Soil Stabilization Using Zein Biopolymer

To evaluate the geotechnical properties of a soil mass, different soil specimens were prepared in the lab by mixing various proportions of quartz, smectite, and illite. Liquid limit, plastic limit, and volume change behavior in terms of compression and swelling indices were measured according to the procedure mentioned in the respective ASTM methods. Those minerals are considered as the most common minerals that are found in expansive soils that include mudstone/clay stone, marl and shale. Such expansive soils are always considered as problematic soils in geotechnical engineering. The results show that plasticity index and liquid limit depend on the proportion of smectite and total clay content. A parabolic relationship could be observed between the liquid limit and proportion of smectite. Smectite is mainly controlling the plasticity characteristics. Likewise, volume change properties also depend on the proportion of smectite and liquid limit. A parabolic relationship was observed between the compression index and proportion of smectite, whereas a linear relationship was observed between the liquid limit and compression index. The results clearly show that we can estimate the coefficient of consolidation, and compression and swelling indices of a soil mass with reasonable accuracy with liquid limit and proportion of dominant clay mineral. This finding has a great significance in the geotechnical engineering because with a small amount of soil that can be collected from a boring core, we will be able to evaluate liquid limit, mineralogical composition, and clay content. Those parameters can be used to estimate the compressibility and hydraulic conductivity of a soil mass. They are very important in numerical simulation, foundation design, and many other applications in geotechnical engineering.

Geotextiles, a group of high-performance materials, have grown during the last decades into needful auxiliaries when it comes to infrastructure, soil, construction, agriculture and environmental applications. Although geotextiles made of synthetic fibers (geosynthetics) are considered a modern achievement, the basic concept dates back to ancient times when textiles consisting of locally available natural fibers were employed to increase the stability of roads and soils. In recent decades, considering the growing interest in environmental protection and sustainable development based on using renewable resources and the recovery and recycling of waste of various origins, the use of natural fibers-based geotextiles is a viable alternative, despite their limited-life service owing to their biodegradability. In addition to this feature, their low cost, good mechanical properties and large-scale accessibility recommend them for geo-engineering applications, environmental sensitive applications in geotechnical engineering, such as land improvements and soil erosion control. This paper focuses on geotextiles as a versatile tool in environmental applications given their high theoretic and practical relevance as substantiated by recent literature reports. Natural and synthetic geotextiles are presented herein, as well as their features that recommend them for geo-engineering. Insights on the main types of applications of geotextiles are also included, along with a wide variety of materials employed to perform specific functions.

Steel slag has similar characteristics with sand, and pure steel slag used as geotechnical backfill material is an effective way to improve the comprehensive utilization rate of waste steel slag. In order to study characteristics of pure steel slag for application in geotechnical engineering, the compressive deformation characteristics and shear strength characteristics of steel slag under different water contents were explored by unidirectional consolidation compression tests and direct shear tests. Change rules of densities, compressive moduli, cohesion and internal friction angles of steel slag under different water contents were analyzed. It can be concluded that the compressive modulus of steel slag decreased with increasing the water content. The compressive modulus of dry steel slag was larger, reaching the level of medium sand. Compression moduli at different water contents were higher than those of silt soil and soft clay. Steel slag can be used as backfill material instead of mud soil and soft clay in the treatment of soft soil foundation. The cohesion of steel slag increased and the internal friction angle decreased with increasing the water content. The shear strength of dry steel slag was similar to that of medium sand, indicating that steel slag was more suitable as roadbed filling above the groundwater level.

PurposeThe quest to reduce the cost of concrete which is a major construction input has prompted investigations into assessing the suitability of alternative sources of conventional materials. This paper aims to report the compressive strength and workability of lateritic gravel used as all-in aggregate for concrete production.Design/methodology/approachThree prescribed mixes from all-in aggregate concrete were compared with concrete from lateritic gravel. The paper investigated the variation in strength of four different mixes – 100: 0, 90: 10, 80: 20 and 70: 30 – when portions of the lateritic gravel were replaced with pit sand, respectively, using varying water cement ratios to achieve optimal workability.FindingsThe density and compressive strength of each cube was measured on the 7th and 28th test dates. An increase in slump and compressive strength was observed in the lateritic concrete, as portions of the lateritic gravel were replaced with sand. However, the rate of increase in the compressive strength tended to decrease with increase in part replacement of lateritic gravel with sand indicating that there was a threshold of percentage of sand increase after which the compressive strengths are likely to decrease. This work never reached this threshold, but it is estimated to be about 40 per cent.Research limitations/implicationsInvestigations focused on lateritic gravel sampled from two sites to represent samples from both the forest and savannah belt.Practical/implicationsLateritic gravel can be used as all-in aggregate for non-structural concrete.Originality/valueThe compressive strengths achieved were better than those for the available normal all-in aggregate used.

In many areas, natural soil does not have necessary resistance, some additives such as cement and microsilica are added to increase their resistance. In this research, the effect of microsilica on the strength and physical characteristics of fine sand stabilized with cement in sand samples containing cement and microsilica will be discussed. For this purpose, samples of fine sand with three different ratios of cement (2, 4, and 6 percent of soil weight) and four different ratios of microsilica (0, 0.5, 1, and 1.5 percent of soil weight) were mixed with optimal moisture, after Two curing periods of 1 and 7 days were subjected to compression and uniaxial compressive strength tests. The results of the experiments indicate that with the increase in the amount of cement and microsilica, the optimum moisture content in the density increases, the specific weight of the mixture of sand, cement and microsilica increases by adding these materials up to a certain amount, but after that it begins to decrease. . With increasing processing time, uniaxial compressive strength and rupture strain both increase. With a curing time of 1 day, for a fixed cement ratio, the compressive strength of sand-cement increases with the increase of microsilica up to about 20% of the cement weight, but after that, the resistance ratio decreases.
 With a curing time of 7 days for a constant cement ratio, the compressive strength increases with the increase of microsilica. It is also observed that in both curing times for different cement ratios, with the increase in the amount of microsilica, the relative deformation of the fracture increases.

The increasing demand for sustainable construction materials has prompted research into alternative materials, one of which is glass powder. This study evaluates the effect of adding glass powder on the compressive strength and modulus of elasticity of concrete. An experimental method was conducted with variations in glass powder content of 0%, 1%, 2%, 3%, and 4% by aggregate weight. The concrete was tested to determine its compressive strength and modulus of elasticity, with testing carried out at the Civil Engineering Laboratory. The results showed that the addition of 2% glass powder provided the optimal increase in compressive strength, reaching 20.75 MPa, compared to concrete without glass powder, which had a compressive strength of 17.27 MPa. The addition of 3% and 4% also improved compressive strength, though slightly lower than the 2% addition. Conversely, the 1% glass powder addition reduced the compressive strength to 10.82 MPa. The modulus of elasticity of the concrete increased significantly with the addition of 3% glass powder, reaching 2,924.670 MPa, which is higher than concrete without glass powder (2,353.373 MPa). The most significant increase occurred between 1% and 2% glass powder. However, with 4% glass powder, there was a slight decrease in the modulus of elasticity.

Production of geopolymer concrete using natural pozzolan: A parametric study

This study investigated the compressive strength of hardened cement paste and the formation of Calcium Silicate Hydrate (C-S-H) with the addition of nano silica (SiO2). Compressive strength testing was performed using MTS and Forney testing machines to determine stress-strain curves and compressive strength of the materials. The hydration process and formation of C-S-H and Calcium Hydroxide (CH) was examined using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). This study also incorporates the use of vacuum curing, in comparison to that of the traditional water curing method. Results indicate an increase in compressive strength using 1, 3 and 5% of nano silica to cement replacement by volume in comparison to the control mix (without nano silica). The optimum cement replacement to yield maximum strength was of the 1% nano silica content. The formation of C-S-H increases significantly during the early testing days which correspond with the drastic increase in compressive strength. The hydration process continues to increase throughout the 56 day trails at a moderate rate. The traditional water curing method proves to be more efficient and beneficial than of the vacuum curing method. However, vacuum cured results showed only about a 5% reduction in compressive strength after 56 day tests in comparison to the water curing method.

Basalt fiber (BF) can notably improve the mechanical properties of lightweight aggregate concrete (LWAC) through its crack-bridging and pull-out mechanisms, making it suitable for application in super high-rise buildings and large-span structures. This study assesses the influence of BF contents of 0%, 0.1%, 0.3%, 0.5%, and 0.7% (relative to the weight of cementitious materials) on the workability, mechanical properties, and microstructure of LWAC. The results showed that adding BF to LWAC can moderately weaken the slump, significantly enhance the mechanical properties, and lead to a maximum increase in specific strength of 7.3%. Compared with LWAC without BF, the maximum increases in compressive strength, flexural strength, and elastic modulus of LWAC with BF at 28 days were 24.7%, 33.9%, and 38.57%, respectively. In the microstructure, BF can connect the cracks in the internal structure of concrete, which is an important factor to consider when choosing a fiber to improve the mechanical properties of concrete. These conclusions provide a reference point for improving the mechanical properties of LWAC.

Pulverized coal combustion (PCC) dry bottom ash is a by-product of coal combustion that originates from the burning of pulverized coal to produce electricity. Because of the increasing costs associated with the disposal of bottom ash and the environmental regulations in place, a significant need exists to develop alternate methods for profitable and environmentally safe uses of this waste material. The physical properties of bottom ash are similar to those of natural sand, with particle sizes ranging from fine gravel to fine sand with low percentages of silt and clay-sized particles. Bottom ash has been used in the past as a substitute for aggregates in concrete. However, not much effort has been made in examining the geotechnical engineering properties of bottom ash, and as a consequence its use in geotechnical engineering applications is still very limited. Characteristics of bottom ash depend on the type of coal burned and the type of furnace used to burn the coal. This paper presents the results of an experimental study conducted to obtain technical data on the geotechnical engineering properties of Illinois PCC dry bottom ash amended with bentonite, which data are needed to assess its use for geotechnical engineering applications. Bottom ash modified with up to 20% bentonite by weight of bottom ash was tested to determine the effects of bentonite on consistency, moisture-density relationships, shear strength, and hydraulic conductivity of the bottom ash-bentonite mixtures.

SummaryA comparative study of optimization techniques for identifying soil parameters in geotechnical engineering was first presented. The identification methodology with its 3 main parts, error function, search strategy, and identification procedure, was introduced and summarized. Then, current optimization methods were reviewed and classified into 3 categories with an introduction to their basic principles and applications in geotechnical engineering. A comparative study on the identification of model parameters from a synthetic pressuremeter and an excavation tests was then performed by using 5 among the mostly common optimization methods, including genetic algorithms, particle swarm optimization, simulated annealing, the differential evolution algorithm and the artificial bee colony algorithm. The results demonstrated that the differential evolution had the strongest search ability but the slowest convergence speed. All the selected methods could reach approximate solutions with very small objective errors, but these solutions were different from the preset parameters. To improve the identification performance, an enhanced algorithm was developed by implementing the Nelder‐Mead simplex method in a differential algorithm to accelerate the convergence speed with strong reliable search ability. The performance of the enhanced optimization algorithm was finally highlighted by identifying the Mohr‐Coulomb parameters from the 2 same synthetic cases and from 2 real pressuremeter tests in sand, and ANICREEP parameters from 2 real pressuremeter tests in soft clay.

As urbanization progresses, the demand for high-rise buildings and underground spaces is growing, and the need for firm geotechnical construction materials, efficient excavation methods, accurate testing instruments, and innovative geotechnical engineering theories and technologies is increasing. By investigating the phenomena of strengthening and toughening in nature, hydrophobic and ice-phobic, friction anisotropy and drilling as well as excavation, etc, researchers have found that organisms have distinctive external morphology and organization. By imitating the external morphology, structural characteristics or movement mechanism of organisms, novel ideas, new principles, and innovative theories can be provided for the innovation and sustainable development of geotechnical engineering. This paper mainly expounds on the bio-inspired application in geotechnical engineering from three perspectives: geo-materials, geotechnical components, and drilling & excavation equipment, and lists typical application cases. In conclusion, this paper presents a summary and prospects of bio-inspired geotechnical engineering, offering fundamental insights for future research.

The aim of this research was to undertake laboratory testing to investigate the beneficial effects of epoxy resin grouts on the physical and mechanical properties of sands with a wide range of granulometric characteristics. Six sands of different particle size and uniformity coefficients were grouted using epoxy resin solutions with three ratios of epoxy resin to water (3.0, 2.0 and 1.5). A set of unconfined compressive strength tests were conducted on the grouted samples at different curing periods and a set of long-term unconfined compressive creep tests in dry and wet conditions after 180 days of curing were also carried out in order to evaluate the development of the mechanical properties of the sands, as well as the impact of water on them. The findings of the investigation showed that epoxy resin resulted in appreciable strength values in the specimens, especially those of fine sands or well graded sands, grouted with the different epoxy resin grouts. Whilst the higher compressive strength and elastic modulus values at the age of 180 days were obtained for the finer sand, which ranged from 2.6 to 5.6 MPa and 216 to 430 MPa, respectively, the lower compressive strength and elastic modulus values were attained for the coarser sand with low values of the coefficient of uniformity, which varied from 0.68 to 2.2 MPa and 75 to 185 MPa, respectively. Moreover, all grouted sands showed stable long-term creep behaviour, with high values of the creep limit ranging from 67.5 to 80% of compressive strength. The presence of water had a negative marginal effect in the majority of the grouted specimens. In terms of physical properties, the permeability and porosity were estimated. The permeability of fine sands or well graded sands was decreased by two to four orders of magnitude. Using laboratory results and regression analysis, three mathematical equations were developed that relate each of the dependent variables of compressive strength, elastic modulus and coefficient of permeability to particular explanatory variables.

Comparative Study on Impact of Rice Husk Ash and Fly Ash in Concrete Mix Design for Different Grades of Concrete

Cosmic-ray muography has several current and many promising future applications in geosciences, geotechnical engineering, and mining engineering. Muography, if applied to these disciplines, is based on alternating muon flux attenuation in soils and rocks due to anomalous density heterogeneity in the media. Muography can be used for detecting and imaging lithological boundaries, structural geological features, hydrothermal alteration zones, and ore bodies in geological research and mineral exploration. Muography can also be employed for mining planning, tunneling, drifting, and rock mass monitoring. There are possibly a great number of other future applications in geosciences, geotechnical engineering, and mining engineering on Earth and even on Mars and the asteroids. However, one challenge is that muography originates outside the realm of classical physics (and conventional geophysics), and hence most geoscientists, geoengineers, and mining engineers are not yet familiar with its principles and applications. We anticipate the usage and commercial availability of muography will expand in the future, and muographic surveys will become as essential to geophysics as the more traditional methods are today.