Effect of Reinforcement on Properties of Silty Sand

The variation of the stress-strain behavior and shear -parameters of reinforced silty sand is studied. The geotextiles were provided at different heights in the sample and tested in unconsolidated undrained condition. Two types of geotextiles, woven and nonwoven were used as reinforcement and the experiment was conducted at three water contents. Tests were performed on samples prepared at OMC, dry of OMC and wet of OMC in order to study the effect of water content. The results demonstrated that geotextile inclusion increases the peak strength, axial strain at failure. The sample was found to fail due to bulging between the layers. Keywords: Optimum Moisture Content, Maximum Dry Density, Unconsolidated Undrained, Deviator Stress, Normal Stress

Volume change in compacted claystone-bentonite mixtures as affected by the swamp acidic water

Water containing sulfuric acid with a pH up to 3 is prevalent in swampy areas. This article focuses on the effects of the solution on volume change of compacted claystone?bentonite mixture. Claystone was obtained from Banjarbakula landfill and it was mixed with bentonite on a 5, 10, 15, and 20% dry mass basis. Samples possessed the dry density of 16 kN/m3 and moisture content of 10, 15, and 20%. The odometer examined the samples' swelling and compression in both pure and acidic water. Characterization tests i.e., XRF, XRD, and FTIR were also performed. The results showed that swelling and compression were affected by initial moisture and bentonite content. Samples with a moisture content of 20% showed compression in acidic water. Acidic water changed the water absorbed on the clay surface without altering the mineral. A mixture containing 20% bentonite compacted to optimum moisture content was found at best in reducing the acidic water effects.

Stabilization of Soil by Use of Waste Tyre Rubber

In India, the scrap or waste tyres are being generated and accumulated in huge volumes causing an increasing hazard to the environment. In order to eradicate the negative effect of these confessions and in terms of sustainable development, there is great interest in the recycling of these non-hazardous solid wastes. So we can stabilize the soil by using waste tyre rubber, which is available as a waste in more numbers. The objective of this study is to study the improvement of bearing capacities of the clay soil using waste tyre rubber. To examine the optimum moisture content present in the soil by using waste tyre rubber and also to study the improvement of settlement of clay soil by using waste tyre rubber.

DESIGN AND EXPERIMENT OF CENTRIFUGAL COLLISION TEST DEVICE FOR MILLET AND SWEET BUCKWHEAT GRAIN

This critical collision damage force of millet and sweet buckwheat grain and the shelling force of shelled granular materials are important basic data for research of threshing and shelling technology and equipment. In order to master the linear velocity and collision force of grain with different moisture content when collision damage occurs, a centrifugal collision test device is designed. Based on the dynamic and kinematic analysis of grain in the centrifugal rotary table, the collision force between grain and steel plate was measured by PVDF piezoelectric pressure sensor and data acquisition system. The results showed that: under the same moisture content, the higher the rotational speed, the higher the grain crushing rate; at the same rotational speed, with the increase of moisture content, the crushing rate first decreased and then increased. When the moisture content of Jingu-21 and Yuqiao-4 is 19.7% and 17.8%, respectively, the grain crushing rate was the lowest. In terms of the anti-collision ability of grain, the optimum moisture content of threshing is between 19.7% and 21% for millet. For sweet buckwheat, the optimum moisture content of threshing is 17.8% ~19%, while the optimum moisture content of shelling by centrifugal sheller is about 11%. The faster the rotational speed of centrifugal rotary table is, the greater the linear speed of grain is, and the greater the collision force is. When the linear velocity of grain was 8.32 m/s and 11.30 m/s respectively, the millet grain moisture content was 11.1% and 20.9% respectively, damage began to appear, and the corresponding collision force was about 5.51 N and 10.6 N, respectively. When the linear velocity of grain was 8.32 m/s and 11.30m/s respectively, and the moisture content was 11.1% and 22.8% of the sweet buckwheat grain respectively, damage began to appear, the corresponding collision force was about 8.92 N and 12.79 N, respectively. When the rotating speed of rotary table was 910 r/min, the linear speed of grain was 27.05 m/s, the crushing rate of millet and sweet buckwheat grain in harvest period were 56.30% and 63.76%, respectively, and the crushing rate of millet and buckwheat grain with 11.1% moisture content were 86.27% and 89.4%, respectively. The research results can provide theoretical basis for design and optimization of millet and sweet buckwheat combine harvester, threshing device and shelling device.

Effect of Coarse Content on Compaction Test

The compaction is a mechanism to densify the loose soils. The maximum soil densification can be achieved by optimization of the desirable optimum moisture content (OMC) and maximum dry density (MDD). The maximum dry density and the optimum moisture content were affected by several parameters. The coarse content (CC) is one of these parameters. This paper studied the effect of the coarse content on the compaction parameters (MDD, OMC). Several sand-kaolin mixtures had coarse content ranged from 30 % to 80 % and moisture content ranged from 12% to 20% were used to inspect the relationship between CC, specific gravity (Gs), MDD, OMC, and bulk density. The results presented five empirical correlations with coefficient of determination (R2 ≥ 0.98) between CC, Gs, MDD, OMC and bulk density. The comparison between the current study and previous researchers indicated that both soil type and moisture content have significant effect on the efficiency of the empirical correlation equations between the maximum dry density, specific gravity, and coarse content. The results indicated a linear relationship between coarse content toward maximum dry density and specific gravity where both MDD and Gs increased with an increase CC. In contrary, the results showed non-linear relationship between optimum moisture content and coarse content where OMC decrease with an increase CC.

Influence of Waste Marble Dust on the Improvement of Expansive Clay Soils

The marble process industry from Shaq Al-Thouban region, which is located in East Cairo, Egypt, produces a huge amount of marble wastes every day during the cutting and processing stages. Up to now, most of these wastes are dumping on open land which creates serious environmental problems. The amount of waste marble from the processing stage is about 20 to 25% of the total processed stone. Egypt also suffers from the problem of expansive soil that occupies a large area of its lands, especially in the new cities that are built on these lands. The primary purpose of this study is to use this waste material in the soil stabilization in point of view utilization of this waste as local low-cost materials and elimination of their negative environmental impacts. The waste marble dust was mixed with expansive soil samples with various percentages of 5%, 10%, 15%, 20%, and 25% by dry weight of soil. Different tests including Atterberg’s limits, standard Proctor compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), swelling percentage, linear shrinkage (LS) tests, and XRF and XRD analyses were conducted for natural and marble dust stabilized soils. The soil mixtures used for UCS, CBR, and swell tests were compacted at the optimum moisture content (OMC) and maximum dry density (MDD) using the standard Proctor compaction method and cured for 7 days. The results of the tests showed that there are significant effects in enhancing the properties of expansive soils. Also, the results showed that as the percentage of the marble dust increases the plasticity index, the swelling potential of the expansive clayey soil decreases. Furthermore, the optimum moisture content decreases, and the maximum dry density increases. Also, UCS, CBR, and the calcite content of the soil mixtures increase with the increase in marble dust content.

Strength Enhancement of Fibre Reinforced Peat with Fly Ash as Stabilized Subgrade Layer

High content of organic matter and fibre within peat results in a high degree of porosity; causing peat to have low bearing capacity. This study focuses on the application of nylon fibre as reinforcing material with fly ash as the chemical stabilizer to enhance the strength of the peat. The standard proctor tests were conducted to obtain the optimum moisture content (OMC) for all samples in which these OMC is then used for sample preparation of both the Unconfined Compressive Strength (UCS) tests and the California Bearing Ratio (CBR) tests. Samples for this study were categorized into control samples and modified samples for comparison purposes. Additives that were being used in this study are 5% cement, 5% nylon fibre and 10%, 15%, and 20% fly ash. For UCS test, the samples were cured for 7, 14, 28 and 56 days, whereas only 7 days of curing for CBR test. Throughout the study, improvements of strength were observed where sample added with 5% cement, 5% nylon fibre and 10% fly ash recorded the highest compressive strength value, of 123.71 kN/m2. As for CBR test, all samples exceeded the minimum requirement of 12% CBR value for subgrade design recommended by JKR Malaysia with the highest CBR value obtained from samples added with 5% cement and 10% fly ash. The CBR values were 43.85% and 43.70% for unsoaked and soaked condition, respectively.

Effect of Waste Tire Reinforcement with and without Cement Additives on Peat Strength Improvement

This paper presents the peat ground improvement techniques using waste-tire as a fibre reinforced material. In this study, two sizes of the waste-tire are chosen, which are 0.05 mm and 1-3 mm, respectively. The collected peat is classified as Sapric peat with the degree of decomposition of H7 based on von Post classification with high moisture content of 400% was recorded. The Sapric peat is treated with the waste-tire at designated percentages of 5%, 10% and 15% with the addition of 5% of cement acting as a binder. The untreated and treated peat without and with cement content are compacted at the optimum moisture content for both the Unconfined Compressive Strength (UCS) test and Direct Shear Box Test. The specimens were air-cured for 7, 28, 56, and 90 days. Hypothetically, higher percentages of rubber improve the shear stress value of the treated peat. According to the results the finer size (0.05mm) of the tire produces a higher shear stress, which may due the finer sizes of the waste-tire filled the void between the soil particles. Further, from the 90 days of curing UCS results, there is a significant increase in compressive strength with the increase percentage of the waste-tire peat mixed samples. In summary, soil stabilized by the scrap-tire is believed to decrease the optimum moisture content and the maximum dry densities, but it helps in increasing the unconfined compressive strength value. Stabilizing by using the tire wastes not only increasing the strength of the soil, but it also helps in reducing the disposal problems.