domain: spi spi

text:
Jeffrey Ken

B Balangao

Karla S Vera

Israel A Caingles

Baguhin

MORPHOLOGICAL AND ENVIRONMENTAL CHARACTERIZATION OF LIME SLUDGE/FLY ASH STABILIZED SUB-BASE MATERIALS

Keywords: chemical stabilization, lime sludge, fly ash, sub-base

In chemical stabilization, cement and lime can be replaced with fly ash (FA) and lime sludge (LS) in the soil treatment. Therefore, the stabilized soil by the latter industrial by-products has to undergo morphological and environmental characterization for further assessment. In this work, morphological characterization thru scanning electron microscopy (SEM) was conducted on six subbase samples treated with FA (15 to 50% utilization) and LS (held constant at 10%). This is to validate internally the utilization of the latter materials in the stabilization process of the said samples. Further, the US EPA 1311 method or the Toxicity Characteristics Leaching Procedure was also employed on the samples to assess if they are environmentally safe to use or not as determined by the presence of heavy metals; cadmium (Cd), lead (Pb), cobalt (Co) and zinc (Zn) thru atomic absorption spectroscopy (AAS). Results revealed thru SEM that the treated samples were composed of a combination of spherically-and irregularly-shaped particles. The spherically-shaped particles are the FA particles whereas the irregularly-shaped, those of LS. However, the US EPA 1311 results showed that the treated samples passed the requirements for cadmium and lead according to TCLP standard limits. However, for Philippine standards such as those in DAO 2016-08 and DOH Administrative Order 2017-0010, all the samples did not pass especially for the lead requirement. The amounts of the LS may be varied, this time, in treating the samples instead of FA to produce a more environmentallysound subbase material when assessed thru US EPA 1311. This can be further validated too thru SEM characterization when there are more irregularly-shaped particles in the micrographs than those of fly ash particles.

INTRODUCTION

In chemical stabilization, cement, lime, asphalt, and even fly ash are required to mix with soil for stabilization purposes. Among the chemical substances mentioned, the most common in soil treatment are cement and lime [START_REF] James | Industrial wastes as auxiliary additives to cement/lime stabilization of soils[END_REF]. Over-dependence on the latter chemicals have led construction cost in soil stabilization to remain high. Therefore, there has to be a sustainable and cost-efficient method along the way. And the best option to do it is to replace the latter chemicals with potential raw materials in the soil stabilization. Cement and lime are replaced with industrial and agroindustrial waste by-products as stabilizers in the stabilization process as evident in previous studies owing to the best option. Among the by-products that are used as stabilizers are lime sludge [START_REF] Chandak | Effect of lime sludge on strength and compaction of soil[END_REF][START_REF] Coban | The use of lime sludge for soil stabilization[END_REF][START_REF] Nagaraju | An experimental study on paper mill lime sludge as stabilizing agent[END_REF][START_REF] Lorenzo | Effects of Sugar Mill Lime Sludge Treatment on the CBR and UCS of Expansive Soil in Bukidnon[END_REF][START_REF] Suthar | Bearing ratio and leachate analysis of pond ash stabilized with lime and lime sludge[END_REF][START_REF] Caingles | STRENGTH PROPERTIES OF CHEMICALLY STABILIZED ROAD SUBBASE MATERIALS WITH LIME SLUDGE AND FLY ASH[END_REF], hypo sludge [START_REF] Usha | Soil stabilization for pavement using lime and hypo sludge[END_REF][START_REF] Mahendran | Utilization of hypo sludge for the stabilization of red soils along with cement and molasses[END_REF][START_REF] Kumar | Soil stabilization by utilization of hypo sludge and lime[END_REF][START_REF] Ghouse | Study on Strength Characteristics of Hypo Sludge Stabilized Lithomarge Soil[END_REF], rice husk ash [START_REF] Basha | Stabilization of residual soil with rice husk ash and cement[END_REF][START_REF] Choobbasti | Influence of using rice husk ash in soil stabilization method with lime[END_REF][START_REF] Muntohar | Engineering properties of silty stabilized with lime and rice husk ash and reinforced with waste plastic fiber[END_REF][START_REF] Roy | Soil stabilization using rice husk ash and cement[END_REF], and fly ash [START_REF] Caingles | STRENGTH PROPERTIES OF CHEMICALLY STABILIZED ROAD SUBBASE MATERIALS WITH LIME SLUDGE AND FLY ASH[END_REF][START_REF] Dahale | Effect OF flyash and lime on stabilization of expansive soil[END_REF][START_REF] Sharma | Effect of fly ash, construction demolition waste and lime on geotechnical characteristics of a clayey soil: a comparative study[END_REF][START_REF] Unsever | Stabilization of clay soils using fly ash[END_REF][START_REF] Turan | Use of class C fly ash for stabilization of fine-grained soils[END_REF][START_REF] Simatupang | The mechanical properties of fly-ash-stabilized sands[END_REF]. With the utilization of these industrial by-products in soil treatment, the soil properties should never be compromised but rather be improved such as the bearing capacity, water permeability, or risk of liquefaction [START_REF] Zorluer | The usability of industrial wastes on soil stabilization[END_REF]. The improvement of the soil properties such as strength and durability can lead them to be completely suitable for construction as purposed [START_REF] Alhassan | Effect of Rice Husk Ash on Cement Stabilized Laterite[END_REF]. In subbases or bases, for example, improving the geotechnical properties of the pavement layers is vital for the appropriate purpose and proper function of the structures. The success of pavements also depends on the underneath layers like these bases, subbases, or subgrades [START_REF] Coban | The use of lime sludge for soil stabilization[END_REF]. Locally, fly ash generated from a coal power plant at the municipality of Villanueva, Northern Mindanao, Philippines, is currently utilized along with lime sludge to stabilize road subbases [START_REF] Caingles | STRENGTH PROPERTIES OF CHEMICALLY STABILIZED ROAD SUBBASE MATERIALS WITH LIME SLUDGE AND FLY ASH[END_REF]. It is believed to be the first of its kind work combining fly ash of the host town with lime sludge from a sugar milling plant in Bukidnon, Philippines, in chemical stabilization. Because of the continuous generation of fly ash in the plant, the host town has been utilizing it for construction purposes; as well as the neighboring towns [START_REF] Caingles | STRENGTH PROPERTIES OF CHEMICALLY STABILIZED ROAD SUBBASE MATERIALS WITH LIME SLUDGE AND FLY ASH[END_REF][START_REF] Balangao | Production of Autoclaved Aerated Concretes with Fly Ash from a Coal Power Plant in Misamis Oriental, Philippines[END_REF][START_REF] Jabile | Assessing May-June the suitability of fly ash and rice husk ash from Misamis Oriental, Philippines in producing bricks for pedestrian and light traffic applications[END_REF].

However, in the utilization, the environmental properties of these construction materials were not determined. Although the best option for reducing fly ash generation at the plant is its massive utilization for construction materials such those of other agro-industrial wastes [5-6, 8, 20, 24-27], there has to be an assessment that these materials are environmentally-safe to use or not. This is because fly ash contains heavy metals [START_REF] Xu | Status of trace element emission in a coal combustion process: a review[END_REF][START_REF] Levandowski | Chemical and petrographical characterization of feed coal, fly ash and bottom ash from the Figueira Power Plant, Paraná, Brazil[END_REF]. Hence, the US EPA 1311 method or the Toxicity Characteristics Leaching Procedure (TCLP) is applied to these construction materials with fly ash. In this work, the US EPA 1311 method was conducted to subbase samples stabilized with lime sludge and fly ash. Further, morphological characterization was also employed on the treated samples to validate the utilization of the two raw materials thru their particles as revealed by scanning electron microscopy. The combination of these raw materials was already tested as resources for the chemical stabilization of road subbase materials and has resulted in an impact on their geotechnical properties [START_REF] Caingles | STRENGTH PROPERTIES OF CHEMICALLY STABILIZED ROAD SUBBASE MATERIALS WITH LIME SLUDGE AND FLY ASH[END_REF] as in those other studies which also used resource combinations for a specific purpose [START_REF] Suthar | Bearing ratio and leachate analysis of pond ash stabilized with lime and lime sludge[END_REF][START_REF] Usha | Soil stabilization for pavement using lime and hypo sludge[END_REF][START_REF] Jabile | Assessing May-June the suitability of fly ash and rice husk ash from Misamis Oriental, Philippines in producing bricks for pedestrian and light traffic applications[END_REF][START_REF] Balangao | DESIGN AND DEVELOPMENT OF A MANUALLY-OPERATED HYDRAULIC HOT-PRESSING MACHINE FOR AGRICULTURAL WASTES-BASED PARTICLEBOARD APPLICATION[END_REF][START_REF] Jabile | UTILIZATION OF SAWDUST AND RICE HUSK FOR PARTICLE BOARD APPLICATION[END_REF][START_REF] Getes | Evaluation of the compressive strength of paver blocks with the inclusion of Mangima stone and Eggshell powder[END_REF][START_REF] Balangao | ISOTHERMAL REDUCTION SMELTING OF MIXED CHROMITE-LATERITE SAMPLES WITH COCONUT CHARCOAL AS REDUCTANT UNDER ARGON ATMOSPHERE IN A VERTICAL ELECTRIC ARC FURNACE[END_REF][START_REF] Balangao | Production of Iron-Chromium-Nickel Metal Alloys Via Reduction of Mixed Chromite Ore from Zambales and Laterite Ore from Taganito, Surigao del Norte under Argon Atmosphere[END_REF]. Therefore, it is just appropriate to also assess their morphological and environmental properties also as construction materials.

MATERIALS AND METHODS

Characterization of Raw Materials

Lime sludge was collected from a sugar milling company in Bukidnon, Philippines whereas the fly ash was sourced out from a coal power plant in Villanueva, Misamis Oriental, Philippines. They were air-dried and sieved using the no. 200. For chemical composition, raw samples were sent to Ostrea Mineral Laboratories, Inc. in Laguna, Philippines for oxide analyses. On the other hand, samples were sent to the Chemistry Analytical Research Laboratory of the Ateneo de Davao University for surface morphological and elemental May-June analyses using Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), respectively.

Preparation of Blended Samples

Some variations of blended samples are presented in Table 1 below. Type 1 Portland cement available in the market was used. This was also sieved using the no. 200 before mixing with soil, lime sludge, fly ash, and water. As stipulated in the Philippines' Department of Public Works and Highways (DPWH) Blue Book (2013), the amount of cement to be added to the soil aggregate shall be from 6 -10 mass percent of the dry soil. Therefore, the maximum amount of cement added was within 1% for the sets of the mixture. The fly ash was utilized up to 50%. For the lime sludge, the utilization was held at 10% all throughout. The raw samples were thoroughly mixed until a uniform color was observed. The prepared blended samples were tested in a separate study for compaction and California Bearing Ratio (CBR) to evaluate their capacities as sub-base materials.

Morphological Characterization of the Lime Sludge/Fly Ash Treated Subbase Samples

The Scanning Electron Microscopy (SEM) of the treated samples was conducted at the Chemistry Analytical and Research Laboratory in Ateneo de Davao University, Davao City, Philippines. The SEM was employed to view and assess the morphologies of the treated samples in 1000X and 5000X magnifications, respectively, to validate the utilization of the fly ash and lime sludge in the stabilization of road subbase materials.

Conduct of US EPA 1311 Method to Lime Sludge/Fly Ash Treated Subbase Samples

The Toxicity Characteristics Leaching Procedure (TCLP) or the US EPA 1311 method was also conducted for the treated samples. This is to assess the potential of the toxic metals to be leached when it will be finally disposed of in sanitary landfills that they should not exceed the regulatory limits cited by the Philippines' Department of Environment and Natural Resources (DENR) Administrative Order 2016-08 (DAO 2016-08) and Department of Health (DOH) Administrative Order 2017-0010 as analyzed by Atomic Absorption Spectrophotometer (AAS). The 1.5-gram samples were then dissolved with glacial acetic acid. The amount of such extraction fluid was equal to 20 times the masses of the said samples. Leaching was done for 18 hours. After leaching, the leachates were separated from the solid phases by filtering through a certain micron filter. The AAS analyses of the leachates for cadmium (Cd), cobalt (Co), zinc (Zn), and lead (Pb) were conducted at the Water Laboratory of the University of San Carlos, Cebu City, Philippines.

RESULTS AND DISCUSSION

Characteristics of Lime Sludge and Fly Ash

Both the fly ash and the lime sludge underwent oxide and SEM characterizations to validate their utilization of the sub-base samples as stabilizers. Table 2 below displays the oxide composition of the fly ash sample used in the study. It is clearly evident that fly ash is rich with mainly SiO2, Al2O3, Fe2O3, and CaO. According to ASTM C 618, the fly ash is a Class C type because the total content in wt% of the SiO2, Al2O3, and Fe2O3 is 61.61% greater than 50%. Further, the % CaO is 31.44% greater than 10%. This is in consonance with previous studies that also obtained Class C-type fly ash [START_REF] Balangao | Production of Autoclaved Aerated Concretes with Fly Ash from a Coal Power Plant in Misamis Oriental, Philippines[END_REF][START_REF] Misra | Stabilization characteristics of clays using class C fly ash[END_REF][START_REF] Nalbantoğlu | Effectiveness of class C fly ash as an expansive soil stabilizer[END_REF][START_REF] Guo | Compressive strength and microstructural characteristics of class C fly ash geopolymer[END_REF][START_REF] Li | Mechanical properties and microstructure of class C fly ash-based geopolymer paste and mortar[END_REF]. A Class C type of fly ash has both pozzolanic and cementitious properties relative to its purpose in construction. On the other hand, Table 3 presents the oxide composition of the lime sludge sample. It can be observed that the sample is rich in SiO2 and CaO, as in the previous studies [START_REF] Hart | Characterization of lime sludge for engineering applications[END_REF][START_REF] Sabat | Utilization of bagasse ash and lime sludge for the construction of flexible pavements in expansive soil areas[END_REF][START_REF] Sahu | Strength studies of Dadri fly ash modified with lime sludge-a composite material[END_REF][START_REF] Sahu | Stabilization of fly ash and lime sludge composites: Assessment of its performance as base course material[END_REF]. The oxides present in the samples actually indicate their potential utilization in construction. The surface morphologies of both fly ash and lime sludge samples in both 1000 X and 5000X magnifications are shown in Figs. 1 and2 below. It can clearly be seen that fly ash is internally composed of predominantly spherically-shaped particles [START_REF] Balangao | Production of Autoclaved Aerated Concretes with Fly Ash from a Coal Power Plant in Misamis Oriental, Philippines[END_REF][START_REF] Jabile | Assessing May-June the suitability of fly ash and rice husk ash from Misamis Oriental, Philippines in producing bricks for pedestrian and light traffic applications[END_REF][START_REF] Diamond | Particle morphologies in fly ash[END_REF][START_REF] Bada | Evaluation and treatment of coal fly ash for adsorption application[END_REF][START_REF] Khairul Nizar | Study on physical and chemical properties of fly ash from different areas in Malaysia[END_REF]. On the other hand, the lime sludge sample is consisting of irregularly-shaped particles that are clustered and/or agglomerated [START_REF] Sahu | Strength studies of Dadri fly ash modified with lime sludge-a composite material[END_REF][START_REF] Sahu | Stabilization of fly ash and lime sludge composites: Assessment of its performance as base course material[END_REF][START_REF] Sahu | The use of fly ash and lime sludge as partial replacement of cement in mortar[END_REF]. In this study, SEM analysis of the treated samples was obtained. So later, in the treated samples, the aforementioned spherically-shaped and irregularly-shaped particles of both fly ash and lime sludge, respectively, will be distinguished. Moreover, the EDS spectra of both fly ash and lime sludge samples were also obtained. The EDS would reveal elemental analyses of the two samples. This technique can determine the presence of heavy metals in the samples. There should be no heavy metals in the treated samples in order that they are environmentally safe to use as purposed. In this study, the US EPA 1311 method or the Toxicity Characteristics Leaching Procedure (TCLP) was conducted on treated samples to assess the presence of heavy metals in them. Therefore, the EDS analyses of the samples would help explain the said assessment.

May-June

The EDS spectra of the samples are shown in Figs. 3 and4. It is clearly revealed that the fly ash has traces mainly of Si, Fe, Ca, and O. This is in support of the oxides revealed in Table 2. However, the lime sludge sample has mainly the elements, Si, Ca, and O. Therefore, the said sample has mainly oxides of Si and Ca and is in correspondence to its oxide analysis revealed in Table 3. Now there are no heavy metals stipulated in the samples as in their EDS spectra. But the most reliable method for elemental analysis is the liquid method. So, the US EPA 1311 method has to be conducted to verify the presence of heavy metals which may or may not be likely to occur in the treated samples.

Surface Morphologies of Lime Sludge/Fly Ash Treated Subbase Samples

The surface morphologies of the treated samples were also obtained through Scanning Electron Microscopy (SEM). This is to validate and assess that the raw materials, fly ash, and lime sludge, were really employed as stabilizers to subbase samples in the study. Thus, as revealed in Figs. 1 and2, the treated samples should have a combination of particles that are spherically-and irregularly shaped. Fig. 6 shows SEM morphologies of 10% LS -1% OPC -20% FA treated samples in 1000X and 5000X magnifications, respectively. The sample is still composed of more predominantly spherically-shaped particles than irregularlyshaped particles as it was treated with 20% FA which is greater than that of 10% LS. In Fig. 7, the SEM morphologies in all magnifications applied show still a combination of spherically-shaped particles and irregularly-shaped particles. More spherically-shaped particles are observed than agglomerated irregularly-shaped particles. This is so because the sample was treated with 25% FA and 10% LS. Some irregularly-shaped particles can be observed on top of the bigger spheres, especially in Fig. 4.3b.

Fig. 8. Morphologies of 10% LS -1% OPC -30% FA treated sample at a) 1000 X magnification; b) 5000 X magnification

In Fig. 8, the sample was treated with 30% FA and still 10 %LS. Thus, it can still be observed that the spherically-shaped particles are more predominant than the irregularly-shaped ones. There are also spherically-shaped particles that are having with them on their surfaces these irregularly-shaped ones. In Fig. 9, it can be observed in all magnifications that the spherically-shaped particles are more prevalent than the irregularly-shaped ones. This is because, this time, the %FA utilized was increased to 40% already. It is evident also that most of the spherically-shaped particles do have in their surfaces some of these agglomerated irregularly-shaped ones. Lastly, Fig. 10 shows that both big and small sphericallyshaped particles are still more prevalent than the irregularlyshaped ones in all magnifications. This time, the sample was treated with 50% FA and still 10% LS. It can also be observed that bigger and even smaller spheres carry some irregularlyshaped particles.

Environmental Analyses of Lime Sludge/Fly Ash Treated Samples

The Toxicity Characteristics Leaching Procedure (TCLP) or the US EPA 1311 Method was conducted for the treated samples. The TCLP test was conducted to determine if the stabilized materials are environmentally safe to use by assessing the contents of the heavy metals present in the sample such that they should not exceed the standard limits. This study is limited to the analyses of cadmium (Cd), cobalt (Co), zinc (Zn), and lead (Pb) from the leachates through Atomic Absorption Spectroscopy (AAS).

According to Table 4, the contents of cadmium and lead are very much lower in all of the treated samples considering their TCLP standard limits. They basically pass the minimum requirements. However, cobalt and zinc have no standard TCLP limits. Since cadmium and lead satisfied the minimum requirements, the samples are environmentally safe to use. The presence of toxic heavy metals in any fly ash-based products can be greatly associated with the percentage of fly ash in the utilization. The higher the amount of fly ash added, the higher the possibility of having heavy metals in the final products. This is so because fly ash inherently contains toxic metals [START_REF] Levandowski | Chemical and petrographical characterization of feed coal, fly ash and bottom ash from the Figueira Power Plant, Paraná, Brazil[END_REF]. In this study, fly ash was actually incorporated with cement and lime sludge to stabilize soils. However, the addition of both cement and lime sludge basically did not prevent the heavy metals to be seen in the samples, especially for cadmium and lead as in Tables 5 and6; even though the addition supposedly would increase the oxide contents in the mixtures and thus, would immobilize the heavy metals in the stabilized system.

May-June

May-June

CONCLUSIONS

The SEM morphologies showed that the treated samples are composed of a combination of spherically-shaped and irregularly-shaped particles. The spherically-shaped particles are the fly ash particles and the irregularly-shaped pertain to the lime sludge. The SEM characterization validated the utilization of the two solid wastes, fly ash, and lime sludge. On the other hand, the US EPA 1311 test results showed that the treated samples passed the requirements for cadmium and lead according to TCLP standard limits. However, for Philippine standards stipulated in DAO 2016-08 and DOH Administrative Order 2017-0010, all these samples did not pass especially for the lead requirement. Therefore, the samples are not totally environmentally-safe to use for road subbase applications. It can be recommended to vary also the amounts of the lime sludge to the fly ash in treating the samples. And this can be further validated too thru SEM morphological characterization when there are more irregularly-shaped particles, this time, in the micrographs than those of fly ash particles. In this case, more environmentally sound subbase materials are produced especially when assessed thru US EPA 1311 method.

ACKNOWLEDGEMENT

Fig. 1 .Fig. 2 .Fig. 3 .Fig. 4 .

 1234 Fig. 1. Morphologies of the fly ash sample at a) 1000 X magnification; b) 5000 X magnification

Fig. 5 .Fig. 6 .

 56 Fig. 5. Morphologies of 10% LS -1% OPC -15% FA treated sample at a) 1000 X magnification; b) 5000 X magnification Fig.5shows the SEM morphologies of 10% LS -1% OPC -15% FA treated samples at 1000X and 5000X magnifications, respectively. In general, it can be observed that the sample is a combination of spherically-and irregularly-shaped particles. These spherically-shaped particles which are seen dominant all throughout are the fly ash particles whereas the irregularlyshaped particles that form agglomeration are the lime sludge particles. Fly ash particles are predominantly spherical[START_REF] Balangao | Production of Autoclaved Aerated Concretes with Fly Ash from a Coal Power Plant in Misamis Oriental, Philippines[END_REF][START_REF] Jabile | Assessing May-June the suitability of fly ash and rice husk ash from Misamis Oriental, Philippines in producing bricks for pedestrian and light traffic applications[END_REF][START_REF] Diamond | Particle morphologies in fly ash[END_REF][START_REF] Bada | Evaluation and treatment of coal fly ash for adsorption application[END_REF][START_REF] Khairul Nizar | Study on physical and chemical properties of fly ash from different areas in Malaysia[END_REF]. On the other hand, lime sludge particles are irregularly-shaped and show agglomerated or clustered structures[START_REF] Sahu | Strength studies of Dadri fly ash modified with lime sludge-a composite material[END_REF][START_REF] Sahu | Stabilization of fly ash and lime sludge composites: Assessment of its performance as base course material[END_REF][START_REF] Sahu | The use of fly ash and lime sludge as partial replacement of cement in mortar[END_REF]. The distribution of the spherically-

Fig. 7 .

 7 Fig. 7. Morphologies of 10% LS -1% OPC -25% FA treated sample at a) 1000 X magnification; b) 5000 X magnification

Fig. 9 .

 9 Fig. 9. Morphologies of 10% LS -1% OPC -40% FA treated sample at a) 1000 X magnification; b) 5000 X magnification

Fig. 10 .

 10 Fig. 10. Morphologies of 10% LS -1% OPC -50% FA treated sample at a) 1000 X magnification; b) 5000 X magnification

Table 1 . Some Variations of Mixtures Soil Samples Aggregate Base/Subbase Course (%OPC + %LS + %FA)

 1

	A	100% Soil	1%OPC + 10%LS + 15%FA
	B	100% Soil	1%OPC + 10%LS + 20%FA
	C	100% Soil	1%OPC + 10%LS + 25%FA
	D	100% Soil	1%OPC + 10%LS + 30%FA
	E	100% Soil	1%OPC + 10%LS + 40%FA
	F	100% Soil	1%OPC + 10%LS + 50%FA

Table 2 . Oxide Composition of Fly Ash

 2

	Oxide	Wt. %	Method
	SiO2	30.32	Gravimetric
	Al2O3	19.96	Direct Nitrous
			Oxide-Acetylene
			Flame
	Fe2O3	11.33	Direct Air-
			Acetylene Flame
	CaO	31.44	Direct Nitrous
			Oxide-Acetylene
			Flame
	MgO	0.80	Direct Air-
			Acetylene Flame
	Na2O	4.19	Direct Air-
			Acetylene Flame
	K2O	0.52	Direct Air-
			Acetylene Flame
	SO4	0.075	Gravimetric

Table 3 . Oxide Composition of the Lime Sludge

 3

	Oxide	Wt. %	Method
	SiO2	18.76	Gravimetric
	Al2O3	0.29	Direct Nitrous
			Oxide-Acetylene
			Flame
	Fe2O3	8.78	Direct Air-
			Acetylene Flame
	CaO	6.41	Direct Nitrous
			Oxide-Acetylene
			Flame
	MgO	0.31	Direct Air-
			Acetylene Flame
	Na2O	0.09	Direct Air-
			Acetylene Flame

Table 4 . Heavy Metal Concentrations in the Treated Samples as Compared to TCLP Standard Limits

 4

	Heavy Metals	TCLP		Heavy Metals in the LS/FA Treated Samples (mg/L)		Remarks
		Standard
		Limits for	Sample A:	Sample B:	Sample C:	Sample D:	Sample E:	Sample F:
		Heavy	10% LS -	10% LS -	10% LS -	10% LS -	10% LS -	10% LS -
		Metals	1% OPC -	1% OPC -	1% OPC -	1% OPC -	1% OPC -	1% OPC -
		(mg/L)	15% FA	20% FA	25% FA	30% A	40% FA	50% FA
	Cadmium (Cd)	1.00	0.02	0.02	0.02	< 0.008	< 0.008	< 0.008	Passed
	Lead (Pb)	5.00	0.67	0.70	0.51	0.93	0.94	0.89	Passed
	Cobalt (Co)	-	0.61	0.81	0.86	0.82	1.06	0.83	-
	Zinc (Zn)	-	1.03	1.53	1.16	1.44	1.76	1.58	-
	Table 5 shows heavy metals in the samples as compared to the	samples D, E & F passed for cadmium. However, for lead, all
	standard limits stipulated in the Philippines' Department of	the samples failed the assessment. Not all standard limits are
	Environment and Natural Resources (DENR) Administrative	complied with, therefore, the treated subbase samples are not
	Order 2016-08 (DAO 2016-08) for Class AA water bodies.	environmentally safe.
	According to DAO 2016-08, Class AA water is intended for
	waters having watersheds, which are uninhabited and /or
	otherwise declared as protected areas. From the table, only

Table 5 . Heavy Metal Concentrations in the Treated Samples as Compared to Philippines' DENR Administrative Order 2016-08 (DAO 2016-08) Standard Limits for Class AA Water Body

 5

	Heavy Metals	DAO 2016		Heavy Metals in the LS/FA Treated Samples (mg/L)		Remarks
		Standard
		Limits for	Sample A:	Sample B:	Sample C:	Sample D:	Sample E:	Sample F:
		Heavy	10% LS -	10% LS -	10% LS -	10% LS -	10% LS -	10% LS -
		Metals in	1% OPC -	1% OPC -	1% OPC -	1% OPC -	1% OPC -	1% OPC -
		Class AA	15% FA	20% FA		25% FA	30% FA	40% FA	50% FA
		Water
		(mg/L)
	Cadmium (Cd)	0.003	0.02	0.02		0.02	< 0.008	< 0.008	< 0.008	Passed for
										Samples D,
										E & F
	Lead (Pb)	0.01	0.67	0.70		0.51	0.93	0.94	0.89	Failed
	Cobalt (Co)	-	0.61	0.81		0.86	0.82	1.06	0.83	-
	Zinc (Zn)	2	1.03	1.53		1.16	1.44	1.76	1.58	Passed
	In Table 6, a comparison of the Philippines' Department of	did not pass for lead. Therefore, the samples did not
	Health (DOH) Administrative Order 2017-0010 standard	completely pass the standard limits.
	values for inorganic chemical parameters of drinking water is
	shown. Based on the table, only samples D, E & F passed the
	limit for cadmium. On the other hand, all of the treated samples

Table 6 . Heavy Metal Concentrations in the Treated Samples as Compared to Philippines' DOH Administrative Order 2017-0010 Standard Limits

 6

	Heavy Metals	DOH	Admin.		Heavy Metals in the LS/FA Treated Samples (mg/L)		Remarks
		Order 2017-0010
		Standard Limits	Sample A:	Sample B:	Sample C:	Sample D:	Sample E:	Sample F:
		for Heavy Metals	10% LS -	10% LS -1%	10% LS -	10% LS -	10% LS -	10% LS -
		(mg/L)		1% OPC -	OPC -20%	1% OPC -	1% OPC -	1% OPC -	1% OPC -
				15% FA	FA	25% FA	30% FA	40% FA	50% FA
	Cadmium			0.02	0.02	0.02	< 0.008	< 0.008	< 0.008	Passed for
	(Cd)	0.003							Samples D,
										E & F
	Lead (Pb)	0.01	0.67	0.70	0.51	0.93	0.94	0.89	Failed
	Cobalt (Co)	-		0.61	0.81	0.86	0.82	1.06	0.83	-
	Zinc (Zn)	-		1.03	1.53	1.16	1.44	1.76	1.58	-

The authors would like to thank the University of Science and Technology of Southern Philippines in Cagayan de Oro City, Philippines for funding this research study.