**2. Properties of non-traditional supplementary cementitious materials**

Different types of SCMs, namely, RHA, POFA, POCP and EPP from the byproducts of two agricultural industries, namely rice and palm oil were inferred. Both the physical and chemical characteristics of the binders were determined including: (i) the particle size distribution, (ii) visualization of the morphology via scanning electron microscopy (SEM) imaging and (iii) the chemical composition via X-ray fluorescence (XRF). The physical appearance of the RHA, POFA, POCP and EPP along with OPC is shown in **Figure 2**.

Both the raw POFA and POCP are generally available in the palm oil mills; the available forms of POFA or POCP depend on the boiler used in the palm oil mills. The raw materials are normally sieved and then ground to 30,000 cycles in Los Angeles (LA) abrasion machine. The process of obtaining RHA is different from that of POFA or POCP. Some rice plants do use rice husk as fuel for processing the rice and the resulting RHA is further processed as RHA as pozzolans. There are processing plants that produce RHA. The raw materials such as POFA and POCP collected from the palm oil factories are to be processed before their use due to impurities of foreign materials and unburnt palm fibers, large particle size and moisture content. It is required to remove the moisture and larger particles more than 300 μm size; thus, POFA is oven-dried at 100 5°C for 1 day and then sieved through 300 μm sieve. Finally, the sieved POFA particles are finely ground in a LA machine. Based on the requirement, the POFA particles are ground to 30, 000 to 60,000 cycles in the LA machine. To remove excessive unburnt carbon which will affect the potential pozzolanic properties, the POFA can be heated at 500°C for a certain period in a furnace. The same approach was previously employed and reported as to be effective in removing the excessive unburnt carbon in the POFA [3–6]. **Figure 3** shows the SEM image of OPC and RHA. Similarly, **Figure 4** shows the SEM image of POFA before and after grinding process.

In comparison to POFA, the processing of POCP involves a slightly different approach. The palm oil factories produce POFA or POC based on the boilers employed in the burning of palm wastes in their factories. Thus, the burnt by-products can be in the form of fine POFA or large chunks of POC. POC are very light due to porous in nature and have lower specific gravity. The POC chunks are collected from palm oil factories, and they are porous with sizes ranging from 100 to 250 mm. The collected

**Figure 2.** *Physical appearance of OPC, RHA, POFA and POCP.*

**Figure 3.** *SEM image of (a) OPC and (b) RHA.*

**Figure 4.** *SEM image of POFA (a) before and (b) after grinding.*

POC are processed through a crusher to obtain coarse or fine aggregates; the finer part of POC which as less than 2.36 mm can be used to obtain POCP by grinding the finer POC in a LA machine. The SEM picture of the POCP is shown in the **Figure 5**.

The chemical and physical properties of the POFA, POCP and RHA are given in **Tables 1** and **2**, respectively. For the comparison, the properties of OPC are also outlined. The ground RHA has very fine size particles, with approximately 98% passing through a 45 μm sieve; furthermore, the lower specific gravity of 2.30 for the RHA particles makes it lighter compared to 3.15 for ordinary Portland cement. Another aspect of pozzolanic material is their S**–**A**–**F-silica (SiO2), alumina (Al2O3) and iron oxide (Fe2O3) contents. Due to higher silica content in RHA, the SAF content was found about 92%. Based on the X-ray fluorescence (XRF) analysis, RHA falls within the requirements of pozzolanic material based on ASTM C618. On the fineness, the POFA and POCP particles were found to be coarser compared to RHA, as the

*Effect of Non-Traditional Supplementary Cementitious Materials in Concrete DOI: http://dx.doi.org/10.5772/intechopen.111900*

#### **Figure 5.** *SEM image of POCP (a) before and (b) after grinding.*


#### **Table 1.**

*Chemical properties of OPC, RHA, POFA and POCP.*


#### **Table 2.**

*Properties of OPC, RHA, POFA and POCP.*

amounts of retained particles on 45 μm sieve were found about 12% and 29%, respectively. Based on these results, both POFA and POCP confirmed the fineness requirement to be used as pozzolanic materials as per ASTM C618.

**Figures 6**–**9** illustrate the SEM image of the particle shape and surface texture of OPC, RHA, POFA and POCP. It is generally well established that the OPC particles are spherical in shape and solid. However, as noticed from the SEM images shown in **Figures 6**–**9**, the particles of RHA, POFA and POCP have some irregular and angular particles. Further, the SEM images also show the porous nature of POFA particles, and these porous particles must be considered in the mix design due to higher water absorption in these porous particles. Another significant aspect is the presence of the sharp edges in the RHA and POCP particles, and these sharp edges might hinder free movement whilst mixing and reduce the flowability of the mixes.

The particle size distribution of the binding materials is presented in **Figure 10**. It can be clearly seen from the curves that RHA and POFA have similar fineness of OPC, whilst POCP is relatively coarser than OPC. However, the fineness of these materials depends on the grinding time and process. In lab scale, there are restrictions for the

**Figure 6.** *SEM image of OPC.*

**Figure 7.** *SEM image of RHA.*
