Property Evaluation of Cement-Stabilized Macadam Modified via Phosphorus Slag Materials

Phosphorus slag, known as the waste product of the phosphate ore industry, is causing critical environmental issues due to its direct exposure to natural spaces. In this article, a partial replacement of the natural fine aggregate ordinarily used in cement-stabilized macadam (CSM) base by phosphorus slag was explored to be an effective solution for phosphorus slag waste. CSM specimens were fabricated by adding various dosages of phosphorus slag particle and fine powder, whereas the optimum moisture content and maximum dry density were analyzed through compaction tests. Compressive strength, bending tensile strength, fatigue life span, dry shrinkage, and temperature shrinkage performance at different curing durations were investigated to evaluate the properties of modified macadam. Results show that phosphorus slag reduced the early compressive strength of CSM to a small extent, but the compressive strength finally increased at 90 days’ curing. The modified slag particles and slag fine powder exhibited different behaviors to repeated loading, moisture loss, and temperature difference. Finally, according to the strength change, fatigue performance comparison, and shrinkage strain caused by the incorporation of phosphorous slag materials into the CSM, it was verified that 25% of the particles to 40% of the fine powder is the best replacement ratio.

Mix Design of Emulsion Treated Reclaimed Asphalt Pavement and Its Implementation at Field

Reclaimed asphalt pavement (RAP) is a valuable, high quality material that can be replace over expensive virgin aggregates and binder that can be used for technical, economical and environmental reasons. Use of RAP can be favored all over the world over virgin material on the light of increasing cost of bitumen, the scarcity of high quality aggregates and the pressing need to preserve the environment. Overlay and maintenance resolve medium distress, but reconstruction may feasible and economical while Asphalt pavement are badly deteriorated with time and traffic. This requires the removal of existing pavement surfaces. Recycling such construction waste has benefited from economic to sustainability point of view and reduce the exploitation of natural resources. The shortage of virgin aggregate supplies along with the increase in processing and hauling cost have encouraged the use of reclaimed material from the old structure as base course construction materials and involved in regular practice in various countries around the world. Keywords: RAP1-Reclaimed Asphalt Pavement, DBM2-Dense Bitumenous Macadam,ITS3- Indirect Tensile Strength,MDD4- Maximum Dry Density,OMC5-Optimum Moisture Content, HMA6-Hot Mix Asphalt, UCS7-Unconfined Compressive Strength, CIPR8-Cold In Place Recycling.

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

Prediction of California Bearing Ratio from Consistency and Compaction Characteristics of Fine-grained Soils

Soil’s characteristics are essential for the successful design of projects such as airports runway and flexible pavement. CBR (California Bering Ratio) is one of the significant soil characteristics for highways and airports projects. Thus, the CBR property can be used to determine the subgrade reaction of soil through correlations. Many of the soil geotechnical parameters such as compaction characteristics (Maximum Dry Density, MDD; Optimum Moisture Content, OMC), and consistency parameters (Liquid Limit, LL; Plastic Limit, PL; Plasticity Index, PI) can be in charge of changes that happen in soil CBR value. Soaked and/or non-soaked conditions of soils also affect CBR value. Hence, testing soils in a laboratory for CBR calculation is time-consuming that needs notable effort. Therefore, this study aims to generate some useful correlations for soil’s CBR with compaction and consistency parameters for 85 samples of fine-grained soils. The study trials were applied on natural soil samples of various places in Sulaimani Governorate, Northern Iraq. Statistical analysis has been carried out by using SPSS software (Version 28). Soaked CBR is counted, which is important for conditions such as rural roads that remain prone to water for few days. Based on the statistical analysis, there is a significant correlation between LL, PL, PI, MDD, and OMC with CBR as the dependent variable as a single variable equation with R2 of 0.7673, 0.5423, 0.5192, 0.6489, and 0.51, respectively. In addition, the highest value of R2 correlation was obtained between CBR value with consistency and compaction properties as a multiple regression equation with R2 of 0.82. The obtained equations for correlation purposes are successfully achieved and can be used, notably, to estimate CBR value.

Review on Soil Improvement by Using Various Chemical Additives for Foundation

This work aimed to study the most effective chemical additives to increase the strength of the clay soil. The problem statement is to improve the soil strength to avoid failure in the ground. The chemical additives that be used are lime, cement, and fly ash. These chemical additives were commonly used to stabilize the soil and make the shear strength of the soil increase. The data taken was from the previous research, where the data was compared to get the most effective chemical additives to improve the soil stability and soil strength. The percentage of the chemical additive used in the soil mixture was 8% to 10%. The data from previous research was chosen based on the rate used of the chemical additive and the research was taken from Science Directed website only. Data were collected through 30 previous studies using clay and chemical additives such as cement, lime, and fly ash. The data for Plastic Limit, Liquid Limit, Plasticity Index, Optimum Moisture Content, Maximum Dry Density, and Unconfined Compressive Strength was taken by referring to the previous study. Then the data was listed in Microsoft Excel to generate the graph for comparison. All the data obtained are then compared to get which chemicals can increase the strength of the soil. The result of this study shows that the cement was the most effective chemical additive to improve the soil strength and to stabilize the soil than the lime and fly ash.

Geotechnical Characteristics of Benin Formation, Owerri Imo State, Nigeria

A good road network consists of a constant stretch of asphalt laid down for a smooth ride. The spot in the smooth ride on the pavement is commonly referred to as "pavement failure." Soil type, load bearing capacity of materials, zone of vulnerability, resistance to permeation, compressibility, shrinkage limit, and other details are frequently required in order to construct a very good and solid foundation for the planned bridge site. In Nigeria, numerous factors contribute to the failure of road construction projects. They are primarily insufficient research on subgrade and other pavement materials (sub-base and base courses) prior to the start of road projects; flawed engineering, including a poor drainage system and supervision throughout road construction; and shoddy workmanship that was superimposed with asphaltic concrete to improve strength. Within the Niger Delta basin, the study area is located between latitude 5.485°N and longitude 7.035°E. The Benin Formation underpins the study area. It is composed primarily of friable sands, conglomerates, very coarse sandstone, and isolated gravel units, as well as intercalation of Pliocene to Miocene shale/clay lenses. Natural Moisture Content (NMC), Linear Shrinkage (LS), Particle Size Distribution, and California Bearing Ratio were among the laboratory tests performed on samples collected at failed and stable sections of some selected road segments (CBR). When compared to the stable sections, the NMC along the failed sections was on the high side (ranging from 13.11 percent to 26.89 percent) (ranging from 11.11 percent to 16.40 percent). The majority of the tested soils passed the 0.075mm sieve with a percentage greater than the Federal Ministry of Works and Housing's maximum of 35% for subgrade materials. The maximum dry density (MDD) for the samples at failed and stable sections was 1550 kg/m3 to 1860 kg/m3; 1650 kg/m3 to 1980 kg/m3; and the Optimum Moisture Content (OMC) was 8.30% to 20.30%. The soaked CBR values ranged from 2 to 17 percent, while the unsoaked values ranged from 4 to 25 percent.

Deep Neural Network Models for the Prediction of the Aggregate Base Course Compaction Parameters

Laboratory tests for the estimation of the compaction parameters, namely the maximum dry density (MDD) and optimum moisture content (OMC) are time-consuming and costly. Thus, this paper employs the artificial neural network technique for the prediction of the OMC and MDD for the aggregate base course from relatively easier index properties tests. The grain size distribution, plastic limit, and liquid limits are used as the inputs for the development of the ANNs. In this study, multiple ANNs (240 ANNs) are tested to choose the optimum ANN that produces the best predictions. This paper focuses on studying the impact of three different activation functions: number of hidden layers, number of neurons per hidden layer on the predictions, and heatmaps are generated to compare the performance of every ANN with different settings. Results show that the optimum ANN hyperparameters change depending on the predicted parameter. Additionally, the hyperbolic tangent activation is the most efficient activation function as it outperforms the other two activation functions. Additionally, the simplest ANN architectures results in the best predictions, as the performance of the ANNs deteriorates with the increase in the number of hidden layers or the number of neurons per hidden layers.

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 Zeolite on the Compaction Characteristics and Shear Strength Parameters of Cemented Sand

It is well known that in geotechnical engineering, soil stabilization using cement is one of the appropriate approaches for enhancing soil characteristics. With respect to zeolite, its impact on the characteristics of cemented soil has not been fully evaluated. Thus, in the current research, a set of laboratory tests including standard Proctor compaction and direct shear tests (DSTs) considering four cement contents (2, 4, 6, and 8% of sand dry weight) and four zeolite contents (0%, 30%, 60%, and 90% of cement percentage as a replacement material) was carried out. The results indicated that the zeolite reduced Maximum Dry Density (MDD) while it increased value of Optimum Moisture Content (OMC) of cemented sand. Through the DSTs, it has been found that the replacement of cement by zeolite up to 30%, leads to the highest values of shear strength parameters due to the occurrence of pozzolanic and chemical reactions, particularly the production of higher amounts of calcium aluminate and calcium silicate hydrates in comparison with zeolite-free samples.

An investigation into the role of treatment performance and soil characteristics of soil-based wastewater treatment systems

Soil-based onsite wastewater treatment systems (OWTS) are becoming more important for the treatment and disposal of wastewater in areas that have not central wastewater collection and treatment systems. However, there are concerns that OWTS may have adverse effects on public health and environment. The purpose of this study is to treat wastewater with using natural soil column in order to evaluate treatment system performance. Wastewater was applied to two different natural soils at different flow rates of 9, 18 and 36 L/day. The treatment performances of wastewater and geotechnical properties of the natural soils were examined. As a result of this study, the percentage of COD and SS removal in wastewater after soil column filtration were range from 36.2% to 80.5% and 84.4% to 97.9% respectively. pH values of wastewater after the filtration were measured between 7.75 and 8.12. TP and TN removal rates were found in the range of 23.9–76.8% and 12.4–83.0%, respectively. The column effluent water were classified as both ‘high hardness class’ in terms of hardness and ‘polluted water’ in terms of conductivity. Column effluent water were found in ‘low, medium, and high hazard’ classes in terms of SAR. Whereas the PL values of the natural soils were found to increase by up to 4.8% in filtration area, specific gravity decrease nearly 1.1%. The values of LL, PI, maximum dry density, optimum water content, and permeability were changed depending on the soil type. The UCS of the natural soils after wastewater filtration decreased by about 5.9%. It was concluded that natural soils have positive effects on treatment of wastewater in short time.