Study on Stabilization Mechanism of Silt by Using a Multi-Source Solid Waste Soil Stabilizer

Volumes of accumulated solid waste materials of sewage sludge (SS) and municipal solid waste (MSW) in Qatar continue to increase annually with a potentially negative impact on the environment. This paper presents an innovative technology for the production of green cement and advanced construction products from SS and MSW. Chemical composition analyses of the solid waste materials indicated the presence of main oxides available in Portland cement, but at lower contents. The three solid waste materials were incinerated and ground to produce consistent powder materials of similar sizes to Portland cement. The physical and chemical characteristics of the solid waste materials were investigated and compared to that of Portland cement. Paste and mortar mixtures were prepared by replacing 25, 50, and 75% of Portland cement with the different solid waste materials. Solid waste materials were found to influence the fresh properties of concrete, mainly water demand and setting time. Increasing the content of solid waste materials resulted in reduced compressive strength at all tested ages. SS gave the best performance within the solid waste materials investigated. Recommendations are made on the effective use of solid waste materials in various construction applications.

To improve the strength of red sandstone roadbed and elevate the utilization rate of solid waste materials, this study explored the enhancement of red sandstone using three types of solid waste materials: slag‐micronized powder, fly ash, and waste incineration bottom ash. The mechanical properties of various solid waste materials, including compaction, unconfined compressive strength, and disintegration test results, were evaluated to assess the enhancement of red sandstone. Additionally, scanning electron microscopy was employed to analyze the microstructural alterations induced by these materials. The results indicated that the optimal moisture content of fly ash‐improved soil and slag micropowder‐improved soil gradually increased, whereas the maximum dry density decreased with an increase in the solid waste material admixture. At an 11% dosage of waste incineration bottom ash, the maximum unconfined compressive strength reached 2,386 kPa. The soil–water characteristic curves for the different solid waste materials exhibited a similar overall trend. Notably, the disintegration rate significantly slowed at a 9% dosage of fly ash, whereas at 11% dosage of waste incineration bottom ash, the disintegration rate nearly reached 0%, demonstrating optimal improvement effects. This suggested that the bottom ash effectively enhanced the water stability performance of red sandstone and increased its resistance to disintegration. Microscopic analysis revealed that slag micropowder and fly ash were comparatively less effective in enhancing red sandstone. The waste incineration bottom ash efficiently generated substantial cementitious material to fill pores. In summary, employing 11% waste incineration bottom ash was recommended to enhance red sandstone in practical roadbed improvement projects.

Characterization and mechanism study of sulfate saline soil solidification in seasonal frozen regions using ternary solid waste-cement synergy

Systematic assessment of a multi–solid waste cementitious material: Feasibility and environmental impact

Stabilization of iron ore tailing with low-carbon lime/carbide slag-activated ground granulated blast-furnace slag and coal fly ash

Sulfate attack resistance of sustainable concrete incorporating various industrial solid wastes

Experimental study on barrier performance and durability under dry-wet cycles of fly ash based geopolymer cutoff wall backfill

Recent applications of waste solid materials in pavement engineering

Eco-friendly solid waste-based cementitious material containing a large amount of phosphogypsum: Performance optimization, micro-mechanisms, and environmental properties

Engineering sludge, industrial waste, and construction waste are marked by high production volumes, substantial accumulation, and significant pollution. The resource utilization of these solid wastes is low, and the co-disposal of multiple solid wastes remains unfeasible. This study aimed to develop an effective impermeable liner material for landfills, utilizing industrial slag (e.g., granulated blast furnace slag, desulfurized gypsum, fly ash) and construction waste to consolidate lake sediment. To assess the engineering performance of the liner material based on solidified lake sediment presented in landfill leachate, macro-engineering characteristic parameters (unconfined compressive strength, hydraulic conductivity) were measured using unconfined compression and flexible wall penetration tests. Simultaneously, the mineral composition, functional groups, and microscopic morphology of the solidified lake sediment were analyzed using microscopic techniques (X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy + energy dispersive spectroscopy). The corrosion mechanism of landfill leachate on the solidified sediment liner material was investigated. Additionally, the breakdown behavior of heavy metal Cr(VI) within the solidified sediment liner barrier was investigated via soil column model experiments. The dispersion coefficient was computed based on the migration data of Cr(VI). Simultaneously, the detection of Cr(VI) concentration in pore water indicated that the solidified sediment liner could effectively impede the breakdown process of Cr(VI). The dispersion coefficient of Cr(VI) in solidified sediments is 5.5 × 10−6 cm2/s–9.5 × 10−6 cm2/s, which is comparable to the dispersion coefficient of heavy metal ions in compacted clay. The unconfined compressive strength and hydraulic conductivity of the solidified sediment ranged from 4.90 to 5.93 MPa and 9.41 × 10−8 to 4.13 × 10−7 cm/s, respectively. This study proposes a novel approach for the co-disposal and resource utilization of various solid wastes, potentially providing an alternative to clay liner materials for landfills.

Experimental study on the stabilization of marine soft clay as subgrade filler using binary blending of calcium carbide residue and fly ash

Red mud (RM) is a solid waste material with high alkalinity and low cementing activity component. The low activity of RM makes it difficult to prepare high-performance cementitious materials from RM alone. Five groups of RM-based cementitious samples were prepared by adding steel slag (SS), grade 42.5 ordinary Portland cement (OPC), blast furnace slag cement (BFSC), flue gas desulfurization gypsum (FGDG), and fly ash (FA). The effects of different solid waste additives on the hydration mechanisms, mechanical properties, and environmental safety of RM-based cementitious materials were discussed and analyzed. The results showed that the samples prepared from different solid waste materials and RM formed similar hydration products, and the main products were C–S–H, tobermorite, and Ca(OH)2. The mechanical properties of the samples met the single flexural strength criterion (≥ 3.0 MPa) for first-grade pavement brick in the Industry Standard of Building Materials of the People's Republic of China-Concrete Pavement Brick. The alkali substances in the samples existed stably, and the leaching concentrations of the heavy metals reached class III of the surface water environmental quality standards. The radioactivity level was in the unrestricted range for main building materials and decorative materials. The results manifest that RM-based cementitious materials have the characteristics of environmentally friendly materials and possess the potential to partially or fully replace traditional cement in the development of engineering and construction applications and it provides innovative guidance for combined utilization of multi-solid waste materials and RM resources.

Utilization of OPC and FA to enhance reclaimed lime-fly ash macadam based geopolymers cured at ambient temperature

The problem of disposing and managing solid waste materials has become one of the major environmental, economic, and social issues. Utilization of solid wastes in the production of building materials not only solves the problem of their disposal but also helps in the conversion of wastes into useful and cost-effective products. In the present study, solid waste materials of organic and inorganic nature were applied in the production of sustainable cementitious composites (CC) and studied the effect of incorporated wastes on physical and mechanical properties of the resultant CC. The selected solid waste materials were cotton, polyester, PET, carpet, glass, and granulated blast furnace slag (GBFS). These wastes were incorporated in CC in different proportions and form the tuff tiles using moulds (12.5″ × 6″ × 2.5″). The various physical (fineness, setting time, bulk density, and water absorption capacity) and mechanical (flexural strength) properties of all the specimens were determined after curing period of 3, 7, and 28days. The results show that the incorporation of solid wastes in CC did not much affect their physical characteristics. However, the CC incorporated with the selected solid waste materials have a pronounced effect of their flexural strength and found to be higher (12-875%) compared to the plain CC. Similarly, the incorporation of the selected inorganic wastes (302-715 psi) in CC exhibit much higher flexural strength compared to the organic wastes (136-235 psi). The maximum flexural strength was observed when GBFS was utilized as a solid waste. The present work will provide a reliable step for the solid waste management and conversion of such wastes into useful commercial products for concrete manufacturing.

In order to simulate and study the mechanism of cement stabilized soils polluted by different contents of magnesium sulfate (MS), a series of tests were conducted on the cemented soil samples, including unconfined compression strength (UCS) tests of blocks, X-ray diffraction (XRD) phase analysis of powder samples, microstructure by scanning electronic microscopy (SEM), element composition by energy dispersive spectrometry (EDS), and pore distribution analysis by Image Processed Plus 6.0 (IPP 6.0) software. The UCS test results show that UCS of cemented soils reaches the peak value when the MS content is 4.5 g/kg. While, the UCS for Sample MS4 having the MS content of 18.0 g/kg is the lowest among all tested samples. Based on the EDS analysis results, Sample MS4 has the greater contents for the three elements, oxygen (O), magnesium (Mg) and sulfur (S), than Sample MS1. From the XRD phase analysis, C-A-S-H (3CaO·Al2O3·3CaSO4·32H2O and 3CaO·Al2O3·CaSO4·18H2O), M-A-H (MgO·Al2O3·H2O), M-S-H (MgO·SiO2·H2O), Mg(OH)2 and CaSO4 phase diffraction peaks are obviously intense due to the chemical action associated with the MS. The pore distribution analysis shows that the hydrated products change the distribution of cemented soil pores and the pores with average diameter (AD) of 2–50 μm play a key role in terms of the whole structure of cemented soil. The microscopic structure of the cemented soil with MS exhibits the intertwined and embedded characteristics between the cement and granular soils from the SEM images of cemented soils. The microstructure analysis shows that the magnesium sulfate acts as the additive, which is beneficial to the soil strength when the MS content is low (i.e., Sample MS2). However, higher MS amount involving a chemical action makes samples crystallize and expand, which is adverse to the UCS of cemented soils (i.e., Sample MS4).