Developing Suitable Proportions for the Production of Pineapple Leaf Fibers Reinforced Normal Strength Concrete

The present work tried to develop suitable proportions for the production of Pineapple Leaf Fibers (PALF) reinforced Normal Strength Concrete (NSC), an experimental analysis with a mix ratio of 1:1.84:3.27 for cement: fine aggregates: coarse aggregates with constant water to cement ratio of 0.54. The total volume per mixing batch was calculated of 9 cubes + 9 cylinders + 3 beams in order to know the number of materials to be used in casting per batch, and the PALF percentage was taken based on cement weight whereby it starts from the lowest to the maximum as follow 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1%. The tests that were done on fresh concrete were compacting factors and workability using the slump test which was carried out on each fresh mix of concrete. The results showed that PALF can be used to improve the Tensile and Flexural properties of Normal Strength Concrete.


Introduction
The construction industry is one of rapidly growing industries across the world.
In this industry, concrete plays an inherent role and is the most widely used manmade construction material. Concrete will continue to be the leading construction material all over the world due to its versatile advantageous properties impact resistance and heavy weight, hence there is a need to improve the concrete properties [3] [4]. Pineapple Leaf Fibers (PALF) are more compatible natural fiber resource and constitutes a good chemical composition [5]. PALF are a vital natural fiber, which have a high specific strength, rigidity, flexural and torsional rigidity than other fibers; seen all these advantages of PALF and since no one has developed suitable proportion of production of PALF reinforced on NSC it is time to try such fiber. Natural fibers have the advantages of low density, low cost, and biodegradability. When concrete cracks, the randomly oriented fibers start functioning, arrest crack formation and propagation, and thus improve strength and ductility. Natural fibres from pineapple leaves are a good option to study because of their high tensile strength and high cellulose content [6].
The use of PALF reinforcement in construction materials can enhance structural strength and toughness, and this can reduce cracking and shrinkage [7]. Hence this study was made to develop a suitable proportion of production of PALF on properties of NSC.

Materials and Methods
The methods adopted and followed for this study are discussed in the subsequent section. The most important test methods and standards are summarized in Table 1, The materials used in this study were coarse aggregates, fine aggregates, Ordinary Portland Cement (OPC) grade of (42.5 N) East African Standard KS EAS 18.1 was used in the study and water, all of them were collected from Kenya. The PALF materials were obtained from Hand Conifer Company Ltd, Mumbai, India. The fibres were extracted from the leaves by using a mechanical extractor machine [8]. Coarse aggregates were obtained locally and those conforming to BS EN 109-1 specification and limited to a maximum size of 25 mm

Coarse and Fine Aggregates
The fine aggregates used was river sand sieved on a 10 mm BS sieve to remove any coarse particles and the fine aggregates were ranging from 0.15 mm (150 µm) to 10 mm. The coarse aggregates used were crushed angular shaped rocks ranging from 2.36 mm to 25 mm. Table 2 shows the physical properties of both the coarse aggregates and the fine aggregates that were carried out. From these results, the conclusion was made that both aggregates satisfied the standards and therefore could be used in the production of Normal weight concrete reinforced with PALF.

Pineapple Leaf Fibers
PALF were treated in 4% of Sodium Hydroxide Before chemical properties analysis and tensile strength of PALF (NaOH) solution over various duration NaOH is one of the best treatment of natural fibers, in increasing fibers roughness by chemically modifying and cleaning the fibre surface [11] [12]. Table 4 shows the chemical properties that were determined. In this way, three containers (dishes) were put in oven dry for 10 minutes to be cool. The three samples were ready for the experiment, after that, they were weighted.

Water
Water Ordinary portable water conforming to BS 1348-2 (1980) available in the laboratory with a pH of 8.1 was used in the study for mixing and curing of concrete mixes.

Workability of Normal Strength Concrete with PALF
Determination of workability in this study was done by the slump test which was carried out in triplicate on every mix that was made and an average value obtained. Results of the slump test are presented in Figure 1 showing the average slump for each mix versus the percentage addition of PALF in the mix [14].
Considering a constant water/cement ratio of 0.54 which was used in the mix design, as seen from Figure 1, as the content of PALF was increased in the mix,

Water Absorption of Normal Strength Concrete with PALF
As portrayed in Figure 2, PALF incorporation in the concrete mix increased the water absorption of the mixes as the control had the least water absorption whereas there was a subsequent increment as the PALF were increased in the mix.   and 1% PALF additions respectively were obtained as compared to the control mix at 7 days testing, where as 1.81%, 2.47%, 3.24%, 3.87%, and 9.59% at 0.2%, 0.4%, 0.6%, 0.8% and 1% PALF additions respectively as compared to the control mix were obtained at 14 days testing, where as 1.72%, 2.37%, 3.01%, 3.82% and 5.48% percentage reductions at 0.2%, 0.4%, 0.6%, 0.8% and 1% PALF additions respectively were obtained as compared to the control mix at 28 days curing time. From these results (Figure 3) it can be seen that PALF addition had the less percentage reduction in compressive strength compared to normal strength concrete and therefore it offers better compressive strength properties as compared to other percentages of 0.8% and 1% PALF.

Compressive Strength of Normal Strength Concrete with PALF
From these results, the conclusion can be made that the addition of PALF in normal strength concrete reduces its compressive strength. This could be attributed to the adhesion properties due to the smooth texture of the PALF in the mix which reduces the bonding properties of the concrete mix and hence more compacting energy is required to achieve the desired compressive strength of the concrete. Therefore PALF cannot be used to enhance the compressive strength properties of normal weight concrete.    Figure 4 shows graphically an improvement in the splitting tensile strength as the percentage of PALF were added therefore incorporating PALF as reinforced fibers on the Normal Strength Concrete can also improve first crack strength and ultimate ductility index.

Flexural Strength Test on Normal Strength Concrete with PALF
It was also observed that the flexural properties were improved comparing to the control mix of normal strength concrete as the percentage of PALF increased there was an increment of flexural strength value with curing time of 28 days. Table 1 show that there was an improvement in the flexural values at 1% PALF. There were percentage increment of 0.98%, 3.54%, 10.84%, 15.06% and 42.58% for 0.2%, 0.4%, 0.6%, 0.8% and 1% PALF additions respectively were obtained as compared to the control mix at 28 days curing time, but it was observed as shown in Table 5 that the compaction factor was reduced as the percentage of PALF increased.

Results in
The PALF have increased the strength of the normal strength in tensile and flexure more than in compressive, this is showing that the PALF acted more in traction than in compression within the composite.

Conclusions
From this experimental investigation, the following conclusions can be made: 1) PALF have shown that they can contribute to the construction field on Normal strength Concrete, they can reduce cracks in the structure and improve the tensile and flexure properties of NSC.
2) According to the experimental work, PALF reinforced NSC have a limitation when their percentages increase more than 1% of cement weight, the Normal Strength Concrete will not be workable.
3) The best percentage to be used is from 0.2% to 0.8% because it is where the slump was in range, it was found that PALF cannot be used to enhance compressive strength and water absorption.

Recommendations
From this experimental study, the following recommendations were made: For Possible Applications: 1) PALF can be utilized in Normal Strength Concrete to improve the split tensile strength and flexural strength in the production of structural of NSC especially where crack control is a concern especially in water retaining structures.
2) Further studies: a) Investigations should be made on how to improve the bonding properties b) The study at the durability aspect of PALF reinforced Normal Strength Concrete should also be studied.