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Fig. 5. EDAX spectrums of SH-85 additive. Microstructural characterization provides useful information about the underlying mechanisms of a chemical stabilization pro- cess, including elemental composition, mineralogical changes, the

Figure 5 EDAX spectrums of SH-85 additive. Microstructural characterization provides useful information about the underlying mechanisms of a chemical stabilization pro- cess, including elemental composition, mineralogical changes, the

Related Figures (14)

Fig. 1. Particle size distribution of the tested laterite soil.
Fig. 1. Particle size distribution of the tested laterite soil.
Chemical composition of the tested laterite soil and SH-85. Table 2 2.2. Sample preparation and testing program
Chemical composition of the tested laterite soil and SH-85. Table 2 2.2. Sample preparation and testing program
' Determined using the Standard Proctor test. Characteristics of the tested laterite soil. Table 1
' Determined using the Standard Proctor test. Characteristics of the tested laterite soil. Table 1
Fig. 2. Unconfined compressive strengths for untreated and SH-85 stabilized laterite soil, for different additive contents and curing times In order to prepare homogeneous mixtures for unconfined com- pressive strength (UCS) testing, hand mixing of air dried soil, de- ionized water and SH-85 was performed using palette knives. Additive-to-soil mix ratios of 3%, 6%, 9%, 12%, and 15% SH-85 by dry weight were prepared. UCS test specimens were created by compressing a known mass of the resulting soil/additive mixture In the subsequent sections and associated figures in this manu- script, it is helpful to use abbreviations to describe the state of the
Fig. 2. Unconfined compressive strengths for untreated and SH-85 stabilized laterite soil, for different additive contents and curing times In order to prepare homogeneous mixtures for unconfined com- pressive strength (UCS) testing, hand mixing of air dried soil, de- ionized water and SH-85 was performed using palette knives. Additive-to-soil mix ratios of 3%, 6%, 9%, 12%, and 15% SH-85 by dry weight were prepared. UCS test specimens were created by compressing a known mass of the resulting soil/additive mixture In the subsequent sections and associated figures in this manu- script, it is helpful to use abbreviations to describe the state of the
Unconfined compressive strength of granitic residual soils sampled from various locations in the Malaysian Peninsula mixed with different types of stabilizers. Table 3
Unconfined compressive strength of granitic residual soils sampled from various locations in the Malaysian Peninsula mixed with different types of stabilizers. Table 3
Fig. 3. XRD intensity counts for untreated and SH-85 stabilized laterite soil at different curing times.
Fig. 3. XRD intensity counts for untreated and SH-85 stabilized laterite soil at different curing times.
Fig. 4. EDAX spectrums of untreated laterite soil. Fig. 3 provides a comparison of XRD test results for untreated and SH-85 stabilized laterite soil. The XRD results indicated that the main minerals present in the laterite soil were kaolinite (20 = 12.5°, 20°, 35°, 38°, 46°, 55°), quartz (20 = 26°, 36.5°, 42.59, 50°, 62°), goethite (20=21.5°, 37°, 41°, 53°), and gibbsite (20 = 18°, 19°, 27°, 39°) [61]. Although no fundamental changes took place in the XRD patterns of treated samples in comparison to the natural laterite soil, the intensity of the kaolinite peaks appeared to decrease slightly. One possible reason for this reduc- tion was the effect of the stabilizer on the soil matrix and the asso- ciated weathering of the kaolinite minerals. The intensity of the peaks for quartz remained relatively unchanged as a result of the stabilization process. The apparent occurrences of several new reflections can also be observed due to the formation of new prod- ucts at various 20 angles, including 29°, 34°, 47° and 51° for SH-85 treated samples. These peaks are associated with the formation of calcium aluminate hydrate (C-A-H), a cementing compound [38,61].
Fig. 4. EDAX spectrums of untreated laterite soil. Fig. 3 provides a comparison of XRD test results for untreated and SH-85 stabilized laterite soil. The XRD results indicated that the main minerals present in the laterite soil were kaolinite (20 = 12.5°, 20°, 35°, 38°, 46°, 55°), quartz (20 = 26°, 36.5°, 42.59, 50°, 62°), goethite (20=21.5°, 37°, 41°, 53°), and gibbsite (20 = 18°, 19°, 27°, 39°) [61]. Although no fundamental changes took place in the XRD patterns of treated samples in comparison to the natural laterite soil, the intensity of the kaolinite peaks appeared to decrease slightly. One possible reason for this reduc- tion was the effect of the stabilizer on the soil matrix and the asso- ciated weathering of the kaolinite minerals. The intensity of the peaks for quartz remained relatively unchanged as a result of the stabilization process. The apparent occurrences of several new reflections can also be observed due to the formation of new prod- ucts at various 20 angles, including 29°, 34°, 47° and 51° for SH-85 treated samples. These peaks are associated with the formation of calcium aluminate hydrate (C-A-H), a cementing compound [38,61].
Fig. 6. EDAX spectrums of 9% SH-85 treated laterite soil after: (a) 7 days of curing, (b) 28 days of curing, and (c) 90 days of curing In order to obtain more details regarding the surface composi- tion of treated particles, a series of EDAX analyses were performed. Figs. 4 and 5 show the EDAX spectrums for the untreated laterite soil and pure SH-85 additive, respectively. Relatively high intensi- ties of the silicon (Si), aluminum (Al), and iron (Fe) peaks were observed in the untreated laterite soil, which is consistent with its lateritic nature [64]. In addition, the presence of a high intensity peak of calcium (Ca) in the SH-85 sample confirmed its calcium- based nature. Fig. 6(a-c) shows the EDAX results for SH-85 treated samples after 7, 28 and 90 day curing periods, respectively. As shown in these figures, the peak intensities of the calcium have a significant reduction with increases in the curing time. Table 4 shows the cor- responding changes in the ratios of Al:Si and Ca:Si, for different curing times. As shown, there was an appreciable change in Al:Si ratio and the Ca:Si ratio for the SH-85 treated samples as the curing time increased from 7 to 90 days.
Fig. 6. EDAX spectrums of 9% SH-85 treated laterite soil after: (a) 7 days of curing, (b) 28 days of curing, and (c) 90 days of curing In order to obtain more details regarding the surface composi- tion of treated particles, a series of EDAX analyses were performed. Figs. 4 and 5 show the EDAX spectrums for the untreated laterite soil and pure SH-85 additive, respectively. Relatively high intensi- ties of the silicon (Si), aluminum (Al), and iron (Fe) peaks were observed in the untreated laterite soil, which is consistent with its lateritic nature [64]. In addition, the presence of a high intensity peak of calcium (Ca) in the SH-85 sample confirmed its calcium- based nature. Fig. 6(a-c) shows the EDAX results for SH-85 treated samples after 7, 28 and 90 day curing periods, respectively. As shown in these figures, the peak intensities of the calcium have a significant reduction with increases in the curing time. Table 4 shows the cor- responding changes in the ratios of Al:Si and Ca:Si, for different curing times. As shown, there was an appreciable change in Al:Si ratio and the Ca:Si ratio for the SH-85 treated samples as the curing time increased from 7 to 90 days.
EDAX analysis test results: Al:Si, and Ca:Si ratios for 9% SH-85 treated laterite soil at various curing times. The reaction that occurred between the laterite soil constituent minerals and SH-85 was hypothesized to be one of cation exchange and physical bonding. Cation exchange is expected as part of the stabilization process with SH-85, because when the SH-85 is added to a clay-water system, the divalent calcium cations are absorbed into the diffuse double layer, where they can then interact and react with the clay particles directly. The presence of Calcium ions and water allows for chemical reactions with the Aluminum on the surface of the clay particles, which can combine to form calcium aluminate hydrate products. The reduction in the Ca:Si ratio and increase in Al:Si ratio that were observed in the EDAX test results described in the previous paragraph can be attributed to this gen- eral reaction process [11,18,38,65,66]. Table 4
EDAX analysis test results: Al:Si, and Ca:Si ratios for 9% SH-85 treated laterite soil at various curing times. The reaction that occurred between the laterite soil constituent minerals and SH-85 was hypothesized to be one of cation exchange and physical bonding. Cation exchange is expected as part of the stabilization process with SH-85, because when the SH-85 is added to a clay-water system, the divalent calcium cations are absorbed into the diffuse double layer, where they can then interact and react with the clay particles directly. The presence of Calcium ions and water allows for chemical reactions with the Aluminum on the surface of the clay particles, which can combine to form calcium aluminate hydrate products. The reduction in the Ca:Si ratio and increase in Al:Si ratio that were observed in the EDAX test results described in the previous paragraph can be attributed to this gen- eral reaction process [11,18,38,65,66]. Table 4
Fig. 7. FESEM image of untreated laterite soil.
Fig. 7. FESEM image of untreated laterite soil.
Fig. 8. FESEM image of pure SH-85 additive.
Fig. 8. FESEM image of pure SH-85 additive.
FESEM image analysis was utilized in the current study to examine the morphology of the stabilized soil. Figs. 7 and 8 show the results from FESEM imaging of untreated soil and pure SH-85 additive, and Fig. 9(a—-c) show the FESEM results for treated soil after 7, 28 and 90days of curing, respectively. As shown, the untreated soil exhibited a dispersed and discontinuous structure, where the voids and porosity are generally visible because of the absence of hydration products. At the same scale, SH-85 appeared Fig. 9. FESEM images of 9% SH-85 treated laterite soil after: (a) 7 days of curing, (b) 28 days of curing, and (c) 90 days of curing.
FESEM image analysis was utilized in the current study to examine the morphology of the stabilized soil. Figs. 7 and 8 show the results from FESEM imaging of untreated soil and pure SH-85 additive, and Fig. 9(a—-c) show the FESEM results for treated soil after 7, 28 and 90days of curing, respectively. As shown, the untreated soil exhibited a dispersed and discontinuous structure, where the voids and porosity are generally visible because of the absence of hydration products. At the same scale, SH-85 appeared Fig. 9. FESEM images of 9% SH-85 treated laterite soil after: (a) 7 days of curing, (b) 28 days of curing, and (c) 90 days of curing.
Fig. 10. FTIR spectrums for untreated and SH-85 stabilized laterite soil at different curing times.
Fig. 10. FTIR spectrums for untreated and SH-85 stabilized laterite soil at different curing times.
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