Previous prediction models for soil compaction parameters were developed using limited data of specific soils and their accuracy also needs to be improved. This study presents the development of a ...new prediction model for the soil compaction parameters (i.e. optimum water content and maximum dry density) using the multi expression programming (MEP). Numerous soil compaction tests with a wide range of soil classifications and compaction energies are first collected to form a large database. Then, the optimal setting of the MEP code parameters is investigated and determined. The explicit formulations for the two key compaction parameters are finally proposed. The validity and the sensitivity analysis of the model are conducted. The results show that the proposed model enables to predict the soil compaction parameters for all kinds of soils in the database with high accuracy. The monotonicity analysis of the predicted compaction parameters with each input property (four physical properties of soil and one compaction energy) verifies the correctness and the validity of proposed model, showing consistency with the monotonicity concerning the actual data in the database. From the sensitivity analysis about the relevance of each input property on the predicted compaction parameters, it is indicated that the plastic limit and the fines content have more significant influences on the prediction results, while the effect of the liquid limit is the least pronounced.
•A new prediction model for the soil compaction parameters is developed using MEP for large number of soils with high accuracy.•The monotonicity analysis with each input parameter verifies the correctness and the validity of proposed model.•The plastic limit and the fines content have more significant influences on the prediction results.
Simple and quick determination of the optimum water content for tillage (θOPT) is helpful to guide tillage operations. Based on the definition of θOPT that is the water content at the inflection ...point of the soil water retention curve, a simple method was established to estimate the θOPT from saturated water content (θs) (θOPT = 0.75θs). The validation results on 132 soils with varying texture showed that the root mean squared error and mean error were 0.021 and 0.009 g g−1, respectively. These results confirmed that the θs was valuable information for estimating θOPT and the proposed method could give a reasonable estimation for θOPT.
•An experimental program with a systematic laboratory study is presented to assess the optimum material ratio.•The various range of water-to-cement ratio, cement content, and porosity are ...simultaneously considered.•The optimum range of water-to-cement ratio and optimum water content is found for cement-mixed soil.•A new index, namely, the combined material ratio is proposed for the strength analysis.•The strength mobilization mechanism with the water-to-cement ratio and dry density is clarified.
The cement-mixed soils technique is an efficient solution to improve the ground geomechanical properties in infrastructures and construction projects. This paper presents a systematic laboratory study to investigate the optimum water-to-cement ratio existence on the unconfined compressive strength. The soil compaction is controlled during these tests. The results showed that the maximum unconfined compressive strength was not only controlled by the porosity but also the water-to-cement ratio. The results indicated that the optimum range of water-to-cement ratio to mobilize the maximum strength is between 0.75 and 1.25 while the optimum water content is around 15%, and is quite stable for various cement content. Besides, the unconfined compressive strength decreased with increasing the water-to-cement ratio, and the reduction is more significant for higher cement contents. It seems that high cement content could be not sufficient for a large water-to-cement ratio. Finally, a new index, namely, the combined volume ratio is proposed for the strength analysis of cement-mixed soils. Using this index, the unconfined compressive strength of cement-mixed soils can be reasonably predicted. The combined volume ratio allows selecting the ratio of water and cement volume to ensure that the void volume is minimized, and the strength is therefore maximized.
AbstractFrom the rheological behavior of bitumen, one can understand the physical properties of water-foamed bitumen used in warm mix asphalt. Previously, rheological behaviors of water-foamed ...bitumen such as apparent viscosity, agitation torque, and shear rate have not been well documented. The objectives of this study are as follows: (1) evaluating the accuracy of the cup-and-bob test with a dynamic shear rheometer to investigate the rheological behavior of water-foamed bitumen, (2) analyzing the rheological behavior of water-foamed bitumen at various temperatures, and (3) proposing an optimum water content that decreases the apparent viscosity and required agitation torque of water-foamed bitumen. Bitumen with various water contents (ranging from 0.0 to 3.0% bitumen content by mass) were prepared for rheological testing. The optimum water content at each of these foaming temperatures was determined based on the testing results. This study concludes that the current cup-and-bob test methods accurately describe the rheological behavior of water-foamed bitumen. Within the accepted water content range, the apparent viscosity and required agitation torque of water-foamed bitumen decrease more dramatically as water content increases.
Some soils cannot withstand heavy loads due to significantly low California Bearing Ratio and shear strength. So, to reduce this problem treatment of soil is needed to be done using different ...stabilizers like furnace slag, fly ash, limestone fines, bitumen, plastic waste etc. Itis defined as the process for improving the properties of the soil either providing physical or chemical treatments and by blending and mixing of some other materials with the soil. It helps in controlling the shrink-swell properties of soil and also improves the shear strength properties and the capacity of soil to support the loads. This paper is aimed at providing soil stabilization using the waste plastic. The main motive of this research is to evaluate the result of incorporating waste plastic bottles on the geotechnical properties of soil. Various percentages of waste plastic bottles (0%, 0.5%, 1.0%, 1.5% and 2.0%) added in the soil sample and sequel the engineering properties of soil. For this, various laboratory tests were conducted on soil samples like Unconfined Compressive Strength, California Bearing Ratio, and Proctor Test etc. and compared with the soil samples without any plastic waste. The outcome of the study showed that addition of the waste plastic bottles have positive effect on the soil properties which promotes the re-use of waste plastic from industry in an economical and environmentally friendly way and it will also help with the disposal problem of these plastic wastes on some extend.
Soil compaction is one of the basic engineering techniques, which is carried out to guarantee the stability of soils dependent on specified strength. Nonetheless, in large-scale construction ...projects, the estimation of compaction features required tremendous effort and time that can be saved utilizing empirical relationships at the initial phases. It becomes critical to develop models to predict the compaction features, namely the maximum dry unit weight (γdmax) and optimum water content (WOP). This article attempts to develop models to predict the γdmax and WOP of fine-grained clay soils. Geotechnical tests such as grain size distribution, Atterberg limits, specific gravity, and proctor compaction tests are performed to assess soil samples' physical and hyro-mechanical characteristics. Multivariate analysis is conducted using MINITAB 18 software to develop the predictive models. The validation process of developed models includes the determination coefficient, probability value (p-value), comparison of the predicted values with experimental values, comparison of the models proposed in this study with other existing models found in the recent literature, and employing a different soil data set. The predicted values obtained from the models proposed in this research project are more accurate than other models developed recently. The proposed models estimate the compaction features of fine-grained clay soils with acceptable precision.
HIGHLIGHTS
Soil compaction is one of the basic engineering techniques perform to guarantee the stability of soils dependent on specified strength
In large-scale construction projects, the estimation of compaction parameters required tremendous effort and time that can be saved utilizing empirical relationships at the initial phases
This study has developed semi-empirical models to predict the compaction parameters (maximum dry unit weight and optimum water content) of fine-grained soils
GRAPHICAL ABSTRACT
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study introduces a practical energy conversion (EC)-type modeling framework capable of converting the optimum compaction properties of fine-grained soils between any two rational compaction ...energy levels (CELs). Model development/calibration was carried out using a database of 242 compaction test results — the largest and most diverse database of its kind, to date, entailing 76 fine-grained soils (covering liquid limits of 16–256%), with each soil tested for at least three different CELs. On establishing the framework, an independent database of 91 compaction test results (consisting of 34 fine-grained soils tested for varying CELs) was employed for its validation. The proposed EC-based models employ measured optimum water content (OWC) and maximum dry unit weight (MDUW) values obtained for a rational CEL (preferably standard Proctor) to predict the same for higher and/or lower compactive efforts (covering 214–5416 kJ/m3). The 95% lower and upper statistical agreement limits between the predicted/converted and measured OWCs were obtained as −2.16 wc % and +2.25 wc %, both of which are on par (in terms of magnitude) with the ASTM D1557 allowable limit of 2.1 wc %. For the MDUW predictions, these limits were calculated as −0.71 and +0.66 kN/m3, which can also be deemed acceptable when compared against ASTM’s allowable limit of ±0.7 kN/m3 (= ±4.4 lb/ft3). The proposed framework offers a reasonably practical procedure to accurately convert the optimum compaction parameters across different CELs (without the need for any soil index properties), and thus can be used with confidence for preliminary project design assessments.
Generally, the soil requires to be compacted in highway construction. The expansive soil is a special type of soil that is highly susceptible to variations in water content, which affects the degree ...of compaction at the same compaction energy. In the present study, a series of wet compaction tests and dry compaction tests were carried out in the laboratory. Laboratory test results show that dry compaction will produce a higher optimum water content and a higher maximum dry unit weight compared to wet compaction, because its matric suction is smaller. Field compaction tests were also conducted, the results showed that there might be a risk of under-compacting soils during construction caused by different water content change path in actual field conditions.
Soil stratum in Khon Kaen province, located in Northeast of Thailand, is well-known as a wind-deposited fine-grained soil (i.e. silty sand and silty clay). It is normally called “Loess or Khon Kaen ...Loess”. This soil in disturbed stage is usually extracted from the borrow pit and subsequently compacted for infrastructure applications. The compaction resulted in silty sand or silty clay aggregation with unpredictable properties. Although required for infrastructure design, studies on Khon Kaen Loess are limited. Thus, this research examines the compaction behavior and predicts soil parameters at various clay contents under a series of compaction energy on Khon Kaen Loess. The results showed that the maximum dry unit weights of samples could be related to the dry unit weight at plastic limit (PL), while the optimum water content (OWC) was correlated linearly with the PL. The samples with higher PL presented the higher OWC. In addition, the maximum dry unit weight and OWC of samples could be estimated using the developed equations validated with the other research results.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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