Compressive Resilient Modulus Research Articles

Low-dose cement stabilized large particle size graded crushed stone: Laboratory and field investigations

Compared with traditional graded crushed stone (GCS), the maximum aggregate size of large particle size GCS (LPS-GCS) is larger and the content of large-size aggregates is more, which can form an interlocking skeletal structure with a stronger bearing capacity. Nevertheless, LPS-GCS occasionally exhibits unstable performance, and one effective way to enhance LPS-GCS's mechanical and physical properties is to stabilize it with low-dose cement. In this study, four cement contents (1.5 %, 2.0 %, 2.5 %, and 3.0 %, by mass) were selected to form low-dose cement stabilized LPS-GCS (LCS-LPS-GCS) mixtures with a maximum aggregate particle size of 53 mm. Unconfined compressive strength (UCS) and compressive resilient modulus (CRM) tests were performed on LCS-LPS-GCS samples for different cement contents and curing times. Moreover, prediction models and correlations for the UCS and CRM at different curing times were established. Furthermore, a test road was used to evaluate the LCS-LPS-GCS's field compaction level and deflection. Laboratory test results indicated that while the California bearing ratio was significantly higher than that of conventional GCS, the maximum dry density of LPS-GCS designed in this study was close to that of conventional GCS. With the same cement content, LCS-LPS-GCS outperformed conventional GCS in terms of UCS and CRM. Based on the variation law of the mechanical properties, the ideal cement content should be around 2.5 %. There was a strong positive correlation between UCS and CRM scores from LCS-LPS-GCS. The UCS and CRM were appropriate to be predicted by exponential and growth functions models, respectively. The field investigations indicated that asphalt pavements reconstructed with LCS-LPS-GCS had high compaction and low deflection, resulting in better bearing capacity and durability. The results of this investigation can serve as a reference for the design and application of LCS-LPS-GCS base for long-lasting and resilient pavements.

Cement-based and alkali-activated controlled low-strength materials made from cup lump rubber for use as road materials

This research explores the use of cup lump rubber (CLR), an agricultural by-product, as a component in controlled low-strength material (CLSM) for pavement applications in road construction. Two distinct CLSM mixtures were developed: one based on cement and the other on alkali activation. The study evaluated the workability, mechanical properties, and microstructures of both CLSM formulations. Key fresh properties, including slump flow, setting time, and bleeding, were analysed to assess their impact on the self-compaction process. Mechanical characteristics such as unconfined compressive strength, resilient modulus, and wave velocities were also measured. Some CLSM mixtures, both cement-based and alkali-activated, were found to meet the requirements for soil cement bases and subbases. Notably, the resilient modulus values showed significant improvement after 28 days, with certain mixtures achieving subbase-quality gravel standards. The study concludes by recommending the use of both cement-based and alkali-activated CLSMs in pavement design, highlighting their potential to enhance the field of pavement engineering.

Compressive strength, durability, and resilient modulus of cement-treated magnetite and hematite iron ore tailings as pavement material

The extraction and processing of iron ore produce significant amounts of mine tailings, causing environmental problems that require storage in reservoirs or dams. Using these materials in construction helps minimize their adverse impacts. This study analyzed the geotechnical properties of Magnetite and Hematite iron ore tailings (MIOT, HIOT) from the Golgohar mine in Sirjan, Iran. Two IOTs were compacted using the Standard Proctor technique after being treated with 5, 7, and 9 % Portland cement. Following curing time, treated samples were tested at different stress levels for resilient modulus. Based on the results, to meet strength and durability requirements, cement-treated MIOT needs 9 % cement. Contrastingly, only 5 % of the cement for cement-treated HIOT met the criterion. The resilient moduli of untreated MIOT and HIOT materials heavily rely on the confining pressure, resulting in a minimal decrease in modulus by increasing deviatoric stress. The effect of cement on resilient modulus is more pronounced in high confining stresses than in low confining stresses in MIOT and HIOT materials. A comparison of different non-linear models showed that ‘Universal’ model is the best fit for laboratory results of cement-treated MIOT and HIOT materials, as it accounts for hardening and softening behavior.

Investigation on Cement-Stabilized Base with Recycled Aggregate and Desert Sand.

This paper mainly explores the feasibility of using desert sand (DS) and recycled aggregate in cement-stabilized bases. Recycled coarse aggregate (RCA) and DS serve as the substitutes of natural coarse and fine aggregates, respectively, in cement-stabilized bases. A four-factor and four-level orthogonal test is designed to analyze the unconfined compressive strength, splitting tensile strength, and compressive resilient modulus. Furthermore, this paper investigates the effects of cement content, fly ash (FA) replacement rate, RCA replacement rate, and DS replacement rate on the road performance of cement-stabilized bases composed of RCA and DS. The test results reveal that the performance of cement-stabilized bases with partial RCA instead of natural coarse aggregate (NCA) and partial DS instead of natural fine aggregate satisfies the road use. The correlation and microscopic analyses of the test results imply the feasibility of applying DS and recycled aggregate to cement-stabilized bases. This paper calculates and evaluates the life cycle of carbon emissions of desert sand and recycled coarse aggregate cement-stabilized macadam (DRCSM) and finds that both DS and RCA can reduce the carbon emissions of CSM, which has a positive effect on improving the environment and solving the climate crisis. It is hoped that this paper can offer a solid theoretical foundation for promoting the application of DS and recycled aggregate in road engineering.

Mechanical properties and durability analysis of CS-CG stabilized soil: Towards sustainable subgrade soil enhancement

In this study, carbide slag (CS) and coal gangue (CG) powder were utilized to enhance the properties of the subgrade soil. CS-CG stabilized soil underwent lab experiments to assess its mechanical properties and durability. Tests included unconfined compressive strength (UCS), compressive resilient modulus (CRM), and California bearing ratio (CBR) at stabilizer dosages of 5 %, 10 %, and 15 %. Additional tests, such as dry-wet cycling, salt solution immersion, permeability, leaching, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP), were conducted specifically for the 10 % dosage. The mechanical properties and durability were comprehensively analyzed, with a microscopic investigation into pore size. Furthermore, the soil-water characteristic curve (SWCC) of CS-CG stabilized soil is derived through MIP, providing insights into its impact on the material's strength. Results showcased favorable bearing capacity and durability of CS-CG stabilized soil. The optimal mixing dosage is 10 %, with the best ratio being CS: CG= 70: 30. After 6 dry-wet cycles, UCS loss rate was 18.6 %, comparable to 4 % Portland cement (PC) stabilized soil. Dry-wet cycle characteristics surpassed PC and Lime stabilized soils. Immersion in a 5 % NaCl solution for 30 days yielded a UCS of 3.8 MPa at 28-day age, while exposure to 5 % Na2SO4 solution led to an 11.6 % strength decrease compared to NaCl. Permeability coefficient indicated low permeability akin to PC and Lime stabilized soils. Heavy metal content met standards, with minimal increase during cycles. Hydration products mainly comprised C-S-H gel, Ca(OH)2 crystals, and carbonate modification. Analysis suggested capillary and transition pores predominantly, with minimal macropores presence. Dry-wet cycles induced a marginal increase in pore size, with negligible overall impact. SWCC predicted water content (θs) ranged from 30 % to 32 %, with a slight increase in matrix suction during dry-wet cycles. CS-CG stabilized soil shows favorable mechanical properties, durability, and environmental sustainability, indicating its potential as a substitute for traditional cement and lime treatments in subgrade soil reinforcement.

Mechanical Properties and Durability of Steel Slag-mineral Powder-coal Gangue Mixture by Uniform Design for Pavement Base

To realize the utilization of industrial solid waste resources and solve the shortage problem of pavement materials, this paper uses steel slag, mineral powder, and coal gangue to prepare a mixture. A uniform test with 2 factors and 6 levels was designed. Through regression analysis, response surfaces were established to study the mechanical properties of the coal gangue mixture. The hydrated products at different ages were microscopically analyzed by XRD and SEM. The durability including freeze-thaw cycles, dry and wet cycles, and immersion expansion rate were researched. The results show that the 7d unconfined compressive strength of the mixture reaches 2.14 – 6.46 MPa, with a 180d resilience modulus of 954 – 1098 MPa, and a 180d splitting tensile strength of 0.66 – 0.83 MPa. With the increase of steel slag content, the 7d unconfined compressive strength of the mixture first decreases and then increases. The content of mineral powder is positively correlated with the 7d unconfined compressive strength. The 180d compressive resilience modulus decreases first and then increases with the increase of steel slag and mineral powder content. The 180d splitting tensile strength is positively correlated with the content of steel slag and mineral powder. The mixture is less affected by freeze-thaw cycles, with mass loss rates of only 1.77 % – 2.13 %. The mass loss rate of the admixture is 0.87 % – 0.99 % after 10 dry and wet cycles, and the strength is slightly improved. The maximum expansion rate of the mixtures immersed in water for 10d is only 0.28 %. The hydrated reaction between steel slag, mineral powder and coal gangue promotes the formation of more hydration products such as AFt, C-S-H, CaAl2(SiO4), and Ca(OH)2. The C-S-H and CaAl2(SiO4) are intertwined into a dense network to wrap Ca(OH)2, which improves the compactness of the mixture and effectively resists the freeze-thaw expansion stress. The steel slag-mineral powder-coal gangue mixture meets the requirements of relevant norms and can be well used in pavement bases.

Use of geopolymer for stabilising crushed rock base in road pavement

In recent years, the utilisation of fly ash-based geopolymer has been progressively escalating as it has proven to be a potent alternative to conventional cement. The acceptance of geopolymer is primarily credited to its ability to improve soil strength and stiffness, coupled with the advantage of reducing harmful pollution and energy usage. This study is primarily designed to investigate the mechanical performance of Geopolymer-Treated Crushed Rock Base (GTCRB), with a particular focus on uniaxial compressive strength response and the structural durability quantified by the resilient modulus and permanent deformation. This is achieved through an experimental program incorporating Unconfined Compressive Strength (UCS) and Repeated Loading Tri-axial (RLT) tests. The outcomes of the tests suggest that the use of geopolymer tends to fortify the uniaxial compressive strength and resilient modulus of the GTCRB-tested samples, indicating an overall enhancement in the mechanical properties. Of particular note, a design mix containing 6% geopolymer produced an average UCS of 1.2 MPa, aligning with the standard UCS range for cemented lightly-bound base course material, as specified by the Austroads. In terms of the resilient modulus, while treated mixtures satisfied the requirements for permanent deformation, none of the tested samples achieved the stipulated resilience modulus range.

Effect of mechanical properties and microscopic mechanism of cement-stabilized macadam under variable temperature environment with early strength agent

The early strength formation of Cement-Stabilized Macadam (CSM) base materials in cold regions is affected by environmental changes. At the same time, the curing temperature of CSM in the actual service environment did not meet the laboratory standard temperature curing environment (ST-CE). This study explores the evolution law of CSM performance and the influence of an early strength agent (ESA-I) on the early performance of CSM under variable temperature curing environment (VT-CE) in cold regions. The actual service environment for CSM curing was simulated in the laboratory, and CSM specimens with five ESA-I dosages of 0%, 5%, 10%, 15%, and 20% were prepared. The effect of ESA-I on the early properties of CSM under VT-CE was analyzed. The micro mechanism of CSM under different curing environments and ESA-I dosages was investigated based on X-ray diffraction, Fourier transform infrared spectroscopy, and Scanning electron microscope. The experimental results indicated that the early strength formation of CSM was slow in VT-CE, and the 7-day unconfined compressive strength did not meet the construction quality control indicators of CSM material under heavy traffic conditions. It was necessary to extend the curing period to meet the construction requirements. Adding ESA-I could enhance the strength, modulus, frost resistance, and fatigue performance of CSM under different curing environments. Compared with the ST-CE, the VT-CE would weaken the improvement effect of ESA-I on the performance of CSM. The recommended range for ESA-I in VT-CE was 10% −15% based on comprehensive compressive strength and resilient modulus indicators. Microscopic experiments show that under a VT-CE, the hydration rate of cement decreases, the Ettringite content in the hydration products is higher, and the microstructure is loose. Adding ESA-I improves the hydration rate of cement under VT-CE, and the microstructure contains more C-S-H hydration products.

Properties of road subbase materials manufactured with geopolymer solidified waste drilling mud

In this study, geopolymer was adopted as an eco-friendly binding material to solidify waste drilling mud to fabricate geopolymer solidified waste drilling mud (GSWDM) as a pavement material in the subbase. Using precursor dosage, Na2SiO3 solution dosage, and slag powder (SP) dosage as parameters of mix proportion, the optimal mix proportions of GSWDM were determined through compressive strength tests. Based on a series of tests of unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus, the effects of the SP percentage in the precursor and curing age on the mechanical properties of GSWDM were analyzed. The results indicated that all the mechanical properties of GSWDM were improved with the increasing SP percentage in the precursor. The 28-day unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus of GSWDM were improved by 80.8%, 56.3%, 65.3%, and 76.72%, respectively, when the SP percentage in the precursor increased from 60% to 100%. A nonlinear increase in the mechanical properties of GSWDM was observed as the curing age increased, with a significant increase in the curing age from 7 days to 14 days and a slight increase in the curing age from 14 days to 28 days. Moreover, the microstructure of GSWDM was denser as the curing age and the SP percentage in the precursor grew. The results of this study verified that GSWDM can be used as construction material for road subbase.

Effect of Public Fillers on Cement-Stabilized Recycled Mixes of Road Performance: Mechanical Properties, Microstructure, and Durability.

In order to address the challenges of resource utilization posed by construction waste, the substitution of natural aggregate (NA) with public fill (PF) contents was investigated for load reclamation and road grassroots applications. A comprehensive assessment of road performance for the recycled mixture was conducted, focusing on parameters such as unconfined compressive strength, splitting strength, compressive resilience modulus, dry shrinkage, and frost resistance. Additionally, the impact of incorporating PF at various types and replacement ratios on the microstructure of cement-stabilized aggregate (CSA) was analyzed. The results indicated that the unconfined compressive strength of cement-stabilized recycled mixture with varying PF contents meets the base strength requirements for heavy, medium, and light traffic pavement on secondary and sub-secondary roads in China. Notably, the unconfined compressive strength and resilience modulus follow a similar pattern, reaching their peak at a 25% PF content. Microscopic examination reveals that an appropriate PF content leads to the predominant formation of C(N)-A-S-H, hydrotalcite, Ca(OH)2, and CaCO3 as paste reaction products. As the replacement of public fill increases from 0% to 25%, there is a gradual stacking of gel products, which enhances the compactness of the microstructure by cementing together unreacted particles. Consequently, this process reduces dry shrinkage strain and effectively mitigates the formation of reflection cracks. Applying large quantities of public fill to road construction can effectively deal with various waste accumulation problems and produce a novel road material with significant social, economic, and environmental benefits.

Use of industrial wastes for stabilizing expansive clays in pavement applications: durability and microlevel investigation

Expansive clays feature high compressibility and large swelling-shrinkage potential, which may cause significant damage to the infrastructures, including pavements. This study investigates the potential use of industrial waste ash generated from municipal solid waste incineration (MSWI) as a more sustainable treatment method to treat expansive soils compared to the use of conventional coal fly ash. A series of tests was conducted to study the mechanical, durability, and environmental performance of the MSWI fly ash in comparison with the coal fly ash. The study reveals that the compressive strength and resilient modulus of 20% MSWI fly ash treated sample increased to 0.86 MPa and 213 MPa respectively, depicting an increase of 150% and 240% of the control clay specimen. Results also indicate that MSWI treated expansive clay shows better performance during the soaked California bearing ratio (CBR) testings, moisture susceptibility and cyclic wetting–drying tests compared to coal fly ash treated samples. Microlevel investigations reveal that the influence of cation exchange is more decisive in the MSWI-treated clays due to the presence of higher Ca2+ ions, during the early stages, and the influence of hydration is stronger at the later stage of stabilisation. X-ray diffraction (XRD) results show that gismondine, albite, calcite, portlandite, andradite, and ettringite are the main crystalline phases formed during the stabilization. Heavy metal concentrations after the stabilisation are within the allowable limit defined by state regulations. Applying MSWI fly ash as a ground treatment for expansive clays can reduce the consumption of natural resources, promoting a “zero landfill” policy.

Study of Road Performance and Curing Mechanism of Coal Gangue by Curing Agent

Abstract Coal gangue is a type of rock waste product with dark gray color during coal mining and washing. The curing agent stabilizes soils by improving their physico-mechanical properties, allowing the soils to be reused in engineering as the subgrade fill. This study investigates the impact of SAHP curing agent on road performance parameters of coal gangue. The results showed that the road performance parameters of coal gangue increase with the curing agent content. The compressive resilience modulus of 7 days and California bearing ratio of coal gangue with 0.2% curing agent meet the specifications. The scanning electron microscope reveals the presence of agglomerated gels and hexagonal prism crystals between coal gangue particles. The observed crystals are ettringite, and the gels are silicate gel (nSiO2·mH2O) formed by the reaction of Na2O·nSiO2 with CO2 and H2O, as determined by combined X-ray diffraction and energy spectrum analysis. The improved coal gangue by the curing agent can be utilized as subgrade fill, supporting the reuse of coal gangue in highway engineering.

Strength and microscopic pore structure characterization of cement-fly ash stabilized organic soil under freeze-thaw cycles

In seasonal frost areas, an organic soil stratum is often encountered during engineering construction due to the widespread existence of organic soils. The soil stratum will experience frost heave in winter and thaw settlement in summer, resulting in a significant variation in its engineering behaviour, especially for organic soil stratum. In this study, with the help of cement, fly ash, and fulvic acid, cement-fly ash stabilized organic soil (CFOS) specimens were prepared and the unconfined compressive (UC) and mercury intrusion porosimetry (MIP) tests were carried out on CFOS specimens. The effects of fly ash content, number of freeze-thaw cycles (FT-N), and curing period on the strength, resilient modulus, and porosity were investigated. Test results revealed that the fly ash content increased from 0% to the optimum content of 5%, the unconfined compressive strength (UCS) and resilient modulus of CFOS with FT-12 increased by 50.30% and 118.92%, respectively. The pore size distribution (PSD) curve and fractal dimension (Dn) of specimens were obtained from the MIP test. The proportion of macropores was the main factor affecting the UCS of CFOS. With the increasing FT-N, the macropore proportion of CFOS with 5% fly ash content increased by 333.33%, and the UCS decreased by 28.25%. Based on a freeze-thaw damage model, the damage parameters of the CFOS specimens were extracted with the Dn as an independent variable. The microscopic pore characteristics and the relationship between the strength, Dn and damage parameter were analyzed. The microscopic pore structure of specimens with different fly ash contents experienced a change subjected to freeze-thaw cycles. The lower the strength, the lower the Dn of CFOS. The damage parameters quantitatively reflected the damage degree of specimens after freeze-thaw cycles on the micro scale. The damage parameter of CFOS with 5% fly ash content increased by 341.57% with the increase of FT-N. The introduction of fly ash was able to reduce freeze-thaw damage to the specimens. The damage parameter and CFOS strength exhibited a significant correlation. The relationships of the strength and microscopic pore structure of CFOS subjected to freeze-thaw cycles were conducive to a better understanding of the freeze-thaw damage mechanism of CFOS on the micro scale. These findings are beneficial for engineering construction design in seasonal frost areas.

Performance Study on Laterite Road Base Stabilised with Emulsions Incorporating Biochar

This study explores the utilisation of biochar as an innovative and sustainable additive to emulsions for stabilising laterite road base material in pavements, with the environmental benefit of sequestering atmospheric carbon and stable form storing. A diverse range of design mixtures for the treated road base material with the proposed biochar–emulsion binder was developed for experimental validation and subsequent steps encompassed an array of laboratory tests to scrutinise the engineering attributes of the mixtures. The tests were selected to assess various properties such as unconfined compressive strength, tensile strength, resilient modulus, flexural modulus, fatigue life, and deformation characteristics. To gain practical insights from real-world conditions, two field trials were also conducted to evaluate the performance of the stabilised road base. The findings revealed that a design mix incorporating 5% biochar and 6% emulsion delivered an average unconfined compressive strength (UCS) of 1.5 MPa, which adheres to the standard UCS range for cemented lightly bound base course material. The optimal ratio of biochar to emulsion was identified as 1:1.6, which delivered a higher resilient modulus value than did the minimum stipulated by the literature for average daily traffic in the first year of design. As the temperature rose, the stabilised laterite base exhibited a reduction in its flexural modulus; however, it demonstrated minimal susceptibility to fluctuations in frequency. The deformation observed in the wheel-tracking tests for mixtures of the optimum biochar-to-emulsion ratio was less than 1 mm, which is remarkably lower than the maximum requirement outlined in the literature (i.e., 15 mm). Furthermore, visual inspection post-testing detected minimal cracking. These findings indicate that the integration of biochar and emulsion in the construction of road pavements is a promising technique that could contribute to carbon sequestration and climate change mitigation without sacrificing pavement performance. The successful field trials provided further evidence of the feasibility of this novel technique.

Thermoactivated cement from construction and demolition waste for pavement base stabilization: A case study in Brazil.

Construction and demolition waste (CDW) worldwide generation accounts 10 billion tonnes yearly. The major fraction is landfilled requiring innovative recycling methods to reduce the associated environmental impacts and to increase its circularity. Our study demonstrated the feasibility of using different CDW fines to develop recycled cements and optimized the content of CDW recycled cements with well-graded crushed stone (WGCS) for use as pavement base layer. We scaled up the study obtaining CDW cement and aggregates from a local recycling plant, as well as pilot pavement sections designed, constructed and field deflections measured. As results, the CDW cement pastes exhibited accumulated heat values of up to 111 J g-1 and achieved a compressive strength of approximately 16 MPa. The unconfined compressive strength and resilient modulus (RM) achieved using CDW cement and WGCS were 2-3 and >3000 MPa, respectively. The sections constructed using CDW cement exhibited intermediate behaviour compared to those obtained using reference materials (6% Portland cement-WGCS and a conventional granular base made using WGCS). The deflection decreased over time owing to the pozzolanic reaction.

Mechanics and road performance of mudstone modified stabilized gravel subgrade in arid desert areas

This study investigates the feasibility of using mudstone to enhance poorly graded gravel in certain arid regions of the S21 Altay-Urumqi Highway project in Xinjiang. Despite mudstone typically being considered a poor-quality rock, its combination with higher-performance materials like cement, lime, and fly ash can stabilize expansive soils for use as roadbed fill. In the experiments, 30% and 40% mudstone were added to the gravel mixture. The experiments were compared with unmodified K80 and 35% crushed rock mixes. The findings reveal that adding 30% mudstone substantially increased the California Bearing Ratio (CBR) of the gravel mix by over 20%. However, excessive mudstone inclusion could weaken load-bearing capacity. Moreover, mudstone-modified specimens exhibited superior unconfined compressive strength (UCS), splitting strength, compressive resilience modulus (CRM), drying shrinkage resistance, and temperature shrinkage resistance. Under optimum cement dosage, the UCS of mudstone-modified specimens outperformed unmodified specimens, consistently surpassing fly ash-altered groups. Although mixed fly ash initially exhibited lower strength, it gradually approached cement-stabilized strength with an extended curing time. Incorporating crushed stone into the grading curve significantly increased splitting strength due to its high strength and hardness. In contrast, adding mudstone introduced a notable proportion of fine aggregates, resulting in a looser grading skeleton prone to early cracking. This research demonstrates that mudstone enhancement significantly improves roadbed performance, including increased CBR, splitting strength, and crack resistance. The use of mudstone in arid desert areas enhances overall performance while reducing shrinkage coefficients. The suggested approach for semi-rigid pavements in arid deserts recommends specific mineral proportions, various aggregate sizes, an appropriate amount of cement, and 30% mudstone to create dense structures with a higher quantity of coarse aggregate.

Chemical, mineralogical, microstructural and engineering properties of tropical soils stabilised with the combined and individual use of different types of steel slag

The combined use of electric arc furnace slag fines (EAFSF) and ladle furnace slag fines (LFSF) for soil stabilisation was not evaluated in previous works. Previous studies reported limited information on the microscale behaviour of steel slag materials used in soil stabilisation. This work evaluated synergistic effects provided by the combination of EAFSF and LFSF on the stabilisation of clayey and sandy soils. It provided a detailed microscale analysis of raw materials and slag-soil mixes with scanning electron microscopy, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, thermogravimetric analysis, and derivative thermogravimetry. Their compaction behaviour, unconfined compressive strength (UCS), CBR index, swelling, and resilient modulus were also determined. Filler effects, cementitious, pozzolanic, and ion-exchange reactions were discussed. A positive synergistic behaviour was observed when combining 10% LFSF and 5% EAFSF (by soil weight), which provided a structural arrangement that provided increases in UCS and CBR up to 651% and 1500%, respectively

Experimental Study on the Mechanical Properties and Permeability of Cement-Stabilized Permeable Recycle Aggregate Materials

This paper designed cement-stabilized permeable road subgrade materials. Construction demolition waste with recycled aggregate replaced natural aggregate in cement-stabilized materials to utilize recycled resources for construction solid waste. This paper tests the compressive strength, water permeability, bending strength, and compressive resilience modulus of cement-stabilized permeable recycled aggregate materials under different cementitious additive ratios. The results show that at a recycled aggregate proportion of 30% in cement-stabilized permeable recycled aggregate material, the 7-d unconfined compressive strength exceeds 3.5 MPa, and the permeability coefficient surpasses 3.5 mm/s, which can meet the roadbed requirements in China. The incorporation of recycled aggregates significantly reduces the mechanical properties and water permeability of cement-stabilized permeable recycled aggregate materials, while cementitious additives improve the mechanical properties. Specifically, red brick, old concrete, and ceramics in recycled aggregates weaken the mechanical properties of the skeleton structure of cement-stabilized permeable recycled aggregate materials, and the compressive strength, bending strength, and compressive resilience modulus decrease with the recycled aggregate content. Cementitious additives can fill the micro-pores of the interface transition zone of cement-stabilized permeable recycled aggregate materials to improve the cementation strength between aggregates.

Using case study on the performance of rural cement stabilizing construction waste recycling road base

In order to solve the problem of resource utilization of construction waste (C&W) recycled aggregate (RA) in rural road grassroots, natural aggregate (NA) was replaced by RA with 0%, 20%, 40%, 60%, 80% and 100% in the test. The unconfined compressive strength, splitting strength, compressive resilience modulus, dry shrinkage test, and frost resistance test were used to test the road performance of the recycled mixture. In order to improve the strength and crack resistance of cement stabilized regenerated mixture, three different admixtures (polypropylene fiber, expansion agent, and curing agent) were considered based on the orthogonal test to improve the crack resistance of the regenerated mixture, and their influence weights were analyzed. Relying on the Gaobeidian rural road network reconstruction project, the construction waste recycling test road was laid, and the construction quality of compaction, bending, and flatness was tested. The results show that the strength of cement-stabilized recycled mixture peaks when RA content is 20%. When RA content is 0% to 100%, the compressive strength decreases by 22.6%, compressive resilience modulus decreases by 18.7%, and tensile strength decreases by 33.2%. Adding 0.8‰ polypropylene fiber, 0.4% expansion agent, and 1.5% curing agent increased 21.2% 7d unconfined compressive strength, 7.8% in 7d splitting strength, and 43.2% in 14d drying shrinkage coefficient. The construction test results show that adding fiber and low-content construction waste increases the base load capacity, increases the compressive strength by 34.5%, reduces the base deflection by 10.5%, and has good road performance. Finally, considering the test results comprehensively, when the RA content is below 20%, and the polypropylene fiber content is between 0.6‰ and 0.8‰, it can meet the basic construction requirements of secondary and sub-secondary rural regeneration roads in China.

Cement-stabilized large-sized steel slag base course based on vibration compaction method: Mechanical properties, shrinkage properties, and numerical simulation

The excellent mechanical properties and wear resistance of steel slag contribute to the properties of road engineering materials. The hot-stuffing aged slag was chosen as raw material for this study. Cement-stabilized large-sized steel slag (CSLS) mixtures containing different structural types, cement contents, and curing time were prepared by vibration compaction method. Afterward, the properties of CSLS mixtures such as unconfined compressive strength (UCS), indirect tensile strength (ITS), compressive resilience modulus (CRM), dry shrinkage and temperature shrinkage were investigated. Ultimately, the Mises stress and deflection value of CSLS road structure with different construction methods and construction seasons were explored by ABAQUS.