## 5 Results and Discussion  
### Capsules Survival Capability  
Figure 6 shows the pH values of the concretes where the pH level of all concrete mixes containing capsules were higher than pH 11.7, which was obtained for the control concrete, 100%OPC without capsule regardless of the mixing speed level. The result also indicates that a slight increment in pH level with the increase of mixing speed levels. Nevertheless, the pH level of all concrete mixtures was below the pH limit of fresh cement, 12.5 [45], regardless of the mixing speeds. The variation in pH level obtained by all concrete mixes could be associated with less flocculation between cement particles, which is due to the impact during the mixing between all solid components. The dispersion of cement particles allows more surface area of the cement particles to be covered with water to initiate the chemical reactivity. Another consequence is the rapid chemical reactivity leads to more hydration products precipitated on the surface of cement particles. Thus, the calcium hydroxide and the release of calcium ions in the hydration product increased the pH level of the concrete pore solution. The finding also observed a noticeable increase in the pH level for the concrete containing capsules with weak lines surface regardless of the mixing speed levels. It can be seen that the modification of the capsule surface decreased the wall thickness of the capsule, which increased its brittleness [19]. The surface modification, which combines the roughened surface with the engraved line creates points of weakness on the capsule. Thus, this could be associated with a high tendency to rupture due to the impact of aggregate upon the concrete mixing particularly at high mixing speed. Nonetheless, [PERSON] et al. [41] reported that the pH of fresh normal OPC concrete is commonly around 13 and the author also suggested that the fluctuation in the alkalinity of fresh concrete for the first hour was governed by the fast dissolution of the alkali sulphates of cement and the presence of calcium sulphate phases. Given this, the finding suggests that both modified capsule surfaces were well-mixed through the medium mixing speed. In assessing the capsule survivability, the FTIR spectrum analysis on the main chemical products, Si-O bond was measured on the concrete of 1-day age. The reason for this is that the leaking of sodium silicate may react with either calcium hydroxide or pozzolan in cementitious composites to form calcium silicate hydrate (CSH) gel to heal the concrete crack. Thus, the leakage of sodium silicate may produce a rich amount of CSH. As shown in Figure 7, the FTIR spectra of concrete with capsule for all levels of mixing speeds are almost similar. A sharp bending at 993 cm\({}^{-1}\) was observed for all concretes with all capsule surface modifications regardless of the mixing speeds. The Si-O band at 950 cm\({}^{-1}\) confirms the existence of hydration product, CSH in the concretes [46]. Nonetheless, there is a slight shift in peak and shape change to wavenumber about 1000 cm\({}^{-1}\) for concrete with weak line capsule at high mixing speed. It is noted that the bands at 900-1110 cm\({}^{-1}\) are associated with the formation of more CSH gels [14, 47, 48, 49]. Thus, the FTIR spectrum analysis findings agreed with the findings obtained by pH evaluation of concretes containing capsules. The FTIR observations provide indirect confirmation on the existence of hydration product, CSH, by the stretching bands, which corresponds to the availability of the alkalinity in concrete. Furthermore, the findings also suggest that all types of capsule surface modifications were compatible with medium concrete mixing speed. Observation on the capsules after the mixing process was conducted in the study to confirm the defect caused by the stresses during the mixing process on the capsules.