Introduction

Consumption is increasing in the world in line with population growth, and natural resources are reducing in line with the rise in consumption. As a result of this, recycling and sustainable construction technologies have become an important topic due to an increasingly limited supply of natural resources. That large amounts of raw materials are required particularly in the construction industry, road construction, the construction of waste storage areas, and concrete manufacture makes recycling and the use of sustainable materials significant. For this purpose, utilizing industrial waste provides not only prevention of environmental pollution caused by waste, but also contribution to the national economy by using industrial waste in the construction industry. Such industrial wastes as marble dust (MD), molding sand, fly ash, blast furnace slag, phosphogypsum, glass dust and sewage sludge are are environmentally harmful but can contribute to the national economy if they are recycled. Because the development of the marble sector has led to an increase in use of this material, utilizing marble wastes has become an important agenda. MD is released into the environment in the form of aqueous sludge at the end of the cutting process. When the release of MD is uncontrolled, it damages the environment by reducing the water filtering capacity of the soil, preventing the development of vegetation, filling stream beds, and contaminating water resources. In this study, our aim was to show that MD wastes will be able to provide benefits to the economy and the environment by optimizing the processes of soil improvement and concrete production.

In earlier research on the subject, such as the study by Meyers et al. [1], cement and fly ash were used in improving the base layer of parking lots. As a result of curing, it was said that the strength of the mixture increased and that climate change had no effect on the road infrastructure. In the study by Seung and Fishman [2], a variety of aggregate wastes and fly ash were used in a soil base. As a result of these experiments, waste aggregate and fly ash were proven to increase the permeability and reduce the plasticity of these materials.

Okagbue and Onyeobi [3] examined the variation of geotechnical properties of three different red tropical soils by adding varying degrees of MD. In their study, the plasticity and strength properties of red tropical soils were improved significantly with MD usage. Miller and Azad [4] studied changes in soil stabilization from the use of cement kiln dust (CKD). They found that the plasticity and strength properties were improved by adding different percentages of CKD to soils. Cokca [5] examined the effect of adding fly ash to swelling soils in his study. He found that the plasticity, activity and swelling potential of mixtures decreased with an increase in the rate of fly ash and curing. Mishra et al. [6] indicated that marble waste might be mixed with soil used for road infrastructure and filling material.

Zorluer and Usta [7] examined whether MD might be used for improving clay. They showed that by determining the swelling percentage of samples with an odometer test that waste MD affected the swelling potential of clays; they determined that waste MD might be useful for improving the soil. Sabat et al. [8] added varying degrees of fly ash and MD to a swelling soil. They determined that the geotechnical properties of soils were improved significantly by increased amounts of fly ash-marble dust usage. Taspolat et al. [9] investigated the effects of MD used for layers of waste storage on freezing and thawing properties. In this study, MD was added to the clay layer as 5, 10 and 15 % of the total mixture. According to freezing and thawing tests, the weight losses of the soil samples were reduced and strength was increased by using 10 and 15 % MD. Ultimately, they indicated that adding 10 and 15 % MD to impermeable clay layers increased the soil strength against environmental conditions. Firat et al. [10] mixed up 5, 10, 15 and 20 % MD in two different soils, and determined that MD, which was added to the medium- and low-plasticity soils by 15 %, might be used as filler for road infrastructure.

Hossain and Mol [11], in their study, examined whether clay could be improved via changes in its engineering properties from adding volcanic ash and CKD. The strengths of the soil samples were increased due to the usage of volcanic ash and CKD. Alavez-Ramirez et al. [12] studied the stabilization of soil blocks by using lime and sugarcane bagasse ash. They carried out resistance tests on the blocks and found that an added mixture of 10 % sugar cane bagasse ash and 10 % lime gave the most effective result.

Uğurlu [13] determined that stone dust material used as a filler material improved the compressive and tensile strengths of concrete. In addition, he determined that permeability, water absorption and porosity of the concrete decreased. Tasdemir and Atahan [14] in their study stated that limestone fillers filled the pores of aggregate-mortar interface; and this might have played an important role on the permeability and durability of the concrete. Unal and Kibici [15] identified that using MD for concrete mixtures did not constitute a negative effect on the quality of concrete. Their experiment results showed that the addition of MD decreased the porosity within concrete and had the effect of increasing the unit weight of concrete test specimens. Agarwal and Gulita [16] replaced cement at different rates with such wastes as slag, silica fume and MD, in the investigation of mortars whose cement-sand ratio was 1:3 and 1:6, and observed improvements in their compressive strengths. Topcu et al. [17] used MD as a filler material for the production of self-compacting concrete, and identified improvements in fresh and hardened concrete properties with up to 200 kg/m3 usage of MD. Corineldasi et al. [18] identified that MD, which was used as a plasticizer additive in concrete produced by low water-cement ratios, improved the cohesion of the concrete.

This study was comprised of two stages, investigating the use of MD for soil improvement and for concrete production. The purpose of soil improvement is to enhance the physical and mechanical properties of soil by the addition of mineral admixtures. In our study, we investigated the changes in mechanical and physicochemical properties after adding MD to soil. At the stage of concrete production, we used MD as filler material instead of fine aggregate. The changes in the properties of hardened concrete were investigated with this method, which reduced the porosity of the concrete, thus allowing aggregates to show homogeneous distribution without macropores.

Experimental study

Materials and method

The same MD was used for both the soil experiments and concrete experiments. The MD is created from the extraction of marble in various ways or from the process of cutting marble in processing plants. MD is the small-sized marble waste and the majority consists of marble particles under 300 μm. A mixture of 80 % clay and 20 % bentonite as a reference soil was used for the soil tests. This reference soil is classified as high plasticity clay (CH) according to ASTM D2488. The cement used for the concrete tests is CEM IV 32.5-type pozzolanic cement, which is the product of the Bursa Cement Factory. The 5–15 mm (crushed stone I) and 15–25 mm (crushed stone II) crushed stone aggregates obtained from quarries in the Bilecik region and 0–4 mm crushed sand were used as the aggregate. The 1-mm undersieve MD waste was used as a mineral filler material.

Characterization techniques

The hydrometer test, consistency limits (liquid limit, plastic limit), and specific gravity tests were performed in order to determine the physical properties of the mixtures, which were replaced with 5, 10, 15 and 20 % MD, respectively. The maximum dry unit weight and optimum water content values of the mixtures were determined by a standard compaction test. Unconfined compression test specimens were prepared by penetrating the samples with 38-mm diameter tubes, which were prepared with compaction. The mechanical properties of the soil specimens were determined by the unconfined compression test. The pH level also plays an important role in the behavior of clayey soils. The pH values were determined by immersing a glass electrode pH meter into the mixture, due to the fact that mixtures contained bentonite.

In this study, MD was used in 5, 10 and 15 % replacement ratios instead of as fine aggregate for concrete production. The appropriate granulometry was determined by first performing sieve analysis on aggregates that would be used in concrete production. Then concrete production began and the density of the concrete was determined by a slump test. Unit weight, ultrasound pulse velocity and compressive strength tests were performed on the hardened concrete samples. Chemical analyses of the raw materials and soil mixtures were carried out by using an XRF unit (Spectro X-Lab 2000). Mineralogical analyses of the specimens were conducted using an X-ray diffractometer (XRD) (Rigaku, Rint 2200 with a nickel-filtered Cu Ka). The microstructural evolution of the bodies was observed by using a versatile, analytical, ultrahigh-resolution field emission scanning electron microscope (SEM), Zeiss Supra 50 VP, on gold-coated sections.

Evaluation of test results

Chemical and mineralogical analyses

The chemical interactions of the soil mixtures with different MD additive ratios were determined by XRF and XRD analysis. The XRF results of the MD and soil mixtures are given in Table 1. CaO and Fe2O3 increased; SiO2, Al2O3, Na2O and K2O decreased with the increase in MD ratio. The pH test results of the soil specimens are shown in Table 2. The pH value of the 5 % MD soil specimens was the lowest one when compared with the other soil specimens. Also, it can be seen that the pH of the soil specimens were increased with the higher MD replacement ratios above 5 %.

Table 1 XRF results of marble dust (MD) and soil mixtures
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Table 2 pH results of soil mixtures
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X-ray diffractometer analysis results are shown in Figs. 1, 2, 3, 4, 5 depending on the MD replacement ratio. As seen from Fig. 1, the reference soil mineral composition consists primarily of kaoline, quartz and halloysite. The calcite content of the soil mixtures increased with the increased MD replacement ratio (Figs. 2, 3, 4, 5). This increment is related to the chemical composition of the marble dust.

Fig. 1
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XRD analysis of reference soil

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Fig. 2
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XRD results of the 5 % soil specimens

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Fig. 3
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XRD results of the 10 % MD soil specimens

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Fig. 4
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XRD results of the 15 % MD soil specimens

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Fig. 5
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XRD results of the 20 % MD soil specimens

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Physical and mechanical analyses of soil

Physical properties of the MD and soil mixtures are given in Table 3. The plasticity index (PI) reduces with increasing MD content. It was thought that increased MD content aided the flocculation and aggregation of the clay particles. This also increased the grain size due to agglomeration of the clay particles. The grain size distribution curve of MD and reference soil, and the grain size distribution curve of MD additive mixtures are given in Figs. 6 and 7, respectively. The variation of the curve shown in Fig. 7 is due to the addition of MD to the reference soil. The optimum moisture content (OMC) and maximum dry density (MDD) values of the soil mixtures were calculated by standard compaction tests. The standard compaction test was carried out according to ASTM D698 [19]. In this study, the test specimens were prepared at the optimum water content.

Table 3 Index characteristics of MD and soils
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Fig. 6
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Grain size distribution of the MD and reference soil

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Fig. 7
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Grain size distribution of the used soil mixtures

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The unconfined compression strength of the reference sample and MD additive mixtures is given in Table 4. The test was performed on cured and uncured soil specimens. According to test results, all the MD additive mixtures showed better strength performance than the reference soil specimen. The unconfined compression strength value of 5 % MD additive soil showed a higher unconfined compression strength value than the 10 % MD additive soil. However, the unconfined compression strength value of the 15 % MD additive soil was higher than the unconfined compression strength value of the 10 % MD additive soil and lower than the unconfined compression strength value of the 5 % MD additive soil. As seen from test results, the unconfined compression strength of the uncured specimens were lower than the cured specimens.

Table 4 The unconfined compression strength test results
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Microstructural investigation of soil

Scanning electron microscope images of specimens used in soil experiments are given in Fig. 8. The magnifications of the SEM images were chosen as ×15,000 magnification. According to the SEM images, it was seen that if the MD content increased, there occurred a porous structure. As seen from Fig. 8a, the microstructure of the reference specimen had fewer pores and there were thin pore layers between the kaoline and bentonite plates. These layers, seen like a heterogeneous structure, were generated by these layers settling one on top of each other, respectively, as flat layers and mixed layers. The curled flaky structure shows bentonite clays in this microstructure. In Fig. 8b, the 5 % MD additive mixture has non-porous, continuous and bentonite layers, resulting in a structure without pores. According to Fig. 8c, the structure of the 10 % MD mixture contains less pores, and bentonite plates extending in semi-continuous plates. In Fig. 8d, the microstructure of the 15 % MD additive mixture is a more dispersed structure. As seen from Fig. 8e, the 20 % additive mixture has a structure of kaoline plates with parallel arrangement. According to the SEM images, the 5 % MD additive mixture showed a flocculated structure due to the MD content increasing the strength of the reference soil. Over this MD admixture ratio, a dispersive structure was seen on SEM images of soil mixtures with strength reduction.

Fig. 8
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SEM images of a reference soil specimen; b 5 % MD soil specimen; c 10 % MD soil specimen; d 15 % MD soil specimen; e 20 % MD soil specimen

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Physical and mechanical analyses of concrete

The grain distribution optimization of aggregates used in concrete production was made according to the results of our sieve analysis. Appropriate aggregate mixture ratios were determined by ensuring that the mixture granulometry remained between A32–B32 reference granulometry curves. The granulometry curve of the aggregate mixture used in concrete production was given in Fig. 9. Concrete tests were carried out on 15 × 15 × 15-cm cube specimens. Mixture compositions of the concretes produced for our tests are given in Table 5. The MD used in the fresh concrete mixtures was replaced by weights of sand at 5, 10 and 15 % respectively. The consistency of the fresh concrete mixtures was determined by a slump test. The water-cement ratio of the mixtures was determined in order to obtain a 10-cm constant slump value. The water requirements of the concrete mixtures were increased due to the increasing replacement ratios of MD. The use of MD led to water requirements of up to 12 % for the concrete mixture.

Fig. 9
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Granulometry of the aggregate mixture used for concrete specimens

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Table 5 Mixed proportion of concrete mixtures
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The early-age physical and mechanical properties of hardened concrete specimens are shown in Table 6. The unit weight of early-age 7-day hardened concretes increased with the use of 5 % MD. A 5 % MD additive especially increased the compressive strength and ultrasound pulse velocity values of the concrete specimens. It was seen that MD as a filler material led to a concrete with low porosity, because it filled the micropores in the concrete. The physical and mechanical properties of 28-day hardened concrete specimens are shown in Table 7. The unit weights of 5 and 10 % MD used, hardened concrete specimens were higher than the reference concrete specimen. According to the ultrasonic pulse velocity test results, the 5 % MD used concretes value was 9 % better than the reference sample. In addition, the compressive strength was determined to be 16 % better than the reference concrete specimen. However, it was noticed that using 10 % and more MD reduced the concrete's compressive strength.

Table 6 Test results of 7-day cured concrete specimens
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Table 7 Test results of 28-day cured concrete specimens
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It was determined through the XRF analyses of MD specimens that the material lacked pozzolanic properties because it had very little silica, alumina and iron phases, which are rich in CaO. It was identified that its contribution to the strength was only in terms of reducing the space between pores. Through SEM analysis, the diameter and ratio of the macropores were seen to decrease with the increase in MD additive.

Microstructural investigation of concrete

Scanning electron microscope investigations were performed on the sections taken from fracture surfaces of concrete specimens (Fig. 10). The pore structure of the concrete was examined and comparisons were made based on the ratio of MD additives. An SEM image of the reference specimen is given in Fig. 10a. According to this image, the pore distribution in the concrete was widespread. Pore diameters were determined to vary between 2.308–1.194 mm in the dimensional analysis on macropores. These pores are the size expected for a normal concrete. An SEM image of the 5 % MD additive concrete specimen is given in Fig. 10b. The highest pore diameter was determined to be 1.586 mm in the investigation carried out on the surface of the sample. An SEM image of the 10 % MD additive concrete specimen is given in Fig. 10c. The highest pore diameter was determined to vary between 124 and 332 μm in the investigation carried out on the surface of the specimen. Based on these results, the number of pores decreased in parallel with the increase in MD additive. An SEM image of the 15 % MD additive concrete sample is given in Fig. 10d. In the examination carried out on the surface of the specimen, it was noticed that the number of pores decreased and the macropores vanished. These results from the filler effect of MD showed a decreasing effect on the porosity of concrete; however, it caused decreases in compression strengths due to the increased amount of water added to mix the concrete.

Fig. 10
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SEM images of used concrete specimens with MD added, at ×90 magnification. a reference; b 5 % MD; c 10 % MD; d 15 % MD

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Conclusions

This article demonstrates the usability of marble wastes as mineral additives in soil improvement and concrete production. The following conclusions can be drawn from this study:

  • It was noticed that the 5 % MD additive soil mixture had the highest strength and gave pH results with flocculated mixtures. XRD and XRF experiments showed that CaO increased with the addition of MD.

  • According to unconfined compression test results, the strength of the 5 % MD soil mixture had the highest strength value. Consequently, it was observed that 5 % MD additive in soil gave the most effective result.

  • The unconfined compression strength of the soil specimens was increased due to prolonged curing time.

  • The use of MD as the filler material in concrete production decreased the workability of fresh concrete and increased the water requirement of the concrete mixtures. However, the use of plasticizers in concrete mixtures can reduce this detrimental effect.

  • According to the physical and mechanical concrete test results, the use of 5 % MD improved the properties of concrete due to the reduced porous structure. However, the use of higher MD ratios decreased the compressive strength of concrete specimens depending on the increased water–cement ratio of the concrete mixture.

  • It can be suggested that according to mechanical and microstructure analyses, the optimum usage of MD in soil improvement and concrete production is 5 % against fine aggregate.

  • The use of waste materials in the construction industry will help to decrease environmental pollution and economic costs. Thus, the utilization of MD in soil improvement and concrete production has the potential to be highly beneficial for sustainable construction technologies.