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Low-volume roads are anticipated to have less traffic and provide access to socio-economic activities in rural areas. The present study deals with the stabilisation of soil with locally available waste materials, i.e. low calcium fly ash (FA) and brick dust (BD). These two wastes are available abundantly and lead to an increase in pollution levels. Initially, lime was added to make the silty clayey soils plastic-free. The initial consumption of lime was found to be 5%. Then, the soil was stabilised with cement fly ash and cement brick dust techniques for strength, durability and shrinkage evaluation. The cement was varied from 2 to 8% with FA and BD by fixing the ratio to 1:3 as per AASHTO guidelines. The unconfined compressive strength (UCS), indirect tensile strength test and California bearing ratio were conducted for strength evaluation. The wetting and drying cycles were evaluated for durability analysis. The linear shrinkage cracking was evaluated after the curing period of 28 days. It was observed that there was a magnificent increase in strength and durability values. The maximum UCS attained value was so high that it could act as a replacement for the granular sub-base layer in the pavement structure. The linear shrinkage evaluated at fixed relative humidity was significantly reduced. The statistical analysis reported that there was a significant difference between the two admixtures. The utilisation of these wastes not only enhances strength, but also deficits the cost of construction along with reducing the pollutants in the environment. [ABSTRACT FROM AUTHOR]

Although many commercial stabilizers are available for the treatment of poor soils; agricultural, agro-industrial, and environmentally friendly stabilizers are always encouraged. In this study, an attempt has been made to assess the effects of brewery spent grain ash (BSGA) on lime-treated clay for stabilization of an expansive clay to be used as road construction material. Brewery spent grain (BSG) is an agro-industrial solid waste product obtained during the brewing of beer. Through burning in an open cylinder, it is converted to BSGA. The clay was subjected to preliminary tests to classify and identify some required engineering properties of the sample. Initially, samples were thoroughly mixed with lime by weight of clay to determine the optimum amount of lime needed throughout the experiments. Through laboratory execution trials, 10% lime was determined to be the optimal amount. Following, BSGA was added to the treated clay, which was previously treated with 10% lime, at various percentages of 2, 4, 6, 8, and 10% BSGA by weight of clay. At 0% BSGA, the unsoaked and soaked California bearing ratio (CBR) rose from 13.56 and 8.24% to their greatest values of 14.99% and 9.3%, respectively, at 6% BSGA. Unconfined compressive strength (UCS) values rose from 112.63 kN/m2 at 0% BSGA to 130.31 kN/m2 at 6% BSGA, which is the highest value. Therefore, it was discovered that BSGA can be a beneficial addition to lime stabilization in clay soil. [ABSTRACT FROM AUTHOR]

Expansive soils are extremely susceptible to swelling and shrinkage associated with seasonal changes in their moisture content. This can cause serious damage to structures constructed on expansive soils. Stabilization using additives is widely used to mitigate the concerns of expansive soils by controlling the changes in volume, thereby increasing the strength and durability of the soils. Multistabilizers, including a low percentage of conventional additives with nonconventional additives, can reduce the costs of stabilization. The performance of the stabilized soil can be enhanced by admixture optimization to ascertain that the agent's ratios are quite adequate to meet the optimal levels of modification. Unfortunately, despite the development of advanced techniques for investigating the stabilization of expansive soil, limited studies are devoted to the optimization of admixture to soils. Hence, in this research, an approach based on rough set theory, a mathematical data mining approach, is presented for multiagent optimization for efficient treatment of expansive soils. The multiadditives used in this study are almond shell ash (ASA), volcanic rock dust (VRD), and portland cement (PC). The differential free swell test, the California bearing ratio test, and the unconfined compressive strength test were applied for assessing the characteristics of the stabilized soil specimens. The obtained results and the confirmatory tests demonstrated that a combination of 20% ASA and 20% VRD with 8% PC provides the optimum results in the properties of expansive soil. The microstructural analysis denoted an enhanced modification of the soil engineering properties. The outcomes of this research confirm that the rough set optimization procedure is highly suitable for application in multiagent optimization for the efficient treatment of expansive soils. [ABSTRACT FROM AUTHOR]

The low bearing capacity of expansive soils often results in serviceability issues and premature failures of infrastructure built upon them. Various studies have demonstrated the use of different soil treatment methods using mechanical or chemical approaches to stabilize the weak ground as a precaution. Most of the reported studies are limited to either lab-based investigations or field monitoring works without the scientific connection between theory and translation. This study aims to verify the field application of a novel soil stabilization method by conducting laboratory-controlled experiments and field performance testing as verification. Enzyme–based soil stabilization was adopted for in-situ clay soil in combination with ordinary portland cement as a sustainable stabilization approach. Soil samples were collected at different regions from the field to evaluate the effectiveness and the mechanism of soil stabilization in the field by the means of replicating stabilization at the laboratory scale using identical mixing proportions of the additives. The mechanical behavior of stabilized soil was assessed through the unconfined compression strength and California bearing ratio test methods. In addition, the changes in the chemical composition of the soil due to the additives were evaluated through the X-ray diffraction testing technique and microporosity test using 2D images translated to 3D profiles from X-ray micro CT tomography. The efficacy of field stabilization was evaluated by conducting the falling weight deflectometer test in the stabilized site. Results from the study are useful to understand the efficacy of field soil stabilization and enhance the reliability of enzyme–based stabilization in practice. [ABSTRACT FROM AUTHOR]

This work presents an experimental study on the physico-mechanical and microstructural characteristics of stabilised soils and the effect of wetting and drying cycles on their durability as road subgrade materials. The durability of expansive road subgrade with a high plasticity index treated with different ratios of ground granulated blast furnace slag (GGBS) and brick dust waste (BDW) was investigated. Treated and cured samples of the expansive subgrade were subjected to wetting–drying cycles, California bearing ratio (CBR) tests, and microstructural analysis. The results show a gradual reduction in the California bearing ratio (CBR), mass, and the resilient modulus of samples for all subgrade types as the number of cycles increases. The treated subgrades containing 23.5% GGBS recorded the highest CBR value of 230% under dry conditions while the lowest CBR value of 15% (wetting cycle) was recorded for the subgrade treated with 11.75% GGBS and 11.75% BDW at the end of the wetting–drying cycles, both of which find useful application in road pavement construction as calcium silicate hydrate (CSH) gel was formed in all stabilised subgrade materials. However, the increase in alumina and silica content upon the inclusion of BDW initiated the formation of more cementitious products due to the increased availability of Si and Al species as indicated by EDX analysis. This study concluded that subgrade materials treated with a combination of GGBS and BDW are durable, sustainable and suitable for use in road construction. [ABSTRACT FROM AUTHOR]

This study investigated the different geotechnical characteristics of soil stabilization with the addition of lime and rice husk ash (RHA) in varying amounts (3%, 5%, 7%, and 9% lime, and 4%, 8%, 12%, and 16% RHA). A series of compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), pH, and X-ray diffraction (XRD) tests were performed in the laboratory to assess the impact of the considered admixtures on the stabilized soil parameters. This study also proposes the successful integration of an artificial neural network (ANN) and a Gaussian process regression (GPR) with the experimental UCS observations. The lime concentration, RHA concentration, and curing period were considered as the input parameters, and UCS was considered as the response. The proposed framework was extended to analyze the compressive behavior of treated soil on the minuscule level. Such coupled machine learning-based experimental investigation can provide deep insight into the soil behavior which otherwise would have remained unexplored due to the prohibitive nature of performing laboratory experiments on a large scale. The findings demonstrated the effectiveness of RHA in addition to lime in stabilizing the considered expansive soil. With the addition of lime and RHA mix, the UCS and CBR values of the treated soil increased significantly. [ABSTRACT FROM AUTHOR]

This paper presents heave and pullout studies of plain granular pile-anchors (GPAs) and geogrid-encased GPAs. Experiments were conducted in California bearing ratio (CBR) moulds and fabricated moulds of size 381 × 381 × 457 mm in expansive clays. The GPA method is an innovative technique developed for reducing heave and improving bearing capacity and pullout capacity. In this study, GPAs were encased in geogrids to augment the engineering performance of the system. Tests were conducted in CBR moulds and fabricated larger moulds to study and compare the heave and pullout behaviour of plain GPAs and geogrid-encased GPAs. The results indicated that the clay beds reinforced with geogrid-encased GPAs showed better heave and pullout behaviour. Heave decreased by 90.8% and 92.5%, respectively, in the case of plain and geogrid-encased GPAs installed in the CBR moulds and by 95.12% and 98.3% in the case of plain and geogrid-encased GPAs installed in fabricated large moulds. Pullout load on geogrid-encased GPAs in CBR moulds improved by 42.17% over that on plain GPAs and pullout load on geogrid-encased GPAs in the fabricated large moulds improved by 52.25% over that on plain GPAs. [ABSTRACT FROM AUTHOR]

This experimental study examines the efficacy of the inclusion of randomly distributed polypropylene fiber (PP) reinforcement on the engineering properties of expansive clays. The effect of PP fiber inclusions (0%-0.8%) on compaction, unconfined compressive strength (UCS), elastic modulus (E50), California bearing ratio (CBR) and swell-consolidation parameters of test soil were explored. Experimental results showed significant improvement in the strength parameters of treated soils with an optimal fiber content at about 0.4% by weight of soil. The swell-consolidation parameters were also observed to be significantly ameliorated in fiber-reinforced samples. Test results indicate that the use of PP fiber as a reinforced stabilizer for expansive clays not only benefits the sustainable utilization of fiber wastes in soil stabilization, but also reduces the environmental footprint globally. [ABSTRACT FROM AUTHOR]

Oil pollution causes deterioration of the physical, chemical, mechanical, and geotechnical characteristics of affected soil leading to loss of soil productivity for engineering purposes. Different stabilization methods serve as a remedy for such soil to regain its loss engineering properties. This study was concerned with the utilization of lime to stabilize crude oil contaminated soil and to investigate its efficacy for soil stabilization. The study also focused on determining the geotechnical properties of crude oil contamination and matching the result with standard specifications established for engineering works. Hydrated lime, expansive clayey soil, contaminated soil, and potable water were the materials used for the experimental investigation. The contaminated soil was treated with 6.5% lime and 0–20% crude oil contaminated materials obtained from oil exploration sites in North-Eastern Nigeria and per standard test method for laboratory evaluation of consistency limits, compaction properties, California bearing ratio (CBR), and microstructural and mineralogical assessments. The experimental results obtained were further tested statistically through one-way ANOVA and F-statistics to establish the source of variation for the geotechnical properties, while multiple linear regression and correlation statistics helped draw the connection between the consistency limits, compaction, and CBR properties of the soil-lime-COCM blend. Results indicated a coefficient of determination of 99.86. The contaminated soil materials were found to show optimal performance at a 5% ratio and 6.5% of lime for civil construction purposes. [ABSTRACT FROM AUTHOR]

Weak subgrade is the main problem facing most highway projects. Therefore, this study focuses on trying to improve the properties and increase the strength of weak, clayey, swelling soil for use as a subgrade for pavement structural sections. This trial was developed using a mix of granular and chemical stabilization for the soil. Granular stabilization was applied firstly by mixing natural sand at different percentages of 20%, 35%, and 50% of the total weight of clayey, swelling soil samples to find the minimum percentage that could be added to improve it to sandy, clayey soil, which is acceptable as a subgrade according to the Egyptian highway specification code. Secondly, chemical stabilization was applied to enhanced sandy, clayey soil to increase its strength properties. This was performed by adding chemical additives (lime, cement kiln dust (CKD), fiberglass, Addicrete 11, and gypsum) at different ratios of 2%, 4%, and 6% of the total weight of the samples of enhanced sandy, clayey soil. An experimental program was conducted consisting of characteristics and consistency tests, the California bearing ratio (CBR) test, a proctor test, and a consolidated-drained (C-D) tri-axial shear test. The results showed that 50% sand was the minimum percentage that could be mixed with swelling, clayey soil for granular stabilization to be enhanced and become sandy, clayey soil, which is accepted as a subgrade layer according to the Egyptian highway specification code. In addition, using a mix of granular and chemical stabilization increased the compressive strength of this enhanced subgrade by adding 6% lime or cement kiln dust (CKD) of the total sample weight. They enhanced the strength of the soil and reduced its plasticity. Adding 6% fiberglass and polymers could slightly enhance the desired properties; however, it is not recommended to use them due to their slight effect and economic cost. In addition, it is not recommended to use gypsum at more than 4% due to its negative effect on CBR. [ABSTRACT FROM AUTHOR]

Australian design practice for granular pavements with lime-modified subgrades is very conservative and does not consider the initial and long-term strength improvement. It recommends that the assigned California bearing ratio (CBR) of a modified subgrade soil should not exceed 15% for most roads. Two types of clay soils with plasticity indices of 22% and 42.5% were treated herein with their minimum lime demand (MLD) and tested to evaluate the modification influence on their properties. These properties include pH, compaction, compressive strength, bearing capacity, resilient modulus, and permanent deformation. Three different mellowing periods, 24, 48, and 72 h, between lime treatment and compaction, were used in this study to identify their optimum mellowing periods. Analysis of testing results for long-term compressive strength and CBR showed that MLD improves both soils' compressive strength and bearing capacity. Using the actual CBR values of lime-treated soils in designing the cover over subgrade results in a 30% reduction in pavement thickness. Lime modification of these soils also improves their resilient moduli and permanent deformation. The best results are achieved with mellowing periods of 24 h for Soil A and 72 h for Soil B. These optimum mellowing periods reduced permanent deformation of Soil A to less than 0.15% and 0.11% for Soil A. Considering the study findings, it is believed that thinner pavements can be designed and built on modified subgrades with MLD, which will help road agencies save funds. [ABSTRACT FROM AUTHOR]

Tire wear particles (TWPs) are significant contributors to microplastic pollution in the environment, yet there is limited scientific information concerning their impact on soil hydraulic properties. This study aimed to investigate the impact of TWPs at different concentrations (1, 4, 8, and 16% of the air-dried mass of packed soil samples, w/w) on the water retention curves (WRC) of southern California soils with five different textures (clay, clay loam, silt loam, sandy loam, and loamy sand). The concentrations of 8% and 16% were selected to represent extreme pollution scenarios that might occur near highway corridors. High-resolution water retention data, spanning from saturation to oven dryness, were generated using HYPROP™ and WP4C dew point meter instruments. We also developed WRC scaling equations based on the quantity of TWPs. The bulk density of the samples decreased as the TWP concentration in soils increased. The inclusion of very high concentrations of TWPs (8% and 16% w/w) led to a significant reduction in soil moisture content in the intermediate and dry ranges across various soil textures. However, at the same moisture range, adding 1% TWPs had a minimal impact on soil moisture reduction, while the influence of the 4% TWPs concentration treatment was noticeable only in loamy sand and partially in clay loam soils. Additionally, the overall plant available water decreased with increasing TWP concentrations, except for the clay soil. The texture-specific scaling models exhibited promising performance, with RMSE values ranging from 0.0061 to 0.0120 cm3 cm−3. When bulk density was included as an additional input predictor to construct a single scaling model for all textures, the RMSE increased. Nevertheless, it still indicated a good fit ranging from 0.007 to 0.024 cm3 cm−3, highlighting the suitability of simple scaling for identifying WRC in TWPs-polluted soils, particularly for practical purposes. The findings of this study can contribute to a better understanding and quantification of the impact of TWPs on soil hydrology. • HYPROP and WP4C were used for high-resolution measurement of soil water retention from saturation to dryness. • The impact of tire wear particles (concentrations 1–16%) on the water retention curve of 5 soil textures was investigated. • A linear scaling model accurately estimated the soil moisture reduction in the plant available water range due to TWPs. [ABSTRACT FROM AUTHOR]

The objective of the present study was to increase the strength and stiffness of silty clay and silty sand subgrades for building economic and sustainable asphalt pavements. Advanced cyclic load tri-axial (ACLT) and California bearing ratio (CBR) tests were performed to obtain the experimental and theoretical resilient modulus (M R) of the soil subgrades, respectively. In addition, the impact of the stabilization of the plasticity and compaction characteristics of the soil subgrades was determined. The insight into the mechanism of the stabilization was obtained by determining the mineralogical and microstructural properties of the stabilized soils through X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests, respectively. The combined inclusion of 20% brick kiln dust and 20% pond ash resulted in 186% increase in the CBR, 224% increase in the experimental M R , 96% increase in the theoretical M R , 2.07 times higher pavement service life, 23% savings in cost, and 28% reduction in the CO 2 emissions associated with pavement construction. The enhancement in the CBR and M R of the soils was attributed to the increased inter-particle friction, improved particle size distribution in stabilized clay and sand, and a concurrent reduction in the plasticity of clay. The study highlights the real-world usage of the ACLT test to get the real M R of soil subgrade rather than the over-estimated theoretical M R. For precise estimation of M R from CBR, a correlation between CBR and experimental M R was established. • Pavements built with soil subgrades of low strength and stiffness develops ruts, depressions, and corrugations. • Advanced cyclic load triaxial test is mandatory for the performance evaluation of soil subgrades under dynamic loading. • Experimental approach gives true value of resilient modulus (M R) while theoretical approach overestimates the M R. • Economic and sustainable pavement construction can be achieved with the waste stabilized clay and sand subgrades. • Promotion of use of waste materials for soil subgrade stabilization will help build economic and sustainable pavements. [ABSTRACT FROM AUTHOR]

Efficient utilization of problematic soils such as soft clay by imparting additional strength using various stabilization techniques is done to improve soil properties. The application of nanomaterials in the area of soil stabilization has great potential to create a stiff skeleton, especially when blended with cementitious materials. Using the response surface method, this study focused on studying the effects of single and blended cementitious systems, comprising cement (0% to 20%), slag (0% to 20%), and nanosilica (0% to 2.4%), on the properties of soft clay in wet conditions [water-to-soil ratio (w/s) of 53% to 87%]. The mechanical [California bearing ratio (CBR), unconfined compressive strength up to 91 days] and durability (freezing-thawing durability factor) properties of stabilized clay were investigated, and the bulk trends were corroborated by thermogravimetry and microscopy analyses. Based on statistical analysis, incremental addition of cement, slag, and nanosilica led to the systematic increase in the properties of soft clay, albeit to different extents and with different mechanisms. At the low w/s (53%), superior mechanical and durability properties were obtained for soft clay stabilized with the ternary binder comprising cement, slag, and nanosilica. Numerical optimization showed that stabilizing this weak type of soft/expansive clay is possible, but the results (proportions, performance, cost) varied based on the target design criteria and application. [ABSTRACT FROM AUTHOR]

According to the geotechnical section of the Kyoto Protocol, researches on nontraditional materials such as polymers and new methods like biological soil stabilization have been developed. This study aimed to investigate and compare the effect of chemical and biological stabilization of clay subgrade soil. For chemical stabilization, polymers called cationic polyelectrolyte (CPE) and Nicoflok were used. For biological stabilization, the microbial-induced calcium carbonate precipitation (MICP) method was adopted and a biopolymer solution called Beta-glucan was employed. In both methods, the dry density of the soil decreased and its optimum water content and pH increased. The Plastic Limit of the soil increased after stabilization with CPE and decreased in stabilization with other stabilizers. All four additives increased the uniaxial compressive strength and the elasticity modulus of the soil. The effect of Nicoflok and biopolymer was more evident. Despite similar results in the uniaxial test, the increasing effect of Nicoflok on the resilient modulus (MR) was more than that of the biopolymer. Raising the dose of these two stabilizers and also the curing time changed the resilient behavior of the fine-grained soil to coarse-grained under different stress conditions. Nicoflok and biopolymer-stabilized samples exhibited a higher California bearing capacity (CBR) and durability compared to the untreated sample, with the effect of Nicoflok being more significant. The estimate of design MR for these samples using the stress-dependent model was more accurate compared to the conventional correlations with CBR. Therefore, chemical stabilization with the Nicoflok is economically feasible, while biological stabilization using the biopolymer is environmentally suitable for the studied soil. [ABSTRACT FROM AUTHOR]

Plastic clays in subgrade may cause major engineering defects such as excessive heave or settlement during the wet season that contribute to the formation of uneven geometry at the pavement surface. Soil stabilization is often a requisite to ameliorate the engineering properties of soft soils or reactive clays. This study investigates the application of nano-silica and nano-alumina to improve the California bearing ratio (CBR) of a local clay. The clay was treated with cement (2%–8%), with nano-additive (0.1%–1.5%) and with cement and nano-additive (3% cement + 0.1%–1.5% nano-additive). The compacted sample was cured for 7 days and subjected to soaked and unsoaked CBR tests. The soaked CBR of the nontreated clay increased by 49% and 27% for 1% nano-silica and 1% nano-alumina treated clay, respectively. Although 3% cement addition improved the CBR of the soaked clay by 28%, the combination of 3% cement with 1% nano-silica and nano-alumina resulted in 196% and 164% increase in the soaked CBR of the nontreated clay, respectively. The combination of nano-additives and cement yielded the same soaked CBR as if 6%–7% cement would have been used. Clay treated with 1% nano-silica and 3% cement achieved the highest CBR value within the tested samples and the sample treated with 1% nano-alumina and 3% cement achieved the lowest free swell potential. The scanning electron microscopy (SEM) micrographs of the treated clay showed the formation of uniform fabric with fewer pore spaces and calcium silicate hydrate (CSH)/calcium aluminate hydrate (CAH) products within the fabric of nano-additive treated clay. [ABSTRACT FROM AUTHOR]

This paper attempts to study the effects of acidic and alkaline waters on the geotechnical properties of a particular type of clay with low plasticity from the northeast areas of Isfahan that have been evaluated with pH values adjusted from 3 to 8. The remoulded specimens were placed in moulds under the influence of acid and alkaline rains with different pH values and years of precipitation. Atterberg limits tests, soil permeability coefficient, California bearing ratio (CBR) test and unconfined compressive strength (UCS) of soil specimens with various pH values were used to evaluate soil mechanical changes relative to soil with neutral acidity. In order to identify internal structural mechanisms of soil before and after artificial raining on the specimens, scanning electron microscopy and pH drainage tests of specimens were performed. The results of the interaction of rain and soil with shifting from neutral values were evaluated over a period of precipitation fluxes from 1 to 20 years. In overall, the more is the acidity or alkalinity of the artificial rain, the more will increase the Atterberg limits and the soil permeability compared to the soil specimens under artificial rain with pH = 7; and the decreasing trend is observed in UCS values and CBR. [ABSTRACT FROM AUTHOR]

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly. • Experimental investigations on finding synergistic performance of clayey soil, lime and waste rubber tyre powder. • Atterberg's limits, shear, compaction, CBR, & microstructural characteristics shows better performance of modified mixes. • Optimised clay-lime-RTP mix reports 44% and 88.63% improvements in shear strength and bearing capacities respectively. • Decrement in productional cost of up to 39% for modified geo-mixes in road pavement and foundation constructions. [ABSTRACT FROM AUTHOR]

The study showcase the optimization of California bearing ratio (CBR) values of expansive soil treated with cement kiln dust (CKD) and metakaolin (MTK) blend based on Scheffe optimization method. The CBR values utilized in the design of road infrastructure is an important parameter because it provides the rating of soil material for use as subgrade, sub-base and/or base course of road pavement. Therefore, applying Scheffe optimization technique will eliminate the random selection of design mix ratios and other associated disadvantages during CBR tests. Based on the optimization exercise and it results, the maximum CBR (unsoaked and soaked) values of 69 and 50 % were achieved with a corresponding mix ratio of 1.0:0.30:0.35:0.50 for black cotton soil, water, cement kiln dust and metakaolin respectively. During the course of this study, the laboratory results were used to develop two CBR models. The scheffe models developed are Ŷ=34X1+46X2+40X3+69X4-8X1X2-4X1X3+34X1X4+8X2X3+34X2X4+30X3X4 and Ŷ=17X1+28X2+22X3+50X4-10X1X2-6X1X3+42X1X4+8X2X3+40X2X4+40X3X4 for CBR unsoaked and soaked, respectively. In addition, the mathematical models were statistically scrutinized, confirmed for the adequacy and validity based on the outcomes of student t-test and analysis of variance (ANOVA). Also, the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques were used to explore the morphological and composition variations of the natural soil in contrast with the typically optimized soil-CKD-MTK blend. However, the SEM of the unaltered soil sample showed a smooth like surface, whereas the soil mixture optimally treated does not show same but rather demonstrated a rough like surfaced morphology. Thus, the observed variations might be due to the alterations of the soil fabrics possibly enhanced by the development of cementitious compounds (calcium silicate hydrate and calcium aluminate hydrate) as a result of pozzolanic reaction. [ABSTRACT FROM AUTHOR]

The waste generated from the agriculture and construction sector is a serious threat to the environment due to its disposal problems. This study is an attempt to utilize agriculture and construction waste to stabilize the geotechnical properties of clayey soil to use the composite as sub-grade material. For this purpose, rice husk ash (agriculture waste) and construction demolition waste (used construction waste) are mixed in varying amounts in clayey soil alone and along with lime to obtain the best sub-grade material. The results of the experimental testing reveal that the geotechnical properties of clayey soil are improved by stabilizing it with various waste materials thereby solving their disposal problem thus sustaining a healthy environment. The use of wastes and lime in combination improves the unconfined compressive strength, California bearing ratio, and resilient modulus of the composite. The mix obtained on the addition of rice husk ash and construction demolition waste along with lime can be used as a sub-grade material thus achieving higher economic benefits. [ABSTRACT FROM AUTHOR]

The effects of alkali-activated slag on the engineering properties of clayey soil were investigated. The mix proportion parameters were chosen by using Taguchi's experimental design methodology. Four factors (ground-granulated blast-furnace slag content, concentration of sodium hydroxide solution, sodium hydroxide-to-sodium silicate weight ratio and alkaline solution-to-slag weight ratio) were assessed in order to obtain the greatest compaction properties, uniaxial compressive strength and California bearing ratio (CBR). Significant improvements were observed in the mechanical properties (unconfined compressive strength (UCS) and CBR) of the clayey soil with addition of the stabilisers. Optimal values (15% slag content, sodium hydroxide concentration of 6 M, sodium hydroxide-to-sodium silicate ratio of 0·5 and alkaline solution-to-slag ratio of 2·5) increased the UCS of the compound from 8 to 100 kg/cm2 at 7 d. The excessive addition of alkaline solutions weakened the strength parameters of the soil. The results showed that the most influential factor was the alkaline solution-to-slag weight ratio. The Taguchi method is an effective and suitable experimental method for optimising alkali-activated slag parameters. [ABSTRACT FROM AUTHOR]

• RCA-clay mixture can be a reliable and eco-friendly alternative as subgrade layers. • Recycled concrete aggregate (RCA) inclusion in expansive clay subgrade leads to higher strength and resilience modulus. • The optimum proportion of Clay-20 %RCA-9 %GBS mixture is found to be strong enough to be used as subgrade/subbase layers. • The model proposed by MPDGE provides a good prediction for the M r values of treated expansive clay subgrade. • This paper can encourage and further promote the use of recycled concrete aggregate in the road construction industry. In urban areas, due to urban development and lack of space, roads may be built on the expansive clay subgrade. Expansive clay soils increase in volume when in contact with water and shrink by losing water. Recycled concrete aggregates (RCA) are one of the components of construction and demolition (C&D) wastes that can be used instead of natural resources in road construction projects. In this research, a combined method of mechanical and chemical stabilization was used to evaluate the use of RCA as a mechanical stabilizer and granulated blast furnace slag (GBS) as a chemical stabilizer to improve the strength and resilience characteristics of expansive clay subgrade. Laboratory results showed that adding RCA wastes to expansive clay subgrade reduced atterberg limits (LL, PL, and PI) and optimum water content (OWC) and increased the maximum dry density (MDD), California bearing ratio (CBR), and uniaxial compression strength (UCS). Expansive clay subgrade with 20 % RCA was treated with GBS chemical stabilizer in order to achieve a minimum 7 days target strength of 1.7 MPa for subbase application. A series of repeated load triaxial (RLT) tests were performed according to the AASHTO T307 procedure and resilient modulus (M r) values of the stabilized clay subgrade specimen were evaluated at different curing times under cyclic loading. Also, the proposed Mechanistic-Empirical pavement design Guide (MEPDG) model was used to predict M r values in different confining and deviator stresses which showed a good correlation with the measured M r values. Finally, the improvement of the clay subgrade stabilized with RCA and GBS was also supported by SEM analysis. The results obtained from this research showed that the use of RCA, in addition to reducing disposed waste and environmental pollution, can improve the physical and mechanical characteristics of expansive clay Subgrade layers. [ABSTRACT FROM AUTHOR]

[Display omitted] • The incorporation of nanoclay and rice plant fibers improves the mechanical properties of clay soils. • As a reinforcement, rice fibers increase the interlocking and binding of soil particles, while nanoclay's viscous gel increases cohesion. • Rice plant fiber is a highly renewable and eco-friendly material that can be an alternative to traditional stabilizers when combined with nanoclay as a natural material. Conventional stabilizers such as cement and lime are extensively used to improve the mechanical properties of soils. However, these materials suffer from geo-environmental concerns, especially greenhouse gas emissions. In this respect, incorporating sustainable and renewable materials into the soil is an effective technique to enhance its mechanical properties. This study investigated the effect of rice fibers (as a low-cost and eco-friendly material) and nanoclay on soil's mechanism and mechanical performance. In this study, pure soil samples and three nanoclay dosages (0.4, 0.8, and 1%) and three rice fiber ratios (0.3, 0.6, and 0.9%) in three lengths of 5, 10, and 15 mm in random distribution were tested. The prepared samples were characterized through compaction, unconfined compressive strength (UCS), direct shear strength, tensile strength, California bearing ratio (CBR), and scanning electron microscopy (SEM) examinations. First, the optimum amount of nanoclay was determined based on the compressive strength test. Then, the effect of optimum nanoclay and randomly distributed rice fibers was investigated on the mechanical properties of stabilized soil. The results showed that the shear and compressive strengths of the reinforced soil were higher than those of the control samples. An increase in the dosage of rice fibers improved the failure strain, soil ductility, and shear strength. The optimum amount of fibers was 0.9%, exceeding which led to fiber twisting and agglomeration. However, increasing the nanoclay content decreased the failure strain. According to the microscopic examination, when fibers were combined with nanoclay, the interaction between soil particles and fibers increased due to the filling property and the formation of a viscous gel. Overall, fiber added with nanoclay improved the mechanical properties of clay soil and could be used as a low-cost and sustainable option for soil improvement. [ABSTRACT FROM AUTHOR]

The present study demonstrates the effect of using natural kenaf fibres on the strength behaviour of weak subgrade soils. The two types of soils classified as silt of high compressibility (MH) and clay of intermediate compressibility (CI) are used in this study. Laboratory compaction, soaked California bearing ratio (CBR) and unconfined compressive strength (UCS) tests are conducted on soil samples reinforced with kenaf fibres at four different percentages (i.e., 0.0625%, 0.125%, 0.25% and 0.50%) by weight of soil. Maximum improvements of 150% in CBR and 84% in UCS are reported when silty soil is reinforced with kenaf fibres, whereas these increases are only 18% and 40%, respectively, in case of clayey soil. Smaller post peak strength loss and greater failure strain are observed for soil samples reinforced with various percentages of kenaf fibres with more pronounced effect in case of silty soil. The scanning electron microscope images indicate significant bonding between soil particles and fibres in case of silty soil, thus causing stress transfer from soil to reinforcing material, which leads to strength enhancement, whereas this is lacking in clayey soil. Multiple linear regression analysis is used to develop predictive models for soaked CBR and UCS in terms of compaction characteristics and fibre content. [ABSTRACT FROM AUTHOR]

To characterize the effect of precipitation events, management practices, and soil type on vineyard carbon (C) dynamics, we monitored CO2 emissions and labile C pools from nine vineyards in Lodi Wine Grape District, California, from April 2011 to December 2012. These commercial vineyards are replicates of three soil series (Redding, San Joaquin, and Tokay), representing a spectrum of soil texture and degree of soil development. We hypothesized that soil characteristics would influence the magnitude of CO2 efflux occurring in response to precipitation and management events in a Mediterranean climate. During each field visit—bimonthly (April–October) and monthly (November–March)—we measured CO2, soil temperature, and gravimetric water content (GWC) from vine and intervine (alleys) rows. Monthly, we collected soil samples for dissolved organic C (DOC), which tended to be greater in the alleys of San Joaquin and Redding than Tokay in summer but decreased after the onset of precipitation. In mid-May and mid-October 2012, CO2 efflux was higher in Tokay than in San Joaquin or Redding. Carbon dioxide efflux across all soils increased as a result of seasonal management practices (i.e., tillage and mowing of cover crops). Management practices distinguished soil DOC between vine rows and alleys from June to October 2012. Soil type or clay content influenced CO2 efflux across these vineyards, as did GWC and soil temperature. This 20-mo study indicated that CO2 efflux responded to soil disturbance from management practices, precipitation, and irrigation. [ABSTRACT FROM AUTHOR]

Applying synthetic fibers is one of the most effective physical methods for soil improvement and stabilization. In this paper, we determine the effects of polypropylene (PP) and poly vinyl alcohol (PVA) fibers contents (0.2, 0.5, 1.0 and 1.5%) at environment temperature (25 °C) and various freezing soil temperatures (0, −5, −10 and − 15 °C) on stabilization of the clayey sand soil (SC) samples. The results show that for both types of fibers, by simultaneous increasing of fiber content and lowering the temperature, the values of the unconfined compressive strength (UCS), elastic modulus (EM), ductility and California bearing ratio (CBR) increase, and they all reach their maximum values for 1.5% fiber content at −15 °C. Moreover, we show that PVA fibers perform better compared to PP fibers in increasing of UCS, EM, ductility and CBR values for different fiber contents and temperatures. This can be attributed to the fact that PVA has higher tensile and flexural strength compared to PP fiber. • The effect of freezing soil temperatures (FSTs) on strength parameters of a clayey sand (SC) soil stabilized by poly propylene (PP) and poly vinyl alcohol (PVA) fibers is investigated. • For both types of PP and PVA fibers, by simultaneous increasing of fiber content and lowering the temperature (FSTs effect), the strength parameters of SC soil samples are increased. • The strength parameters of SC soil samples reinforced by PP and PVA fibers reach their maximum values for 1.5% fiber content at −15 °C. • The PVA fibers perform better compared to PP fibers in increasing of strength parameters for different fiber contents at environment temperature and FSTs. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic not only poses an unprecedented threat to global health but also severely disrupts the natural environment and ecosystems. Mitigating the adverse impacts of plastic-based personal protective equipment (PPE) waste requires the cooperation of professionals from various fields. This paper discusses a novel, cleaner approach to soil stabilisation by repurposing the nitrile gloves into a sustainable road material to improve the mechanical properties of expansive clay soil as pavement subgrade. For the first time, extensive geotechnical testings, including standard compaction, unconfined compressive strength (UCS), unsoaked California bearing ratio (CBR), repeated load triaxial (RLT), and swelling-shrinkage tests, were carried out to investigate the engineering performance of different proportions of the shredded nitrile gloves (SNG) (e.g., 1%, 1.5%, 2%) were blended with expansive clay (EC). In addition, surface roughness, scanning electron microscopy (SEM), and X-ray micro-CT analyses were conducted, and images were obtained to study the microstructural modification of the EC-SNG mixtures. The experimental results indicated that the blend of expansive clay with SNG helped in increasing the compressive strength, resilient modulus, and CBR and assisted in reducing the swelling and shrinkage of the soil. SEM and surface roughness analyses indicated the interaction between the soil matrix interface and the rough surface of the SNG. The main reasons for increasing the strength and stability of clay soil could be attributed to the high tensile strength of the SNG and the formation of the three-dimensional grid, and friction between the soil particles and SNG. According to the X-ray micro-CT test results, the incorporation of SNG led to an increase in closed porosity. [Display omitted] • An innovative approach to mitigate the problem of medical waste generation associated with COVID-19 is presented. • A cleaner and sustainable subgrade was developed by using discarded nitrile gloves. • The addition of 1.5% SNG to the soil provided the highest strength properties. • SNG reduced the swelling and shrinkage of the expansive clay subgrade. [ABSTRACT FROM AUTHOR]

Expansive clays are problematic soils as they contain minerals that swell when wetted and shrink during drying. Highway construction on expansive soils requires some form of chemical stabilisation or other treatments to improve pavement performance. Many commercial and waste by-products, such as cement, lime, fly ash and slag, are used as chemical stabilisers to treat expansive clays. Municipal solid waste incineration (MSWI) fly ash is a product obtained from waste-to-energy plants which have attracted increasing attention to prevent land contamination and to reduce landfill costs. This paper investigates the stabilisation mechanism and hydro-mechanical performance of MSWI fly ash-stabilised high plasticity expansive clays. In this study, compressive strength, California bearing ratio (CBR), dynamic cone penetration, shrinkage and swelling, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray micro-computed tomography (micro-CT) tests were conducted to understand the performance of MSWI fly ash for the treatment of high-plasticity expansive clay. The study found that MSWI fly ash reduces swelling potential and increases the ten-day soaked CBR to about 80%. Microlevel analysis showed that hydration reaction, cationic exchange, flocculation, and agglomeration between clay sheets are the key phases in MSWI fly ash stabilisation. In addition, the porosity of the clay reduced from 3.43% to 0.18% after stabilisation with 20% MSWI fly ash. The outcomes from the study provide guidance on using MSWI ash for improving problematic soils while enabling an efficient way to manage municipal solid wastes. [Display omitted] • Application of municipal solid waste incineration ash (MSWI fly ash) to stabilise high plasticity clay was investigated. • MSWI fly ash stabilised samples exhibit negligible swelling and shrinkage. • Even for extreme rainfall cases, MSWI fly ash stabilised samples perform well. • Cationic exchange and hydration are the main stabilisation mechanisms. • Porosity of clay reduced from 3.43% to 0.18% after stabilisation with 20% MSWI fly ash. [ABSTRACT FROM AUTHOR]

• Same CBR-M R relationship cannot be used for different types of soil. • General CBR-M R relationship underestimate or overestimate the M R of subgrade soils. • Surcharge weight has positive impact on the strength properties of clayey soils. This research investigated the effect of surcharge weights on California bearing ratio (CBR), resilient modulus (M R), and swell potential of subgrade soils (A-4 and A-2-4), commonly used by the road construction industry. Nine different surcharge weights ranging from 2.27 kg to 20.75 kg were applied on both soil samples. The swelling was determined after soaking for 96 h, and the ultrasonic pulse velocity technique was used to determine the M R. CBR values for A-4 and A-2-4 soil increased from 3.5-23% to 18.5%-43.6%, respectively with increasing surcharge weight from 2.27 to 20.75 kg. A-4 soil showed decrease in swelling from 1.30% to 0.14% by increasing surcharge weight from 2.27 to 20.75 kg. The M R values of for A-4 and A-2-4 soil also increased from 35 to 135 MPa and 299–525 MPa, respectively with increasing surcharge weight from 2.27 to 20.75 kg. The M R values obtained through the ultrasonic pulse velocity technique, when compared with the CBR values, showed that the general equation of CBR-M R relationship developed by Garber and Hoel in 2015 overestimates the M R values of A-4 soil and underestimates the M R values of A-2-4 soil; Moreover, same CBR -M R equation cannot be used for all types of subgrade soils. [ABSTRACT FROM AUTHOR]

A prototype pier load test program was performed to study the load-deformation and energy-dissipation characteristics of the response of drilled piers under static and dynamic axial loads. The field tests consisted of six fully instrumented drilled concrete piers 61-76 cm (24-30 in.) in diameter and 5.8-9.1 m (19-30 ft) in length. The piers were constructed on a stiff, sandy clay site adjacent to the University of California, Berkeley campus. A dynamic Fundex pile load test (PLT) was performed on each pier, followed by a static-compression or tension test and a second PLT. The field tests revealed that the stiffness and capacity of a soil-pier system depend significantly on the loading rate. For the type of piers and soil considered in the field test, the increase in dynamic stiffness versus static stiffness is approximately 20-40% at almost all displacement levels. The ultimate dynamic capacity increases approximately 30% compared with the static case. The multiple PLTs conducted on the same drilled pier also indicated that a pier may experience up to 50% stiffness and strength degradation when subjected to full load reversal. The test program showed that the PLT is a fast, innovative method to get useful site-specific information for seismic design of the pier foundation. [ABSTRACT FROM AUTHOR]

The principles of irrigation and drainage in cracking soils differ markedly from non-cracking soils, and are not thoroughly understood. This paper presents a conceptual model to simulate water and salt flows in cracking soils of the Imperial Valley, CA, in the presence of ground water that contributes partially to ET demand of crops. A salt reactivity function is introduced in the model to account for mineral precipitation (salt deposition) and mineral dissolution (salt pick up). The conceptual water flow model assumes that surface irrigation water moves into the cracks, infiltrates horizontally to wet the soil profile and a fraction bypasses below the root zone into the shallow ground water and is retained for later crop extraction via upflow. Then, water drains vertically through the soil profile step by step, and root water extractions are calculated. When ET exceeds available water upflow of ground water is calculated. Provision for reclamation leaching before the next crop is also made. The associated conceptual salt transport model involves complete mixing of invading and resident soil water. Salt concentration from ET is subjected to a salt reactivity function to obtain salt deposition of calcite and gypsum to obtain salt concentration after precipitation. This reactivity function is also used in the inverse when two or more waters mix to transform salt after precipitation to salt concentration after ET. The flow of salts follows the water transport algorithum. The model has been applied to a point in the Imperial Valley and observed data from Bali et al. () was used for calibration. Simulated point data from four successive years of alfalfa, reclamation leaching, wheat and lettuce are evaluated in this paper. [ABSTRACT FROM AUTHOR]

Assesses the potential of the reduced-runoff surface irrigation method for clay soils to limit tailwater runoff and evaluates its impact on crop production and soil salinity throughout an alfalfa hay production cycle in Imperial Valley, California. Background on water conservation efforts in the area; Information on related studies; Research methodology; Results and discussion; Summary and conclusions.

The construction of buildings on expansive soils poses considerable risk of damage or collapse due to soil shrinkage or swelling made likely by the remarkable degree compressibility and weak shear resistance of such soils. In this research, rice husk ash (RHA) was added to expansive soil samples in different quantities of 0%, 4%, 8%, 12%, and 16% by weight of soil to determine their effects on the plasticity index, compaction parameters, consolidation performance, and California bearing ratio (CBR)of clay soil. The results show that the use of RHA increases the effective stress and decreases the void ratio and coefficient of consolidation. Adding 16% RHA resulted in the greatest reduction in the hydraulic conductivity, void ratio, and coefficient of consolidation. The void ratio decreased from 0.96 to 0.93, consolidation coefficient decreased from 2.52 to 2.33 cm2/s, and hydraulic conductivity decreased from 1.12 to 0.80 cm/s. The addition of RHA improved the soil properties and coefficient of consolidation due to the high density and cohesiveness of RHA. The results of this study can be used to provide a suitable basis for the treatment of expansive soil to provide improved conditions for infrastructure construction. [ABSTRACT FROM AUTHOR]

• In this study, different types of green cement-free soil stabilizers are proposed. • CKD outperforms cement based on enhancing kaolinite clay soil strength properties. • Silica fume and nano-silica are considered stabilization's activators. • Replacing cement with CKD significantly reduces environmental pollutions. • Nano-silica should not be applied more than 1% in clayey soil stabilization. This investigation aims to assess the nano-silica and silica fume effectiveness on engineering clay soils' characteristics stabilized with cement kiln dust. Laboratory tests, including Atterberg limits, standard Proctor compaction, unconfined compressive strength, and California bearing ratio, were performed. The manufactured specimens were tested 7 and 28 days after preparation to analyze the curing time impacts on soil's strength characteristics. Meanwhile, changes in the chemical and microstructures of soil were observed using scanning electron microscope examination and X-ray diffraction analysis. Subsequently, the mixtures were compared based on eight environmental parameters. To this end, a new environmental index was developed to consider all environmental criteria simultaneously. Afterward, three criteria, including 28-day unconfined compressive strength, environmental index, and unit price, were taken into account as sustainability criteria. Moreover, the gray relational analysis was employed to examine the mixtures' sustainability. The results demonstrated that the amount of 1% nano-silica and 15% silica fume by dry soil weight was an optimum addition content of employed activators for enhancing the CKD-treated soil's geotechnical properties, respectively. Furthermore, the sustainability evaluation revealed that CKD-treated soil was the most sustainable mixture. Given the sustainability effects, nano-silica addition less than 2% and silica fume to the CKD-stabilized soil can lead to propose treated soil with considerably more sustainability than cement. It is essential to highlight that the sustainability of CKD-treated soils containing silica fume was considerably more than that of stabilized soils comprising nano-silica. [ABSTRACT FROM AUTHOR]

• Zinc oxide nanoparticles used as a stabilizer to increase the effect of lime. • The strength of the lime-stabilized soil increased up to a lime content of 6%. • An optimum nano-ZnO content of 1.5% obtained for all three tests. • The increase in the shear strength relates to the cementation and cohesion. • By increasing the curing time, the strength increases indicating enhancement in the formation of CSH over time. The present study investigated the effect of zinc oxide (ZnO) nanoparticles on the geotechnical properties of lime-stabilized silty clay soil using uniaxial compressive strength, direct shear and Californian bearing ratio tests as well as scanning electron microscopy of the improved microstructure of the specimens. The optimum lime content of 6% increased the strength of the soil specimens. Tests on the specimens cured for 7 days showed that their strength increased with an increase in the soil cohesion and cement bonds. The ultimate strength was recorded at the optimum nano-ZnO content of 1.5. The nano-ZnO acted as a filler in the lime and ZnO-stabilized specimens, causing formation of smaller crystals and increasing reactivity, which increased the strength of the soil specimens. SEM micrographs revealed a more homogenous and finer microstructure with a lower surface porosity with the addition of nano-ZnO. [ABSTRACT FROM AUTHOR]

Determines the effect of clay crack flow on tail water quality and crack flow's contribution to salt leaching conducted on farm fields in Brawley, California. Soil sampling; Experiments conducted on each soils; Sampling of surface water.

Uncertainty in application rates of nitrogen (N) limits the effectiveness of nutrient management plans that aim to realize yield goals while minimizing environmental N losses. Measuring N application rates accurately is especially difficult in manure dependent cropping systems. California dairies use both solid manure and process wastewater (PWW) to fertilize forage crop fields. California dairy farmers measure the ratio of N applied to N removed from each crop field, the N Ratio, based on many uncertain measurements of the quantity and concentration of applied N sources. In this study, a Monte Carlo based model was used to propagate the uncertainty of each application measurement to the overall N application rate. Then the Monte Carlo model was used to stochastically vary the N application rate around farmer measured values for two forage fields (A: silty clay soil, B: sandy loam soil) over a 5 year period. The N Ratios and groundwater nitrate concentrations were simulated for 1000 stochastic N application scenarios using the HYDRUS-1D water and solute transport model and the results were compared to monitoring well measurements. Results showed that uncertainty in measurements of N applied in PWW were the dominant source of uncertainty in total N application rates, contributing 64 to 94% of overall uncertainty. N Ratio uncertainty varied widely between harvests. The average upper and lower limits of the 95% confidence interval deviated from the median simulated N Ratio by 0.25 (range: 0.13 to 0.48) and 0.27 (range: 0.12 to 0.55), respectively, among all harvested crops. Simulated groundwater nitrate concentrations were lower than monitoring well measurements by an average of 20 and 2 mg L−1 for Fields A and B, respectively. All simulated and observed nitrate concentrations in groundwater recharge from both fields were three to eight times the federal maximum contaminant level for nitrate as N of 10 mg L−1. Determining and reducing uncertainty in measurements of N applied in PWW is likely the most impactful way to improve accuracy of overall N application rates. Within current measurement and management systems, measurements of N application in manure dependent cropping systems are not accurate enough to identify application rates that will both support yield goals and reduce environmental N losses. Unlabelled Image • Precise nitrogen (N) applications are challenging in manure based cropping systems. • A stochastic model of overall N application combined error from all measurements. • Stochastic HYDRUS-1D simulations quantified error in crop N uptake and N leaching. • Uncertainty in measurements of N applied in dilute manure limit overall accuracy. • Realizing sustainable N application rates requires more accurate measurements. [ABSTRACT FROM AUTHOR]