**ANALYSIS OF THE STRENGTH OF BAMBOO REINFORCED PLASTIC BOTTLE **
**CONCRETE BEAMS FOR LOW-COST HOUSING **

*Johann Snow S. Cabatuando*^{1}*, Cliff Nicollette T. Del Pilar*^{1}*, Andrea Mitzi O. Villaverde*^{1}*, and Engr. Natassha Mae V. Quinsaat*^{2 }

*1**Bachelor of Science in Civil Engineering Area, College of Engineering and Information Technology *

*2**Faculty Member, Civil Engineering Area, College of Engineering and Information Technology *

**ABSTRACT **

The world consumes about a million plastic bottles a minute, with the Philippines as one of the top plastic polluters. It is currently one of the many crises that the Philippines is experiencing. Using plastic bottles in designing a reinforced concrete beam is one of the many examples in the modernization of sustainable structures. An alternative for traditional construction materials is the key point, thus, this study incorporated the use of bamboo fibers as reinforcement in replacement of steel which is known for its high cost. Bamboo is known for its low-cost, wide availability and it is well known for its diverse properties. This research intends to investigate the flexural capacity of bamboo reinforced plastic bottle concrete beams for low-cost housing, determine the potential of this model in the field of construction, and analyze its effect on cost.

**Keywords: bamboo reinforcement, steel reinforcement, concrete blocks, plastic bottles, low-cost housing **

**INTRODUCTION **

The Accreditation Board for Engineering and Technology (ABET) circumscribed engineering as a profession that develops ways to engage economical materials and forces of nature (Wright, 2002). Engineering is a compendious field that is divided into various disciplines and sub-disciplines.

These disciplines are categorized into four main categories, namely:

mechanical, chemical, electrical and civil. Civil engineering, specifically, deals with the design and construction of different infrastructures like bridges, roads, high-rise buildings, and houses. It is said to be dated back to ancient Egypt when construction of shelter, infrastructure, and transportation was considered essential. The field of civil engineering is considered as the refinement of civil society by the application of scientific knowledge. Fulfilling basic human needs and helping others in their daily lives is a civil requirement (What is Engineering, n.d.). In the construction industry, construction materials have their own significance and engineers need to consider its quality. Also, one of the things to consider is the cost of the project which is the problem when it comes to low-cost housing.

*Theoretical Background *
*Synthesis *

The aim of this study is to provide alternative materials for the construction of low-cost housing, specifically plastic bottles incorporated into concrete beams and bamboo as reinforcement. Aside from this, another aim is to help the environment by utilizing disposable plastic bottles. Thus, it dwells on the economic and environmental impact of using these materials without the sacrifice of strength.

Past studies have shown that plastic bottles incorporated into concrete beams have provided an increase in compression strength. Some have shown that the use of plastic bottles filled with sand has resulted in only 35% of the usual costs of construction.

Further, bamboo is known as being high in tensile strength which could reach up to 370 MPa, thus making it a suitable alternative to steel. Aside from its high tensile strength, a study has stated that the required energy for the production of bamboo is 50 times lower than that of steel. Though proper treatment is required, it can be cost-effective most especially in places in which they grow in abundance.

In light of the characteristics stated above, this study will provide insight as to the combined strengths of these two materials and its impact on cost as an alternative to low-cost housing.

*Theoretical Framework *

Unlike other studies which use bamboo as reinforcing bars as their main focus, this study uses two materials in obtaining the flexural capacity of the specimen through application in low-cost housing without sacrificing the strength of the structure. Many materials were already steeped in the studies about increasing the flexure capacity and reduce the cost of the materials without using the substandard materials. The four samples and the

curing days were used as parameters. The ratio of cement and sand
was also used. However, the fixed parameter was used in this study was the
curing which is the 7^{th} and 28^{th} days.

**METHOD **

In this study, the researchers decided to use a mix ratio of 1:2:4. The
bamboo and steel reinforcements were tested for its tensile strength
according to ASTM E8. A total of 12 cylinder specimens (6 cylinders w/ bottle
and 6 cylinders w/o bottle) were produced and tested for compressive
strength according to ASTM C192 on its 7^{th} and 28^{th} day of curing. A total of
24 concrete beam specimens (4 specimens each for PRC, PBRC, BRC, and
PSRC) were produced according to ASTM C192 and tested for flexural
strength according to ASTM C293 on its 3^{rd} and 14^{th} day of curing.

*Tensile and Compressive Test*

This phase focused on the testing of the tensile strength of three bamboo strips, three 12 mm steel rebars, and the compressive strength of the concrete cylinder reinforced with a 500 ml plastic bottle.

*Sample Specimen *

A total of 24 concrete beams with different reinforcements were in this study. For the specimens of Phase 2: A, B, C, and D, three specimens each were tested for the 3rd and 14th day.

*Table 3.1: Description and Abbreviation of Specimens *

PHASE 2 DESCRIPTION ABBREVIATION

A Plain Reinforced Concrete

Beam PRC

B Bamboo Reinforced Concrete

Beam BRC

C Plastic Steel Reinforced

Concrete Beam PSRC

D Plastic Bamboo Reinforced

Concrete Beam PBRC

*Cured Samples for Testing *

The sample specimens were tested under a high rate of loading in UTM according to ASTM C293 standards. The flexural strength of the PRC, BRC, PSRC, and PBRC beams that have been cured for 3 and 14 days were tested.

*Flexural Test Results *

After conducting the tests, the researchers evaluated the result of the concrete beams that were tested. The ultimate load and flexural strength of each specimen were compared in order to determine if plastic bottles and bamboo fibers can be an effective alternative to steel reinforcement for low- cost housing. The researchers prepared the cost analysis and statistical analysis of each specimen to determine whether the capacity of a plastic bottle concrete reinforced with bamboo fiber will be suitable in building low-

*Design *

### Figure 1: Conceptual Framework

*Antorcha Vol. 6 No. 2 (March 2019) *

*Design *

The research comprises a dependent and independent variable. The independent variable is considered the predictive variable and the dependent variable is the outcome being measured due to the effect brought by the independent variable. Thus, in this study, the researchers chose to use the role of the strength of concrete as the independent variable, and the use of the other materials (such as the plastic bottles, bamboo reinforcement, and steel reinforcement) as the dependent variable. Using the universal testing machine (UTM), the strengths of the multiple specimens were tested and compared.

**RESULTS AND DISCUSSION **

*Flexural Test Results *

The four types of beams were tested on its 3^{rd} and 14^{th} day of curing.

Three specimens were tested each curing day.

Table 4.1 Summary of Results for PRC
**PRC **

**Specimen ** **Curing Day ** **Flexural Strength **
**Load **

**(kN) ** **Mpa ** **Average **
**(Mpa) **

A 3 30 4

3.67

B 3 31 4

C 3 21 3

D 14 43 6

6.67

E 14 53 7

F 14 52 7

The flexural strength of the PRC beam on its 3^{rd} and 14^{th} day of curing
resulted in average strength of 3.67 MPa and 6.67 MPa, respectively.

Table 4.2 Summary of Results for BRC
**BRC **

**Specimen ** **Curing Day **

**Flexural Strength **
**Load **

**(kN) ** **Mpa ** **Average (Mpa) **

A 3 21 3

2

B 3 13 2

C 3 10 1

D 14 21 3

3

E 14 20 3

F 14 21 3

The flexural strength of the BRC beam on its 3^{rd} and 14^{th} day of curing
resulted in average strength of 2 MPa and 3 MPa, respectively.

Table 4.3 Summary of Results for PBRC
**PBRC **

**Specimen ** **Curing Day **

**Flexural Strength **
**Load **

**(kN) ** **Mpa ** **Average (Mpa) **

A 3 10 1

1.33

B 3 10 1

C 3 13 2

D 14 18 2

2.33

E 14 19 2

### F 14 20 3

The flexural strength of the PBRC beam on its 3^{rd} and 14^{th} day of curing
resulted in average strength of 1.33 MPa and 2.33 MPa, respectively.

Table 4.4: Summary of Results for PSRC
**PSRC **

**Specimen ** **Curing Day ** **Flexural Strength **
**Load **

**(kN) ** **Mpa ** **Average (Mpa) **

A 3 49 6

6

B 3 43 6

C 3 46 6

D 14 59 8

7.33

E 14 54 7

F 14 57 7

The flexural strength of the PSRC beam on its 3^{rd} and 14^{th} day of curing
resulted in average strength of 6 MPa and 7.33 MPa, respectively.

Data shows that the PSRC beams attained the highest strength, while the PBRC beams attained the lowest strength.

*Figure 4.1: Flexural Strength of PRC, BRC, PSRC, and PBRC *

**Data Analysis **

*Table 4.5: Significant difference between BRC and PRC. *

**Curing day ** **Mean ** **SD ** **T-**

**value ** **P-**

**value ** **Interpretation **

Day 3 PRC 3.67 0.58

2.50 0.08 Not Significant BRC 2.00 1.00

Day 14 PRC 6.67 0.58

11.00 0.01 Significant BRC 3.00 0.00

*Df = 2, T-tabular value = 4.303 *
3.67
2.00

6 1.33

6.67 3.00

7.33 2.33

### 0.00 2.00 4.00 6.00 8.00

### PRC BRC PSRC PBRC

### Strength (MPa)

### 3rd and 14th day Strength of Beam Specimens

### Day 14 Day 3

Table 4-13 presents a significant difference between BRC and PRC. No
significant difference was observed between PRC and BRC on the 3^{rd} day with
a p-value of 0.08. However, significant differences were observed on the 14^{th}
day with a p-value of 0.01 thus, the null hypothesis was rejected. The mean
value showed that differences occurred because PRC was statistically higher
with a mean of 6.67 than BRC with a mean value of 3.00.

*Table 4.6: Significant difference between PSRC and PRC *

**Curing day ** **Mean ** **SD ** **T-**

**value ** **P-**

**value ** **Interpretation **

Day 3 PRC 3.67 0.58

-7.00 0.02 Significant PSRC 6.00 0.00

Day 14 PRC 6.67 0.58

-1.41 0.23 Not Significant PSRC 7.33 0.58

*Df = 2, T-tabular value = 4.303 *

Table 4-14 presents a significant difference between PSRC and PRC. No
significant difference was observed between PRC and PSRC on 14^{th} day with a
p-value of 0.23 but it was previously signed with a p-value of 0.02 thus, the
null hypothesis was rejected on the 3^{rd} day. The mean value showed that
differences occurred because PSRC was statistically higher with a mean of
6.00 than PRC with a mean value of 3.67.

*Table 4 - 7: Significant difference between PBRC and PRC *

**Curing day ** **Mean ** **SD ** **T-**

**value ** **P-**

**value ** **Interpretation **

Day 3 PRC 3.67 0.58

4.95 0.01 Significant PBRC 1.33 0.58

Day 14 PRC 6.67 0.58

9.19 0.00 Significant PBRC 2.33 0.58

*Df = 2, T-tabular value = 4.303 *

Table 4-15 presents a significant difference between PBRC and PRC.

Comparison between PRC and PBRC was significant on the 3^{rd} day with a p-
value of 0.01 thus, the null hypothesis was rejected on the 3^{rd} day. The mean
value showed that differences occurred because PBRC was statistically higher
with a mean of 3.67 than PRC with a mean value of 3.67. Differences
remained significant on the 14^{th} day with a p-value of 0.00 thus, the null
hypothesis was rejected on the 14^{th}day. The mean value showed that
differences occurred because PBRC was statistically higher with a mean of
6.67 than PRC with a mean value of 2.33.

*Cost Analysis *

The cost computed here is on a per beam basis. The amount of cement, sand, and gravel was computed by multiplying the volume of the beam to the values tabulated in Table 4 – 16. The amount was then multiplied to the market price for each respective material.

*Table 4 - 8: Concrete Proportion *

**FOR MATERIALS ESTIMATE **

**Mixture Class ** **Cement in 40kg Bag ** **Sand ** **Gravel **

A 9.00 0.5 1

*Table 4 - 9: Summary of Prices for PRC and BRC *
**PRC & BRC **

**Computations ** **Price **

Volume 0.01 m^{3} -

Cement 0.11 bags PHP 24.45

Sand 0.01 m^{3} PHP 8.27

Gravel 0.01 m^{3} PHP 16.54

**TOTAL PHP 49.26 **
The total cost for PRC and BRC is Php 49.26 per beam.

*Table 4 - 10: Summary of Prices for PRC and BRC *
**PBRC & PSRC **

**Computations ** **Price **

Volume 0.01 m^{3} -

Cement 0.10 bags PHP 22.38

Sand 0.01 m^{3} PHP 7.57

Gravel 0.01 m^{3} PHP 15.14

**TOTAL PHP 45.09 **
The total cost for PSRC and PBRC is Php 45.09 per beam.

*Figure 4 - 4: Cost Analysis of PRC, BRC, PSRC, and PBRC *

The cost was computed through the concrete proportion (based on the class mixture) multiplied to its price. The cost obtained is only based on the volume of the beam specimens. Thus, the difference in cost between the beams with and without plastic bottles is Php 4.17.

*Table 4.11: Difference between PRC & BRC and on PBRC & PSRC on Cost of *
*Cement, Sand, Gravel *

** ** **PRC **

**& BRC ** **PBRC & **

**PSRC ** **Diffe-**

**rence ** **T-value ** **P-**

**value ** **Interpre-**
**tation **
Cement

(bags) PHP

24.45 PHP

22.38 -9.2%

Sand (m3) PHP

8.27 PHP

7.57 -9.2% 0.220 0.837 Not Signi- ficant Gravel

(m3) PHP

16.54 PHP

15.14 -9.2%

*Df = 2, T-tabular value = 4.303 *

PHP 49.26

PHP 45.09

### PHP 43.00

### PHP 44.00 PHP 45.00 PHP 46.00 PHP 47.00 PHP 48.00 PHP 49.00 PHP 50.00

### PRC & BRC PBRC & PSRC

### Pr ic e

**Cost**

*Antorcha Vol. 6 No. 2 (March 2019) *

Table 4.19 presents the comparison between PRC & BRC and on PBRC &

PSRC on Cost of Cement, Sand, Gravel. The table showed that PBRC & PSRC was cheaper by 9.2% than PRC & BRC however when compared, the p-value was 0.837 which means that there is no significant difference between PRC &

BRC and on PBRC & PSRC on Cost of Cement, Sand, Gravel. This means that the cost of both groups is statistically similar.

*Figure 4 - 5: Graphical presentation of the difference between PRC & BRC and *
*on PBRC & PSRC on Cost of Cement, Sand, Gravel *

**CONCLUSION **

Statistical analysis was done based on the data results obtained and this will determine whether the data is significant or insignificant. If the p- value is less than or equal to 0.05 (p≤0.05) it is interpreted as significant; and if the p-value is greater than 0.05, it is interpreted as insignificant.

The 28^{th}-day compressive test results of the cylinder with and without
bottles showed significant difference with a p-value of 0.02. The tensile test
for steel and bamboo resulted in a p-value of 0.01, thus significant. The 14^{th}-
day flexural test results of the PSRC, BRC, and PBRC was compared to the
flexural test results of PRC which served as the control sample. The PRC and
PSRC beams are both reinforced with steel, while the BRC and PBRC beams
are reinforced with bamboo. The PSRC and PBRC beams contain plastic
bottles within while the PRC and BRC beams do not. The statistical results of
PRC compared to PSRC, BRC, and PBRC showed a p-value of 0.23
(insignificant), 0.01 (significant), and 0.00 (significant) respectively. For costs,
the beams were separated into two groups: beams with no bottles (PRC and
BRC) and beams with bottles (PBRC and PSRC). The beams with no bottles
are more expensive than the beams with bottles by 9.2%.

For future researchers, test the raw materials to be used and then determine the mix ratio to be used based on the results. Look for alternative ways to incorporate the use of plastic into the beam, one example of this is the use of pulverized plastic. When computing for the cost analysis, instead of computing it per beam, provide a cost analysis for a whole low-cost house.

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PHP 24.45

PHP 22.38

PHP 8.27

PHP 7.57 PHP 16.54

PHP 15.14

### PHP 0.00 PHP 5.00 PHP 10.00 PHP 15.00 PHP 20.00 PHP 25.00

### PRC & BRC PBRC & PSRC

### Co st

## Cost Analysis per Specimen

### Cement (bags) Sand (m3) Gravel (m3)

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*Antorcha Vol. 6 No. 2 (March 2019) *