**1. Introduction**

Tunisia has plenty of agricultural waste products such as Alfa fiber, *Posidonia oceanica*, wood and palm fiber. Such as these fibers with many advantages: renewable, cheaper, abundance and easy to use [1] in construction and building materials. These natural fibers are cellular solids with enormous specific surface area, high porosity and low thickness [2, 3]. Currently, various composite based on clay minerals and natural fibers are being tested as cementitious composites in a wide range of applications such as construction. Especially, silica materials have good thermal insulation properties. However, low mechanical [4] resistance. This is the reason that different procedures were created to improve physico-chemical properties of the wood fibers

with clay and cement [5–7]. These days, silica aerogels have numerous applications including thermal and / or acoustic insulation, and additionally acoustic protection, natural remediation, aviation and biomedicine [8–12].

Lately, as a result of energy consumption and inside the reason of energy-saving, recently works makes a specialty of developing building materials having alluring mechanical and thermal insulating homes. However, improving the mechanical residences induces a lack of thermal insulation overall performance. Today, area heating and cooling comprise the most significant level of general power fed on in homes [13].

The thermal performance of the building envelope is a key factor in determining the measure of the energy required for the comfort of nature. In this regard, a few examinations consider reason that energy consumption can be improved by joining thermal insulation materials in to walls and roofs. Thermal insulation can be characterized as a material that eases back that slows the heat flow in side rout side the building. For its determination, thermal conductivity is the fundamental property to look for. Currently, the research of bio based materials, of natural fiber, of organoclay were used to reinforce cement, to improve the qualities of cementitious materials, to accelerate the formation and the precipitation of hydration [14–17], works to enhance the mechanical properties of the composite and their resistance. In this sense, numerous scientists investigated clay, which belongs to the phyllosilicate family, was due to the permeable media, in exchange, it could also be mixed with many fibers considered as a material with a wide range of applications. The example of clay-based materials was selected.

In which case, there is good reason to use modified clay such as chlorite, Kaolinite and Illite, are considered as filler in the composite material [18], to enhance the properties of cement thanks to its low cost, availability and its excellent characteristics. Besides, in many studies, it was remarkable to note that the role of organoclay has gained many interests on both academic and industrial research [19] due to the excellent performance as well as the way to modify, to as clay-based composite [20].

It's important to mention that natural fibers has grown develop environmentalfriendly construction materials. These fibers are biodegradable, lighter and abundant resources for examples: sisal, Flax, Hemp, Bamboo, coir and others [21]. Despite all the advantages of natural fibers, there are some disadvantages, which have confined their applications in the cementitious composites. Initially, for natural fiber, the interfacial bond existing between the fiber and the cement matrix is relatively weak and about the degradation of fibers in a high alkaline of cement adversely affects the mechanical properties and durability of natural fiber reinforced composites [22]. Additionally, for the organoclay, one of the most problem it that increasing the amount of organoclay conducts to reduction of mechanical propreties.

In this work, concrete based composite materials prepared and reinforced with wood fiber and organoclay (OC) particles is used to improve their mechanical quality and to decrease the alkalinity of the matrix through diminishing the Ca(OH)2. Another is to upgrade microstructures qualities of the grid and to add to the bonding existing between the matrix and the wood filaments [23].

In which case, there is a valid justification to utilize the SDBS as surfactant between the platelets of clay treated with CTAB, organoclay can respond with Ca(OH)2 of the concrete hydration products and form structure additional calciumsilica-hydration (CSH) gel. The advantage of the utilization of organoclay is to improve microstructures and mechanical propreties of prepared materials. The wood fibers were characterized via Zeta potential. Fur there more, organoclay in powder

*Thermal Conductivity and Mechanical Properties of Organo-Clay-Wood Fiber in Cement… DOI: http://dx.doi.org/10.5772/intechopen.102321*

form was characterized via structure X-ray diffraction, FTIR and SEM. The organoclay prepared by treating clay with cetyl tri methyl ammonium bromide (CTAB) on the mechanical. Thermal conductivity and physical properties of wood fibers reinforced cement composites is also studied and investigated.

### **2. Materials and methods**

#### **2.1 Materials**

Wood Fiber (WF) and organo-clay (OC) modified with CTAB were used as reinforcements for the cement matrix-composites (**Figure 1a** and **b**).

The clay platelets used in this investigation is a natural Kaolinite treated with CTAB. The CTAB (Mw 336.39 g mol−1) is a quaternary alkyl ammonium salt is a cationic surfactant, soluble in water and utilized in the preparation of OC. A bout the SDBS (Mw 348.48 g mol−1) is sodium dodecyl benzene sulfonates is an anionic surfactant

utilized in the fabrication of composites.

Ordinary Portland cement (OPC NF P 15–301) was used in all mixes of the cement works of Enfidha (**Table 1**).

#### **2.2 Preparation of Organoclay**

Clay was prepared to be modified with CTAB, for 3 hours characterized by XRD and SEM in order to determine the amorphous phase of modified clay. To have organophilic clays, you should introduce 10 ml of chlohydric acid [1M]. Then this acid solution is carried in a temperature of 80°C.

And when this temperature became stable, we introduce 10−2 moles of CTAB, which we wish to ionize. After three hours of agitation at 80°C, we introduce 10 g of clay. And after three hours of cationic exchange, the clay is filtered and inserted to eliminate the inorganic cations. Finally, the phases of washes are finished and the clay is dried in the steam room at 80°C.

Many works have shown that CTAB surfactant intercalation does not only change the hydrophilic surface characteristics of the clay but also significantly increases the clay interlayer basal spacing.

**Figure 1.** *(a) Wood Fiber (b) Organoclay.*


**Table 1.**

*Chemical composition and physical properties of OPC.*

#### **2.3 Treatment of wood fibers**

To treat the surface of the fiber, the wood fibers were immersed in the aqueous solution of Sodium hydroxide (NaOH) at pH = 12 for 1 hour at 80°C. They were then washed until the pH reached about seven. Finally, the wood fibers were subsequently dried at 80°C for 24 hours. This chemical treatment was aimed at enhancing and improving the mechanical properties by ameliorating the adhesion exciting between fibers/matrix.
