Kapok Fiber Cement Board for Wall Claddings College of Engineering Materials Engineering Department
Renato F. Segovia, ENME5A Isidro Rhey H. Gonzales, ENME5A Rudolph P. Silva, ENME5A
Table of Contents Chapter I Introduction -------------------------------------------------------------------------------------------- 1 1. Objectives ------------------------------------------------------------------------------------------- 2 2. Significance of the Study -------------------------------------------------------------------------- 3 3. Definition of Terms ---------------------------------------------------------------------------------4 4. Scope and Limitation ------------------------------------------------------------------------------- 5 Chapter II Review of Related Literature 1. Kapok Fiber ------------------------------------------------------------------------------------------ 6 1.1 Kapok Fiber as Reinforcement 2. Composite Materials -------------------------------------------------------------------------------- 7 3. Fiber Composite ------------------------------------------------------------------------------------- 8 4. Cement Bonded Board ------------------------------------------------------------------------------ 9 5. Synthesis ---------------------------------------------------------------------------------------------- 9 Chapter III Methodology -------------------------------------------------------------------------------------------- 10 Process Flow -------------------------------------------------------------------------------------------- 11 1. Make Pure Cement Board -------------------------------------------------------------------------- 12 1.1 Mixing Procedures 1.2 Forming 1.3 Curing of Cement Board 2. Make Fiber-reinforced Cement Board ------------------------------------------------------------ 13 2.1 Mixing Procedures 2.2 Forming
2.3 Curing of Fiber-reinforced Cement Board 3. Determination of Kapok-reinforced Cement Board and Pure Cement Board Properties -- 14 3.1 Water Absorption Test ------------------------------------------------------------------- 14 3.2 Impact Resistance Test ------------------------------------------------------------------- 15 3.3 Flexural Strength Test -------------------------------------------------------------------- 15 3.4 Compressive Strength Test--------------------------------------------------------------- 15 5. Analysis of Significant Differences --------------------------------------------------------------- 15 6. Verification and Selection of Best Proportion --------------------------------------------------- 16
Chapter I Introduction There are several abundant fibers that can be found in Philippines and has a potential to be used as reinforcement in the development of cement fiber composites, and one these fibers is the Ceiba Pentandra or also known as kapok fiber. Fiber cement boards are common and widely used in construction of buildings and houses. This is due to the properties these materials exhibit; they are very durable, flexible and have a variety of uses. However, fiber cement boards have problems; one example of this is the toxicity of some of the composition of asbestos-based fiber cement boards. Asbestos is highly toxic and can cause deterioration of health; it mainly affects the lungs contributing to a severe lung cancer. Another problem in fiber cement board is that it degrades when exposed to moisture over a long period of time, one example of this the non-asbestos fiber cement board like HardiFlex. To resolve these problems in the properties of fiber cement boards, fiber compositions should be replaced with a more resilient, non-toxic, moisture-resistant and pest resistant natural fiber. Kapok fiber exhibits these good characteristics. Kapok (Ceibapentandra) fiber is a silky, cotton-like substance that surrounds the seeds in the pods of the Ceiba tree. They are buoyant, resilient, moisture resistant, pest resistant and smooth, kapok possess powerful performances in a lightweight package. It is said that kapok fiber repels water like rain on a ducks back. When a substance does this we call it, hydrophobic. This hydrophobic quality results in the quick-drying, buoyant and moisture-resistant properties, which makes kapok fiber remarkable among natural fibers. When kapok fibers are put under tension they completely return to their original length when the tension is removed. Kapok fiber is empty of nutritional content thus kapok fiber is pest resistant so it won’t mat or felt easily (Chaput, 2012). Using kapok fiber as a reinforcement matrix, the cement-bonded board will going to be moisture resistant because kapok fiber is hydrophobic making the cement board reinforced with kapok enhance its moisture-resistant properties compared to other cement-bonded board like HardiFlex. The advantage of moisture resistant cement boards is that it will withstand degradations because of exposure in wet environments. This study aimed to find out whether kapok fiber could be a good reinforcement in the production of fiber cement boards.
1. Objectives The main objective of the study is to produce Kapok-reinforced cement board.
Specifically, this study aims: 1.1. To produce a 305mm x 152mm x 16mm cement board reinforced with kapok fiber with a composition of: 1.2.1. 40% Portland cement, 55% sand and 5% kapok fiber. 1.2.2. 40% Portland cement, 53% sand and 7% kapok fiber. 1.2.3. 40% Portland cement, 50% sand and 10% kapok fiber. 1.2.4. 40% Portland cement, 45% sand and 15% kapok fiber. 1.2. To determine the properties of kapok-reinforced cement board and pure cement board. 1.3.1. Water absorption 1.3.2. Impact resistance 1.3.3. Flexural strength 1.3.4. Compressive strength 1.3. To determine the significant difference between pure cement board and cement board reinforced with kapok fiber based on water absorption, impact resistance, flexural strength and compressive strength tests using One Way ANOVA. 1.4. To verify the best proportion of Portland cement, sand and kapok fiber in making Kapokreinforced cement board by using Criteria Method.
2. Significance of the Study This study would greatly help, primarily to the different sectors of the community, namely:
2.1. Structural Industries: This study will benefit the structural industries by introducing a new composite material at which the composition is abundant in nature and at the same time it is water proof, fire proof, non-corrosive, high strength and durable.
2.2. Community:
The study will benefit the community by producing such quality composite board that can be used as claddings, fire proofing walls, thermally insulative ceilings and exterior cover for building walls. 2.3. Fiber Industries: The study will benefit by initiating new ideas on the other uses of kapok fiber by converting it for structural purposes. 2.4. Future Researchers: The study will exhibit new knowledge and it will open the new ideas for innovative and useful composite materials. 3. Definition of Terms For better knowledge and understanding, the following words with their meanings are listed below:
A composite material is a combination of two or more materials (reinforcing elements, fillers, and composite matrix binder) differing in form or composition on a macro scale.
Curing is a process of setting and hardening of a cement material such as concrete or a grout; in this study, it is the process used for drying and hardening of kapok fiber cement board.
Fiber Cement Board is a composite building material made of sand, cement and cellulose fibers.
Flexural Strength is the ability of the material to resist deformation under load.
G. I. (Galvanized Iron) Sheet is an Iron that is coated with zinc to protect it from rust.
Impact Resistance is the resistance of a material (as metal or ceramic ware) to fracture by a blow, expressed in terms of the amount of energy absorbed before fracture.
Kapok Fiber is a fine, silkily lustrous fruit fibers from the fruit walls of the capsules, 10 20 cm in length and 3 cm in thickness, of the kapok tree (Ceiba pentandra).
Portland cement is a hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverizing clinkers consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition.
A Vernier Caliper is a measuring device that consists of a main scale with a fixed jaw and a sliding jaw with an attached Vernier scale. In this study, it was used as a measuring device for the thickness of the fiber cement board.
Water Absorption is a test method used to determine the percent absorbency of water to the specimen in specified duration of immersion.
4. Scope and Limitation
The study focuses on the making of cement board reinforced with kapok fiber. The experiment will be conducted in the 2nd semester of the academic year 2012-2013. The researchers will Posttest-only as experimental design. The statistical methods of analysis will be used to the results of the experiment using Mean and One Way analysis of variance to determine if the results of the experiments on composite board will meet the desired properties. The fiber cement board will be tested accordingly by means of flexural strength, water absorption and impact resistance while the cost of materials and the labor will not be included in the data of the results and the equipment for testing will be all improvised. The standards of ASTM in test methods will be followed in the materials testing procedures with corresponding dimensions of 12in. x 6in. x 16mm (305mm x 152mm x 16mm) for flexural strength test and 4in. x 4in. x 16mm (100mm x 100mm x 16mm) for water absorption test. The kapok fiber cement board will be tested to compare its properties with pure cement board to know if there is significant difference in its mechanical properties.
Chapter II
Review of Related Literature
This chapter consists of several topics that support the foundation of the study of kapok fiber cement board. In this chapter kapok fiber, composite materials, fiber composite and cement bonded board are discussed to condense the idea of creating the kapok fiber cement board.
Related Studies
Figure 2.1: Kapok Fiber 1. Kapok Fiber Kapok fiber was isolated and analyzed microscopically, and the physicochemical properties were determined by spectroscopic methods. Some tests were done to determine the effective utilization of kapok fiber. Microscopic analysis of the higher structure of kapok fiber gave quite different results from cotton fiber, which has a significantly homogeneous hollow tube shape and is composed of cellulose (35% dry fiber), xylan (22%), and lignin (21.5%). Kapok fiber is characterized by having a high level of acetyl groups (13.0%). Usually cell walls of plants contain about 1%-2% of acetyl groups attached to non-cellulosic polysaccharides. Kapok fiber is significantly hydrophobic and does not get wet with water (Hori, 2007).
Kapok Characteristics Average Density
0.29 g/cm3
Average Linear Density
0.064 tex
Average Diameter
20.5m
Average Length
20mm
Moisture Regain
10%
Figure 2.2: Kapok Fiber Properties
1.1 Kapok Fiber as Reinforcement Natural fabric-based thermoset composites are generally lower in strength performance compared to hybrid composites. However, they have the advantages of design flexibility, cost effectiveness, lack of health-hazard problems and recycling possibilities. Hybridization with some amounts of synthetic fibers makes these natural fabric composites more suitable for technical applications such as automotive interior parts. Kapok fabric is one of the important lignocellulosic plant fabrics and has been used as reinforcement for hybridizing with glass and sisal fabrics in polyester matrix. This study focused on the performance of impact properties of kapok/ glass and kapok/sisal fabrics reinforced polyester hybrid composites. Results show that hybridization with glass fabric enhanced the performance properties. Similarly, addition of kapok fabric to sisal/ polyester composites enhanced the properties. The effect of alkali treatment of fabrics on impact strength of these composites was studied. Notched Izod impact strength of the hybrid composites exhibited great enhancement (34%). Analysis of fabric distribution in the composite and fracture surface was performed to study the breakage and fracture mechanism of the fabric (Reddy and Naidu, 2008). Natural fiber reinforced composites have gained popularity nowadays because of their processing advantage and good technical properties. The present work includes the processing, characterization of kapok fiber reinforced epoxy composites. Keeping in this view the present study has been undertaken to develop a polymer matrix composite (epoxy matrix) and kapok fiber (Reinforcement) and to study its structural and electrical properties. This study is concerned to investigate the percentage of crystallinity, surface structure, dielectric constant, dielectric loss and resistivity (Mani and Rayappan, 2012).
7
2. Composite Materials Composite materials for construction, engineering, and other similar applications are formed by combining two or more materials in such a way that the constituents of the composite materials are still distinguishable, and not fully blended. One example of composite material is concrete, which uses cement as a binding material in combination with gravel as a reinforcement. In many cases, concrete uses rebar as a second reinforcement, making it a three-phase composite, because of the three elements involved. Generally, composite materials have excellent compressibility combined with good tensile strength, making them versatile in a wide range of situations (Grosz, 2010).
Figure 2.3: Classification of Composites (Callister, 2001).
3. Fiber Composite Fiber Reinforced cement (FRC) composites have been classified according to many criteria, such as the fiber material ( steel, synthetic, natural organic) or the level of performance, a general, simple and convenient classification has been recently suggested. Such a classification suggests a level of performance irrespective of the fiber type, fiber content, or matrix composition. FRC composites are particularly suitable for structural applications. These include stand-alone applications, for example, pipes or thin sheets, applications in parts of structures such as those in impact resistant and protective structures (Naaman, 1996).
The behavior of the fiber reinforced cement composites (FRCC) can be described and quantified by a variety of parameters, such as strength and strain capacity, toughness index, and fracture energy, obtained from tests in tension or bending in large number different configurations including varying specimens geometries and test setups. Depending on the details of the individual testing procedures, a particular composite may be characterized and classified inconsistently. To enable the evaluation of FRCC performance, a common basis for comparison is required, which will reflect the relevant material characteristics (Fischer, 2004). 4. Cement Bonded Board A typical formulation would be about 5- 10% asbestos fibers, 30-50% cement, and about 40-60% silica. The second development was to replace some of the asbestos reinforcing fibers with cellulose fibers from wood. This was not widely adopted except for siding products and wet-area lining sheets. The great advantage of this development was that cellulose fibers are hollow and soft, and the resultant products could be nailed rather than by fixing through predrilled holes (Welly, 2010). 5. Synthesis The researchers conduct research on kapok fiber as reinforcement due to the properties that kapok fiber exhibits. The reinforcement of kapok fiber in cement board will have good effect especially in its impact strength, flexural strength, water absorptivity and compressive strength. Kapok fiber is water resistant, pest resistant and lightweight; these are the significant properties that kapok fiber has compared to other natural fibers present.
Chapter III Methodology The researchers will conduct experiment and testing for different proportions of Portland cement, sand and kapok fiber to determine the best formulation of components in order to attain the best properties of fiber-reinforced cement board. The (3) three different proportions of fiberreinforced cement board and the commercial fiber cement board (HardiFlex) will be tested in (3) three material testing procedures, namely, flexural strength test, water absorption and impact resistance. The results in the (3) three material testing procedures will give the researchers the conclusion if there are significant differences between kapok-reinforced cement board and commercial fiber cement board (HardiFlex) using statistical analysis: One Way ANOVA and to verify the best proportion of Portland cement, sand and kapok fiber using Criteria Method.
Process flow charts of the fabrication of kapok fiber cement board: Gathering of materials Mixing
Forming
Curing Product Testing Analysis of Data
Verification / Selection
Figure 3.1. Process Flow Chart for Production of Kapok Fiber Cement Board
1. Production Kapok Fiber-reinforced cement board
The kapok fiber-reinforced cement board will consist of Type 1 Portland cement, kapok fiber and sand. The sand will be sieved with mesh no. 12 (ASTM C778-02), 1.68mm screen opening. Basing with the total mass of the board, 840g, the weight proportions are:
Table 1: Fiber-reinforced cement board ratio. Portland cement
Kapok Fiber
Sand
Water/cement ratio
Wt%
weight, g
Wt%
weight, g Wt%
weight, g
0.55 wt./cement
Ratio 1
40%
336g
5%
42g
55%
462g
184.8g
Ratio 2
40%
336g
7%
58.8g
53%
445.2g
184.8g
Ratio 3
40%
336g
10%
84g
50%
420g
184.8g
Ratio 4
40%
336g
15%
126g
45%
378g
184.8g
1.1Mixing Procedures The researchers will mix first the Portland cement and sand. When the mixture is thoroughly mixed, water will be slowly added. When the mixture is ready, the researchers will add the kapok fiber randomly and will be mixed. 1.2 Forming The dimension of the cement board will be 16mm x 305mm x 152mm for flexural testing based on ASTM C1185-03 and 16mm x 100mm x 100mm for water absorption testing based on ASTM C1185-99. The researchers will use an improvised molder made of G.I. (Galvanized iron) sheets.
Figure 3.2 Molder Dimensions
Figure 3.3 Kapok Fiber Cement Board 1.3 Curing The researcher will set a curing period of 7 days for Cement board and kapokreinforced cement board based on ASTM C150 standards.
2. Determination of Kapok-reinforced cement board and Commercial fiber cement board properties To determine the properties of the kapok fiber cement board and Cement board, the eresearchers will conduct (4) three types of material testing namely,compressive strength test, flexural strength test, water absorption and impact strength to determine whether the final product attain significant properties with corresponding proportion.
2.1 Water Absorption Test For the purpose of these test methods, the increase in mass of the test specimen expressed as a percentage of its dry mass after immersion in water for 48 hours. The dimension of the specimen will be 16mm x 100mm x 100mm for water absorption testing based on ASTM C1185-99. A %=[( W-D)/D] x100 Where: A%= water absorption expressed as percentage W = weight after immersion D
= weight before immersion
2.2 Impact Resistance Test The resistance of a material (as metal or ceramic ware) to fracture by a blow, expressed in terms of the amount of energy absorbed before fracture. The researcher will use the Charpy Impact Testing. Units will be in Joules.
E= WgR (cos β - cos α )
Where: W= mass of the hammer g= acceleration due to gravity R= Length of the moment arm β= angle after impact α= angle before impact
2.3 Flexural Strength Test The strength of a material in bending, expressed as the stress on the outermost fibers of a bent test specimen, at the instant of failure.
Ơf=
Where: P = load applied measured in N (newton) L = Length of the specimen from the point b = width d = thickness Ơf= Flexural strength The researchers will use Universal Testing Machine (UTM) for this kind of material testing. The unit that will be used is N/m2 (newton per square meter). The dimension of the specimen will be 16mm x 305mm x 152mm for flexural testing based on ASTM C1185-03.
2.4 Compressive Strength Test The strength of a material in compression, determines behavior of materials under crushing loads. Ơc=F/A F=force A= area of the specimen Ơc= Compressive stress
The researcher will use Universal Testing Machine (UTM) for this kind of material testing. The unit that will be used is Mpa (megapascal). The dimension of the specimen will be 16mm x 305mm x 152mm for Compressive testing based on ASTM C1185-03.
3. Analysis of Significant differences The researchers will use statistical methods of analysis. To determine the significant differences between commercial fiber cement board (HardiFlex) and cement board reinforced
with kapok fiber the researchers will use One Way ANOVA (Analysis of variance) to analyze the data. Table 2: Mechanical test results Ratio 1
Ratio 1
Ratio 2
Ratio 2
Ratio 3
Ratio 3
Ratio 4
Ratio 4
Hardifle
Hardiflex
x Trial 1 Trial 2 Trial 3
The researchers will find the value of F and compare it to Fα,u,v , where α is the level of significance, u is the degree of freedom numerator and v is the degree of freedom denominator. If F> Fα,u,v with respect to α level of significance, there is a significant difference in the mechanical properties results.
4. Verification and Selection of best proportion The researcher will verify the best proportion using Criteria Method of product selection. Table 3: Result Flexural
Ratio 1 wF1
Ratio 2 wF2
Ratio 3 wF3
Ratio 4 wF4
HardiFlex wF5
Strength Water
wW1
wW2
wW3
wW4
wW5
Absorption Impact Strength Compressive
wI1 WC1
wI2 WC2
wI3 WC3
wI4 WC4
wI5 WC5
Strength Total
∑w1
∑w2
∑w3
∑w4
∑w5
Formula: meanvalue w= highest mean
x 25.00% (Flexural, Impact, Compressive)
w= [
lowest mean x 25.00 ¿ mean value
(water)
The researchers will select the highest ∑w; the highest score in the ∑w will be the best proportion.
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