Assessing the Potential of a Waste Material for Cement Replacement and the Effect of Its Finennes in Soft Soil Stabilisation

This paper represents the results of experimental work to investigate the suitability of a waste material (WM) for soft soil stabilisation. In addition, the effect of particle size distribution (PSD) of the waste material on its performance as a soil stabiliser was investigated. The WM used in this study is produced from the incineration processes in domestic energy power plant and it is available in two different grades of fineness (coarse waste material (CWM) and fine waste material (FWM)). An intermediate plasticity silty clayey soil with medium organic matter content has been used in this study. The suitability of the CWM and FWM to improve the physical and engineering properties of the selected soil was evaluated dependant on the results obtained from the consistency limits, compaction characteristics (optimum moisture content (OMC) and maximum dry density (MDD)); along with the unconfined compressive strength test (UCS). Different percentages of CWM were added to the soft soil (3, 6, 9, 12 and 15%) to produce various admixtures. Then the UCS test was carried out on specimens under different curing periods (zero, 7, 14, and 28 days) to find the optimum percentage of CWM. The optimum and other two percentages (either side of the optimum content) were used for FWM to evaluate the effect of the fineness of the WM on UCS of the stabilised soil. Results indicated that both types of the WM used in this study improved the physical properties of the soft soil where the index of plasticity (IP) was decreased significantly. IP was decreased from 21 to 13.64 and 13.10 with 12% of CWM and 15% of FWM respectively. The results of the unconfined compressive strength test indicated that 12% of CWM was the optimum and this percentage developed the UCS value from 202kPa to 500kPa for 28 days cured samples, which is equal, approximately 2.5 times the UCS value for untreated soil. Moreover, this percentage provided 1.4 times the value of UCS for stabilized soil-CWA by using FWM which recorded just under 700kPa after 28 days curing

The Utilisation of Two Types of Fly Ashes Used as Cement Replacement in Soft Soil Stabilisation

This study represents the results of an experimental work using two types of fly ashes as a cement replacement in soft soil stabilisation. The fly ashes (FA1 and FA2) used in this study are by-products resulting from an incineration processes between 800 and 1200 ˚C. The stabilised soil in this study was an intermediate plasticity silty clayey soil with medium organic matter content. The experimental works were initially conducted on soil treated with different percentages of FA1 (0, 3, 6, 9, 12, and 15%) to identify the optimum FA1 content. Then FA1 was chemically activated by FA2 which has high alkalinity by blending the optimum content of FA1 with different portions of FA2. The improvement levels were evaluated dependent on the results obtained from consistency limits and compaction tests along with the results of unconfined compressive strength (UCS) tests which were conducted on specimens of soil treated with FA1 and FA2 and exposed to different periods of curing (zero, 7, 14, and 28 days). The results indicated that the FA1 and FA2 used in this study effectively improved the physical and geotechnical properties of the soft soil where the index of plasticity (IP) was decreased significantly from 21 to 13.17 with 12% of FA1; however, there was a slight increase in IP with the use of FA2. Meanwhile, 12% of FA1 was identified as the optimum percentage improving the UCS of stabilised soil significantly. Furthermore, FA2 was found effective as a chemical activator to FA1 where the UCS was improved significantly after using FA2

“Simulation of Soil Pile Interaction of Steel Batter Piles Penetrated in Sandy Soil subjected to Pull-out Loads”

Super structures like offshore platforms, tall buildings, transition towers, skyscrapers and bridges are normally designed to resist compression, uplift and lateral forces from wind waves, negative skin friction, ship impact and other applied loads. Better understanding and the precise simulation of the response of batter piles under the action of independent uplift loads is a vital topic and an area of active research in the field of geotechnical engineering. This paper investigates the use of finite element code (FEC) to examine the behaviour of model batter piles penetrated in dense sand, subjected to pull-out pressure by means of numerical modelling. The concept of the Winkler Model (beam on elastic foundation) has been used in which the interaction between the pile embedded depth and adjacent soil in the bearing zone is simulated by nonlinea

Nonlinear analysis of single model piles subjected to lateral load in sloping ground

Uncertainty associated due to soil-pile interface and unreliable assessment of the pile bearing capacity constructed in sloping ground have been cited as barriers to the wide utilizations of the deep foundations in sloping ground. Extensive studies were conducted concerning the failure mechanism of laterally loaded piles penetrated in horizontal ground. However, the number of studies regarding the pile in sloping ground is scarce in literatures. In this research, a detailed of numerical modelling using Winkler theory is discussed on the basis of finite element and experimental tests for models input parameters to examine the behaviour of the model piles penetrated in sandy soil subjected to lateral load. An Aluminium of open-ended model piles were utilized embedded in dense dry sloping sand of 1.5 horizontal to 1 vertical (1.5H: 1V). Three piles aspect’s ratio of (18, 24 and 30) were selected to examine the behaviour of both flexible and rigid pile. The results revealed that lateral soil stiffness, effective passive wedge, flexural rigidity, EI, pile slenderness’ ratio (lc/d) and sand morphology as confirmed by scanning electronic microscopy, SEM observation play a key-role on the factors effecting the pile capacity and its lateral response

Mechanical Activation of a Waste Material Used AS Cement Replacement in Soft Soil Stabilisation

Waste materials, sometimes called by-product materials have been increasingly used as replacement materials to reduce the usage of cement in different construction projects. In the field of soil stabilisation, waste materials such as pulverised fuel ash (PFA), biomass fly ash (BFA), sewage sludge ash (SSA), etc.; have been used since the 1960s. In this study, a particular type of a waste material (WM) was used in soft soil stabilisation as a cement replacement combined with the effect of mechanical activation, using grinding, to enhance the performance. The stabilised soil in this study was an intermediate plasticity silty clayey soil with medium organic matter content. The experimental investigations were conducted to find the optimum content of WM by determining the Atterberg limits and the unconfined compressive strength (UCS) of soil samples containing (0, 3, 6, 9, 12, and 15%) of WM by the dry weight of soil. The UCS test was carried out on specimens exposed to different curing periods (zero, 7, 14, and 28 days). Moreover, the optimum percentage of the WM was subject to different periods of grinding (10, 20, 30, 40mins) using a mortar and pestle grinder to determine the effect of grinding and its optimum time by conducting UCS tests. The results indicated that the WM used in this study improved the physical properties of the soft soil where the index of plasticity (IP) was decreased significantly from 21 to 13.10 with 15% of WM. Meanwhile, the results of UCS test indicated that 12% of WM was the optimum and this percentage developed the UCS value from 202kPa to 700kPa for 28 days of curing. In terms of the time of grinding, the results revealed that 10 minutes of grinding was the best for mechanical activation for the WM used in this study

“Analysis of The Lateral Response of A Reinforced Concrete Pile Penetrated In Sand Soil Using Finite Element”

Pile foundations are slender elements, underneath a major structure, frequently used for many decades as load carrying and load transferring systems from shallow inadequate subsurface soil layers to deep and stiff bearing strata with high degree of efficiency. Moreover, the laterally loaded response of concrete reinforced piles penetrated in sandy soil is normally analysed using Winkler Model (beam on elastic foundation), in which the sand-pile-sand interaction is simulated by highly nonlinear p–y curves. The present study presents the result of numerical analyses of the behaviour of reinforced concrete squared model piles (400 mm in diameter) with embedment depth-to-diameter ratio (L/d) of (20)penetrated in a calibrated chamber of pre prepared dense sand relative density

Piles in sandy soil: A numerical study and experimental validation

Pile foundations are structural elements, highly recommended as a load transferring system from shallow inadequate soil layers into competent soil strata with high performance. There are several theoretical and numerical approaches available concerning the pile bearing capacity in cohessionless soil, however, there is a need for the development of an accurate and more robust predictive model. In this technical note, the details of experimental work to investigate the pile bearing capacity penetrated in dense sub rounded sand as confirmed by scanning electronic microscopy (SEM) tests with a Dr of 85% is discussed. A testing programme comprised of three types of model piles (steel open-end, steel closed-end and concrete pile). The piles slenderness’s ratios (lc/d) are varied from 12, 17 and 25 to simulate the behaviour of both flexible and rigid pile designs. In addition, a novel approach of multi-layered artificial neural networks (ANNs) based on the Levenberg-Marquardt approach (LM) was developed. Finally, the accuracy of the developed ANN model was evaluated using independent test data. The results indicated that the optimised model is highly suited for predicting of the pile-load capacity for the described soil with correlation coefficient, R and root mean square error (RMSE) of 0.97095 and 0.074025 respectively

Settlement Prediction of Model Piles Embedded in Sandy Soil Using the Levenberg–Marquardt (LM) Training Algorithm

This investigation aimed to examine the load carrying capacity of model piles embedded in sandy soil and to develop a predictive model to simulate pile settlement using a new artificial neural network (ANN) approach. A series of experimental pile load tests were carried out on model concrete piles, comprised of three piles with slenderness ratios of 12, 17 and 25. This was to provide an initial dataset to establish the ANN model, in attempt at making current, in situ pile-load test methods unnecessary. Evolutionary Levenberg–Marquardt (LM) MATLAB algorithms, enhanced by T-tests and F-tests, were developed and applied in this process. The model piles were embedded in a calibration chamber in three densities of sand; loose, medium and dense. According to the statistical analysis and the relative importance study, pile lengths, applied load, pile flexural rigidity, pile aspects ratio, and sand-pile friction angle were found to play a key role in pile settlement at different contribution levels, following the order: P > δ > lc/d > lc > EA. The results revealed that the optimum model of the LM training algorithm can be used to characterize pile settlement with good degree of accuracy. There was also close agreement between the experimental and predicted data with a root mean square error, (RMSE) and correlation coefficient (R) of 0.0025192 and 0.988, respectively. © 2018, Springer International Publishing AG, part of Springer Nature

Stabilisation of soft soil using binary blending of high calcium fly ash and palm oil fuel ash

Lime and/or Ordinary Portland cement (OPC) are the traditional binders used in soft soil stabilisation. However, their manufacture has a negative impact on the environment. This paper reports the results of experimental work for the optimisation of a binary blended cementitious binder (BBCB) using two types of fly ash as an alternative for use in soft soil stabilisation. The optimum content of the high calcium fly ash (HCFA) was initially determined along with the effect of grinding activation on the performance of HCFA. Subsequently, the effect of palm oil fuel ash (POFA) pozzolanic reactivity on the engineering properties of soft soil, stabilised with HCFA, was investigated by producing different binary mixtures of HCFA and POFA. Based on the Atterberg limits and unconfined compressive strength (UCS) tests, the combination of POFA with HCFA results in a considerably lower plasticity index (PI) and higher compressive strength than those obtained from the soil treated with HCFA alone. Substantial changes in the microstructure and binders of the stabilised soil over curing time were evidenced by SEM imaging and XRD analysis. A solid and coherent structure was achieved after treatment with BBCB as evidenced by the formation of C-S-H, portlandite and ettringite as well as secondary calcite