Influence of Waste Marble Dust on the Improvement of Expansive Clay Soils

The marble process industry from Shaq Al-Thouban region, which is located in East Cairo, Egypt, produces a huge amount of marble wastes every day during the cutting and processing stages. Up to now, most of these wastes are dumping on open land which creates serious environmental problems. The amount of waste marble from the processing stage is about 20 to 25% of the total processed stone. Egypt also suﬀers from the problem of expansive soil that occupies a large area of its lands, especially in the new cities that are built on these lands. The primary purpose of this study is to use this waste material in the soil stabilization in point of view utilization of this waste as local low-cost materials and elimination of their negative environmental impacts. The waste marble dust was mixed with expansive soil samples with various percentages of 5%, 10%, 15%, 20%, and 25% by dry weight of soil. Diﬀerent tests including Atterberg’s limits, standard Proctor compaction, unconﬁned compressive strength (UCS), California bearing ratio (CBR), swelling percentage, linear shrinkage (LS) tests, and XRF and XRD analyses were conducted for natural and marble dust stabilized soils. The soil mixtures used for UCS, CBR, and swell tests were compacted at the optimum moisture content (OMC) and maximum dry density (MDD) using the standard Proctor compaction method and cured for 7 days. The results of the tests showed that there are signiﬁcant eﬀects in enhancing the properties of expansive soils. Also, the results showed that as the percentage of the marble dust increases the plasticity index, the swelling potential of the expansive clayey soil decreases. Furthermore, the optimum moisture content decreases, and the maximum dry density increases. Also, UCS, CBR, and the calcite content of the soil mixtures increase with the increase in marble dust content.


Introduction
Expansive soils are those that have major volume changes accompanied by changes in water contents. It swells when water is added and shrinks when it is evaporated. e swelling behavior is due to the presence of highly reactive clay minerals such as montmorillonite and smectite. ese changes, swelling and shrinkage, in soil volume can cause light structures built on this soil to move unequally and crack. Problems of expansive soil have appeared as cracking and break-up of light building foundations, pavements, roadways, slab-on-grade members, channel linings, irrigation systems, gas pipelines, water pipelines, and sewer lines. e previous research estimated the cost of damage because powder, pyroclastic dust, limestone dust, granite dust, and mine tailings). Leaving the waste materials to the environment directly can cause environmental harm. Hence, recycling waste materials into sustainable civil engineering applications is of universal importance, as new ways to keep the natural resources and reducing the amount of waste materials being sent to landfills are sought globally. Recycling waste has become a research topic to eliminate its negative effects on the environment and its contribution to the economy. Also, recycling of waste keeps this material from being dumped into landfills and consuming landfill space. Many countries are functioning on the way to recycle and reuse solid wastes in applied science applications, like the assembly of concrete mix and therefore the manufacture of bricks, decorative plastic coating, ceramic tiles, cement, activated carbonate, lime, hollow blocks, wall tiles, and filler materials for embankments [3][4][5][6][7]. Stabilization using solid wastes is one of the different techniques to improve the engineering properties of problematic soils to make them suitable for construction [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Expansive soils occupy large areas of Egyptian lands, and due to the large population increase, the Egyptian government was forced to establish new cities on these lands. Major engineering problems have appeared in the constructions built on it. So, it was necessary to focus on finding suitable methods to improve the properties of this soil using the local waste material. Nature has gifted Egypt with huge deposits of high-quality marble and granite. Egypt produces over 50 different types of marble and granite with an annual production of about 3.5 million tons. So, it ranks as the fifth producer and the seventh exporter of marble and granite in the world. Quarries and factories for marble and granite are found in different places in Egypt as shown in Figure 1 [25].
Shaq El-ouban region in Katameyya is considered the largest industrial gathering in Egypt for processing marble and granite. It has the maximum concentration of marble and granite factories in Egypt reaching around 400 factories. is area was occupied by quarry workers quarrying the limestone within the hills and mountains of Katameyya at the beginning. Along time, interested investors in this area were granted about 10,000 m 2 for the value of $12 per m 2 to build their stone factories. Quarrymen who began to add the limestone hills switched their stone factories to figure in marble and granite which proved more profitable. In Shaq Al-ouban, a major quantity of stone slurry is generated from the processing of stones. Generally, it is forbidden to discharge this slurry in the public sanitary system because of its highly alkaline nature. So, the slurry is stored in basins and the settled sludge is collected and disposed of near the factories. After drying, the collected powder heaps become airborne, causing air pollution and water contamination, in addition to increasing soil alkalinity and reducing its richness and plant productivity. e high pH of the dry slurry makes it harmful to the lungs and eyes [26]. e marble stones industry is one of the greatest promising business areas of the mining sector in Egypt. is industry is increasing gradually due to the increasingly greater demand for the Egyptian stones, whether on the local or the international scale which led to a progressive production rate more than ever before. is waste can be classified into two groups that are mining or quarrying waste and processing waste. About 50% of the mined marble becomes waste during the process of mining to finishing marble. Usually, these wastes are found in the form of boulders, grits, fines, and slurry. e amount of wastes from the cutting and sawing process can easily reach 20 to 25% of the total volume of the block. ese wastes need a large area of land to be disposed of [4].
In recent years, some efforts have been undertaken to consider the possibilities of reusing marble and granite powders for soil stabilization. e marble dust powder has a huge amount of lime content and had been suggested by numerous researchers for expansive soil improvement. Several studies [27][28][29][30][31][32][33][34][35][36] examined the enhancement of expansive soils by the addition of marble dust in different percentages. ey showed the advantageous uses of marble dust alone or in combination with chemicals and waste stabilizers such as lime, cement, and fly ash to improve the various properties of expansive soils. Additionally, the coarser particles and the major shear strength due to the high internal friction of marble dust are useful for improving the workability, plasticity, and strength of expansive soil.
Singh and Yadav [37] have examined the effect of marble dust added with various percentages from 0% to 10% by weight of dry soil. e test results indicated a big variation in consistency limits of samples containing marble dust. e liquid limit decreased from 67.49% to 52.01%. e plasticity index decreased from 37.16% to 10.43%. Also, the differential free swell decreased from 60% to 14%, showing a considerable decrease in swelling behavior. Sabat and Nanda [38] studied the effect of marble powder with rice husk ash on expansive soil. e results indicated that by the addition of marble powder and rice husk to the soil, the California bearing ratio and unconfined compression strength values increase. Saygılı [39] indicated that marble dust addition enhances the shear strength parameters and reduced the swell potential of the expansive soil. Moreover, marble dust had a noticeable role in the hydration process because of its high calcium content. Also, marble dust addition to the clay  samples will decrease the cost of constructing structures on problematic soils and finding new utilization areas for waste marble dust which will diminish the environmental pollution. Besides, using waste marble dust in problematic soils will have a great role in the economy and keeping the resources. Sivrikaya et al. [40] studied the effect of calcite marble powder (CMP) and dolomitic marble powder (DMP) on the geotechnical properties of cohesive soils. Atterberg limits, linear shrinkage, expansion index, and one-dimensional consolidation tests were executed on untreated and treated samples with 5, 10, 20, 30, and 50% of waste CMP and DMP. e laboratory test results indicated that the waste marble powders were effective in soil stabilization by reducing the plasticity index from 49 to 26% and from 21 to 9% for the high-plasticity clay (CH) and the high-plasticity silt (MH) samples, respectively, and also, expansion index from 45 to 20 and from 32 to 7 for CH and MH samples, respectively, swelling index from 0.0030 to 0.0012 and from 0.013 to 0.010 for CH and MH samples, respectively, compression index from 0.013 to 0.010 and from 16.2 to 10.5 for CH and MH samples, respectively, and linear shrinkage from 16.2 to 10.5% for the CH sample. Jain et al. [41] investigated the influence of marble dust for improving the geotechnical behavior of expansive soil. Comprehensive geotechnical tests (consistency limits, free swell index, compaction characteristics, one-dimensional consolidation tests, and unconfined compressive strength) have been carried out using a wide range of marble dust contents up to 80% to adjust the content of marble dust for soil stabilization and to understand its interactive behavior with soil. e main results indicated that marble dust can be utilized effectively to enhance soil plasticity and to control the swell behavior. e results showed that marble dust accelerates the strength of soil at early curing periods and that the optimum improvement in the strength behavior of the soil is gained with a marble dust content of 20%. Also, it is concluded that the production of a cheap and more strong soil layer by using these wastes can help the civil engineer to ensure the economy in the infrastructure project and address environmental degradation.
From the literature review, it has been observed that limited studies have been carried out using marble dust in the improvement of expansive soil properties although there is a large amount from this material and large areas have expansive soils in the world. is study highlights the practicality of using local marble waste dust and mixing it with expansive soil to achieve the economy and preserve the environment. To achieve this objective, a laboratory study was carried out to examine the impacts of local marble waste dust on the improvement of expansive soil properties. e behavior of this expansive soil amended with marble dust is inspected in terms of Atterberg's limits, standard Proctor compaction, unconfined compressive strength, California bearing ratio, swelling percentage, linear shrinkage tests, and chemical and mineralogical analysis by X-ray fluorescence (XRF) and X-ray diffractometer (XRD) at different percentages of marble dust.

Materials
e materials used in this study are expansive soil and marble dust.

Expansive Soil.
e expansive soil (ECS) sample was collected from the village El-Salheya, Qena city, Egypt (latitude 26°08′18″N and longitude 32°49′10″E). e soil sample was collected at 1.5 m depth from the ground level. e disturbed soil was excavated, kept in polythene bags, and transported to the laboratory for experiments. e average geotechnical properties of the soil are shown in Table 1. Based on the liquid limit and the plasticity index, and according to Holtz and Gibbs [42], Chen [43], and IS 1498 [44], the soil can be classified as medium expansive. e particle size distribution for untreated expansive soil is shown in Figure 2.

Marble Dust.
e used marble dust (MD) was taken from the "Shaq Al-ouban" region which is located in south Cairo, Egypt, as a by-product from the cutting and the processing industry. Figure 3 shows the different shapes of MD resulted from the stone factories in the Shaq Alouban region. e specific gravity of the marble dust was found to be 2.76. e marble dust was prepared by drying in an oven for 24 hours at the temperature of 105°C to remove moisture and then pulverized repeatedly using a plastic hammer before being used to remove any agglomeration from powder. Particle size distribution analysis showed that the used marble dust consists of 12% clay, 35% silt, and 53% sand. e particle size distribution for marble dust is shown in Figure 2. e chemical components of the expansive soil and marble dust were analyzed according to XRF tests. Table 2 shows that the expansive soil has silicon dioxide as the major component with minor contents of Al 2 O 3 and Fe 2 O 3 , indicating its siliceous nature. On the other hand, MD consists mainly of calcium oxide with minor contents of SiO 2 , indicating its carbonate nature. By using X-ray diffraction, it is shown that the soil consists of quartz and montmorillonite as a major mineral constitute, while the main components of marble powder are calcite minerals as shown in Figure 4.

Testing Methods
Marble dust was mixed with the expansive soil by different proportions (5%, 10%, 15%, 20%, and 25%) by the dry weight of the soil. To achieve the objectives of this study, a series of laboratory tests were conducted on untreated (UECS) and treated expansive soil (TECS) by performing the sieve analysis, in accordance with ASTM D6913, 2017, Atterberg's limits, in accordance with ASTM D4318-10e1, 2010, compaction characteristics (maximum dry density and optimum moisture content), in accordance with ASTM D698, 2003, unconfined compressive strength (UCS), in accordance with ASTM D2166, 2003, California bearing ratio (CBR), in accordance with ASTM D 1883, one-dimensional swell tests, in accordance with ASTM D4546, Advances in Civil Engineering 3 2003, and linear shrinkage (LS), in accordance with BS 1377-2:90, 1990. Samples for different tests were remolded at their maximum dry density and optimum moisture content. Moreover, a chemical and mineralogical analysis was performed to investigate the reaction products of the stabilized soil.

Effect of MD on Atterberg's Limits.
To illustrate the effect of MD content on the plasticity characteristics of ECS, values of Atterberg's limits (liquid limit (LL), plastic limit (PL), and plasticity index (PI)) were determined. e test results for UECS and TECS are presented in Figure 5. It can be seen that the addition of MD has a significant effect on Atterberg's limits of the expansive soil. Liquid limit, plastic limit, and plasticity index decrease with the increase of MD percentages. e liquid limit decreases from 42.12% to 29.5%, the plastic limit decreases from 25% to 18.8%, and the plasticity index decreases from 17.12% to 10.7% with increasing the adding marble dust from 0% to 25%, respectively. Also, it is obvious that the rate of decrease for Atterberg's limits is more until reaching the adding percentage from MD to 15%; after that, the rate is small. A significant reduction in liquid limit indicates the expected reduction in the degree of the potential expansiveness of the TECS. is is attributed to the nonplastic nature of the marble dust particles. is result complies with the results of previous studies [17,20,30,40,41]. A regression model has been established to predict Atterberg's limits of the expansive soil stabilized with different percentages of MD. e models are where LL T and LL U are the liquid limit of treated and untreated expansive soil (%), respectively, PL T and PL U are the plastic limits of treated and treated expansive soil (%), respectively, PI T and PI U are the plasticity index of treated and untreated expansive soil (%), respectively, MD is the percentage of marble dust (%), and R 2 is the coefficient of determination. Figure 6 shows the positions of the virgin expansive soil and MD stabilized expansive soil in the plasticity chart. It is clear that, with the increase of MD percentage, the soil changes from CI (inorganic clay of medium plasticity) to CL (inorganic clay of low plasticity) as per the unified soil classification system. is has happened due to the replacement of fine-grained particles of expansive soil with coarse-grained particles of MD. Also, the expansive soil changes from medium to low expansive.
is result is compatible with that of a study performed by [40].

Effect of MD on the Compaction Characteristics.
Standard compaction tests were carried out on UECS and TECS. e results of these tests are shown in Figure 7. It can be noticed that the addition of MD led to shifting the compaction curves to the left and above the compaction curve of UECS. Figure 8 shows the variation of maximum dry density (MDD) with the percentage of MD. It can be seen that with the increase in the percentage of MD, the MDD of soil goes on increasing. e MDD increases from 18.42 kN/m 3 to 20.2 kN/m 3 when MD is increased from 0 to 25%. e reason behind the increase of MDD is due to the occupation of the void spaces of waste marble dust by the clay soil particles and the cementitious effect of CaO present in the MD and also the replacement of MD particles having high specific gravity with soil particles having a low specific gravity of mixes. Further, the significant improvement in the particle size distribution of ECS (i.e., predominated with clay-sized particles) with the addition of MD (i.e., predominated with sand-sized particles) results in improving the resistance against compaction effort and thereby increases in MDD [41]. However, Okagbue and Onyeobi [45] concluded that         Advances in Civil Engineering where MDD T and MDD U are the maximum dry density of treated and untreated expansive soil (kN/m 3 ), respectively. Figure 9 shows the variation optimum moisture content (OMC) with the percentage of MD. It was found that, with the increase in the percentage of MD, the OMC of soil goes on decreasing. e OMC decreases from 13.1% to 11.2% when MD is increased from 0 to 25%, respectively. e reason for such behavior is due to the replacement of soil particles (fine particles) with MD particles (coarser particles) and thus increases the coarser particles in the mix, leading to the decrease of total surface activity and therefore lesser water-adsorptive capacity. A regression model has been established to predict the OMC of the expansive soil stabilized with different percentages of MD. e model is where OMC T and OMC U are the optimum moisture content of treated and untreated expansive soil (%), respectively.
It can be summarized that the compaction characteristics of ECS are influenced expressively by the addition of MD. Similar behaviors of compaction characteristics have been described by several previous researchers for ECS amended with MD [20,27,32,40,41].

Effect of MD on Unconfined Compressive Strength.
e unconfined compressive tests were carried out on an untreated expansive soil specimen and five treated expansive soil specimens mixed with the various percentages of MD at their MDD and OMC for 7 days of curing time. is curing time was selected due to previous research showing that increasing the curing time to more than 7 days does not have a significant effect in increasing TECS strength [31,41]. e results of tests in the form of unconfined compressive strength versus strain are presented in Figure 10. From this figure, it can be seen that with an increase in the percentage of MD, the UCS of soil goes on increasing. e UCS increases from 417 kPa to 600 kPa when MD is increased up to 25%; i.e., the UCS value of TECS is 1.44 times as compared to UECS. On the other hand, failure strain indicates a decreasing trend with the increment of MD content. is is evidence of higher stiffness. e increase in the strength of MD stabilized expansive soil may be attributed to the improvement in the gradation, and the increase in the compactness of the soil matrix is due to the decrease in porosity and the enhancement in the interparticle bonding between the soil and MD. In addition, the pore-filling effect of fine powder. As already discussed, this powder is an inert addition and could be assumed as ultrafine aggregates filling voids. Figure 11 displays the relation between the UCS and the adding percentages of MD to the expansive soil. It can be seen that there is a linear trend of increase in the value of the UCS as the MD increases for all treated samples under the 7 curing periods. Also, the rate of increase is more up to 20% MD; after that, the rate is low. Similar improvement in UCS of expansive soil stabilized with MD was reported by Jalal et al. [32], where an experimental study was performed using different percentages (0%, 2%, 4%, 6%, 8%, and 10%) from marble industry waste (MIW) to stabilize expansive soil. e results indicated that MIW is an efficacious additive for enhancing the unconfined compressive strength of tested clay soils, and the optimum MIW content can be observed as 10%. ey attributed this to soil-lime reaction, and an increase of 300% and 154% in the unconfined strength is recorded at 3 days and 7 days, respectively. On the other hand, Jain et al. [41] investigated the effect of MD on stabilization of expansive soils using a wide range of MD contents 0%, 5%, 10%, 15%, 20%, 25%, 40%, 60%, and 80%. e results revealed that the strength of the soil increases continuously with an increase in MD content up to 20%, regardless of the curing period. A further increase in the MD Advances in Civil Engineering 7 content leads to lower strength of the soil. However, it is interesting to note that the strength of the soil is constantly enhanced with an increase in the curing period at any MD content. Hence, a marble dust content of 20% can be considered as the optimum MD content from the viewpoint of strength in terms of amending the soil. Choksi et al. [46] conducted expansive soil stabilization utilizing waste marble powder in dosages of 10%, 20%, 30%, 40%, 45%, and 50% by weight of soil. e results revealed that there is a significant increase in UCS with an increase of the dosage of MD, and this increase reaches the maximum at 45% of MD, and after that, it decreases. It can be concluded from the results of this study and the results obtained from previous studies that UCS of expansive soil generally increases with the increase of adding MD. However, the optimum content of MD differs from one study to another, and these variations can be attributed to the different components of expansive soil and the MD from one place to another. A regression model has been established to predict the UCS of the expansive soil stabilized with different percentages of MD. e model is where UCS T and UCS U are the unconfined compressive strength of treated and untreated expansive soil (kPa), respectively.

Effect of MD on California Bearing Ratio (CBR)
. e soaked CBR tests were performed on UECS and TECS with different percentages of MD at maximum dry density and optimum moisture content for 7 days of curing time. e results of the tests are presented in Figure 12. From this figure, it can be seen that, with increasing the content of MD, the soaked CBR of soil goes on increasing. e soaked CBR increases from 6.19% to 12.9% when MD is increased up to 25%. ere is a 108% increase in soaked CBR of soil at this percentage of MD as compared with untreated soil. e improvement can be attributed to filling voids between expansive soil grains by MD and also improvement in gradation and thereby an increase in MDD of soil; consequently, CBR values were increased. Based on these results, it can be concluded that the expansive soil treated with MD performs better as a subgrade material, which requires a lower thickness of the base course compared with the untreated expansive soil. is behavior is generally compatible with previous studies [17,27,32,41]. A regression model has been established to predict the CBR of the expansive soil stabilized with different percentages of MD. e model is where CBR T and CBR U are the California bearing ratio of treated and untreated expansive soil (%), respectively.

Effect of MD on Swelling Potential.
One-dimensional swell percentage versus time graphs were obtained from one-dimensional swell tests on an untreated expansive soil specimen and five treated expansive soil specimens mixed with the various percentages of MD at their MDD and OMC for 7 days of curing time. e seating load specified by the standard is 6.9 kPa. e swell percentages with respect to the logarithm of time plots are depicted in Figure 13. It can be observed that the tested specimens swelled for 1440 minutes and then became constant. Also, there is a significant effect on the decrease of the axial swelling ratio of treated expansive soil with increasing MD percentages. When the soil reaches its maximum heave, the final heave was measured, and swelling potential (S%) was calculated according to the following equation:  Advances in Civil Engineering where H p is the maximum height of the soil specimen at the end of the primary swell and H o is the initial height of the soil specimen. Figure 14 depicts the variations of swilling potential with percentages of adding MD to the expansive soil up to 25%. It can be seen clearly that as the percentage of MD increases, the swilling potential gradually decreases.
is happened due to the replacement of the swelling particles of the soil with the nonswelling particles of MD that works as an inert material. e ratios of decrease were reported as 11.17%, 31.67%, 66.67%, 76.67%, and 91% with adding MD by 5%, 10%, 15%, 20%, and 25%, respectively.
is observation agrees well with previous studies on the efficacy of marble dust utilization in reducing the swelling potential of expansive soil [17,20,31,33,34,36,47]. A regression model has been established to predict the swelling potential of the expansive soil stabilized with different percentages of MD. e model is S T (%) � −0.2354MD + SU, where S T and S U are the swelling potential of treated and untreated expansive soil (%), respectively.

Effect of MD on Linear Shrinkage. Linear shrinkage (LS)
tests were carried out to determine the one-dimensional shrinkage of stabilized expansive soils in terms of MD content. e test trough was filled with a stabilized soil specimen at the liquid limit. e trough with wet material was placed in a drying oven and dried at a temperature of 110 ± 5°C for about 24 h until all shrinkage stopped. e length of the dry soil samples was measured with digital calipers, and the values of linear shrinkage were determined for the stabilized ECS samples. e results of the tests are presented in Figure 15. From this figure, it can be seen that the LS decreases drastically with increasing MD contents, where the linear shrinkage of the stabilized ECS samples was found to be decreased from 10.7% for UECS to 4.9% for TECS with 25% MD. Also, the linear shrinkage of the stabilized ECS samples was found to be decreased by 4.39%, 20.37%, 35.79%, 45.79%, and 54.21% with adding MD by 5%, 10%, 15%, 20%, and 25% to expansive soil, respectively. ese results are consistent with the previous studies [35,40] where LS T and LS U are the linear shrinkage of treated and untreated expansive soil (%), respectively.

Chemical and Mineralogical Analysis.
e chemical interaction of the expansive soil mixtures with different MD additive ratios was determined by XRF and XRD analysis for 7 days of curing. e XRF results for UECS and TECS are shown in Table 3. From these results, it is found that the clay material presents a typical composition and is constituted mainly by silica and alumina and minor contents of CaO, MgO, K 2 O, TiO 2 , SO 3 , and MnO. A significant amount of iron oxide (11.94%) is responsible for a darker coloring of the sintered samples. e loss on ignition (LOI) (8.64%) is within the usual range for expansive clay material and is associated with volatile components and organic matter. e marble dust is formed basically by calcium oxide (CaO) with minor contents of SiO 2 , Al 2 O 3 , Fe 2 O 3 , MgO, K 2 O, and SO 3 indicating its carbonate nature. e loss on ignition (LOI) is higher than the clay material (21.56%) and results from the decomposition of carbonates (calcite and dolomite). e high alkaline Earth oxide content, particularly CaO, present in the MD will act as a fluxing agent during the sintering process. Also, it is found that CaO and Fe 2 O 3 increased; SiO 2 , Al 2 O 3 , Na 2 O, and K 2 O decreased with the increase in MD ratio. Although marble dust is reported as a chemically inert material [48], the alteration in the atomic percentage of CaO, Al 2 O 3 , and SiO 2 of the soil with an increase in marble confirms the possible ionic reactions. Jain et al. [41] indicated that the reaction between the ionic elements could be the reason behind the decrement in the Si and Al in the soilmarble dust with curing periods. e Si and Al from the soil and the Ca from the marble dust react in the presence of water to form cementitious compounds, which is an important factor for enhancing the strength behavior and for reducing the swelling percentage of the soil. e XRD analyses of soil-marble dust mixes at the curing period of 7 days are compared with the mineralogical analyses of the parent materials (soil and marble dust) to examine the formation and variation in mineral peaks. As shown in Figure 16, the parent soil is predominated with montmorillonite and quartz whereas the marble dust is   Table 3. Similar behavior was also reported in the literature [7,41]. In Table 3, MD is the marble dust, MD0 is the untreated expansive soil, MD5 is the treated expansive soil with 5% MD, MD10 is the treated expansive soil with 10% MD, MD15 is the treated expansive soil with 15% MD, MD20 is the treated expansive soil with 20% MD, and MD25 is the treated expansive soil with 25% MD.

Conclusions
e following conclusions can be drawn from the experimental results on the stabilization of expansive soil with marble dust: (1) From the point of view of waste management, environmental conservation, and the economy, it is recommended that MD be used for stabilization of expansive soil with a substantial save in the cost of construction.
(2) Substantial decreases in Atterberg's limit, LL, PL, and PI were observed. e liquid limit decreases from 42.12% to 29.5%, the plastic limit decreases from 25% to 18.8%, and the plasticity index decreases from 17.12% to 10.7% with increasing the amount of MD up to 25%. e rate of decrease is more up to 15%, and after that, the rate of decrease is low. (3) e classification of expansive soil changes from medium expansive soil to low expansive soil when stabilized with 25% MD. (4) e maximum dry density (MDD) and optimum moisture content (OMC) of expansive soil increase and decrease with increasing percentages of MD, respectively. MDD increases from 18.72 kN/m 3 to 20.2 kN/m 3 and the corresponding OMC decreases from 13.1% to 11.2% with increasing the amount of MD up to 25%, and these variations are linear. (5) e UCS increases from 417 kN/m 2 to 600 kN/m 2 , i.e., improved by 47.48% at the addition of 25% MD to the expansive soil for 7 days of curing periods. Also, the rate of increase is more up to 20% MD; after that, the rate is low. On the other hand, failure strain indicates a decreasing trend with the increment of MD content. (6) e soaked CBR of expansive soil goes on increasing with an increase in the percentage of addition of MD. e soaked CBR increases from 6.19% to 12.9% when MD is increased up to 25%. ere is a 108% increase in soaked CBR value as compared to untreated soil when 25% MD was added. is increment is related to the chemical composition of the marble dust, indicating the formation of a compacted soil matrix, and thereby, resulting in an optimum increase in the strength and a decrease in the swelling percentage.

Data Availability
e data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest
e authors declare that they have no conflicts of interest.