Higher California Bearing Ratio Values Research Articles

Modeling the service life of temporary airfield operational surfaces under multi-pass aircraft trafficking

Expeditionary Airfield (EAF) surfacing systems are designed to create temporary aircraft operating surfaces. Modeling the service life of EAF surfacing systems including the matting system, aircraft, and subgrade, has historically proven difficult, exacerbated by variability between systems and the multitude of mechanisms that can constitute failure. The study presented herein outlines the development and implementation of a performance modeling approach that includes a multi-scale scheme that accounts for local characteristics of the connection points of the EAF matting system, coupled to the global characteristics of the matting array to predict cyclic passes to failure. Finite element studies were conducted for an EAF surfacing system brickwork configuration subjected to aircraft strut loads over varying California Bearing Ratio (CBR) subgrades to calibrate a transfer function to full-scale trafficking experiments. The proposed framework is then used to predict the rate of subgrade deformation for additional lay patterns, which successfully ranked the performance of each relative to full-scale trafficking experiments. An approach is proposed to couple the rate of subgrade deformation with local finite element models to capture increasing joint damage as permanent deformation accumulates, and supplemented by a variable amplitude cycle counting and damage accumulation algorithm that yields reasonable agreement with full-scale experiments while capturing the transition in failure mechanisms at higher CBR values. The results of the study presented herein captures the propensity for end connector and subgrade failure over a range of subgrade CBRs and shows promise for a broader performance framework that can be extended to other EAF surfacing systems, aircraft types, and specific matting lay patterns.

The Effect of Soaking on CBR Values in Soft Soils Stabilized with Stone Ash and Sand

Constructing in the soft soil is necessary to improve. The improvement of soft soil by mixing natural materials, namely stone ash and sand, reduces the impact of environmental damage when using chemical additives. Variations of materials mixture were 0%, 5%, 10%, 15%, and 20%. To determine the strength of the soil that has been mixed with natural materials, a test called the California Bearing Ratio (CBR) is carried out. The CBR laboratory test illustrates the conditions that will occur in the field. This CBR test was carried out using soaked and un-soaked methods. For testing by soaking, mixed variations of 0% and 5% obtained a low CBR value. The highest was 10% mixed variation and decreased to 15% and 20%. The CBR test without soaking had the highest CBR value at 5% mixture variation and the lowest at 0%. Adding a mixture variation above 5% causes the CBR value to decrease slowly. The results of the tests show that soaking the soil makes the soil condition saturated with water so that the resulting CBR value becomes very low.

Bearing capacity of Percut Sei Tuan clay stabilized with palm shell ash

Improvements to the bearing capacity of the soil have been carried out and developed at this time, one of which is the stabilization of clay soils. There are several alternatives to solve low soil bearing capacity, one of which is using geo-synthetic materials but has a weakness in terms of high cost. Another alternative is to add palm shell ash as a stabilizing agent. The effect of adding palm shell ash has not been thoroughly studied, so further research is needed. The material added is palm shell ash with a variation of 0%, 4%, 8%, 10%, and 12% in each test. The tests carried out in the laboratory were water content (w), specific gravity test (Gs), Atterberg limit test, sieve analysis (sieve analysis), soil compaction test, and CBR (California Bearing Ratio) test. The CBR test was carried out by curing the soil for 1, 3, 5, and 7 days with a mixture of palm shell ash before compaction. The soil in this study belongs to the A-7-5 group. The CBR (California bearing ratio) value increased with the increase in the palm shell ash percentage in the mixture after curing the soil. The highest CBR value was in the variation of 12% palm shell ash with a 7-day curing period of 6.92% with a soil bearing capacity of 5.06.

A Study on Crushed Coconut Shells as Stabiliser to Soil

Road construction over soft subgrade soil is a major issue affecting cost and scheduling of highway projects. Many techniques have been conducted to strengthen the highway soil subgrade. One of them are using additives such as coconut shells, rice husk ash, stone dust, and fly ash. to strengthen the soil. The strength of the subgrade is commonly expressed as California Bearing Ratio (CBR). In this study, the crushed coconut shells (CCS) of 65 mm to 10 mm ranges of size was mix with the laterite soil. A series of unsoaked CBR test were conducted with an addition of 1, 2, 3, 4, 5, 6, 7 and 8% of CCS to determine the strength of the stabilized laterite soil. The laterite soil is classified as sandy SILT of high plasticity (MH) according to British Standard Classification System (BSCS). The results show that the CBR values of the stabilized soil increase with an increasing percentage the CCS. The stabilized soil with 4% CCS is the highest CBR value, 27.5%. The CBR% then decreasing as further additional of CCS %. The stabilised soil with an 8% CCS content had the lowest CBR value at 5.25%, which is lower than the unstabilised laterite soil’s CBR value. It is concluded that the additions of CCS have greatly improved the soil strength with the increment increase of CBR value. Hence CCS has a good potential for upgrading the CBR value of subgrade soil.

Geotechnical Investigation and Microanalysis of Black Cotton Soil Amended with Guar Gum and Polyethylene Terephlate Fibre

Polymer-based soil stabilization has fascinated substantial interest in the field of research intending to gain a better knowledge of the anticipated soil characteristics after polymer treatment. Intricate research on the engineering performance of expansive soil which is highly challenging due to its swell and shrink nature based on variations in water regime, treated with guar gum, a biopolymer made from gum along with polyethylene terephthalate fibre, one of the most generated plastics, resulting in massive waste, is accomplished through this entire experimental investigation. Comprehensive geotechnical tests and microstructural examinations have been performed to optimize the guar gum for enhancement of soil properties and to comprehend the interactive mechanism with the soil. The biopolymer at dosages 0.5%, 1%, 1.5%, and 2% was added to the soil. Polyethylene terephthalate Fibre with an aspect ratio of 28 is used with the soil at an increment of 0.4% up to 1.6%. The optimum dosage of biopolymer was mixed with polyethylene terephthalate fibres, and its effect on geotechnical properties was carried out separately. From the experimental investigations, it is comprehended that there is a reduction of 27% and 40% in plasticity index and swelling, respectively, at an optimum dosage of 0.5% GG when compared to untreated soil. Furthermore, there is a marginal decrease of 24% in dry density, 310% increase in CBR value, and 33% reduction in compressibility of the soil treated with 0.5% GG with 1.6% PET fibre, when compared to virgin soil. The present study was conducted to improve the subgrade soil strength beneath the pavements. The usage of biopolymer and its combination with polyethylene terephthalate fibres shows that there is a considerable improvement in modifying the geotechnical properties, and its coupling effect contributes to higher California bearing ratio values. According to the outcomes of this investigation, it is proven that biopolymer and polyethylene terephthalate fibre is definitely an alternate to conventional materials. The present study was conducted to improve the subgrade soil strength beneath the pavements.

Lateritic Soil Improvement Using Lime and MOFIC

This study investigates the effects of mucilage from Opuntia ficus-indica cladode (MOFIC), a bio-modifier, on Lime-stabilized Lateritic soil's durability and index features. Specifically, this research assessed the alterations to the Atterberg limits, compaction characteristics, California bearing ratio (CBR), index values and the unconfined compressive strength (UCS) properties of the soil samples and the stabilised samples through laboratory experiments. Lime + MOFIC was added to the soil at 0%, 2%, 4%, 8%, 12% and 16% wt (%) of soil. The result confirms alteration in the index and strength characteristics of the soil upon the addition of MOFIC to the Lime-treated Lateritic soil. The geotechnical characteristics of the soil improved from a subgrade soil to a subbase material upon the addition of 2% of LIME + MOFIC; with the presence of Lime + MOFIC at 2–4%, the bearing capacity of the soil improved from a subgrade material to a subbase material according to the Nigerian General Specification. The highest CBR value in Lime-stabilised was 56%, while the CBR value of Lime + MOFIC-stabilised soil was 70%. This represents a 20% increment in CBR. The presence of polysaccharides in MOFIC enhanced the soil binding attributes of the Lime and hence accelerated the strength properties of the soil. The promotion of green construction and reduction in environmental impacts of using Lime motivates the use of MOFIC in the study. Based on the result of the experimental research, MOFIC is thereby recommended as an eco-friendly alternative for enhancing engineering properties of pavements interlayers. The addition of MOFIC improved the index and strength properties of pavement interlayer material in road construction.

Improvement of bearing capacity of clay that is stabilized with bamboo charcoal powder

A building construction must be built on the soil with good bearing capacity. Increasing of bearing capacity of the soil can be done by adding material of soil stabilizer. Bamboo charcoal powder was used in this study as a stabilizer for clay. The percentage of the addition of bamboo charcoal powder to clay soil in this study was 5%, 10%, and 15%. The California Bearing Ratio (CBR) test was carried out on original clay and stabilized clay to determine the bearing capacity of the soil. The results of this study as showed an increase in the CBR value of each percentage of the addition of bamboo charcoal powder. The highest CBR value was the addition of 15% bamboo charcoal powder with an increase in the CBR value of the original clay by 82.87%. The increase in the CBR value of the soil indicates that there is an increase in the bearing capacity of the clay due to the addition of bamboo charcoal powder

Pemanfaatan Limbah Penambangan Bukit Kapur Untuk Stabilisasi Tanah Lempung ( Clay )

Soil stabilization by adding new materials is one of the alternatives to soil repair that can improve the properties of the soil, namely by mixing new materials and soil that is then compacted. Waste left over limestone hill mining,among others in the form of materials with various sizes of granules. This study aims to review the effect of the addition of limestone hill mining waste material on the density and value of the California Bearing Ratio (CBR) of clay soil. Tests conducted only on a laboratory scale with variations in the increase in limestone hill mining waste levels are 0%, 5%, 10%, and 15% to the total weight of the mixture. Laboratory CBR testing is performed under optimum water content conditions. The results showed that the stabilization of soft soils using limestone hill mining waste, can increase the density and value of soil CBR. The most optimal level of use of limestone hill mining waste and which provides the highest CBR value is for the addition of 5%of limestone hill mining waste with a CBR value of 26.5%.

Performance of granular road base and sub-base layers containing recycled concrete aggregate in different ratios

ABSTRACT In this study, the usability and performance properties of recycled concrete aggregates (RCA) as granular road base (GRB) and granular road subbase (GRSB) material were investigated. A natural aggregate and the RCAs obtained from concretes with three different compressive strength and mixtures created by adding the RCAs to NA at the ratios of 25, 50 and 75% were used. Physical properties, modified Proctor, resilient modulus, permanent deformation, California bearing ratio (CBR), and permeability tests were carried out on all mixtures. Resilient modulus values (Mr) were obtained using three different resilient modulus models. The highest Mr value among pure RCAs was observed for RCA2 (average of 200 MPa). For the mixture samples, the highest Mr values were obtained in the mixtures containing RCA1 (average of 250 MPa). The minimum of permanent deformation value (ϵ p ) for the mixtures was obtained when the ratio of the RCA1 in the mixtures was 50% (ϵ p = 0.238%). The obtained CBR values were not related to the Mr values, and the highest CBR values were found for the pure RCAs (average of 126%). High permeability coefficient values (average of 9.973×10−6 m/s) were obtained for the RCAs. As a result, it was more appropriate to blend the RCAs with the natural material rather than to use them in pure form. In general, it was appropriate to use 50% of RCAs in the mixtures. It was observed that if concrete compressive strength is as high as in RCA1 (18.5 MPa), RCA can be used even in the mixture at a ratio of 75%.

Performance Characteristics of Road-base Containing Mixed Steel Slag and Cathode Ray Tube Glass

One way to promote sustainability in construction is through the preservation of natural resources and utilization of recycled wastes. This paper describes a laboratory study on the use of steel slag and cathode ray tube (CRT) glass for road base pavement layer. Measurements of the physical and mechanical characteristics of each sample are taken to evaluate the effectiveness of using these materials in road base pavements. The laboratory evaluation comprised of Los Angeles abrasion value (LAAV) test, California bearing ratio (CBR) test and performance characterization; the unconfined compression strength (UCS) and indirect tensile strength (ITS) tests were also performed. The values for LAAV are satisfactory, indicating that the steel slag and granite mixtures have adequate resistance and abrasion for use as road base pavement aggregates. The higher percentages of steel slag in the mixture produced higher CBR values for both the soaked and unsoaked mixtures. Test results also show that the mixtures containing up to 70% steel slag and 15% CRT glass meet the standards requirements. Results of the UCS and ITS tests for performance characterization showed that the performance of the sample mixture was enhanced significantly upon incorporating a higher percentage of steel slag in the mixture. The lab test results showed that the mixture composing of granite, steel slag and CRT glass is a suitable alternative made from recyclable materials, for use in road base pavement layer.

The stabilization of soft soil using admixture of palm oil boiler ash and MATOS

Banjarmasin has an alluvial area with soft soil thickness of 28-42.4m. Therefore, the land is not structurally feasible for construction due to the low California Bearing Ratio (CBR). One of the solutions used to overcome this problem is soil stabilization. This study aims to examine the effect of adding palm oil boiler ash and MATOS in accordance with CBR value to stabilize soil conditions. The laboratory CBR method was used to determine the original and stabilized conditions of the soil. The initial and stabilized soils used an admixture of 2% MATOS as an additive and palm oil boiler ash with percentage variations of 6%, 9%, and 12% of the dry weight soil. This was further kept for 7 days curing before being tested. The result showed that the highest CBR value is obtained at the variation of 6% palm oil boiler ash + 2% MATOS with an increase in CBR value of 7.542% from the original soil condition.

SOIL STABILIZATION AND IMPROVEMENT OF MARINE CLAYS USING CEMENT AND LIME IN A MARSHLAND

This study assesses the stabilization of marine clay soil using cement and lime to improve on the subgrade material. The tests conducted include: the natural moisture content, specific gravity, sieve analysis, Atterberg limit, compaction and California Bearing Ratio (CBR). The types of stabilization used were mechanical and chemical. The results obtained were classified using AASHTO classification system and based on the results the soil corresponds to group A-6 soils. The highest CBR values of 33.24% and 424.35% were obtained at 20% cement content for unsoaked and soaked and for lime the highest CBR values were 5.07 and 10.46 for 11% lime content for both unsoaked and unsoaked. Based on the results obtained, the addition of cement and lime to clay soil in the presence of water improved the CBR values for soft clay stabilization for highway construction with low traffic volume. It is therefore concluded that the addition of cement and lime to clay soil improved the bearing capacity and the maximum dry density of the clay soil. Further research should be carried out to examine the effects of industrial by-products on effective clay soil stabilization.

Bearing Capacity Improvement of Expansive Soil: Stabilization with Cement and Iron Oxide Additive

This research is intended to increase the bearing capacity and durability of expansive clay subgrade with Portsoil Composite Cement (PCC) and Iron Oxide additives. Using two variants of the stabilization material composition; composition-1 is soil with 5% of PCC, and composition-2 is soil with 5% PCC + 0. 04% Iron Oxide). Tests include swelling potential, durability, and CBR (California Bearing Ratio). The test results showed that the performance of stabilization using composition-2 was able to reduce swelling potential on day 3 by 94. 44% (14. 44% greater than using composition-1), reducing the potential for volume increment by 94. 15% (greater 15. 02% compared to using composition-1) and weight to 93. 31% (15. 32% greater than using first). The highest CBR value in the 3 wet-dry cycle periods was nature soil 2. 32%, using composition-1 reached 25. 26%, while using composition-2 reached 36. 93% (11. 67% greater than CBR value using composition-1). That the addition of 0. 04% Iron Oxide to PCC-soil stabilization can significantly improve cement performance for expansive clay stabilization as a road subgrade.

Effect of Graded Oil Palm Kernel Shells on Compaction of Weak o Problematic Sub-Grade Soils

AbstractSub-grade is the ultimate load bearer of vehicular traffic load in a pavement structure. A weak sub-grade or problematic soils require some improvements like soil stabilisation, soil reinforcement and/or capping of the sub-grade layer. These sub-grade improvement methods increase the total project cost because non-local materials such as cement, geosynthetics and hydrated lime are commonly used. The use of graded oil palm kernel shells (OPKS) which are local, cheaper and readily available as a soil improvement material was assessed in this research. This assessment was done by mixing sub-grade material with 2.8 mm, 5 mm and 10 mm graded OPKS. 10 %, 20 % and 30 % of each graded OPKS was added separately to the soil to form nine composite materials. These composite materials including the natural soil were tested for their California Bearing Ratio (CBR) values. The investigation proved that the composite made of 20 % 2.8 mm graded OPKS yielded a soaked CBR of 23.5 % which is a 197.47 % increase in soaked CBR compared to that of the natural soil. The soaked CBR samples of the graded OPKS composite materials absorbed lesser amounts of water in comparison to that of the natural soil. This behaviour implies that some capillary force created at un-soaked condition in the composite materials was preserved; therefore, the composite materials generally have higher CBR values than the natural soil. Keywords: Oil Palm Kernel Shells (OPKS), Problematic Soils, Lightweight Aggregate (LWA)

Ground improvement using waste shell for farm roads and embankments

The bearing capacity of subgrade soil plays an important role in the performance of agricultural earth structures such as farm roads or earth embankments. It also has a strong link to the budgeting efficiency of those agricultural earth structural projects. One way to improve the subgrade of soil is by using stabilised material in the subgrade layer. Shell husk waste is one of the construction materials that can be used as a substitute for the subgrade layer. The utilisation of shell husk waste has several purposes such as protecting natural aggregate and preventing problems that arise from the untreated abandoned shell husk waste. In this research, shell husk waste was used as farm road subgrade material. To understand the bearing capacity of soil specimens, a series of California bearing ratio (CBR) tests were carried out by using several types of subgrade layers containing different percentages of shell husk in the soil-shell husk mixture. Three types of subgrade layers were used: subgrade upper layer, subgrade bottom layer, and subgrade double layer, containing 0 (control), 10, 20, and 30% shell husk in soil-shell husk mixture. The experimental results showed that the addition of shell husk in soil leads to improvement in the CBR values of the ground as compared to control specimens. It was further revealed that by increasing the percentage of shell husk in the soil-shell husk mixture, the CBR value was improved significantly. The highest CBR value was achieved by using subgrade upper layer with a 30% shell husk in soil-shell husk mixture. The results obtained are encouraging with regard to the utilisation of the waste shell husks for improving the bearing capacity of agricultural earth structures such as farm roads and earth embankments.