Pavement Sub-base Material Research Articles

Strength and Durability Properties of Marginal Lateritic Soil-Bagasse Ash Based Geopolymer with Cement Supplements as Pavement Subbase Materials

Strength and Durability Properties of Marginal Lateritic Soil-Bagasse Ash Based Geopolymer with Cement Supplements as Pavement Subbase Materials

Feasibility of utilizing recycled concrete aggregate blended with waste tire rubber and drywall waste as pavement subbase material

Feasibility of utilizing recycled concrete aggregate blended with waste tire rubber and drywall waste as pavement subbase material

Amelioration of flexible pavement subbases using fly ash and natural fibres

The use of fly ash as a stabilizing element has already been demonstrated to be successful. Moreover, the CBR values of fly ash do not meet IRC criteria. This study intends to analyze the addition of coir fibre, a natural and environmentally sustainable resource, as a reinforcing material. Fly ash and coconut coir are waste materials that can be locally sourced, making them cost-effective and environmentally friendly materials. The article discusses the benefits of fly ash and coconut coir in flexible pavement subbases, highlighting their potential as a sustainable solution for road construction and maintenance. The laboratory experiments conducted on fly ash subbases reinforced with various percentages of coconut coir ranging from 0.1, 0.2, and 0.3 prove that the addition of natural fibres can enhance the subbase's strength properties, with a maximum improvement observed at a 0.2% reinforcement level. Further, the cyclic plate load tests conducted on the treated fly ash subbase at optimum conditions provide valuable insights into the subbase's performance under repeated loading conditions. The results suggest that the natural fibres performed satisfactorily in improving the subbase's load-carrying capacity and reducing rebound deformations, indicating that this approach can be a viable alternative to conventional pavement subbase materials.

Life cycle assessment of lightweight cellular concrete subbase pavements in Canada

ABSTRACT The use of Lightweight Cellular Concrete (LCC) as a subbase alternative to typical flexible pavement subbase material in cold regions is gaining attention. Since a setback of using LCC is its high cement content, which is a significant source of carbon dioxide (CO2) emissions, it becomes imperative to consider this aspect when proposing LCC for pavement applications. This study evaluated the environmental impact of three densities (400, 475, and 600 kg/m³) of LCC produced with two methods (wet and dry mix) and compared to two types of unbound granular material (granular A and B) as flexible pavement subbase. The pavement performance was predicted using MEPDG and WESLEA software and compared with measured field responses as a basis for maintenance strategy. The Life Cycle Assessment (LCA) results showed that lower-density LCC pavements decreased environmental costs by reducing total life CO2 emissions by up to 16% and reducing environmental impact for Carbon monoxide, Sulphur dioxide, Nitrogen oxide, Particulate Matter (PM)2.5, PM10 and total PM compared to granular A and B pavements. As LCC density increased, more emissions occurred, showing the importance of density to emissions output. This research demonstrates the potential benefits of using LCC as an alternative subbase pavement material.

Laboratory and Field Evaluation of Stabilized Fly Ash as an Alternative Material for Sustainable Pavements

Thermal power plants in India produce a large quantity of fly ash, which is harmful to the environment. Underutilization of fly ash and the scarcity of natural minerals have created the need for an unusual construction strategy to prevent huge waste dumps on valuable land and to preserve fast-depleting resources. A study was conducted to determine the efficacy of lime-stabilized fly ash blended with quarry fines as flexible pavement subbase materials. The laboratory investigations were conducted to determine compaction characteristics, unconfined compressive strength, California bearing ratio (CBR), and durability to obtain the optimal quarry fines, fly ash, and lime (QFL) mix. The durability of QFL mixes was studied using 12 wetting–drying cycles. Using the strength and durability criteria specified by the Indian Road Congress, the optimum mix proportion of 40Q:60F+3L was determined. Pavement analyses were performed using the IITPAVE program. The QFL mix was observed to be superior to conventional granular subbase (GSB) layer material in terms of service life and cost-effectiveness. A field investigation was carried out on trial test sections constructed using the optimum QFL mix and GSB in the subbase layer of pavement. Field dry density and dynamic cone penetrometer (DCP) tests were performed on the compacted subgrade and subbase layers to assess the desired quality assurance in the construction of test sections. The early structural performance assessment of pavement sections using a falling weight deflectometer (FWD) test indicated that QFL could effectively replace conventional GSB.

Stabilization/Solidification of Petroleum Oil-Contaminated Soil using Different Stabilizers to Deliver a Pavement Subbase Material

Stabilization/Solidification of Petroleum Oil-Contaminated Soil using Different Stabilizers to Deliver a Pavement Subbase Material

Recycling phosphogypsum in subbase of pavement: Treatment, testing, and application

This study aims to recycle the phosphogypsum (PG) as pavement subbase material. First, the physical and chemical properties of the PG before and after calcination treatment were characterized. Then the mix design, as well as the performance evaluation of the PG mixture, were detailed. Finally, the engineering application and economic analysis of the PG mixture for paving subbase pavement were presented. It is found that incorporation of the calcined PG (CPG) can help form gel structure to stabilize the PG. Meanwhile, addition of lime can neutralize the water-soluble phosphorus contained in the PG to improve the early strength of the CPG-stabilized PG. The optimal mix proportion of the CPG-lime stabilized PG by mass is determined as PG: CPG: lime = 89: 9: 2. In addition, as compared to the PG stabilized with the traditional inorganic binder materials, the CPG-lime stabilized PG has higher unconfined compressive strength (UCS) and better resistance to the water damage and fatigue damage caused by the water content variation. The field cores extracted from the paved CPG-lime stabilized PG subbase were experimentally observed to have a 7 d UCS as high as 3.69 MPa. Moreover, reuse of the CPG-lime stabilized PG is proven to be a highly economic and environment-friendly pathway for subbase paving, of which total cost per unit cube meter is 504.5 % lower than that of the commonly-used lime-fly ash stabilized soil. These findings identify the feasibility of utilizing the PG for pavement subbase construction.

Construction and demolition waste as raw material in pavements layers

The proper management of demolition construction waste from the construction industry is an issue that has gained relevance over the last years in several research centers around the world and, in this context, researches on the potential of using construction and demolition waste to execute pavement layers have been stood out. The paper presented results of a research performed to evaluate the characteristics of the material produced by a waste treatment/beneficiation industrial plant. Tests to verify the suitability of the material as pavement subbase material were performed according Brazilian code - grain-size distribution composition, maximum characteristic dimension, shape particle index (SPI), contaminant percentage and sieving process. The results obtained indicated that the recycled aggregates investigated performed well in all the requirements of the reference standards used and only one correction, related to grain size distribution, was performed using a sieving process. It is important to highlight that the tests and analyses must be performed constantly when forming each aggregate batch, since the recycled aggregates are usually quite heterogeneous, with characteristics that may vary depending on the type of work, construction materials used or period of the year.

Engineering Characteristics and Environmental Risks of Utilizing Recycled Aluminum Salt Slag and Recycled Concrete as a Sustainable Geomaterial

Recycled aluminum salt slag (RASS) is an industrial by-product generated from the melting of white dross and aluminum scraps during the secondary smelter process. Insufficient knowledge in the aspects of engineering characteristics, and the environmental risks associated with RASS, is the primary barrier to the utilization of RASS as a substitute material for natural quarry materials in the field of geotechnical construction. In this research, comprehensive geotechnical and environmental engineering tests were conducted to evaluate the feasibility of utilizing RASS as a sustainable geomaterial. This was undertaken by comparing the laboratory testing results for RASS with a well-known recycled material, namely recycled concrete aggregate (RCA), and the relevant specifications set forth by the local road authority. The geotechnical engineering assessment included particle size distribution, flakiness index, organic content, pH, particle density, water absorption, modified Proctor compaction, aggregate impact value, Los Angeles (LA) abrasion, hydraulic conductivity, and California bearing ratio (CBR). The CBR results of the RASS samples satisfied the minimum CBR value (>80%) for usage as pavement subbase material in road construction. In addition, the repeated load triaxial (RLT) tests were carried out on the RASS samples to assess the response of the RASS under cyclic loading conditions. Furthermore, a range of chemical tests, consisting of leaching and polycyclic aromatic hydrocarbon tests, were also performed on the RASS to address the environmental concerns. Comparing the chemical test results with the environmental protection authorities’ guidelines provided satisfactory evidence that RASS will not pose any environmental and health issues throughout its service life as a geotechnical construction material.

Role of Lime-Fibre on Mechanical Strength and Resilient Characteristics of Pond Ash

Shortage of traditional pavement materials on the one hand and management of vast output of coal ash from thermal power stations on the other hand are the major challenges facing the construction industry. In this regard, the present work is focused on the investigation of laboratory studies—aimed to evaluate the use of coal pond ash as a pavement subbase material. A series of unconfined compression, bearing ratio and repeated load triaxial (RLT) tests were performed on pond ash through the individual and combined effect of lime and fibre contents to investigate the pavement-geo mechanical parameters such as unconfined compressive strength (UCS), California bearing ratio (CBR), resilient modulus (MR), and permanent deformation (ϵp). The effect of additives and the impact of various stress levels (both confining and deviatoric) on pond ash were investigated. The test results indicate that there was a significant improvement in the above properties of pond ash with an addition of lime and fibre. The optimum performance of pond ash was observed at lime content of 8% and fibre content of 1% individually. The combined effect of both additives further enhanced the efficiency of pond ash significantly up to lime 8% + fibre 1.0%; thereafter, the improvement was minimal for increased additive contents. The measured MR and ϵp values were compared and validated with the existing mechanistic-empirical prediction models and observed satisfactory results.

Stabilization of lateritic soil by ladle furnace slag for pavement subbase material

The effect of ladle furnace slag or LFS on the mechanical properties of the lateritic soil mixes for use as a subbase course material in the pavement structure was investigated. The lateritic soil grade E with the lowest mechanical properties was studied by mixing the LFS in the ratios of 5 to 12 wt%. The pavement material criterion of the Thailand Department of Highways was used to qualify the liquid limit, plasticity index, the California bearing ratio, and the swelling index of the mixed lateritic soil with the LFS. An increase in the California bearing ratio of the lateritic soil under the soaked condition was found to be positively correlated with the increasing LFS. Meanwhile, the liquid limit and the plasticity index decreased, leading to a decrease in the swelling index of the lateritic soil containing LFS. Using LFS reduced the total fine-particle ratio in the soil mixture but effectively enhanced the degree of compaction and swelling tolerance in the lateritic soil mixture. 10 wt% LFS is strongly recommended as a minimum admixture in the lateritic soil due to the highly improved plasticity and the mechanical properties of the lateritic soil for a subbase course material selection under the standard specifications.

The potential use of lightweight cellular concrete in pavement application: a review

Protecting the pavement subgrade to increase the service life of road pavements is an aspect currently being explored. Several alternative pavement subbase materials are being considered, including Lightweight Cellular Concrete (LCC). Due to its lower weight, LCC incorporating industrial by-product, making it sustainable, and ease of use amongst other benefits, is seen as a potential candidate. This paper reports reviewing the potential application of LCC within the pavement structure with a specific application as a subbase. It examines the various properties such as modulus of elasticity, compressive and tensile strength, Water absorption, and freeze-thaw resistance necessary for pavement application. It also assesses its use in the field in Canada considering the design methods utilized. Some limitations and gaps for LCC application in pavements are also established and recommendations on how to further its use and performance. This review concludes that LCC possesses potential as a pavement subbase alternative; however, other mechanical properties like LCC’s fatigue life is essential. A comparative field study is also recommended to monitor actual performance and various factors on performance.

Recycled Concrete Aggregate as Alternative Pavement Materials: Experimental and Parametric Study

Recycled concrete aggregate (RCA) is one of the alternatives to virgin material that has engendered interest in recent years, especially as an alternative aggregate. There are limited available studies assessing the suitability of RCA as a base or subbase material in pavements. Therefore, the present research describes different laboratory experiments to determine the possibility of using RCA as alternative subbase material for road pavement in order to conserve natural resources and reduce geoenvironmental effects. Modified compaction tests, particle-size distribution, Los Angeles abrasion, Atterberg limits, specific gravity, California bearing ratio, and repeated load triaxial tests were carried out for that purpose. RCA was also reinforced with both biaxial and triaxial geogrids for material optimization. Shakedown analysis and parametric investigation using some constitutive models were conducted for further assessment. The physical and geotechnical properties showed that RCA is strong enough and fulfills the local road authority requirements to be used as a subbase material. The resilient modulus values of the reinforced RCA with geogrid was higher than the unreinforced RCA; in addition, the permanent deformation properties of reinforced RCA with geogrid was found to be smaller than that of the unreinforced RCA. The shakedown ranges varied from A to B, which indicates that RCA can be used as pavement subbase material when it is compacted with moisture content less than the optimum. The parametric investigation showed that some constitutive models are capable for assessing the behavior of both reinforced and unreinforced materials.

Cement-treated recycled glass and crushed rock blends: modulus of rupture and stiffness properties

ABSTRACT Recycled waste materials are increasingly being used as low carbon construction materials in civil infrastructure works, as recycled materials have significant carbon savings compared with virgin quarried materials. In this research, the stiffness and modulus of rupture properties of crushed rock (CR) blended with recycled glass (RG) were evaluated. The engineering properties of the four cement-treated CR/RG blends evaluated were: 100% CR100 (100CR), 90% CR with 10% RG (CR90/RG10), 80% CR with 20% RG (CR80/RG20), 70% CR with 30% RG (CR70/RG30). 3% dosage of general blend (GB) cement was used in all the RG/ CR blends. The results indicated that cement-treated RG/CR blends, with up to 20% RG, are suitable as pavement subbase materials. Unconfined compression strength (UCS) values met the minimum requirement for 7 days of curing for all the CR/RG blends. The results of repeated load triaxial (RLT) tests and flexural beam tests were found to be within the ranges reported for the previous testing on other accepted recycled and quarry products. Based on this laboratory assessment, RG can be recommended for incorporation as a supplementary material in cement-treated CR pavement applications, which will increase the uptake of recycled products as a civil engineering construction material.

Comparison between cement and fly ash geopolymer for stabilized marginal lateritic soil as road material

ABSTRACTThe stabilisation of marginal lateritic soil using cement and fly ash (FA) geopolymer with a liquid alkaline activator was investigated. In this study, soil with satisfactory gradation and percentage of wear was selected. Only the soaked California Bearing Ratio (CBR) value must be enhanced to satisfy the requirement to form a suitable pavement subbase material. Field CBR tests were conducted for both geopolymer- and cement-stabilised soils used as pavement subbase materials. The soaked CBR of cement- and FA-geopolymer-stabilised marginal lateritic soil of various mixing percentages at 14 days satisfied the standard requirements specified by the government agencies in Thailand. Equations were established from field test data to predict the CBR at any testing time. The CBR development of cement-stabilised soil took more time than that of geopolymer-stabilised soil. The appropriate mixing percentages of cement and FA geopolymer with marginal lateritic soil were 3–5 and 4–8%, respectively. Microstructural analysis indicated that the stabilised soil exhibited a denser structure, which corresponded to the CBR increment. The findings of this study will enable the implementation of cement and FA geopolymer as successful stabilisers for pavement subbase materials.

Reliability Evaluation of Optimum Moisture Content of Tropical Black Clay Treated with Locust Bean Waste Ash as Road Pavement Sub-base Material

A FORTRAN based first-order reliability program (FORM) was used to assess the suitability of tropical black clay (known as black cotton soil) treated with locust bean waste ash (LBWA) mixtures as road pavement sub-base material. Soil was treated with up to 10% LBWA and compacted with British Standard light, BSL; West African Standard (WAS) and British Standard Heavy (BSH), energy. Laboratory results were used to generate a regression model for the reliability analysis using optimum moisture content of compaction (OMC) as dependent variable and the relevant soil parameters; LBWA; gravel content (GR); specific gravity (Gs); plasticity index (PI); sand content (Sa) and percentage fine (PF) as independent variables to compute reliability/safety indices. The results indicate that for the laboratory-based model, reliability index is sensitive to variability in all the soil parameters with the exception of PF which have constant safety index values. Results showed that locust bean waste ash, LBWA; GR; Gs, PI and Sa are greatly influenced by the coefficient of variation and therefore must be strictly controlled in LBWA treated black cotton soil for use as sub-base material in road pavement. Safety indices of −1.29 to −0.58, −0.041 to −0.415 and 1.33 to −0.224 were recorded for the effect of OMC on the reliability indices of BSL, WAS and BSH compaction energy respectively. Stochastically, results obtained did not produce acceptable safety index value of 1.0 as recommended by the Nordic Committee on Building Regulations. Therefore, more potent additives such as cement or lime are recommended to model optimum moisture content of compaction for black cotton soil–LBWA mixtures for use as sub-base material for road pavement.

Engineering and Environmental Assessment of Recycled Construction and Demolition Materials Used with Geotextile for Permeable Pavements

This paper describes laboratory testing to investigate the suitability of recycled construction and demolition (C&D) materials as alternative subbase materials for permeable pavements. Permeable pavements are increasingly being used as urban stormwater management systems. Three commonly found recycled C&D waste materials, crushed brick (CB), recycled concrete aggregate (RCA), and reclaimed asphalt pavement (RAP), were investigated to assess their suitability as permeable pavement subbase materials. Geotextile was also used in this research to trap pollutants. The laboratory tests included basic physical characterization such as particle size distribution, specific gravity, water absorption, Los Angeles abrasion, California Bearing Ratio (CBR), and modified Proctor compaction tests. In addition, hydraulic conductivity tests were undertaken in a laboratory test setup with different influent suspension percentages and moisture contents. Temporal variations of effluent suspension percentages were investigated to assess clogging effects. It was found that the geotextile layer did not have any effect in terms of permeability of the C&D materials. The chemical assessment included organic content, pH value, trace element, and leachate concentration for a range of contaminant constituents and compared with maximum allowable limits in soil and natural water as well as with the environmental protection authorities' requirements. In terms of geotechnical and chemical assessment for permeable pavement applications, RCA was found to be a suitable alternative construction material for permeable pavements, while CB was borderline and RAP did not meet some of the specified requirements.

Reclaimed Asphalt Pavement and Recycled Concrete Aggregate Blends in Pavement Subbases: Laboratory and Field Evaluation

In recent years, efforts have been made to incorporate reclaimed asphalt pavement (RAP) into pavement base or subbase applications by means of cement binder stabilization. This approach, however, may not be an environmentally friendly solution due to the high carbon footprint involved in the production of Portland cement. Recycled concrete aggregate (RCA), on the other hand, has been widely accepted in pavement applications. The sustainable solution of blending RAP with RCA was investigated in this research in an attempt to facilitate the usage of this blend as an alternative pavement subbase material. An extensive suite of geotechnical laboratory tests was undertaken on RAP with contents of 100, 50, 30 and 15% in blends with RCA. Results of the research study indicated that RAP/RCA blends with a low 15% RAP content meet the repeated load triaxial requirements for use in pavement subbase layers. Results of field performance of a pavement subbase constructed with untreated 100% RAP, at a private haul road field-demonstration site, confirmed that it had insufficient strength requirements to meet local road-authority pavement-subbase requirements. RAP and RAP/RCA blends, although found in this study to be not fully compliant with the local road-authorities requirements, could be potentially considered for lower traffic usage, such as haul roads and footpaths.

Geotechnical Properties of Recycled Concrete Aggregate in Pavement Sub-Base Applications

Abstract This paper presents a laboratory investigation of the geotechnical properties of recycled concrete aggregate (RCA). The properties of RCA were compared with state road authority requirements to assess its performance as a pavement sub-base material. The experimental programme included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. The Los Angeles abrasion loss tests indicated that the RCA is durable. CBR values were found to satisfy the local state road authority requirements for sub-base material. Repeated load triaxial tests established that the RCA would perform satisfactorily as a pavement sub-base material in the field. The results of the laboratory testing undertaken in this research indicated that RCA satisfied the criteria for use in pavement sub-base applications.

Geotechnical Properties of Waste Excavation Rock in Pavement Subbase Applications

AbstractThis paper presents the findings of an extensive laboratory investigation on the geotechnical properties of waste excavation rock in pavement subbases. The waste excavation rock used in this study originated from “basalt floaters,” or surface excavation basalt rock (basalt). Traditionally, this material would have been disposed as waste, often into landfill. The engineering properties of the crushed basaltic waste rock were compared with the local road authority specifications to assess its performance as a pavement subbase material. The experimental program was extensive and included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. The Los Angeles abrasion loss value obtained indicated that the crushed basaltic waste rock is durable. California bearing ratio values were found to satisfy the local state road authority...