allows the reduction of water to cement ratio (w/c). The effect of the addition of chemical additives improves the performance of the concrete paste (fresh and hardened properties) drastically. Not only performance of the concrete paste (fresh and hardened properties), significant cost saving can be seen due to the reduction in the amount of water use.
Based on this knowledge about the factors affecting the strength of concrete, several studies has been done. 2 mix proportion had been use for further studies.

Mix proportions from the first studies: (Construction Materials for 3D printing)

For this mix proportion, the addition of Superplasticiser (SP) has been investigated whether it has an impact on the flowability and buildability of the concrete (mortar). The studies reported that mix with a low water to cement ratio (w/c), addition of Superplasticiser (0.95% to 2.5% of the water weight) increases the compressive strength and flowability of the mix. However, significant reduction of buildability capacity can be seen. Accelerator and retarder were added to the mix. The water to cement ratio (w/c) was found to be 0.39 and the Superplasticiser (SP) content to be 1.9% of the water weight.
End result/product expected from the mix:

Mix proportion from the second studies: (Construction Materials for 3D printing)

Out of the 5 mix present in this studies, Mix 4 was selected to be the more optimum mix design to be used for 3D printing. From the same studies, Mix 4 had been used to print a ‘wonder’ bench by Loughborough University.
‘Wonder’ bench printed by Loughborough Unversity:

According to the studies, the shear strength of Mix 4 is feasible for 3D printing process without any hiccups throughout the process. Studies showed that the density of the mix was found to be 2300 kg/cm3 and the compressive strength to be in the range of 100 – 110 MPa.
4. Material & Methods
4.1 Component Used in the Mix
Typical ingredients use to make concrete remain constant. The ingredients include cement, water and aggregate in a form of sand. In the recent, the addition of Superplasticiser, fly ash and silica fume has been included in the process. Cement, fly ash and silica fume formed the binder component of the mix. However, the cement used in this studies has been pre-mix with fly ash under a particular ratio. Hence, the cement would be classified as the brand of the cement, ‘Phoenix’.

Chemical composition of cement, fly ash and silica fume:

4.2 Casting Process for Mould casted and 3D-printed sample
For this research, the mix will be manufactured in both mould casted sample and 3D-printed sample. The sequence of each mix component would be from the coarser material to the finer material, hence it would be as such: sand, cement, fly ash, silica fume and the liquid components (water and superplasticiser).
For mould casted sample, it will be casted in a cube mould with a dimension of 100 mm×100 mm×100 mm.
Mould used for casting:

For printed sample, it will be printed using the 3D printer that has been set up by the School of Engineering, Temasek Polytechnic.
3D printer set-up from School of Engineering:

4.3 Preparation Process for Testing
Flow of the preparation process:

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4.3.1 Water/Air Curing
After the sample has successfully either by mould casted or 3D-printed, the sample would be required to undergo water/air curing process for 21 – 28 days. Water/air curing is a process to control the amount of moisture loss from the concrete during the hydration process. It is mainly design to prevent the loss of moisture from the concrete as it is gaining strength at the same time. This water/air curing process can take place either after the sample is casted/3D-printed or during the manufacturing process. Hence, it could provide time for the cement to be hydrated. Hydration process takes time (the time taken would be more of days and weeks rather than a few hours), water/air curing must be done at a reasonable period of time. This process is crucial in order to achieve the potential strength and durability of the sample. Temperature will also affect the rate of hydration of the cement.
The time taken for the sample to be water/air cured depend on the properties of the concrete, the use of the concrete and the current condition (temperature and humidity of the surrounding).

As been shown on the graph, concrete only achieve 40% of the strength when it is allow to dry out instantly which is similar to the one has been cured for 180 days. However, at 28 days of curing process, the concrete is able to achieve 95% of the strength. Therefore, for this research purposes, the sample will be cured for 28 days.
4.4 Different Type of Test and Its Process
There will be a few test that could be run in-house and others to be done with the help of outside vendors. Those test that could be done in-house would be slump, water absorption, compressive/tensile strength and Ultrasonic Pulse Velocity (UPV).
4.4.1 Slump Test
Slump of a concrete could be used to measure the viscosity of the concrete in fresh state. In other words, it is used to determine the workability and flowability of the concrete in its fresh state. For a concrete in fresh state to call as workable, it must be able to be transport, place and finish without any segregation.

Slump Test Procedure:

4.4.2 Water adsorption test
Water absorption is one of the important step for the durability of the concrete. The durability of the concrete on the exposed surface determined by the rate of harmful agent penetrate through the concrete. Permeability and porosity of the concrete and the strength of the concrete to related to its sorptivity. It can be determined on a 100 mm cube after 21 – 28 days of water curing. The samples were dried in a hot air, alternatively it could be place inside an oven. The sample is then to be submerge in water and measure the amount of weight gain at regular time intervals.
4.4.3 Compressive/Tensile Strength
It can be test through the use of Rebound Hammer or the use machine such as Instron. Instron can be universally used as to determine the compressive and tensile strength of the concrete. Tensile strength of the concrete is the ability of the concrete to resist the force which tend to pull the concrete apart. However, as of in house, due to the lack of additional machinery and the limitation of the machinery, the compressive strength of the concrete would be sent to a vendors. As a good gauge for the compressive strength of the concrete, the use of Rebound Hammer is necessary.
4.4.3.1 Rebound Hammer
Rebound hammer test, or also known as Schmidt Hammer, is used to provide a convenient yet quick indication of the compressive strength. Or in other words, It is used to find the possible compressive strength of the concrete with suitable co-relations between the index produce on Rebound hammer and the compressive strength from the graph provided on the hammer itself. It also can used as device to differentiate out the acceptable parts of the concrete from the questionable parts or to compare the strength of 2 different structure.
Rebound hammer:

4.4.4 Ultrasonic Pulse Velocity (UPV)
Ultrasonic Pulse Velocity (UPV) test is use to check the quality of the concrete and natural rocks. This test, unlike Rebound hammer or compressive/tensile strength, is non-destructive. In this test, the quality of the concrete, including the strength of the concrete, is assessed by the measurement of velocity of ultrasonic pulse passing through the concrete. The time taken for the ultrasonic pulse to pass through the concrete are taken into consideration too. However, Ultrasonic Pulse Velocity (UPV) test could only be done if the surface of the concrete is flat and smooth. Higher velocities would mean that the concrete is of a good quality and continuity of material. Vice versa, slower velocities would mean that cracks or voids present inside the concrete.
UPV Test set-up:

5.5 Results
5.1 Slump Test
Comparison between a couples of variable has been tested to determine it would affect the slump of concrete in fresh state. For this slump test, out of all the variables, the test mainly concentrate on the effect of addition of Superplasticiser (SP), using different type of cement and different water to cement ratio (w/c). The slump of each mix is being measured over the time period of 40 minutes. The first 30 minutes of the test, the slump is being measured at a regular time interval of 10 minutes. The last 10 minutes of the test, the slump is being measured at a regular time interval of 5 minutes.
Comparison between the additions of the Superplasticiser (SP):
Mix proportion use in the comparison: (measurement in grams)
Sand Cement (Phoenix) Water
1040 1560 586.56

Water to cement (w/c) ratio: 0.376
Results:
Red = Mix without the addition of Superplasticiser (SP)
Blue = Mix with the addition of Superplasticiser (SP) (0.70% of the water weight)

Analysis
The addition of Superplasticiser (SP) do affects the slump of the mix. However, unlike the mix without the addition of Superplasticiser (SP), the slump varies over the period of 40 minutes. From 10 minutes to 20 minutes, the slump height decrease by 6 mm, a significant drop compared to the other. Whereas, the slump of the mix without the addition of Superplasticiser has a gradual decrease before eventually the slump height is constant. The slump height decrease by 1 mm until the 30 minutes. The slump reach a constant height of 10 mm.
Comparison between 2 different types of cement
The comparison between Ordinary Portland Cement (OPC) and Phoenix will be made in 2 different water to cement (w/c) ratio.
Mix proportion use in the first comparison: (measurement in grams)
Cement Water
2800 1000

Water to cement (w/c) ratio: 0.357

Results:
Red = Phoenix
Blue = Ordinary Portland Cement (OPC)

Mix proportion use in the second comparison: (measurement in grams)
Cement Water
2000 620

Water to cement (w/c) ratio: 0.31
Results:
Red = Phoenix
Blue = Ordinary Portland Cement (OPC)

Analysis
In general, the slump of the mix with water to cement (w/c) ratio of 0.357 has a much higher slump height compare to the mix with water to cement (w/c) of 0.31. Mix using Phoenix cement has a much higher slump height compared to the mix using Ordinary Portland Cement (OPC). The slump height of the mix using Phoenix cement drastically drop throughout the time period. For example, the slump height drop drastically from 18 mm to 11 mm when the water to cement (w/c) ratio is 0.357. Whereas, for the mix using Ordinary Portland Cement (OPC), the slump height remain constant in both water to cement (w/c) ratio.
5.2 3D-printed Sample and Its Mix Proportion
From the result of the slump test obtain, 4 mix proportion has been used for 3D printing.
Mix (1): M2W9 (measurement in percentage)
Sand Binder
40 60

P
Percentage on Binder:
Cement Silica Fume
90 10

Water to binder ratio: 0.34
Superplasticiser (SP) added: 0.80% of water weight
Results:
Failed to print any sample, only mould casted samples were available for testing.
Mix (2): Ems 0.7 (measurement in percentage)
Sand Binder
37.75 62.25

Percentage on Binder:
Cement Silica Fume
90.9 9.1

Water to binder ratio: 0.3246
Superplasticiser (SP) added: 0.70% of water weight
Results:
Successfully print a sample block (dimension of 200mm×100 mm×100 mm). Mould casted samples were also available for testing.

Sample block printed using Ems 0.7 mix:

Mix (3): Ems 0.76 (measurement in percentage)
Sand Binder
37.75 62.25

Percentage on Binder:
Cement Silica Fume
90.9 9.1

Water to binder ratio: 0.3246
Superplasticiser (SP) added: 0.76% of water weight
Results:
Fail to print any sample, only mould casted sample were available for testing.
Mix (4): CCP/0.306 & CCP/0.322
Cement that was used in this experiment will be Phoenix cement, unless it is stated. No Superplasticiser (SP) added into the mix>
Water to cement (w/c) ratio: 0.306 & 0.322
Results:
Successfully print several sample block (dimension of 100mm×100mm×100mm & 400mm×100mm×100mm). Mould casted samples were available for testing.
Sample block printed using CCP/0.306:

5.3 Water Absorption Test
4 Cubes of different mix proportion had been used for the test. Initial weight of the sample cubes were measured before being immersed in water of room temperature for 30 minutes. Final weight of the sample cubes were taken after 30 minutes.
Mix proportion for sample cube (1): M2W9 (measurement in grams)
Results: (measurement in grams)
Initial Final
2020 + 0.837% 2037

Mix Proportion for sample cube (2): Ems 0.70 (measurement in grams)
Results: (measurement in grams)
Initial Final
2022.1 + 0.628% 2034.8
2039.7 + 0.686% 2053.7
Average: +0.657%
Mix Proportion for sample cube (3): Ems 0.76 (measurement in grams)
Results: (measurement in grams)
Initial Final
1986.9 + 0.674% 2000.3
1994.5 + 0.782% 2010.1
Average: + 0.728%
Mix Proportion for sample cube (4): CCP/0.306 (measurement in grams)
*Cast in 2 different date, 14/8 and 23/8
Results: (measurement in grams)
14/8
Initial Final
1860.7 + 2.94% 1915.4
1872 + 2.94% 1927.1
23/8
Initial Final
1865.7 + 3.02% 1922.1
1872 + 2.92% 1887.9
Average: + 2.96%
Analysis:
M2W9, Ems 0.76 and Ems 0.7 have similar percentage of the total average weight gain throughout the process, ranging from 0.60% to 0.80%. However, CCP/0.306 has a average of 2.94%, which is much more higher than the other 3 mix. The difference between CCP/0.306 and the other mix will be the absence in a more significant mix component, such as sand and silica fume. The absence of these mix component might cause the much different in the percentage of total average weight gain.
All the sample cubes used in this test were mould casted. Value was not able to obtain from the 3D-printed sample due to the dimension of the sample cubes were not up to the requirement. Therefore, value for 3D-printed sample was not obtain.
5.4 Compressive/Tensile Strength
5.4.1 Compressive Strength Test by Vendors
Sample cubes used in this experiment had 2 different water to cement (w/c) ratio of 0.306 and 0.322. The sample sent out for testing include both mould casted sample and 3D-printed sample. Cement used in this experiment was Phoenix cement, unless is stated otherwise.
Results: (measured in KN for Max Load and N/mm2 for Stress @Failure)
*CCP/n = Mould Casted Sample, water to cement (w/c) of n
*3DCP/n = 3D printed sample, water to cement (w/c) of n
CCP/0.306
Date of Casting Max Load Stress @Failure
14/8 387.815 38.78
1/8 367.799 36.78
1/8 375.554 37.56
Average (Max Load): 377.056 KN
Average (Stress @Failure): 37.71 N/mm2
3DCP/0.306
Date of Casting Max Load Stress @Failure
31/7 484.781 48.48
31/7 475.167 47.52
25/7 551.060 55.11
Average (Max Load): 503.669 KN
Average (Stress @Failure): 50.37 N/mm2
CCP/0.322
Date of Casting Max Load Stress @Failure
1/8 361.484 36.15
1/8 384.947 38.50
Average (Max Load): 373.216 KN
Average (Stress @Failure): 37.32 N/mm2
3DCP/0.322
Date of Casting Max Load Stress @Failure
18/7 384.137 38.41
Average (Max Load): 384.137 KN
Average (Stress @Failure): 38.41 N/mm2
Analysis
In general, regardless of the water to cement (w/c) ratio, 3D-printed sample could hold more weight than mould casted sample. At water to cement (w/c) ratio of 0.306, 3D-printed sample, in average, could hold 33.58% more weight than mould casted sample. Whereas, at the water to cement (w/c) ratio of 0.322, in average 3D-printed sample could hold 2.93% more weight than mould casted sample.
5.4.2 Compressive Strength Test by Rebound Hammer
Due to the irregular surface of the 3D-printed sample cube, Rebound hammer test could only be done on mould casted sample. 4 sample cubes of different mix proportions were used for test in this experiment.
Mix proportion for sample cube (1): M2W9
Results: (measured by index)
Side 1 Side 2 Side 3 Side 4
30 34 35 32
34 28 31 37
29 33 32 30
34 33 31 31
Average: 31.7
Mix proportion for sample cube (2): Ems 0.7
Results: (measured by index)
Sample cube (1)
Side1 Side 2 Side 3 Side 4
34 34 28 26
32 31 32 24
28 30 30 22
28 32 34 23

Sample cube (2)
Side 1 Side 2 Side 3 Side 4
28 32 30 28
28 36 28 32
28 34 30 28
32 32 32 30
Total Average: 29.2625
Mix proportion for sample cube (3): Ems 0.76
Results: (measure by index)
Sample cube (1)
Side 1 Side 2 Side 3 Side 4
33 27 32 28
32 28 28 32
28 28 32 28
29 26 28 30
Sample cube (2)
Side 1 Side 2 Side 3 Side 4
32 32 28 26
28 35 26 23
27 30 27 22
30 32 26 29
Total Average: 29.0625
Mix proportion for sample cube (4): CCP/0.306
*Cast in 2 different date, 14/8 and 23/8
Sample cube (1) (14/8)
Side 1 Side 2 Side 3 Side 4
18 33 31 26
30 35 32 26
24 34 40 28

Sample cube (2) (14/8)
Side 1 Side 2 Side 3 Side 4
22 19 24 21
31 38 39 39
32 37 36 36
Total Average: 30.46
Sample cube (1) (23/8)
Side 1 Side 2 Side 3 Side 4
36 21 24 23
38 32 36 35
36 36 34 35

Sample cube (2) (23/8)
Side 1 Side 2 Side 3 Side 4
22 29 29 20
29 28 26 37
31 36 36 34
Total Average: 30.96
Analysis
Index for each sample cube that was tested fall in the range of 29 to 31. There is no anomaly in the trend, all the result fall within the range. Having the sample with M2W9 mix with the highest index, followed by sample with CCP/0.306 mix and lastly sample with Ems 0.7 and Ems 0.76.
5.5 Ultrasonic Pulse Velocity (UPV)
Due to the requirement of having the surface to be flat and smooth, 3D-printed sample would not be tested. 4 sample cubes of different mix proportion were used for this test.
Mix proportion for sample cube (1): M2W9
Results: (measured in micro.s for time and m/s for speed)
Time Speed
24 4156
24.2 4115
24 4166
24.3 4115
Average (Time): 24.125 micro.s
Average (Speed): 4140.5 m/s
Mix Proportion for sample cube (2): Ems 0.7
Results: (measured in micro.s for time and m/s for speed)
Time Speed
23.8 4201
25.8 3875
23.9 4184
24.2 4132
Average (Time): 24.425 micro.s
Average (Speed): 4098 m/s
Mix Proportion for sample cube (3): Ems 0.76
Results: (measured in micro.s for time and m/s for speed)
Time Speed
23.8 4201
24.6 4065
24 4166
26.4 3787
Average (Time): 24.7 micro.s
Average (Speed): 4054.75 m/s
Mix Proportion for sample cube (4): CCP/0.306
*Cast in 2 different date, 14/8 and 23/8
Results: (measured in micro.s for time and m/s for speed)
14/8
Time Speed
26 3831
26.3 3792
37 3701
27.7 3614
Average (Time): 29.25 micro.s
Average (Speed): 3734.5 m/s
23/8
Time Speed
30.2 3372
26.7 3744
26 3851
26.2 3814
Average (Time): 27.275 micro.s
Average (Speed): 3695.25 m/s
Analysis
In average, sample with CCP/0.306 mix has much slower velocities compare to the other 3 mix. Sample with CCP/0.306 has a velocity of 3695.25 m/s, whereas the other mix has an average velocity in total of 4097.75 m/s.
6 Discussion
6.1 3D Printing Process
From the result shown, there are a lot of 4 different mix proportion that had been used. All of the 4 mix were not part of the original plan. The original plan was to use M2W9 mix throughout the project. However, due to certain problem occurred during the project, certain changes need to be made.
Originally, M2W9 was plan to be used throughout the project. However, the mix was not able to be extruded out of the nozzle when the nozzle diameter was 15 mm. In between the 3D printer run, water or cement was added into mix. Calculation of the new proportion of the mix was done. As a result, new mix proportion was found. During the process, the effect of adding in different amount of Superplasticiser (SP) was unknown. In conclusion to it, it was determined as 0.70% and 0.76% of water weight. Therefore, the mixes were labelled as Ems 0.70 and Ems 0.76. Some problem occur when Ems 0.76 was used during the 3D printer run. Whereas, when Ems 0.70 was used, the first sample cube was printed (shown at the result section). Near to the end of the internship, it was agreed that the basic should be done right before advancing to a more complex mix proportion. In other words, cement paste (consist of cement and water only) will be used instead of mortar (consist sand, cement, silica fume, Superplasticiser (SP) and water). Phoenix cement was used for the cement paste mix. Hence, the mix was labelled as 3DCP/0.306 for 3D-printed sample cube and CCP/0.306 for mould casted sample. Several sample cubes were able to be printed. Samples could only be printed when the diameter of the nozzle increases from 9 to 15/16 mm.
The quality of each sample cubes that were printed was different from each other. However, same mix proportion was used throughout the process. Not only was the mix proportion, the 3D printer set up the same throughout the project which the diameter of the nozzle to be 15 mm. For example, when cement paste of 0.306 water to cement (w/c) ratio for 3D printer run, different quality was produces at different casting date.
3D-printed sample cube (7/8):

3D-printed sample cube (31/7):

Sample cube that was 3D-printed on 7/8 could not hold up its own structure. However, on the earlier date of 31/7, the sample cube could hold up its own structure without slumping down.
The use of external help, such as blower and a mould, to support the structure of the 3D-printed sample was much needed. For example, CCP/0.306 was used.
3D-printed sample cube without any external help:

It can be observes that the 3D-printed sample does not have any shape to it. It can be seen as the sample are slumping, making the structure to fall apart. When the use of heat blower and mould cast was used, the difference in the end product could be seen. The 3D-printes sample could hold its structure to meet its requirement on the dimension.
The use of heat blower:

The use of mould:

6.2 Final Comparison
In general, 3D-printed sample cubes have a much higher compressive strength compare to mould casted sample. However, the final statement about the properties of the sample could not be deduced as certain tests were not conducted on the 3D-printed sample.
Mould cast was used to support the structure of all 3D-printed sample used in the experiment. The main difference between the 3D-printed sample and mould casted sample is that air bubble was not release on the 3D-printed sample. According to studies, allowing air bubble to be trap inside the sample cube help to achieve concrete of a higher strength. This is due to the reduction of the amount of water used in the mix. However, the workability of the concrete will not be affected due tot the reduction of the amount of water added.
7. Conclusion
3D printing do improve the quality of the cube that is printed in terms of compressive strength. Comparing to conventional method of casting a cube, 3D printing do help to reduce the amount of labour that is required. Not only the labour work, but it also reduces the amount of time required for the sample to dry out.
However, as much as it help to reduce the amount of time required for the sample to dry out, it takes a quite a long time to print 1 sample cubes. It takes around 1.5 to 2 hours just print a sample cube with a dimension of 100mm×100mm×100mm. This time period include the time required for mixing all of the dry ingredient. However, in comparison to conventional method, with the same time required, at the minimum 4 sample cubes with the same dimension could be casted. 3D printing used up more dry material than conventional method to print a sample cube. 4 kg of dry material are required to print a sample cube. However, for conventional method, it only required 3 kg of dry material to cast a sample cube.
The end product from 3D printing is not guarantee. Most of the time, the quality of the 3D-printed sample is not up to the requirement in order for it could be tested. Hence, the properties of the cubes could be obtain. The structure of the 3D-printed samples cube could not hold its own structure unless the external help, such as the use of mould and heat blower, is put in place. By doing so, the true meaning of 3D printing could be overlap with conventional method of casting a sample cube.
In summary, the idea of the use 3D printing in the industry is a great innovation. It could help the industry to ‘build’ a much sturdy structure to live in. Not only could it reduce the amount of risk that present at construction site, significant reduction on the amount of manual labour present. 3D printing could help to overcome the problem of lack of skilled labour. However, it could use up more time to build a simple structure.
7. Remarks
Side experiment was done throughout the project. The use of Ordinary Portland Cement (OPC) as the cement gives a much higher compressive strength than Phoenix cement.
Results: (measured in KN for Max Load and N/mm2 for Stress @Failure)
Date of Casting Max Load Stress @Failure
7/8 697.286 69.73
7/8 646.805 64.68
Average (Max Load): 672.046 KN
Average (Stress @Failure): 67.20 N/mm2
The average of the Max Load is much more by 33.43%. Experiment could be done based on the use of Ordinary Portland Cement (OPC) as the cement in the future

8. References
9. Appendices