UNP Research Journal Vol. XIX January-December 2010 37
The gasoline-fed welding machine – an alternative for oxy-acetylene welding was designed and fabricated using metal working concepts. The fume reservoir fuel tank and accessories, including welding torch assembly were fabricated. The proposed gadget – a gasoline fed welding machine as an alternative to oxyacetylene-fed welding was conceptualized to considerably decrease the fuel consumption in welding without sacrificing the quality of the finished product with what is already acceptable to the market – the oxyacetylene-fed welding machine.
Qualitative testing were made to identify the capacity of the set-up as to the type of material connected as well as the purposed of the welding connection, adjustments needed per type of material and purpose; observations as to the machines performance when wielding the identified materials, application to different filler rods, as well as position and motion to the torch.
Interpreting the observed results per applied pressure and temperature, with the type of material connected, the following could be derived; light color of flame suggest a pressure of 0.5 psi (3.454KPa) and temperature close to 3149oC.
Bright/faint red flame indicated that a pressure from 2 psi to 3 psi (13.816 to
20.724 KPa) and a temperature close to 3260oC is already attained. Aluminum melts a 343oC And would attain a sound weld when connected to another aluminum materials at this temperature.
The gas-fed welding machine is only capable of producing light and full red color of flames, while oxy-acetylene could produce three flame qualities, light, dull red and bright/faint red. The machine could not weld steel material to itself, and to other materials, specifically aluminium and copper.
Technical fields where gasoline-fed welding machine is advisable for refrigeration and air conditioning electrical shop, automotive shop and goldsmith bracing joints of copper tubes and soldering of splitter and joints. It is also for

38 UNP Research Journal Vol. XIX January-December 2010 repair of leaks, broken and joints of clutch, steering wheels and brake piping systems of automobiles. And finally for broken gold jewelry repairs, gold smithing and welding of gold bars.
Industries have been dubbed as the backbone of economy. In a country where the economy is at stake, industries play a significant role in spurring economic activities.
Industries are further supported by technologies which facilitate the operation of machines and processing of raw materials.
Occupying the basic foundation of technologies are scientists and inventors. It is their prime role to continuously search for facilitative gadgets to improve productivity in terms of minimized use of resources.
Creativity is a human capacity to conceptualize mechanisms from abstraction to actualization. Need has been the driving force to cause people to develop their creative thoughts.
Welding is presently the most handy method of fastening structural members in construction, as well as in working with building accessories, farm gadgets, and other domestic appurtenances by the metal working industry. This is the process of joining materials (usually metals) by heating them to suitable temperatures such that the materials coalesce into one material (Salmon and Johnson, 1996: 190). In structural undertaking, fastening members in the joint of a truss could be done by means of filler materials and connecting plates, the most common of which is the gusset plate. Because of the heat requirement, the fastened members have to be subjected to heat to sufficiently melt the joining members. This is the role of the oxy-acetylene, the fuel most frequently used to operate welding machines globally.
Due to the fast increase of oil prices, the cost of oil products, which are the key to the operation of mechanized gadgets, have continuously rose. Their presence is inevitable, thus, industries totally depend upon oil to operate. This now causes the dilemma of industries, small and big alike. However, the small businessmen and entrepreneurs are more affected by the increase in oil prices. Thus, the need to design low-consuming yet comparably performing industrial gadgets would somehow ease up oil-related investments of industries.

Design and Development of a Gasoline-Fed Welding Machine 39
This proposed gadget- a gasoline-fed welding machine as an alternate to oxyacetylene-fed welding, has been conceived to considerably decrease the fuel consumption in welding, without sacrificing the quality of the finished product with what is already acceptable to the market- the oxyacetylene-fed welding machine.
Generally, this research work came out with the design of a gasoline-fed welding machine that would comparatively perform as an oxyacetylene-fed welding machine, with identified limitations as to types of material used and the purposes the welding is intended for.
Having attained the main objective, the following specific objectives were realized:
1.
Fabricated the fume reservoir and fuel tank and accessories, including welding torch assembly.
2.
Tested the performance of the connected major parts for three types of materials: a) aluminum, b) copper, and c) steel when connected to similar materials, as well as the performance when different materials are welded together.
3.
Identified the specific purposes in the use of the materials under consideration where its performance is equally comparable to the oxy-acetylene-fed gadget.
4.
Emphasized the economic advantages of the proposed gadget vis-à-vis the oxyacetylene welding.
5.
Set the welding specifications.
The design of the gasoline-fed welding machine proceeded through the following paradigm. It is operated manually (pedalled) to produce a certain pressure and a corresponding flame quality that would join selected materials out of fusion. The welding specification shall be formulated resulting from the trials conducted, as to which flame quality and pressure combinations would produce sound joints.

40 UNP Research Journal Vol. XIX January-December 2010
Pressure
Gasoline Tank
Type & Size of
Conn. Materials
Welding Torch
Assembly

Flame
Welding
Specification s
Figure1. The Research Paradigm
The following concepts are tools used by the researchers to develop the mechanism proposed herein.
The Oxy-Acetylene Welding
Oxy-Acetylene welding uses the principle that when acetylene is mixed with oxygen in correct proportions and ignited, the resulting flame is one of the elements for burning. This flame which reaches a temperature of 630 o F melts all commercial metals so completely that metals to be joined actually flow together to form a complete bond without the application of any mechanical pressure or hammering. In most instances, some extra metal in the form of a wire rod is added to the molten metal in order to build up the seam slightly for greater strength. In very thin materials, the edges are usually flanged and just melted together. In either case, if the weld is performed correctly, the section where the bond is made will be as strong as the based metal itself.
The oxy-acetylene flame is employed for a variety of other purposes, notably for cutting metal, case hardening, and annealing. As a matter of fact, it can be used in practically any situation which involves joining metal parts.
Oxyacetylene welding, commonly referred to as gas welding, is a process which relies on combustion of oxygen and acetylene. When mixed together in correct proportions within a hand-held torch or blowpipe, a relatively hot flame is produced with a temperature of about 3,200 o C. The chemical action of the oxyacetylene flame can be adjusted by changing the ratio of the volume of oxygen to acetylene.

Design and Development of a Gasoline-Fed Welding Machine 41
Three distinct flame settings are used, neutral, oxidizing and carburizing.
Neutral Flame Oxidizing Flame Carburizing Flame
Welding is generally carried out using the neutral flame setting which has equal quantities of oxygen and acetylene. The oxidizing flame is obtained by increasing just the oxygen flow rate while the carburizing flame is achieved by increasing acetylene flow in relation to oxygen flow. Because steel melts at a temperature above 1,500 o C, the mixture of oxygen and acetylene is used as it is the only gas combination with enough heat to weld steel. (http://www.twi.co.uk/j32k/protected/band_3/jk3.html)
The Blow Torch
Blow torch is a common name for a simple heating torch, which burns liquid fuel with ambient atmospheric air after vaporizing it using a coiled tube passing through the flame. The blow torch is operated by air pressure and gasoline fuel. Its principle of operation uses gasoline as the primary fuel to braze copper tubes and metals. Air pressure is introduced inside the sealed tank with gasoline. ( http://en.wikipedia.org/wiki/blowtorch)
The welding device is one of the most important tools for refrigeration and automotive technicians, electricians, tinsmitry and other allied works.
To provide the reader a clearer understanding about the study, key words and phrases are defined as they were used in the research.
Acetylene.
A colorless, highly flammable or explosive gas, C
2
H
2
, used for metal welding and cutting and as an illuminant. Also called ethyne It is the resulting gas from the chemical reaction between calcium carbide added to water.
(http://www.answers.com/topic/acetylene?cat=health)
Alloy.
A homogeneous mixture or solid solution of two or more metals.
(http://www.answers.com/alloy?cat=health)

42 UNP Research Journal Vol. XIX January-December 2010
Aluminium . A silvery-white, ductile metallic element, the most abundant in the earth's crust but found only in combination.
Bronze.
An alloy of copper and tin.
Copper.
It is a soft, tough and ductile metal which could not be heat-treated but will harden when cold-worked.
Collapse under its own weight.
The tendency of a joined metal to melt disallowing itself to be connected due to its exposure to a relatively high temperature, while the other joint metal has not yet reached its melting point.
Filler Rod . A material that acts as paste to facilitate the joining of metals when heated. For joining aluminum to another aluminum material, an aluminum filler rod and flux are required, for joining aluminum to copper, aluminum to steel copper alloy for strong bond; for copper, silver or bronze filler rod and borax flux is required for copper to copper connection, bronze to copper connection, copper to steel and copper to copper steel alloy for strong bond.
Flame Quality . The visual description of the temperature and pressure combination produced by the process of burning when oxygen and acetylene are combined in equal proportions, which could be: a) light, b) dull red, and c) bright/faint red. a) Light color – flame is balanced (oxygen and acetylene) the molten metal flows smoothly like syrup, with very few sparks, cleanse clear b) Dull Red Color – white/light cone becomes short and the color changes to dull red or purpush hue. The flame burns with a decided roar. c) Bright/Faint Red – white cone appears at the tip enveloped by another fanshaped cone which has a feathered edge. Metal melts. It has a tendency to boil.
Pressure.
Force exerted per unit area.
Sound weld . A quality of welded materials where proper fusion of connected materials is attained, characterized by smooth and uniform lining of the edges.
Steel.
A generally hard, strong, durable, malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon, depending on the desired alloy properties, and widely used as a structural material.
(http://www.answers.com/steel)

Design and Development of a Gasoline-Fed Welding Machine 43
Welding . is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. (http://en.wikipedia.org/wiki/Welding)
This study made use of the experimental type of research in three phases:
Phase 1.
Design and fabrication of gasoline receiver tank, fume gas reservoir tank and the welding torch to be used in undertaking the observations by combining the principle of the oxyacetylene and the blow torch discussed earlier.
Phase 2. Qualitative testing to identify the capacity of the set-up as to the type of material connected, as well as the purpose of the welding connection, adjustments needed per type of material and purpose; observations as to the machine’s performance when welding the identified materials, application to different filler rods, as well as position and motion of the torch.
Phase 3. Economic comparison of the proposed gadget with the oxy-acetylene welding.

44 UNP Research Journal Vol. XIX January-December 2010
After several trials, the results of welding two materials using the gasoline-fed gadget are being reflected in Table 1, while the results when the same trials were done using oxy-acetylene are reflected in Table 2.
In Table 1, the maximum pressure attained by the proposed set-up was only 1 psi.
It can only produce light and dull red flame. A thorough analysis of Table 1 highlights the following observations:
1.
Aluminium materials, 1/16” to 1/8” in diameter, are joined soundly with just a light flame produced; but would collapse if the temperature is increased to cause a dull red flame.
2.
Aluminium and copper with diameters ranging from 1/16 in to 1/8” are joined soundly with a light flame; the aluminium would collapse when the flame turns dull red, but the copper is still in its normal state.
3.
Aluminium and steel with diameters ranging from 1/16 in to 1/8” do not join with a light color flame; neither for a dull red flame, because the aluminium has reached its melting temperature while the steel has not yet reached its own.
4.
The proposed gadget could not produce the sufficient temperature and pressure to join copper and steel materials together; neither is it capable to connect copper and steel together.
In Table 2, the maximum pressure attained by the oxy-acetylene was 3 psi, and it was capable to produce a bright/faint red quality of flame which the proposed gadget could not produce. The following are the significant observations noted:
1.
With the same diameter of materials, aluminium has a sound weld with a light flame, while they melt with a dull red and bright/faint red flame. Similarly, the aluminium materials in Table 1 melted when joined with the dull red flame.
2.
Exactly similar with the result in Table 1, the same sized aluminium and copper are joined soundly with a light flame; the aluminium collapsed when the flame turned dull red, but the copper is still in its normal state; and while with the bright/faint red flame, the aluminium melted and a portion of the copper has been cut.
3.
When aluminium was joined with steel, there was no successful connection because the aluminium melted ahead of the steel.
4.
When copper materials with diameters ranging from 1/16” to ¼” were connected together, no fusion resulted with just a mere light red flame, a smooth, syrupy connection was made with the dull red flame, and not uniform thinning and cutting resulted when the flame was bright/faint red.

Table 1. The Performance of the Gas Fed Welding Machine per Type of Material
Type of Material
Connected
A. Aluminum
A.1. Aluminum to
Aluminum
A.2. Aluminium to Copper
A.3. Aluminum to Steel
B. Copper
B.1. Copper to
Aluminum
(similar to A.2)
Compressed Air
+ Gasoline
Pressure (Fume)
0.5 to 1 psi
0.5 to 1 psi
0.5 to 1 psi
0.5 to 1 psi
Size/ Thickness of
Connected Rod or
Tube, in inches
1/16 to 3/16
1/16 to 3/16
1/16 to 3/16
1/16 to 3/16
Flame
Quality
Welding Quality Remarks
Light Sound Weld Good jointing result
Dull red Collapse under its own weight Destroyed (melted)
Light Sound Weld for 1/16 to 1/8” diam Good jointing result
Dull red
Light
Dull red
Aluminium collapses under its own weight Aluminum melts; copper is still in place.
No fusion
Members could not join w/ the attained pressure
No fusion
Aluminum melts; steel retains its original appearance
Light
Dull Red
Sound Weld for 1/16 to 1/8” diam
Sound Weld for 3/16” but not for ¼”
Good joints result
Aluminum melts
B.2. Copper to Copper
B.3. Copper to Steel
C. Steel
C.1. Steel-to -
Aluminum
(similar to A.3)
C.2. Steel-to -
Copper
(similar to B.3)
0.5 to 1 psi
0.5 to 1 psi
0.5 to 1 psi
0.5 to 1 psi
1/16 to 3/16
1/16 to 3/16
1/16 to 3/16
1/16 to 3/16
Light
Dull Red Sound weld; good joint results
Light
No fusion
Dull Red No fusion
Light Sound Weld for 1/16 to 1/8” diameter
Dull Red Sound Weld for 3/16” but not for ¼”
Light
Dull Red
No fusion
No fusion
No fusion
Members could not join w/ the attained pressure
Good jointing result
Members could not join w/ the attained pressure
Copper melts
Good joints result
Aluminum melts
Members could not join
Copper melts
Light
No fusion
C.2. Steel- to -
Steel
0.5 to 1 psi 1/16 to 3/16
Dull Red
No fusion
Members could not join w/ the attained pressure
Members could not join w/ the attained pressure

Table 2. The Performance of the Oxy-acetylene per Type of Material.
Type of Material
Connected
A. Aluminum
Oxygen
Pressure
Acetylene
Pressure
Size/
Thickness of
Conn. Rod or
Tube
Flame
Quality
A.1. Aluminum to
Aluminum
A.2. Aluminium to
Copper
1 to 2 psi
1 to 2 psi
A.3. Aluminum to Steel 2 to 3 psi
1 to 2 psi
1 to 2 psi
2 to 3 psi
1/16 to 3/16
1/16 to 3/16
1/16 to ¼”
Welding Quality Remarks
Light
Bright/
Faint red
Light
Sound Weld
Good jointing result for pressurized tube system for
Refrigeration, Air conditioning,
Auto-motive & Electrical works
Members melt Dull red
Dull Red
Collapse under its own weight
Collapse under its own weight
Sound Weld better result w/ smooth ripples
The aluminum collapses under its own weight while metallic ring unites with copper.
Members melt
Good jointing result
Aluminum melts
Bright/ faint
In a second aluminum collapsed while copper is destroyed in appearance due to some part will be cut
Light Red The aluminium melts with smooth ripples, but the steel doesn’t
Dull Red Aluminun collapse under its own weight while steel turns red with metallic ring.
Bright/faint Aluminium collapse while steel turns to red color and thinning its appearance
Aluminum melts
No joining result
Aluminum melts
Aluminum melts

Table 2 continued
Type of Material
Connected
B. Copper
B.1. Copper to
Aluminum
Oxygen
Pressure
Acetylene
Pressure
1 to 2 psi 1 to 2 psi
B.2. Copper to Copper 1 to 2 psi 1 to 2 psi
B.3. Copper to Steel 1 to 2 psi 1 to 2 psi
Size/
Thickness of
Conn. Rod or
Tube
1/16 to 1/4
1/16 to 1/4
1/16 to 1/4
Flame
Quality
Welding Quality Remarks
Light Red Sound Weld better result w/ smooth ripples
Dull Red The aluminum collapses under its own weight while metallic ring unites with copper.
Bright/faint In a second aluminum collapsed while copper is
Light Red No fusion. The joined
Dull Red
Bright/faint destroyed in appearance due to some part will be cut materials turn black
Sound weld. Perfect fusion w/ uniform ripples.
Poor joint
Good jointing result
Aluminum melts
Aluminum melts
No fusion.
Smooth, syrupy welded connection
No fusion, not uniform thinning and cutting appearance
No fusion. Light Red No fusion. The joined materials turn black
Dull Red Sound weld. Perfect fusion w/ uniform ripples.
Bright/faint The flame destroys the copper while the steel turns red
Smooth, syrupy welded connection
No fusion, not uniform ripples

Table 2 continued
Type of Material
Connected
C. Steel
C.1. Steel to
Aluminum
C.2. Steel to
Copper
C.3. Steel to Steel
Oxygen
Pressure
2 to 3 psi
1 to 2 psi
1 to 2 psi
Acetylene
Pressure
2 to 3 psi
1 to 2 psi
1 to 2 psi
Size/
Thickness of
Conn. Rod or
Tube
1/16 to ¼”
1/16 to 1/4
1/16 to 1/4
Flame
Quality
Welding Quality
Light Red Sound weld/ good fusion w/ smooth ripples
Dull Red Aluminun collapse under its own weight while copper steel alloy turns black with metallic ring.
Bright/faint Aluminium collapse wile copper steel turn to red color and thinning its appearance
Light Red No fusion. The joined materials turn black
Dull Red Sound weld. Perfect fusion w/ uniform ripples.
Bright/faint Destroy the copper while the steel turns red
Light Red No fusion. The joined materials turn black
Dull Red Sound weld. Perfect fusion w/ uniform ripples.
Bright/faint Destroy the copper while the steel turns red
Good Jointing result
Aluminum melts
Aluminum melts
No fusion.
Remarks
Smooth, syrupy welded connection
No fusion, not uniform ripples
No fusion.
Smooth, syrupy welded connection
No fusion, not uniform ripples

Design and Development of a Gasoline-Fed Welding Machine 49
1.
Using the same sizes of copper and steel materials to be connected; only the dull red flame produced a successful joint.
2.
Similarly, connected steel materials with diameters ranging from 1/16” to ¼” were only successful with the dull red flame.
The following findings were found to be significant: a.
From the Gasoline-fed welding machine
1.
Aluminum requires just a light color of flame to be welded to another aluminum.
2.
Aluminium requires just a light color of flame to attain a sound weld with copper.
3.
Aluminium could not be welded to steel in any of the two flame qualities produced by the gasoline-fed welding machine.
4.
Copper materials require dull red flame to fuse, thus, they could not attain any fusion with just a light color flame.
5.
Copper and steel materials could not be welded.
6.
Steel materials could not be welded together. b.
From the Oxy-acetylene Welding Machine
1.
Aluminum requires just a light color of flame to be welded to another aluminum.
2.
Aluminium requires just a light color of flame to attain a sound weld with copper.
3.
Aluminium could not be welded to steel in any of the three flame qualities produced by the gasoline-fed welding machine.
4.
Copper materials require dull red flame to fuse, thus, they could not attain any fusion with just a light color flame.
5.
Copper and steel materials are welded soundly at dull red flame quality.
6.
Perfect fusion occurred in connecting steel materials.

50 UNP Research Journal Vol. XIX January-December 2010 c. Economic Comparison Between the Gasoline Fed Welding and the Oxyacetylene Welding Machine
In terms of financially comparing which of the two gadgets are more economical, the following computations were arrived at:
Parameters Gasoline-fed Oxy-acetylene-fed
Investment Cost
Consumption
P 5,000
Ph P42.75, or one (1) liter per hr of continuous welding
P 35,000
P130.00 per hr of continuous welding
Cost of Oxygen per tank – P1,200 (rate of consumption = 1/16 of the tank per hr
Cost of Acetylene per tank – P700 (rate of consumption = 1/10 of the tank per hr
Interpreting the observed results per applied pressure and temperature, with the type of material connected, the following conclusions could be derived:
1.
Light color of flame suggests a pressure of 0.5 psi (3.454 KPa) and temperature close to 3149 o C
2.
Dull red flame suggests a pressure of 1 psi (6.908 KPa) and temperature close to 3220 o C
3.
Bright/faint red flame indicates that a pressure from 2 psi to 3 psi (13.816 to
20.724 KPa) and a temperature close to 3260 o C is already attained.
4.
Aluminium melts at 343 o C, and would attain a sound weld when connected to another aluminium material at this temperature.
5.
The gas-fed welding machine is only capable of producing light and dull red color of flames, while the oxy-acytelene could produce three flame qualities: light, dull red and bright/faint red.
6.
The proposed set-up could not connect steel materials to itself, and to other materials, specifically aluminium and copper.
In view of the above conclusions, the following recommendations are advanced.
Table 3 below summarizes the specific technical field where the gasoline-fed welding performs equally well in comparison to that of oxy-acetylene welding as well as the assessed advantages to be derived in its use.

Design and Development of a Gasoline-Fed Welding Machine 51
Table 3. Identified Technical Fields Where Gasoline Fed Welding is Advisable
Specific Technical
Field a. Refrigeration
and Air
Conditioning b. Electrical Shop
Works c. Automotive
Shops d. Gold Smith
Purpose
For covering leaks and bracing joints, as well as for new installations using copper and aluminum tubes and wirings, like in the piping system of refrigerators, freezers, car aircons, split-type and window aircons.
For bracing/soldering of splices and joints of copper and aluminium wires which are common activities in electric motor repair and rewinding works.
It is also advisable for interior and exterior house wiring installations.
For the repair of leaks, broken end joints of clutch, steering wheels and brake piping systems of automobiles.
For broken gold jewelry repairs, gold smithing and melting of gold bars
Advantage over
Oxy-acetylene
Lighter
More handy for home services
More economical
More economical
More economical
More economical
Jeffues, Larry, 1999. Welding Principles and Applications. New York: Albany Delmar Publishers.
Self, Charles. 1982. Do Your Own Professional Welding. USA: TAB Books Inc.
Brumbangle, James Andel. 1986. Welders Guide, New York: Macmillan Publishing Company.
Salmon, Charles G. and John E Johnson. Steel Structures Design and Behaviour, 2 nd Ed. New York:
Harper & Row Publishers. http://www.twi.co.uk/j32k/protected/band_3/jk3.html http://en.wikipedia.org/wiki/Blow_torch http://www.answers.com/topic/acetylene?cat=health http://www.answers.com/alloy?cat=health http://www.answers.com/steel http://en.wikipedia.org/wiki/Welding

52 UNP Research Journal Vol. XIX January-December 2010
Alfredo R. Rabena, Ph.D.
Nelia V. Aman, Ed.D.
This study explored the possibility of using oyster shells as component of aggregates in the production of 5” CHB by determining its compressive strength and comparing this to the strength of 5” CHB taken from the construction site.
Twelve (12) samples using different proportions were produced by researchers and another three (3) samples were taken from the construction.
All the samples brought to the testing laboratory are below the required compressive strength for non-load bearing concrete hollow blocks. However, it is noteworthy that the samples with oyster shells have higher compressive strength compared with the samples taken from the construction site.
It was also found out that the lesser the number of pieces of CHB produced the higher is the compressive strength.
There are also significant differences among and between the 5” CHB produced using different proportions including the samples taken from the construction site.
In the Philippines, concrete hollow blocks (CHB) are commonly used for exterior and interior walls of buildings especially residential projects. It is also used for perimeter fence, tank, septic vault, drainage canal and many more.
The growing demands of housing projects have led to the increase of construction materials, particularly the cement and aggregates. Since concrete hollow blocks is made of cement and aggregates, it follows that an increase of one material will affect the cost of
CHB. Considering the present economic crisis, the low income household especially those

Analysis on the Strength of 5” CHB with Oyster Shell 53 from the coastal areas will be deprived from having houses made of concrete hollow blocks. The researchers were, then, prompted to develop a new component in the production of concrete hollow blocks which are available from the available area and can be taken for free to reduce the cost of concrete hollow blocks.
Significant researches were already conducted on many different materials for aggregate substitute such as granulated coal ash, blast furnace slag or various solid wastes including fiberglass waste materials, granulated plastics, paper and wood products/wastes sintered sludge, pellets, burnt bagasse ash and others. However, the researchers’ concern is to look for materials in the coastal area which can be used as component of the aggregates for CHB production which is not expensive but with equal or greater compressive strength as the commercial CHB or CHB with 100% aggregates.
Oyster shells ( Crassostrea gigas ) are abundant in the coastal areas of the Ilocos
Region. Some shells are being brought back to the hatchery to produce larvae, but the excess of the oyster shells are filed along the coastal areas which if not recycled become garbage. The researchers were challenged to conduct a study on other way to recycle the oyster shells which could benefit the oyster growers and the community and in same manner will reduce the cost of CHB needed for low-cost housing.
A proportion of oyster shells and aggregates were mixed with cement to produce a
5” CHB to determine the compressive stress and compare this with 5” CHB using 100% aggregates and the 5” CHB which are available in the market.
The result of the laboratory test can be used as basis for other proportions which could meet the desired compressive stress for non-load bearing 5” CHB. Thus, mixtures which will be developed can be recommended for the production of 5” CHB for the construction of low cost housing. In effect, the problem of waste disposal along the coastal areas will be minimized.
The main objective of this study is to determine ways to recycle oyster shells that would benefit the oyster shell growers and the environment. The following are the specific objectives:
1.
Determine the compressive strength of 5” CHB using different proportions
2.
Determine the number of 5” CHB produced per bag of cement using different proportions
3.
Determine the unit cost of 5” CHB using different proportions
4.
Compare the compressive strength of 5” CHB using different proportions

54 UNP Research Journal Vol. XIX January-December 2010
Concrete hollow blocks, being one of the most commonly used construction materials for buildings, has resulted to the increase of its cost. The use of additional material which are abundant and can be acquired for free can reduce the cost of concrete hollow blocks.
Concrete hollow blocks are classified as bearing and non-bearing blocks. Load bearing blocks are those which thickness ranges from 15 cm. to 20 cm. and are used to carry load aside from its own weight. Non-bearing blocks on the other hand, are blocks which are intended for walls, partitions fences or dividers carrying its own weight which thickness ranges from 7.5 cm. to 10 cm. (Fajardo, 2000)
The compressive strength of hollow blocks for non load bearing is 350 psi for individual and 300 psi for an average of 5 CHBs. (PTS 661-09:1968)
Concrete hollow blocks has three whole cells and two one-half cells at both ends having a total of four. These cells vary in sizes as there are different manufacturers using different moulds.
All concrete masonry units are modular in size. The largest units, called blocks, have nominal face dimension of 8 inches in height by 16 inches in length and nominal thickness of 4, 6, 8,10 or 12 inches. The actual dimension is in all cases 3/8” to allow for the thickness of the joint. Permissible dimension tolerance is 1/8” but the practical deviation rarely exceeds 1/32” (Amistad, et.al., 1996).
In the study of Amistad, et.al. (1996) on the Compressive Strength Test of
Concrete Hollow Blocks Manufactured in Ilocos Sur, it revealed that out of 137 samples, only two (2) surpassed the allowed crushing strength of 300 psi for an average of 5” CHBs.
Likewise, the crushing strength has no significant difference among and between the commercial sizes taken from each manufacturer.

Analysis on the Strength of 5” CHB with Oyster Shell 55
The result on the study of Sabalburo, et. al. (2009) showed that the compressive strength is higher for proportions with lesser CHB produced. Furthermore, the lesser the number of pieces of CHB produced the higher is the unit cost per CHB.
The scope of the study covered the testing of strength of 5” CHB produced using the proportions 1:8:1 (1 bag cement, 8 cuft aggregates and 1 cuft oyster shells grind into aggregate size); 1:9 (1 bag cement, 9 cuft aggregates); 1:8:2 (1 bag cement, 8 cuft aggregates and 2 cuft oyster shells grind into aggregate size); 1:10 (1 bag cement, 10 cuft aggregates) and 5” CHB produced commercially.
The researchers hypothesized at .05 level of significance that:
There are no significant differences among and between the compressive strength of samples produced using different proportions and taken from the construction site.
This section presents the research design, sample, data gathering procedure.
Research Design. This study utilized the descriptive method of research. Out of the data gathered, findings were summarized, analyzed, and interpreted.
Sample. The samples used in this study are (15) fifteen pieces. 5” CHB with different proportions. The researchers hired laborers to produce 5” CHB using various proportions identified by the researchers. Samples of 5” CHB were taken from the construction site for testing as basis for comparison. Oyster shells were taken from the coastal area of Caoayan, Ilocos Sur.
Procedure
1.
Oyster shells taken from Caoayan were rinsed with clean water and broken in sizes same as the aggregates.

56 UNP Research Journal Vol. XIX January-December 2010
2.
Aggregates and oyster shells were mixed with cement as to desired proportions using the following proportions:
Samples
A
B
C
D
E
Cement (bag) Aggregates (cuft) Oyster Shells (cuft)
1
1
1
1
Proportions
8
9
8
10 commercial
1
2
3.
The mixed cement, aggregates and oyster shells were placed in a 5” CHB molder tamped and properly compacted.
4.
Molded CHB is then placed on a flat surface and cured for 28 days. Samples were sprinkled with water twice a day.
5.
After 28 days the three samples for each mixture were brought to BIP
Geotechnical and Materials Testing Engineers, an accredited testing laboratory by the Department of Public Works and Highways and tested for compressive strength using the Universal Testing Machine.
6.
The researchers also took 5”CHB from a construction site and brought to the same laboratory for testing.
7.
The average compressive strength were computed and used as basis for analysis.
Table 1 presents the compressive strength of 5” CHB using different proportions. It can be seen that Sample B proportioned at 1 bag of cement and 9 cuft gravel has the highest compressive strength, followed by sample D proportioned at 1 bag cement and 10 cuft aggregates.
It is to be noted that sample A proportioned at 1 bag cement 8 cuft aggregates and
1 cuft oyster shells has a higher compressive strength (204.12 psi) than Sample E which is a commercial 5” CHB (178.52 psi).

Analysis on the Strength of 5” CHB with Oyster Shell 57
Table 1. Compressive Strength of 5” CHB Using Different Proportions
Samples Average Compressive Strength
(psi)
A
B
C
D
E
204.12
332.77
177.28
242.80
178.52
However, all samples have compressive strength which is below the required compressive strength for non-load bearing hollow blocks which is equal to 350 psi.
It is noteworthy that on the study of Amistad, et.al. (1996), only two samples out of
137 samples taken from the manufacturer passed the allowed compressive strength.
This finding implies that concrete hollow blocks being used for building construction have compressive strength below the required strength for non-load bearing concrete hollow blocks which is 350 psi.
Figure 1. Number of 5” CHB Produced Using Different Proportions
It is reflected in Figure 1 that Samples C and D has 48 pcs. 5” CHB each produced per bag of cement while Samples A and B has 40 pcs 5” CHB each.

58 UNP Research Journal Vol. XIX January-December 2010
Sample E which is a commercial 5” CHB has no data on the number of pieces produced per bag, since this is produced in bulk taken from the construction site and the supplier was not identified.
The researchers have also noted the unit cost of 5” CHB produced using different proportions. Among the first four samples produced and proportioned by the researchers, sample B has the highest unit cost and sample D has the lowest unit cost.
Based on the result of the compressive strength it is to be noted that sample B has the highest compressive strength and sample D has the lowest compressive strength.
Table 2. Unit Cost of 5” CHB Produced Using Various Proportions
Samples
No. of
Pieces
Cost
Aggregates
A
B
C
40
40
48
Cement
205
205
205
297.44
334.62
371.80
Labor
100
100
100
Total
Unit
Cost
602.44 15.06/pc
639.62 15.99/pc
676.80 14.10/pc
D
E
48 205 297.44 100 602.44 12.55/pc
9.50/pc.
This confirms the study of Sabalburo et al (2009) that the compressive strength is higher for CHB samples with higher unit cost.
Table 3. ANOVA Table on the Compressive Strength of 5” CHB Produced using
Different proportions
Source of Variation
Between Groups
Within Groups
Total
Sum of Squares
50,347.16
25,858.53
76,205.29
F@.05 = 3.48
Df
4
10
14
Ho is rejected
MSS
12,586.79
2,585.85
F
4.88
Table 3 shows the analysis of variance on the compressive strength of 5” CHB produced using different proportions.
It can be seen that the computed value of F which is 4.88 is higher than the tabular
F-value at .05 level of significance which is equal to 3.48. This implies that there are significant differences among the compressive strength of 5” CHB produced using different proportions.

Analysis on the Strength of 5” CHB with Oyster Shell 59
In order to determine which pair of group means were significantly different or not, the Scheffe’ Method of Least Significant Difference or LSD was employed. The computed
F value was compared with the critical F-value at the .05 level of significance.
Table 4. Multiple Comparison of the Compressive Strength of 5” CHB Produced using Different proportions
Comparison
A versus B
A versus C
A versus D
A versus E
B versus C
F-test
2.4001
0.1045
16.0406*
6.0356*
270.3454*
Comparison
B versus D
B versus E
C versus D
C versus E
D versus E
F-test
109.8494*
267.2701*
42.5273*
0.0132
41.1016*
The Scheffe’s Test yielded that there are significant differences on the compressive strengths between the five groups as revealed in Table 4. It can be seen on the result that almost all the ratio are high which implies that there is a highly significant difference on means of each samples specifically between sample E (commercial) and the other samples prepared by the researchers.
Sample B with the highest average compressive strength and sample C with the lowest average compressive strength showed a highly significant difference.
Based on the findings of the study, the following conclusions were drawn:
1.
The compressive strengths of the samples produced using different proportions and the samples taken from the construction site is below the required strength for non-load bearing concrete hollow blocks.
2.
Sample with oyster shells proportioned at 1:8:1 has a higher compressive strength than the sample taken from the construction site.
3.
The higher the compressive strength of 5” CHB the lower is the number of 5”
CHB produced.
4.
There were significant differences on the compressive strengths of the samples using different proportions.

60 UNP Research Journal Vol. XIX January-December 2010
In view of the aforementioned findings and conclusions derived from the study, the following are hereby recommended by the researchers.
1.
Another set of proportions for 5” CHB with oyster shells shall be prepared in order to reach the required strength for non-load bearing concrete hollow blocks.
2.
In as much as the samples taken from the construction site did not pass the allowed strength and these were being used for building construction, the 5” CHB produced with oyster shell can be used for low cost housing.
3.
However, in order not to sacrifice the strength of buildings with more than one storey, the constructors should subject the concrete hollow blocks for laboratory testing before it is used for construction purposes.
4.
The Department of Trade and Industry should monitor the concrete hollow blocks sold in the market so as to ensure the quality of products being bought by the consumers.
Amistad, Franklyn, et al, 1996. Compressive Strength Test of Concrete Hollow Blocks Manufactured in Ilocos Sur , UNP Research Journal, University of Northern Philippines, Vigan City.
Encarta Encyclopedia, 2001. Concrete Construction.
Fajardo, M. Jr. 2000. Simplified Construction Estimate .
Philippine Trade Standard Specification for Concrete Hollow Blocks (PTS 661-09. 11:1968).
Sabalburo, J. et al. “2009. Compressive Strength of 4” Thick Non-Load Bearing Concrete Hollow
Blocks Using Various proportions and Its Unit Cost.” Unpublished Undergraduate Thesis,
College of Engineering University of Northern Philippines, Vigan City, Ilocos Sur, 2009.
Internet www//http.en.wikepedia.org/wiki/oyster