The roads in the city of Nasiriya in southern Iraq suffer from problems that occur as a result of repeated vehicle loads or due to weak soil and lead to losing their performance and being out of service despite their construction for a very short period. The use of chemical additives to improve the subgrade widely worldwide and give strength and durability to the weak soil while the possibility of using chemical additives for the substrate in Al-Nasiriya is still practically limited. The study aimed to verify the use of chemical additives (cement, lime, and ferric chloride) and to know their effect on the properties of Al-Nasiriya soil. The results showed a clear improvement in the UCS test when using chemical additives, and then the optimal percentages of additives were determined and were 9%, 10%, and 2% respectively, in addition to knowing the effect of the curing period (1, 7 and 14) days on the results of the test. For the other tests (maximum dry density, CBR, swelling, and optimum moisture content) were verified for the optimal chemical percentages and it was observed that the CBR values increased and the swelling values decreased after treatment and soaking in water for all additives, while the compaction parameters had a different behavior between the materials additive used.
Chemical additives were used in this research to improve the properties of the road subgrade layer. Cement, lime, and ferric chloride were used. Laboratory tests such as unconfined compressive strength, consistency limits, and wheel truck test were conducted. The results showed that adding these chemicals to the soil increases the ability of the soil to work, its resistance, and its durability. The optimum percentage of chemical additives that is suitable for the addition to the soil of Al-Nasiriya city were 9 %, 10 %, and 2 % corresponding to cement, lime, and ferric chloride, respectively. According to the unconfined compressive strength test and with increase curing period, which gave good results in improving the strength of the soil. As for the consistency limits, all additives reduced the liquid limit and plasticity index and increased the plastic limit, according to the wheel track test, at 10,000 passes the Rutting depth was 32 mm for natural soil, also the depths were (14, 19, and 17 mm) with chemical additives, respectively.
Recently, the application of geosynthetics in the reinforcement of weak subgrade is expanded dramatically. However, selection of the geo-material that fits site conditions and soil type is crucial to achieving the success of the overall performance of such improvement. Also, the road life and cost construction are significant keys for evaluating this type of ground treatment. This paper presents an overview of the subgrade strengthening with geosynthetics to acquire a better understanding of the technique and to provide a clear guide for transportation and geotechnical engineers. The rutting failure along with its main causes are highlighted briefly. The types of geosynthetics, their applications and functions are also listed. Besides, the effect of soil type and properties on the efficiency of geofabrics-subgrade reinforcement are presented. Moreover, the effectiveness of geosynthetics on the road’s life and construction costs are discussed. Findings of the reviewed studies referred to the contributions of the technique in strengthening the soft subgrade, extending the service road life, reducing the construction cost and reducing the associated rutting deformation. Most studies presented in this paper have proven the efficiency of utilizing geosynthetics in the pavements to minimize the vertical stress in the subgrade under the wheel path. However, the influence was related to the geo-material type and site-specific conditions.
The highways in Iraq need to be reviewed and evaluated urgently because of the poor condition of the roads, the lack of maintenance and the lack of services. This study provides specific criteria for assessing the condition of the road and determining the level at which it needs to intervene and perform maintenance. The study also proposes a new system for road management in Iraq, which contributes to providing the necessary funds for the continuity of maintenance work and the provision of services that contribute to the convenience of road users. Six criteria were determined to evaluate the efficiency of the road by conducting a survey of the opinions of engineers and academics specialized in the field of roads and these criteria are (Safety, Road Condition, Geometric Design, Cost, Services and Environment) and using the Statistical Product and Service Solutions Program (SPSS) a model was found that links road quality with these criteria. The Toll Road System (TRS) was proposed to collect tolls from road users. This system was compared with the current system in road management in Iraq using the Analytical Hierarchy Process (AHP) program, and the TRS was considered satisfactory by 75% of the sample surveyed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.