Lateritic Gravel Research Articles

Stabilization of lateritic soil with Portland cement and crushed granite for pavement base courses

The aim of this work is to propose reconstituted materials, by cement-based improvement of lateritic gravels and joint cement improvement and lithostabilization, that are technically suitable for use in base courses. The study focused on two (02) different lateritic gravels, LG1 with a fine content of 24% and LG2 with a fine content of 15%. For lithostabilization, 0/25 granite crushed stone was used and the cement used was CEM II/B-LL 42.5. For cement improvement, three (03) cement contents (1%; 1.5% and 2%) were studied, and for joint stabilization, the granite crushed content was set at 10%, with only the cement content varying by 1%, 1.5% and 2%. The mixes were obtained by adding the cement mass calculated from the total gravel mass collected and the cement rate studied to the raw gravel or to a mixture of 90% gravel and 10% granite crushed stone. The results of physical-mechanical tests such as the Atterberg limits, Modified Proctor and California bearing index of stabilized materials were analyzed in comparison with the initial values of raw materials without stabilization. The results show that cement increases the plasticity index but improves the bearing capacity of lateritic gravels better than joint stabilization. However, joint stabilization does improve gravel bearing capacity compared with untreated raw gravel. For use as a base course in accordance with CEBTP specifications [3], in addition to the 10% granite crushed content, LG1 must be upgraded to at least 1.5% cement and LG2 to 1%.

Investigation of the effects of fine dune sand on the geotechnical characteristics of lateritic soil

Lateritic gravels are highly favored as a construction material for road pavements in Africa. With the rise in road construction projects and subsequent increase in traffic and overloading, the required physical and mechanical properties of lateritic gravels have become more stringent. However, the desirable qualities of these materials are diminishing, and their exploitation will soon become an environmental problem. This study aims to enhance the physico-mechanical properties of the remaining lateritic gravels by incorporating fine dune sand sourced from Dori, in the Sahelian region in Burkina Faso. This lithostabilization was made by formulating mixtures with varying proportions of fine sand (10%, 20%, and 30% by weight). Then, the influence of sand content on the physico-mechanical behavior of lateritic gravels from two sites (Kamboinsin and Saaba) was examined. Results indicate a significant reduction in the plasticity index and an increase in optimal dry density with the addition of sand. Moreover, the California Bearing Ratio (CBR) index substantially improves, particularly with 30% sand content, making laterite from Saaba (LS) suitable as a base layer for road pavement according to CEBTP standards.

Spatial variability of geotechnical parameters of lateritic gravels in an Olama–Ngomedzap road section in a humid tropical area (Cameroon)

Searching for borrow pits often used during civil engineering constructions is an important step that requires a lot of time and money. The nature of the parent rock, climate, topography, vegetation and time influence the formation of lateritic gravels with different geotechnical properties within the same region. The present study aims at finding the spatial variability of geotechnical parameters of lateritic gravels from two different deposits using a variogram and statistical analysis. Out of 122 lateritic gravel samples collected, 69 were from underdeveloped lithic ferrallitic soils (LFS) and 53 from under developed non-lithic ferrallitic soils (NLFS). The mean values of the coefficient of variation (CV) shows that the geotechnical parameters of LFS-derived lateritic gravels are more dispersed than those developed on NLFS. The fines content, plasticity index (PI) and Californian bearing ratio (CBR) variograms observed mainly in the North and NNE parts of the study area, suggest that, the lateritic gravels in this area have average to good geotechnical characteristics. The principal component analysis (PCA) indicates that the CBR and the maximum dry density (MDD) are inversely related to the optimum moisture content (OMC). The discriminant factor analysis (DFA) coupled to the ascending hierarchical classification (AHC) shows three families of lateritic gravels: (1) class 1/3, lateritic gravels characterized by MDD, CBR, consistency index (CI), gravels content, and plastic limit (PL); (2) class 2/3, lateritic gravels characterized by fines content, and maximum grain diameter (Dmax) and, (3) class 3/3, lateritic gravels characterized by OMC, liquid limit (LL), PI, PL, and fines content, that fit for road construction.

Improvement of the bearing capacity of lateritic gravel by a geopolymer binder: road construction in tropical countries

Improvement of the bearing capacity of lateritic gravel by a geopolymer binder: road construction in tropical countries

Influence of mineralogical and geochemical multi-parameters on the geotechnical properties of gneiss-derived lateritic gravels from an equatorial zone, center Cameroon

Influence of mineralogical and geochemical multi-parameters on the geotechnical properties of gneiss-derived lateritic gravels from an equatorial zone, center Cameroon

Effects of Loading and Compaction Conditions on Permanent Strains of Unbound Lateritic Soils from Senegal and Burkina Faso

Permanent strains of granular materials result from the repetitive passage of heavy trucks on the pavement. Pavement design relies mainly on permanent strains to predict rut depths. In order to contribute to the improvement of technical documents used for the design and modelling of pavements in tropical African countries, the researchers have focused on the determination of the permanent deformation parameters of laterites (axial (εp,1) and radial (εp,3) permanent strains). The Repeated Triaxial cyclic Loading (RTL) apparatus was used according to the European standard (EN 13286-7: 2004, Multistage method). Four sites of gravelly lateritic soils chosen, two from Burkina Faso (Badnogo2 and Dédougou) and two from Senegal (Sindia and Lam-Lam) were tested in this research. They are compacted to 95% and more of the optimum with a variation in water content of ±2% of the optimum. The permanents deformations are influenced by the water content, the compaction rate and the stress level. The axial permanent deformation ε1,p (max) decreases by 83.4% when the water content decreases from 12.10% to 7.59%. Moreover with a compactness rate that varies from 95.58% to 100.06%, respectively from a water content that varies from 10.04% to 9.36%, we observe a decrease in deformation ε_(1,p) from 224.340*10-4 to 148.150*10-4 from the 50,000 cycles, which shows the effect of the compactness rate and the stress level on the lateritic gravels materials soils. however, for a good control of permanent deformations on flexible pavements using gravel materials, it is necessary to compact at water contents lower than the optimum added to average compaction rates. Keywords: permanent strains (p), lateritic soils, Repeated Triaxial cyclic Loading (RTL), Sindia, Badnogo2, Dedougou, Lam-lam.

Mechanical characterization of an alternative laterite gravel used as pavement material

Laterite gravels have been successfully adopted as pavement materials in the field. Despite that, they are often rejected in material selection processes because of its base on traditional gradation and consistency limits requirements. To allow a deeper evaluation of such material found abundantly in tropical countries, along to characterizing traditional parameters, repeated load triaxial tests were performed in a Laterite Gravel from Acre/Brazil to evaluate its elastic and plastic behavior through Resilient Modulus (RM) and Permanent Deformation (PD), respectively. In addition, a simulation was conducted in the MeDiNa software, based on the test results considering stress states that are usually applied in pavement layers. The material showed RM values higher than 500 MPa, which was considered high compared to materials such as Quartz and Granite. It was also observed low permanent deformation (below 1 mm for higher tensions applied) and accommodation of displacement (shakedown) for most specimens. The simulation results showed low rutting prediction for the Laterite Gravel applied in highway pavement layers. Thus, the results indicated that the lateritic gravel can be adopted in the composition of base or subbase layers of flexible pavements, even though some limits of the parameters specified by traditional specifications were violated, as expected. In addition, we also highlight the need for adoption of new material selection strategies that are based on key mechanical characteristics to avoid discarding potentially well performing materials.

Geotechnical Suitability of Soils in Road Construction for Sustainable Development in Tropical Africa: Case of Lateritic Graveled Soils of Bandjoun (West, Cameroon)

The environmental impact of the exploitation of geomaterials and their relatively high cost, coupled with the increasingly low financial capital in developing countries, are pushing road actors to turn to inexpensive local ecological materials. The present study is conducted on lateritic graveled soils of Bandjoun (LGSB) in the West Cameroon Region. The aim is to determine whether lateritic gravel soils, particularly those in Bandjoun, can be an ecological and economical alternative to rock aggregates in road construction, considering their geotechnical parameters and environmental impact. These soils were described in the field and were also subjected to complete geotechnical identification in the laboratory. The LGSB presents Californian bearing ratio indices ranging from 26% to 83.3%, a plasticity index of 10.11%, a fines content of 12.05%, an average methylene blue value of 4.25, a water content at the Proctor optimum of 27.6% and a dry density of 1.75 g/cm3. They are silty or clayey gravels and sands of subgroup A-2-7 according to the Highway Research Board classification; sandy and gravelly soils with fines of class B according to the classification of the Road Construction Guide; and silty gravels according to the classification of the Central Laboratory of Bridges and Highways. These soils can be used naturally in pavement layers, in particular in subgrade for all traffic classes and in subbase for low traffic. The tonnage of these soils has been estimated at 18,389 t. The global warming index shows that the use of these soils (18,389 t) in road construction can reduce 31,629–62,706 kg of carbon emissions. The use of lateritic soils in road construction is a very interesting alternative to reduce the environmental impacts associated with the manufacture of rock aggregates. So, lateritic soils should be used instead of rock aggregates for cleaner, more environmentally friendly road construction. The present work presented a specific evaluation of the geotechnical properties and ecological impact of lateritic graveled soils for road construction, as well as their potential for ecological and economic utilization.

Activities and intrinsic properties of the clayey fines four lateritic gravels

The aim of this study was to identify, classify and characterize the activities and correlations between the intrinsic properties of the four lateritic gravels used in construction. The grading curves of the four lateritic gravelly are spread out, but poorly calibrated. Lateritic gravel LG1 contains class B5 silty fines with low plasticity and low swelling. Lateritic gravels LG2, LG3 and LG4 contain clayey fines of low plasticity and medium swelling, class B6. The specific surface area and cation exchange capacity depend on the mineralogy, organic composition and texture of the lateritic gravel. The blue value of the soil characterizes the activity of the clay fines and reflects the surface activity of the lateritic gravels. The four lateritic gravels are inactive and contain minerals (kaolinite, quartz, goethite, hematite). The correlations obtained between the intrinsic properties are linear fits and between the liquidity limit and the specific surface area a non-linear fit of the ExpDec1 model with R2 (0.99). The relationship between activity and surface activity is simply the relative activity.

Study of Correlation between CBR and Certain Physical Characteristics of Lateritic Gravels

The aim of this work is to study the possibility of establishing a correlation between the CBR value and the percentage of fines, the plasticity index, the Proctor density and the water content at the Proctor optimum of laterites that can be used in pavement layers. To this end, data was collected on the physical (percentage of fines, Atterberg limits) and mechanical (Proctor and CBR) characteristics of lateritic gravels available in Togo. In accordance with current standards, the data collected was analysed using Excel software and correlated using Matlab, with CBR as the explained variable and percentage of fines, plasticity index, Proctor density and water content at the Proctor optimum as the explanatory variables. A total of 479 test results on lateritic gravels were identified and used to carry out this study. The results of this study show that it is possible to correlate the CBR as a function of the percentage of fines and density using Matlab software. This correlation is obtained in the form of a bi-harmonic surface linking the CBR to the density and the percentage of fines, which is the solution of a partial differential equation solved by the weak form (numerical approximation using finite elements or finite differences) and not by the strong form (writing a formal solution). Keywords: laterite, road pavement, CBR, correlation

IMPROVEMENT OF LATERITIC GRAVELLY SOILS IN ROAD CONSTRUCTION: PARTIAL SUBSTITUTION OF CEMENT BY GRANITE POWDER

This study focuses on the lateritic gravels of N'DOUCI whose physical properties do not meet the specifications for their use as a road base. Thus, for its use in road construction, a partial substitution of cement by granite powder has been made. Several tests (particle size analysis, chemical analysis, CBR and proctor tests, Atterberg limits, etc.) were carried out to verify the geotechnical and mechanical characteristics of the new material. This study showed that the addition of granite powder in place of cement improved the material properties, i.e. optimum dry density, CBR. The results show that the optimum dry density is 1.95% with a moisture content of 12%. Overall, the results obtained are satisfactory and show that a quantity of 2% cement for 6% granite powder is required for a base course material in road construction. However, it would be useful to use the proportions of 4% cement to 4% granite powder.

Ex-situ and In-situ Manufacturing Procedures for Optimizing the Characteristics of a Soil Concrete Based on Lateritic Gravels and Granitic Aggregates: Application in Road Construction

Ex-situ and In-situ Manufacturing Procedures for Optimizing the Characteristics of a Soil Concrete Based on Lateritic Gravels and Granitic Aggregates: Application in Road Construction

Mechanical characteristics of Avlamè lateritic gravel improved with granite crushed for its use in road construction in Benin

Lateritic gravels are the most abundant road materials used in pavement foundations. With the scarcity of good quality materials, the recourse to lateritic gravels having weak technical characteristics, like the lateritic quarry of Avlamè Benin, is felt with the high price of stabilizers like cement, other methods must be explored in cooperation in order to reduce the cost of stabilization and, consequently, the cost of road construction and the risks related to the environmental pollution In this respect, it is imperative to determine the technical characteristics of the lateritic gravel of Avlamè improved with granitic crushed stone 0/31.5 for its use in the base course of flexible pavements. Thus, an experimental study on Avlamè lateritic gravel with different percentages of granitic crushed stone was carried out following the normative recommendations in road construction. This characterization allowed to highlight the technical properties of the lateritic gravel improved with granite crushed at different percentages. The results obtained show that the pass rate at 80 μm sieve goes from 27.77% to 10.51%, the plasticity index from 17.67% to 11.33%, the dry density at OMC from 2.17 t/m3 to 2.23 t/m3 and the CBR index at 95% at OMC from 58.00% to 108.67%. These results show that mix 2 (85%GL+15%CG), mix 3 (80%GL+20%CG), mix 4 (75%GL+25%CG), mix 5 (70%GL+30%CG) and mix 6 (65%GL+35%CG) can be used as a base course for flexible pavements in accordance with the normative requirements of the CEBTP revised in 2019 and the Catalogue of AGEROUTE-Senegal.

Mechanical characteristics of Avlamè lateritic gravel improved with granite crushed for its use in road construction in Benin

Mechanical characteristics of Avlamè lateritic gravel improved with granite crushed for its use in road construction in Benin

Contribution of geoelectrical soundings and pedological wells to the estimation of the tonnage of lateritic gravels of the northern flank of Mount Bangou: implications for road construction

Contribution of geoelectrical soundings and pedological wells to the estimation of the tonnage of lateritic gravels of the northern flank of Mount Bangou: implications for road construction

Using a Unique Retaining Method for Building Foundation Excavation: A Case Study on Sustainable Construction Methods and Circular Economy

The selection of a retaining method during the excavation of building foundations is always of paramount concern to engineers. In general, the application and use of steel H-shapes are typically practiced by designers to form the entire retaining system; however, sustainability issues, including carbon emission reduction, environment protection, material consumption, and resource circulation, are being increasingly considered when developing a new project. The Linkou Public Housing Project (LPHP), located in New Taipei City, Taiwan, is introduced in this paper to present a sustainable soil-retaining method that also exhibits the principles of a circular economy. The triangular shape of the foundation zone of the LPHP led to difficulty in setting the horizontal strut H-beam system. In this project, the “Anchor Pile with Steel Cable System (APSCS)” was adopted to retain the 11.5 m depth excavation for the LPHP foundation construction. The prime contents of the soil in the Linkou district comprises a laterite–gravel layer mixed with brown silty and sandy clay, with a groundwater level (G.L.) of −25 m. By adopting the sustainable APSCS method, the excavation of the LPHP foundation was safely completed. Approximately NT $350 million in direct and indirect costs of construction was saved, and the duration of the work was reduced by up to 90 days. Furthermore, the carbon emissions were reduced by 677.6 tons due to the diminished use of the steel H-shaped materials. The authors concluded that the use of the APSCS method in the LPHP was successful and it was a valuable reference for other similar projects. Moreover, the authors presented another retaining-system failure case, which was located near the LPHP site, to compare the success of the LPHP.

Evaluating geosynthetic base stabilization on lateritic gravel and granular material under cyclic moving wheel loads

This study presents an experimental investigation on seven geosynthetic stabilized and unstabilized sections subjected to cycling moving wheel loading. Tests were conducted on lateritic clay mixed with gravel and unbounded granular base coarse materials at two different thicknesses. All test sections were constructed on a low California bearing ratio clay subgrade. After constructing each layer, a static plate test was conducted to evaluate the post-compaction strain modulus. Findings indicated that the base coarse deterioration mechanisms were different for both materials. The lateritic base course presented a higher modulus and lower values of permanent deformation compared with the granular base course. It was also observed that the presence of the geosynthetic reduced the maximum rut depth and stress in the subgrade. Lastly, the back-calculated moduli showed that the stabilized sections had a base improvement factor ranging from 1.20 to 2.32. Also, the stabilized lateritic gravel course sections presented an increase in subgrade moduli.

Thermal Characterization of an Eco Conce Based on Lateritic Gravel, Millet Pods and Cement

To simultaneously meet the need of thermal confort and living environment protection, vegetable biomass valorisation in building sector is of particular importance. In this context, the main objective of this study is to produce a lightweight composite concrete based on millet pods and lateritic gravel with a cement matrix for use in buildings to help improve thermal comfort and protect environment. To achieve this, the composite formulation with 250 kg.m-3 cement dosage and an 0.8 water to cement ratio was used to manufacture two type test specimens of (4 × 4 × 16) cm3 dimensions for porosity tests and (4 × 4 × 5) cm3 for thermal tests with a millet pod rate varying from 0 to 6% with a step of 2%. Average thermophysical characteristics of 5 tests carriesd out over 5 days, namely: Thermal conductivity, thermal diffusivity, thermal effusivity, thermal phase and damping, were experimentally measured using fluxmetric method similar to that of mini hot plate method with two Peltier elements as fluxmeters. Results obtained showed that for 0, 2, 4 and 6% millet pods dosage, thermal conductivity values obtained are respectively 1.18 W.m-1.K-1, 0.74 W.m-1.K-1, 0.63 W.m-1.K-1 and 0.61 W.m-1.K-1, i.e., a reduction of 93.44%. For same millet pod dosage, thermal effusivity values are 2157.33 J.m-2.K-1.s-0.5, 1236.34 J.m-2.K-1.s-0.5, 946.03 J.m-2.K-1.s-0.5 and 775.04 J.m-2.K-1.s-0.5, i.e., a reduction of 64.07%. On the other hand, it was observed 3.00.10-7 m2.s-1, 3.56.10-7 m2.s-1, 4.47.10-7 m2.s-1 and 6.25.10-7 m2.s-1, i.e., an increase of 108.33% for thermal diffusivity. With regard to dynamiquc thermal characteristics, it was obtained an increase from 5.43 to 13.18% for thermal damping and, from 61.00 to 84.20 min for thermal phase. Through on the one hand, thermal conductivity and effusivity decrease and on the other hand, thermal damping and phase shift increase, it is retained that characterized eco-concrete should contribute to thermal losses limitation, energiy saving and improved thermal comfort.

Mechanistic evaluation of a monitored pavement constructed with asphalt surface treatment

Este artigo objetiva apresentar os resultados preliminares de um trecho monitorados em Goiás, incorporando análises mecanicistas de modo a contribuir com o banco de dados de materiais, tecnologias e desempenho de um pavimento asfáltico executado com Tratamento Superficial Duplo (TSD). Para isso, nesta pesquisa foram realizados ensaios laboratoriais com os materiais em termos de caracterização, comportamento mecânico e resiliente dos componentes de cada camada, verificando também o comportamento do cascalho melhorado com cimento em três teores diferentes. A seção de teste do pavimento foi monitorada durante a execução e até 6 meses após liberação do tráfego, por meio da determinação das deflexões, das macro e microtexturas, da medida da trilha de roda, da avaliação do tráfego e da identificação dos defeitos aparentes. O dimensionamento do TSD também foi avaliado. As tensões e deformações desenvolvidas ao longo das camadas foram obtidas e os módulos de campo determinados por meio de retroanálise. Os resultados mostraram ganho de desempenho mecânico com a adição de cimento no cascalho, falhas na execução, surgimento precoce de patologias, elevadas deformações nas camadas inferiores à base e superdimensionamento de emulsão no TSD.

Model of the Evolution of the Modulus of Elasticity E, As A Function of the Bearing Capacity Index ICBR of Gravelly Laterites. Case of the Banka Locality (Westcameroon)

The objective of this study is to model the evolution of the values of the modulus of elasticity E as a function of the bearing capacity index ICBR of Banka lateritic gravel, with the aim of reducing the cost and time of laboratory tests for the determination of the modulus of elasticity and the CBR index. Geotechnical identification tests were carried out on 18 laterite samples taken from the Banfeko, Bakoye and Ketcho sites in the Banka locality. ICBR values ranged from 31 to 51.92 and E-modulus values ranged from 80 MPa to 165 MPa. The resulting model is polynomial for all sites of the form: E = a* ICBR 5 + b* ICBR 4 + c* ICBR 3 + d* ICBR 2 + e* ICBR +f This model has the highest degree of interdependence of value 1.