Stabilization of Lateritic Soil with Mahogany (Hardwood) Sawdust Ash

Most naturally occurring laterites possess poor engineering properties despite their extensive uses for filling and subgrade materials. Few works have been reported on the use of mahogany sawdust ash (MSA) for the stabilization of lateritic soils. This investigation explores the effect of Hardwood Sawdust on the performance of lateritic soils as an engineering material. Particle size distribution, natural moisture content, specific gravity and consistency limits tests were conducted on soil samples obtained from burrow pits at Oke-Baale roundabout of Osogbo West-Bye pass road under construction for classification purpose. Engineering behaviour was also investigated through compaction and unsoaked California Bearing Ratio (CBR) performed on natural and admixed specimens, with the inclusion of 2, 4 and 6% MSA by weight of soil. Preliminary tests indicate that the natural samples were well-graded and rated medium as subgrade material in road construction. Reduction in the plasticity index (PI) of samples from 17 to 14% at 4% MSA were observed. MDD decreased to 1.54, 1.38 and 1.45 Mg/m3 at 2, 4 and 6% MSA respectively. The CBR increased to 18.8, 20.2 and 20.4% at 2, 4 and 6% MSA respectively. The research demonstrated that there is an impressive potential for MSA to enhance the mechanical properties of lateritic soils.

Characterization and Classification of Geotechnical Index Properties of Shallow Soil Deposits at Oworoshoki Area, Kosofe Local Government, Lagos, Nigeria

The study of geotechnical index properties of soils in Oworoshoki, Kosofe, Lagos State was conducted to characterize and classify the index properties of soil samples. Disturbed and undisturbed soils were collected at different shallow depths (1m, 2m and 3m) from the study area and laboratory test was conducted. The laboratory test conducted includes natural moisture content, atterberg limits (liquid limit and plastic limit), particle size distribution, specific gravity, unit weight and hydrometer. The results of the test were gotten: natural moisture content as 23.5%, 24.5% and 25.3% , liquid limits (LL) 28.68%, 26.64% and 29.10%, Oworoshoki is non-plastic for the three depths i.e. plastic limit (PL) is 0, particle size distribution percentage passing through BS #200 (0.075mm) are 95.97 %, 97.97%, 98.10% and this shows that the soil sample contain much silt, the samples are non-plastic for all depths (1m, 2m and 3m), specific gravity as 2.61, 2.55 and 2.60, unit weight as 17.5 KN/m3, 18.1kn/m3 and 18.9KN/m3 and hydrometer percentage passing through BS #200 (0.075mm) as 95.97% at 1.0m depth, 97.97% at 2.0m depth and 98.10% at 3.0m depth. Hydrometer test was conducted because 95.97% passes sieve 0.075mm.This shows that the soil contain high amount of silt. Soils from depth 1.0m, 2.0m and 3.0m are non-plastic (NP) because the Plastic Index (PI=0) and the soil samples are classified as A – 3 according to American Association of State Highway and Transportation Officials (AASHTO) System.

Effects of compaction on the erodibility of a residual soil of gneiss

This work aims to verify the effects of the natural structure of a residual soil on its erodibility and the potential, employing compaction, to restore the erosion resistance. It is a residual soil of gneiss that occurs in the state of Santa Catarina, Southern Brazil. Infrastructure earthworks expose this material to the action of water, which can develop severe erosive features. The erodibility evaluation was made using the MCT methodology based on infiltrability and modified loss of mass by immersion tests. These tests were conducted in undisturbed specimens at natural moisture content and in compacted specimens at optimum moisture content. Such tests were also carried out in specimens air-dried for 24, 48, and 96 hours. This soil is inherently erosive, but the natural macrostructure makes it even more susceptible to erosion. Even compaction under modified energy is not able to recover the erodibility resistance. Drying slightly reduces the soil’s erosive potential when compacted, regardless of the compaction energy, but clearly increases the erosive potential of undisturbed soil.

Geotechnical investigation of road pavement failure along arigidi / oke - agbe akoko, southwestern, Nigeria

Twenty soil samples collected from the failed portions in the study area were air dried for two weeks before analyses. Each soil samples were subjected to eight engineering tests which include: natural moisture content, atterberg limit, specific gravity, compaction, unconfined compressive strength, California bearing ratio, grain size and hydrometer analysis. Results showed that the natural moisture content ranged from 17.7% to 37.8%, liquid limit from 48.5% to 62.4%, plastic limit from 18.3% to 26.8%, plasticity index from 25.7% to 37.7%, shrinkage limit from 5.8%-12.5%, optimum moisture content from 14.2% to 32.4%, maximum dry density from 1301 Kg/rn3 to 2002 Kg/rn3. Soaked California bearing ratio ranged from 5% to 17%, unsoaked from 15% to 38%, specific gravity from 2.5 to 2.68, unconfined compressive strength r from 112.8 Kpa to 259.7 Kpa, shear strength from 56.4 Kpa to 129.9 Kpa and hydrometer analysis from 48.5% to 72.1%. Based on the Federal Government specifications for pavement construction, for the soil to be suitable, stabilization with bitumen, Portland cement, lime, coal fly ash, and saw dust should be done. Road pavement failure along Arigidi – Oke Agbe road was due to poor engineering geological condition of the sub-grade soils and poor drainage systems.

A method for determining the natural moisture content of dentin in a clinical setting

The purpose of the study is a quantitative assessment of the yield of dentinal fluid on the surface of the treated dentin of the tooth when restoring its structure with a composite filling material. To achieve this goal, digital images of the coronal parts of the teeth having formed carious cavities were used; virtual models of hard tissues of teeth recreated using specialized computer programs; A computer program that provides the ability to accurately determine the area of the treated dentin tooth. The results made it possible to draw the following conclusions: with an increase in the depth of the carious cavity, the amount of dentin fluid that can stand out on its surface (1–2 mm from the tooth cavity) sharply increases; with an increase in the area of the formed carious cavity (more than 30 mm2), the risk of release of a critical mass of dentinal fluid (more than 0.4 mg), which can adversely affect the strength of the adhesive interaction between the composite material and the hard tissues of the tooth, increases significantly; the same dynamics is observed with increasing time, at which there is the possibility of free exit of dentinal fluid to the surface of the cavity prepared for filling (more than 45 seconds).

Assessment of Gneiss-Derived Residual Soils as Materials Used in Road Pavement Structures

Failure of highway pavement and collapse of building in basement complex of Nigeria is often related to the instability of the residual. This study evaluated the strength characteristics of gneiss-derived residual Soils as materials usable for road pavement structures. A total of eleven soil samples derived from granite gneiss were subjected to laboratory geotechnical analyses based on standard practices. The geotechnical analyses reveal the soils’ natural moisture content, specific gravity, grain sizes, consistency limits, shearing strengths, maximum dry density, and optimum moisture content. Based on AASHTO classification, the soil samples are classified as A-7-6, A-6, and A-7-5. The results of the laboratory analyses revealed that the natural moisture content and specific gravity ranged from 8.30 to 22.70% and 2.6 to 2.8 respectively. Particle size analysis reveals that the coarse contents of the soils ranged from 28.8% to 59.8% and amount of fines ranged from 40.2 to 71.2%. The liquid limit ranged from 31.3% to 68.3%, plastic limit ranged from 20% to 28.0%, plasticity index ranged from 4.8% to 38.90% and linear shrinkage ranged from 5.7 to 13.6%. The maximum dry density ranged from 1481 kg/m3 to 1921 kg/m3 and optimum moisture content ranged from 15.2% to 27.6%. Undrained triaxial shear strength (Cu) ranged from 43.0 Kpa to 250.3Kpa, angle of friction ranges from 11.7 to 29.30, and unconfined compressive strength ranged from 153 to 356.5Kpa. The results indicate that the residual soils are poor sub-grade and foundation materials due to their high amount of fines, linear shrinkage values, plasticity, and swelling potential, as well as low maximum dry density.

Displacements of Object Founded on Expansive Soils—A Case Study of Light Construction

The paper presents results of observations of a light structure damaged by irregular vertical and horizontal deformations on Neogene expansive clays, typical for area in Central Poland. The sensitivity to environmental changes of humidity in such subsoils can activate volume changes, which causes the destruction of many objects susceptible to deformation. Detailed geotechnical investigations, including seasonal fluctuations of natural moisture content, were carried out for over a year, describing the dynamism of conditions of clays in the foundation zone. Parallel geodetic measurements of vertical and horizontal displacements were carried out, using classical precision leveling and the coordinate method of the Leica TDRA 6000 laser station. The network of measurement points has been specially designed and implemented to follow the spatial displacements of the structure. The network points were placed at the bottom of pillars and on the flooring of the structure located in the upper part. In the paper, the results of the vertical and horizontal periodical measurement of displacements of an investigated construction over the year were discussed to identify the main factors influencing the mechanism of damage of the observed structure.

Geotechnical Evaluation of Road Pavement Failure along the Awotan-Akufo Road, Oyo State Southwestern Nigeria

In order to access the cause(s) of road failure and proffer preventive measures for the future reconstruction of the Awotan-Akufo road, southwestern Nigeria, the geotechnical engineering properties of the subgrade soil, asphalt pavement thicknesses, drainage and traffic load were evaluated. Soil samples were collected from test pits 1 m deep and at an interval of 50 m and subjected to geotechnical analyses in accordance to AASTHO specification. The grain size distribution revealed that 70% of the entire samples from Awotan-Lifeforte and Adaba failed sections along Akufo road contain amount of fines more than 35% passing through sieve No. 200. The Natural Moisture Content range from 5.73 - 20.21% (Awotan-Lifeforte section) and the entire samples from Adaba failed sections have high natural moisture content ranging from 16.20 - 23.20%. From Atterberg limit test, the Liquid limit of 12 - 56% (Awotan-Lifeforte section) and 26.00 - 40.00% (Adaba Section) were obtained. The Plastic Limit and Plasticity Index of the soils ranges from 8.43 to 49.10% and 1.01 to 7.0% (Awotan-Lifeforte section), and 23.10 - 35.50% and 1.50 - 7.10% (Adaba Section) respectively. Linear shrinkage varies from 0.80 to 9.60% and from 3.10 to 8.80% for Awotan-Lifeforte and Adaba sections, respectively. The Maximum Dry Density of the soils ranged from 1.625 - 1.835 mg/m3 at Optimum Moisture Content of 13.4 - 17.3% (Lifeforte-Awotan section), and MDD of 1.752 - 1.975mg/m3 at Optimum Moisture Content of 13.4-17.3% (Adaba section). The unsoaked California Bearing Ratio are 30.08, 70.14, 39.08%, and the soaked California Bearing Ratio values are 26.17, 11.41, 33.41% (Lifeforte-Awotan section) respectively. At Adaba section of the road, the unsoaked California Bearing Ratio is 3.46, 87.70, 70.14%, and soaked California Bearing Ratio values are 3.42, 32.56, 39.83%. The average asphalt pavement thicknesses around Awotan-Lifeforte section range from 0.60 - 1.10 inches, and that of Adaba section range from 0.57 to 1.46 inches. The study concluded that the road pavement subgrade is silty clay and the geotechnical properties rated below the specifications of the Federal Ministry of Works and Housing at some failed portions. Asphalt pavement thicknesses are grossly inadequate and far below NAPA 2007 recommendation. As such the road cannot withstand the heavily loaded trucks that ply it on regular basis. All aforementioned contributed to the untimely failure of the road.

Experimental Study of the Effects of Some Selected Geotechnical Indices on the Unconfined Compressive Strength of Lateritic Soil

This study undertook an experimental study of the comparative effects of Atterberg limits, particles size and compaction parameters on the unconfined compressive strength of selected soils. This was with a view to ascertaining which of the combinations of the soil properties will produce a good prediction of the unconfined compressive strength. To achieve this aim, soil samples were obtained from selected locations within Ife Central Local Government Area, Osun State, Nigeria. The following tests were conducted on the soil samples, following standard procedures: natural moisture content determination, specific gravity, Atterberg limits, compaction and unconfined compressive strength. Using Regression tool, the results obtained from the laboratory tests were used to develop the relationships between each of the index properties and unconfined compressive strength. Results showed that the natural moisture content of soil samples ranges between 18.48 % and 25.03 %; specific gravity ranges between 2.35 and 2.69; liquid limit ranges between 39.95 % and 83.98 %; plastic limit ranges between 29.32 % and 51.18 %; and plasticity index is between 8.74 % and 33.56 %. The maximum dry density ranges between 15.30kN/m3 and 19.30kN/m3 with their optimum moisture contents ranging between 13.80 % and 35.50 % while unconfined compressive strength is between 36.00 kN/m2 and 97.14 kN/m2. The results of regression analysis showed that effective size and coefficient of uniformity have the greatest effect (R2 = 0.82) on unconfined compressive strength of the tested soil samples. Therefore, the study concluded that effective size and coefficient of uniformity could be used to estimate the unconfined compressive strength of the soils.