**2.4 Preparation**

#### *2.4.1 Composite materials*

The (OPC) was substituted with an organoclay (0.5, 1 and 1.5%wt).

The (OPC) and organoclay were first to dry mixed for 5 min in mixer at low speed and then mixed. The samples were prepared with 0.65 mass ratios a water/ organoclay –cement.

#### *2.4.2 Curing and samples*

Three series of specimens were prepared of (3.5 × 7 × 1.75) in dimension and were cast in the mechanical tests. All specimens demolded after 24 h of casting and kept underwater for approximately 28 days. Bend test was conducted using an "MTSInsight" Material testing Machine to evaluate, compressive strength.

#### **2.5 Study of physical properties**

Porosity and density were measured and conducted to define the quality of composites. The length, thickness, width and weight are measured to determine the bulk density which was carried out by using the following Eq. (1) [20]:

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

$$\mathbf{D} = md/\mathbf{v} \tag{1}$$

Where D is the density in g/cm3 ,md is the mass of the test specimen (g) and V is the volume of the test specimen (cm3 ). The porosity Ps was calculated using the following Eq. (2).

$$Ps = (m\_s - m\_d) / (m\_s - m\_i) \tag{2}$$

mi = mass of the sample saturated in water.

ms = mass of the sample saturated in air.

#### **2.6 Characterization of composite materials**

The (OC) prepared was analyzed by X-ray diffraction (XRD) in the 2ϴ range between 20 and 80° using CuKα (γ = 1.54060 Å) radiation and was completed by Fourier transform infrared spectroscopy (FTIR) using a Perkin Elmer. The morphology of the organoclay was observed by scanning electron microscopy (SEM) (Hitachi SEM type SU8030 microscope operated at an acceleration voltage of 10 KV and a probe current of 15 pA). The thermal conductivity of different samples was measured by using a "Heat transmission Study Bench – PTC 100".

#### **2.7 Characterization of wood fibers and natural clay**

#### *2.7.1 Zeta (ξ) potential*

A ξ potential analyzer (Malven 2000) was used to measure the electrophoretic mobility of wood fibers in the aqueous suspension. Measurements were conducted on the fine fraction obtained after filtration of the original fiber suspension through a 45-μm screen. ξ-potential measurement repeated on the whole suspension using the streaming potential technique (Mute kSZP06,using a 40-μm screen as an electrode) matched ξ-potential values obtained by electrophoresis. The ξ-potential values reported are the average of four measurements.

#### *2.7.2 X-ray diffraction (XRD)*

The X-ray diffraction patterns were measured with an X-ray diffractometer using CuKα radiation at 40 KV and 30 mA.

#### *2.7.3 Fourier transform infrared spectroscopy (FTIR)*

Fourier transform infrared spectroscopy (FTIR) was used to analyze the change of functional groups at the wood fibers and the natural clay after treatment with NaOH, sulfuric acid and CTAB respectively. This test was carried out with a spectrum FTIR, Perkin Elmer. Samples were measured at room temperature and a resolution of 4 cm−1. All FTIR measurements were done in transmittance mode after baseline correction.

#### *2.7.4 Scanning electron microscopy (SEM)*

Samples of natural clay and organoclay for Scanning electron microscopy were prepared and analyzed with Scanning Electron Microscopy (Hitachi SEM type

SU8030 microscope operated at an acceleration voltage of 10 KV and a probe current of 15pA).

#### *2.7.5 Thermal conductivity*

The measurements of the thermal conductivity characterize the ability of materials to conduct heat energy. The thermal conductivity of different samples of dimensions (24.5 × 1.5 × 24.5 cm) was measured by using a "Heat Transmission Study Bench – PTC 100".
