*3.8.1 Compressive resistance*

• Effect of the Wood Fibers

The effect of WF treated by NaOH on the compressive strength of cement composite can also be seen evaluated. The compressive strength of WF reinforced cement composite is increased from 9,8 to 18.41 MPa about, 90% increases compared to treated WF reinforced cement composite. This enhancement improvement is explained as follows: To enhance the interfacial bond between fibers and the OPC, the matrix could be modified by reducing or consuming the calcium hydroxide. The low value of the compressive strength can be explained by the high sugar and hemicelluloses content of fast-growing wood. Conversely, the chemical treatment proved good mechanical properties.

• Effect of the Amount Organoclay

Effect of OC on the compressive strength of 0, 0.5, 1, and 1%wt. WFT-cement– composites of 28 days age are shown in histograms (**Figure 12**). It can be deduced that the compressive strength was increased by the addition of OC after (28 days) and the greater, the improvement. After 28 days, the compressive strength of 1%wt was 21.76 MPa higher than that of 0.5%wt of OC was 10.11 MPa. The reasons for the enhancement in mechanical properties of composites are as follows. Firstly, the physical effects of 1%wt of OC, including filling, can reduce the voids or the porosities in the cement matrix, in which the OC was uniformly dispersed in the matrix. Thus improving the microstructure of composites denser than the WFT-cement composite, Secondly, another mechanism is the pozzolanic reaction, in which OC reacts with calcium hydroxide (CH) in the cement matrix to produce calcium-silicate-hydrate (C-S-H). However, the addition of more than 1%wt of OC caused a marked decrease in compressive strength. For example, the compressive strength of 2% wt OC was 11.47 MPa. This is due to the poor dispersion and agglomeration of the OC in the cement matrix ata higher percentage of OC contents, which increase of porosity and reduce the bond strength between the fiber and the matrix adhesion. The compressive decreases in the cement-composite with a higher dosage of organo clay.

• Effect The Amount of SDBS

The effect of SDBS on compressive strength of composites with the non-treated wood fiber it shows that the addition of SDBS in cement matrix increased the compressive strength from 9.81 to 11.47 MPa, about 14.47% improvements can be

**Figure 12.** *Compressive strength as a function of organo clay content for control OPC with 6% wt.*

explained by the adhesion and the collusion of fibers in the matrix in the presence of the SDBS.

The SDBS has an essential role in the surface packaging of the fiber; it is defined as a super plasticizer that covers the surface of the fibers and render them hydrophobic. In our case, anionic surfactant is able to agglomerate during the cement to fill the existing pores in the fibers.
