Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Interpretation of Rice Husk Ash on Geotechnical Properties of Cohesive Soil

Grytan Sarkar
Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh

Md. Rafiqul Islam
Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh

Dr. Muhammed Alamgir
Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh

Dr. Md. Rokonuzzaman
Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh

Abstract/ Executive Summary:

This paper demonstrates the effects of rice husk ash (RHA) on the geotechnical properties of soil in stabilized forms specifically strength, workability, compaction and compressibility characteristics. Therefore, laboratory tests such as compaction, Atterberg limits, free swell index, unconfined compressive strength, direct shear and consolidation tests for different percentages of RHA content and original soil samples were performed. These test results show that the soil can be made lighter which leads to decrease in dry density and increase in moisture content and reduced free swelling and compressibility due to the addition of RHA with the soil. Besides that the unconfined compressive strength and shear strength of soil can be optimized with the addition of 10% RHA content.

Keywords: RHA, Index Properties, Strength properties, Swelling and consolidations.

Location:

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Rice husk, Ash, Soil Physical Properties

Objectives:

A mini incinerator has been designed by Ahmed, et al. (1993) in BCSIR laboratory, Dhaka to produce RHA and a comparative study has been carried out in relation to compressive strength and setting time of the pozzolana cement prepared by using this ash and boiler ash.

Methodology:

Specification of Soil Nearly greyish silty clayey soil was used in this study, collected from Khanjahan Ali Hall at Khulna University of Engineering & Technology (KUET) in Khulna, Bangladesh. The collected soils was hard and it was pulverized manually by hammer. Then the soils were screened through the sieve of 4.75 mm apearture before preparing the specimensfor testing. According to the AASHTO classifiation systems, the soil is classified as A-7-6 and acoording to the Unified soil classification sytems, soil is CL (Clay with low plasticity). Specification of RHARHA was prepared by simply burning ricehusk, collected from the locally available mill. In this arrangement, rice husk were kept into a Steel box of 1.5m x 1.5m in dimensions. Five thermocouples with a connecting data logger were used for measuring the burning temperature. Briquettes were usedas fuel to start and maintain fire. The produced RHA contains about 93% silica which is a key factor for improving the properties of soil. Preparation of testing samples The collected soils and ash contents were oven-dried at 105⁰C overnight to remove moisture and repress microbial activity. Then the oven dried samples were mixed throughly by hand in a large tray in a dry state. Combination scheme of soil samples Samples ID Samples Description Soil (gm) RHA (gm) % Ash content Original soil 4000--0R140002005R240003007.5R3400040010R4400050012.5. Testing procedure To determine the workability, compressibility, strength and compaction characteristics of treated and original soil samples several tests were performed in the laboratory. Before conducting the compaction test, thenon-treated and RHA treated soils (5, 7.5, 10% and 12.5% RHA content) were mixed with water for about ten minutes by hand. After that, the mixtures were put into polyethylene bags and mixing was continued by shaking, overturning and pressing the bag to squeeze out the air from the soil voids. In the similar way, different amount of water contents were added to the different soil samples and mixing were done as described before to obtain the optimum moisture content and maximum dry density. A series of standard proctor tests on non-treated and RHA treated soils were conducted according to ASTM D 698. Specific gravity of original and ash treated soil samples were determined according to ASTM D854. Consistency of the original and treated soil samples were determined by Atterberg limit test (ASTM D-4318). The effect of shrinkage of fine grained soils are of considerable significance to cause serious damage to small building and highway pavements. Free swell index of soil samples were determined as per as IS: 2720(Part-40). Ten grams of soil samples were put into two 100ml glass cylinders and the remaining volumes of the cylinders were filled with distilled water and kerosene respectively. After keeping it overnight the volume of soil in each cylinder was measured and from this volume free swell index of soil was determined from the equation shown in below.

Free swell index (%) = Volume of in distilled water Volume of in distilled ker osene/Volume of in distilled Ker osene x100

All thetest specimens for strength and consolidation tests were prepared by compacting the soils mixed with RHA (0, 5, 7.5, 10% and 12.5%) in the standard compaction molds at the corresponding optimum moisture content which has been determined already. The specimens were demolded after completion of compaction and samples of different size were prepared as per requirement for performing the selected test in uncured condition. The uncured unconfined compressive strength of the cylindrical specimens (36 mm diameter and 71 mm length) was determined according to ASTM D-2166. Drained shear strength parameters(c & φ)were determined by direct shear test (ASTM D 3080) of the compacted uncured soil specimens (60mm diameter and 25 mm height). Settlement characteristics of soils were determined by performing consolidation test (ASTM D-2435) on the samples of 63.5 mm diameter and 25 mm height.

Source of Information: Global Journal of researches in engineering, Civil And Structural engineering; Volume 12 Issue 2 Version 1.0 February 2012; Online ISSN: 2249-4596 & Print ISSN: 0975-5861

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In this study the effect of RHA on the geotechnical properties of cohesive soil are investigated and it can be concluded that there is an improvement of all the geotechnical properties of RHA treated soil. It was observed that the maximum dry density of soil decreased with the addition of RHA because of thelower specific gravity of RHA. of the pozzalonic action of RHA and soil, which needs more water. Moreover, the value of liquid limit and plastic limit also increased with the increasing percentage of RHA whereas the value of plasticity index shows different characteristics. Increasing the amount of RHA cause a decrease in shrinkage limit as well increase in shrinkage ratio which improves the shear strength characteristics of soil. The pozzalonic behavior of RHA makes the RHA treated soil coarser than original soil samples due to the agglomerations of RHA and soil particles. This improvement changes the naming of soil from clay to silt. The free swell index test result shows a negative relationship with RHA as it decreased with the increase of RHA content which reduced the possibility of crack formation on the surface of foundation. The optimum unconfined compressive strength was obtained for 10% of RHA content. The best shear strength envelope of soil was obtained for 10% of RHA. The cohesion of soil shows an increasing order for first 5 % of RHA and after that this value decreases with the addition of RHA whereas the angle of internal friction shows a positive relationship with RHA content. From the consolidation test result, it can be concluded that the values of compression index decreased with the increases of RHA and the initial void ration shows positive relation with RHA.

Knowledge Management: Journal