Effects of Fiber Reinforcement on Strength and Volume Change in Expansive Soils

2000 ◽  
Vol 1736 (1) ◽  
pp. 134-140 ◽  
Author(s):  
Anand J. Puppala ◽  
Chisha Musenda

The results of a research study to investigate the influence of discrete and randomly oriented polypropylene fiber reinforcement on expansive soil stabilization are presented. Two expansive soils were used as control soils in the testing program. Two types of fibers and four fiber dosages (0,0.3,0.6, and 0.9 percent by dry weight of soil) were considered. Both raw and fiber-reinforced clayey samples were prepared and subjected to unconfined compressive strength (UCS), volumetric shrinkage, three-dimensional free swell, and swell pressure tests. Test results were statistically analyzed to investigate the effectiveness of fiber reinforcement on strength, swell, and shrinkage characteristics of expansive clays. Results indicated that the fiber reinforcement enhanced the UCS of the soil and reduced both volumetric shrinkage strains and swell pressures of the expansive clays. The fiber treatment also increased the free swell potential of the soils. Practical implications of the findings and future research directions are discussed.

2018 ◽  
Vol 7 (4) ◽  
pp. 81
Author(s):  
Abdulrahman Aldaood ◽  
Amina Khalil ◽  
Ibrahim Alkiki ◽  
Madyan Alsaffar

This research work study the influence of cyclic wetting and drying on free swell potential of untreated and lime treated expansive clayey soils. Such a study is required to understand the behavior of these soils during wet-dry cycles. Two expansive soils (a polwhite bentonite and a kaolinite) with different plasticity indexes were used in this study. The soil samples were treated with different lime content in the order of (3, 5 and 7% by the dry weight of soil). The lime treated soil samples were cured at 20ºC for 28 and 180 days. The untreated and lime treated soil samples were subjected to four wet-dry cycles. Free swell potential and cracks propagation were studied during lime addition and wet-dry cycles. Results showed that, the free swell potential of untreated soil samples; in general; decreased with increasing wet-dry cycles, and all of the soil samples reached equilibrium after the second cycle. While the cracks propagation increased with these cycles, especially of bentonite soil samples. Larger cracks propagation has been observed in the bentonite soil samples. Lime addition enhanced the free swell potential values of  the two expansive soils and there was a drastic decrease in free swelling potential and cracks propagation of these soils. The beneficial effect of lime treatment to control the swelling values was partly lost by the first wet–dry cycles, and the free swell potential increased at the subsequent cycles.


2018 ◽  
Vol 7 (1) ◽  
pp. 33-36
Author(s):  
Rajeena . ◽  
S. P. Jeyapriya .

Naturally occurring expansive clays show detrimental changes in volume when subjected to variation in water content. It leads to significant damages in foundations that are seated on these materials used for the construction in pavement, bridges especially in light weight buildings. The improvement could be in terms of reducing the swelling and differential settlement or increasing the shear strength of clayey soil. Reinforcing soil using fiber is one of the ground improvement techniques in which fibers are mixed randomly with the soil, in similar fashion to mixing with lime, cement or other additives. It eliminates the potential weak planes and maintains the strength isotropy by random reinforcement. The main objective of this study is to investigate the effect of synthetic polypropylene fibers on the swelling and consolidation characteristics of clay soil. The parameters considered for the study include the swelling pressure, swell potential and consolidation characteristics. Polypropylene fiber with aspect ratio (l/d) 12 is varied at 0%, 0.1%, 0.25%, 0.50% and 0.75% by dry weight of the soil is used as reinforcement. The swell potential(S%) and the swelling pressure(P) decreased with the addition of fiber. From the experimental results, 0.5% of polypropylene fiber is considered to be optimum. The results also revealed that the rate of heave formation is very less compared to that of unreinforced soil. From the consolidation test, it was observed that compression index, co efficient of compressibility and co efficient of volume change are 0.22, 0.8 mm2/N and 0.48mm2/N at the optimum fiber percentage.


In geotechnical engineering practice, expansive clay is widely encountered. It poses to be a serious problem especially in metropolitan areas by virtue of its low strength and high compressibility. Further, these soils undergo significant change in volume as a consequence of variation in the moisture content. Soil stabilisation is one such technique practiced to improve the shear strength and to control volume change in expansive clays. Among various stabilisation techniques, Lime has been found to be an effective stabilizer, which appreciably alters the properties of expansive clay. Further, the reaction will be very effective on the usage of nano size particles in the stabilisation of expansive clay. At the first step, the effect of lime stabilisation on geotechnical properties such as grain size distribution, index properties, compaction characteristics, differential free swell and unconfined compressive strength of expansive clay was studied by varying percentages of lime. At the second step, the effect of nano- lime on the properties of optimum soil-lime mixture was investigated. The percentage of nano- lime is varied from 0.25- 1.0% by dry weight of the soil. The measured results show that the use of nano- lime in expansive clay significantly improves its strength and reduces swell behaviour resulting in reduced pavement thickness.


2020 ◽  
Vol 28 (4) ◽  
pp. 1-7
Author(s):  
B. J. S. Varaprasad ◽  
Jayaprakash Reddy Joga ◽  
Suryaprakash Reddy Joga

AbstractA useful method for the disposal of waste from an incineration plant is to reuse it for geotechnical and civil engineering applications. The primary objective of this study concerns the reuse of local incinerated ash from municipal solid wastes in soil stabilization. Municipal Solid Waste Incinerated Ash (MSWIA) is blended with soil in various combinations and tested for its Atterberg limits, unconfined compressive strength (UCS), California Bearing Ratio (CBR), and Free Swell Index (FSI). A 1-D Consolidation Test was conducted, and changes in the soil during the test were examined by a scanning electron microscopic (SEM) analysis. The test results showed that there are increments in the UCS and CBR values with the reductions in the FSI, swell pressure, and swell potential of the treated soils.


2017 ◽  
Vol 3 (8) ◽  
pp. 610 ◽  
Author(s):  
Sadam Hussain

Swelling of expansive clays is one of the great hazards, a foundation engineer encounters. Each year expansive soils cause severe damage to residences, buildings, highways, pipelines, and other civil engineering structures. Strength and deformation parameters of soils are normally related to soil type and moisture. However, surprisingly limited focus has been directed to the compaction energy applied to the soil. Study presented herein is proposed to examine the effect of varying compaction energy of the engineering properties i.e. compaction characteristics, unconfined compressive strength, California bearing ratio and swell percentage of soil. When compaction energy increased from 237 KJ/m3 to 1197 KJ/m3, MDD increased from 1.61 g/cm3 to 1.75 g/cm3, OMC reduced from 31.55 percent to 21.63 percent, UCS increased from 110.8 to 230.6 KPa, and CBR increased from mere 1 percent to 10.2 percent. Results indicate substantial improvement in these properties. So, compacting soil at higher compaction energy levels can provide an effective approach for stabilization of expansive soils up to a particular limit. But if the soil is compacted more than this limit, an increase in swell potential of soil is noticed due to the reduction in permeability of soil.


2020 ◽  
Vol 38 (6A) ◽  
pp. 801-812
Author(s):  
Mohammed A. Al-Neami ◽  
Falah H. Rahil ◽  
Yaseen H. Al-Ani

For any land-based structure, the foundation is very important and has to be strong to support the entire structure. In order for the foundation to be strong, the soil underneath it plays a very critical role. Some projects where the soil compacted by modifying energy is insufficient to achieve the required results, so the additives as a kind of installation and reinforcement are used to achieve the required improvement. This study introduces an attempt to improve cohesive soil by using Polypropylene Fiber instead of conventional kinds used in soil stabilization. Three different percentages (0.25%, 0.5%, and 0.75% by dry weight of soil) and lengths (6, 12, and 18) mm of fiber are mixed with cohesive as a trial to enhance some properties of clay. The results of soil samples prepared at a dry density at three different water conditions (optimum water content, dry side, and wet side) showed that the increase of the percentage and length of polypropylene fiber causes a reduction in the maximum dry density of soils. Soil cohesion increases with the increase of PPF up to 0.5% then decreased. The length of Polypropylene fiber has a great effect on the cohesion of soil and adding 0.5% Polypropylene fibers with a length of 18mm to the soils consider the optimum mix for design purposes to improve the soil. Finally, the soil reinforced by PPF exhibits a reduction in the values of the compression ratio (CR) and accelerates the consolidation of the soil.


2013 ◽  
Vol 649 ◽  
pp. 217-222
Author(s):  
Mircea Aniculaesi ◽  
Anghel Stanciu ◽  
Irina Lungu

The main factor that governs the shrink-swell behavior of expansive soils is the change in water content and the amount and type of clay size in the soil. In this paper, the research made are focused in reducing the swell potential of the studied clay by improvement in two ways: first by stabilization with a combination of eco-cement and Portland cement (1:1 ratio), and second by synthetic fiber reinforcement. A series of laboratory tests were performed on synthetic fiber reinforced expansive soil to determine the potential for using synthetic fiber reinforcement to reduce swell potential of soils. Specimens tested were prepared at two different synthetic fiber dosages 0.2% and 0.4%. The treatment of expansive clay with 5% eco-cement and 5% Portland cement revealed a better improvement of the swelling potential. The synthetic fiber reinforcement of the expansive soil doesn’t lead to a significant improvement of the soil.


2020 ◽  
Vol 195 ◽  
pp. 02023
Author(s):  
Rafael Baltodano-Goulding

Expansive soils can present an unsaturated state where the soil exhibits volume changes due to both moisture variations that change the state of stresses and moisture variations that interact with its mineralogical characteristics. These special kinds of soils are normally clay type soils that had suffered isomorphous substitution creating a charge imbalance of the clay mineral crystals. This imbalance promotes the trapping of water molecules by the clay particles. It is commonly assumed that a high plasticity index can be an indication of a clay´s high swell potential. However, in arid regions, it is possible to have clays with very high swell potential and low plasticity indexes due primarily to a decrease in the state of effective stress, which will produce expansion of the material. It is common practice to study the swelling characteristics of these soils by performing free-swell tests that can be used for designing removal and replacement backfills or drilled shafts. However, the expansion percentage obtained from this type of test is actually in terms of total stresses and not in terms of effective stress, as it is commonly assumed. Moreover, it is highly dependent on the magnitude of the preload used. This paper presents some efforts made to obtain the swelling part of the curve in terms of effective stresses from the traditional free-swell test. It was hypothesized that the shape of this curve could either have the shape of the rebound curve from a saturated consolidation test or a shape similar to the soil-water characteristic curve.


2019 ◽  
Vol 5 (3) ◽  
pp. 624 ◽  
Author(s):  
Sarah Adnan Hussein ◽  
Haifaa Abd Al-Rasool Ali

Current research main aim is to study the effect of adding polypropylene fiber (PPF) on the behavior of expansive soil to reduce the swelling as percentage (0.5, 1 and 2%) of the weight of dry soil. Expansive soil used in this research was prepared artificially by mixing Ca-based bentonite from geological survey and mining company with sandy soil brought from Karbala city as percentage 80% bentonite to 20% sand of dry weight. Multiple laboratory tests have been carried are (Unconfined Compression Test, One-Dimensional Consolidation Test, Swelling Test, Sieve Analysis and Cycle Swell Shrink Test). A conventional odometer cell was modified to allow the study of swell- shrink cycle test to be carried out under controlled temperatures and surcharge pressure. The results showed that the increase in percentage of (PPF) led to decrease the swelling and to increase the unconfined compression strength. The wetting and drying results of (PPF) showed that with continuous cycles the effect of (PPF) keeps on reducing the swelling and the 2% of (PPF) produces less ratio of swell - shrink, which has obtained higher than 57 % in the improvement factor of swell and shrink.


2019 ◽  
Vol 8 (4) ◽  
pp. 9198-9202 ◽  

In this study the investigational results obtained in the laboratory on expansive soils treated with low-cost materials i.e, lime and press mud are used. It is conducted to check the signs of progress in the properties of expansive soil with Press Mud and lime in varying percentages. The test results such as the Unconfined compression test, liquid limit, plastic limit, shrinkage limit, hydrometer analysis and pH obtained on expansive clays mixed with different proportions of lime and press mud are presented and discussed in this work. From the demonstrated result the addition of Press mud with lime in soil stabilization improves the Unconfined Compressive strength of the soil when compared to lime stabilization alone. The index properties of the soil have also been marginally improved due to the addition of Press mud as an admixture.


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