Determination of Types and Characteristics of Laterite Soil as Basic Land for Building Construction

Laterite soil is red soil because it contains iron and aluminum. It is an old type of soil, so it is suitable for all plants. Laterite soils are located in the reservoir area of the Wonogiri Dam - Central Java. The nature of laterite soil that quickly absorbs water and the soil texture is strong and dense indicates the type of soil used for a mixture to make roads. This study aims to identify and characterize the lateritic soils to support the construction of roads that will be used. It is needed to test the soil’s property index, including moisture content test, density test, Atterberg limit, and grain sieve analysis. At the same time, it tested the classification of laterite soil characteristics using standards of USCS and AASHTO. To test the shear strength of the laterite soil is using Direct Shear. Based on the analysis, the laterite soil from sedimentation in Wonogiri dam is classified as poor and does not meet the requirements to be used as a subgrade in building construction. It can be considered include need to improve to carried out first.

Mechanical and Microscopic Properties of Graphite/Laterite Nanocomposites

The effectiveness and improvement mechanism of graphite nanoparticles (GN) in strength properties and microstructure characteristics of regional laterite were analysed in this study. Dry density was also taken into consideration, and the effects of graphite nanoparticle (GN) content and dry density were mainly addressed. Triaxial tests, consolidation tests, and penetration tests were used to analyse the effectiveness of different dry densities and graphite nanoparticle mass ratios on the properties of laterite; microscopic methods such as scanning electron microscopy (SEM) tests were used to analyse the improvement mechanism. The results show that the increase in dry density can make the laterite more compact. The large specific surface area and nanoeffects of the graphite nanoparticles (GN) induce the attraction between soil particles after mixing, both of which make the laterite’s shear strength; compression index and impermeability have been enhanced to varying degrees. The microscopic tests showed that, as the content of graphite nanoparticles (GN) continues to increase, when it exceeds 1.0%, the attraction between soil particles increases and coarse particles are formed, which leads to the increase of the pores of the soil. In addition, the graphite nanoparticles have a certain degree of lubricity, a high amount of graphite nanoparticles enters the laterite soil layer, increasing the distance and gap between the layers, making it easy to separate the coarse particles from the coarse particles, and the strength increase is reduced. However, it is still stronger than that of the plain laterite.

The effect of curing on compressive strength of geo-polymer mortar made rice straw ash, fly ash, and laterite soil

This study aims to analyze the effect of curing on the compressive strength of geopolymer mortar made from straw ash, fly ash and laterite soil. This research is experimental in the laboratory. Geopolymer mortar was produced using straw ash, fly ash and laterite soil with a percentage ratio of 16.67: 41.67: 41.67. The alkaline activator used is sodium hydroxide (NaOH) with a concentration of 12 M. The compressive strength test of 5 × 10 cm cylinders is used to evaluate the geopolymer mortar mixture produced at the age of 3, 7 and 28 days with curing, namely air and water curing. The results showed that the compressive strength of the geopolymer mortar increased along with the increasing age of each curing. The compressive strength values produced in air curing 3, 7 and 28 days were respectively 1.64 N/mm2, 1.72 N/mm2 and 3.22 N/mm2. While water curing, the resulting compressive strength values for each curing are 1.03 N/mm2, 1.63 N/mm2 and 1.68 N/mm2. At the ages of 3, 7 and 28 days, there was an increase in the compressive strength values from water curing to air curing, which were 0.37%, 5.23% and 47.82%, respectively. It can be seen that the compressive strength of the geopolymer mortar made from straw ash, fly ash and laterite soil in air curing is greater than that of water curing.

Physical and Chemical Soil Properties of Mangrove Forests in Vietnam

Recently the area of mangrove (evergreen) forests growing along the coast of Vietnam has been significantly increased by artificial afforestation under the recognition of their ecological role and economic importance. Protection mangrove forests are the largest among all mangrove forests in Vietnam. They act as a belt to prevent coastal roads from erosion and damage due to tides, storms, and tsunamis. However, their role in coastal soil formation is still poorly studied. Soil formation in mangrove forests is influenced by many factors including the following: woody vegetation, tidal saltwater, precipitation, and mountain runoff. The ability of soil to retain water, nutrients, ions, and some other physical and chemical properties is closely related to the soil texture. Long-term monitoring of the soil texture and the content of nutrients in the soil of mangrove forests in the Dam Bay area of the Nha Trang Bay allowed us to distinguish 2 groups of soil phases: typical laterite soil in natural mangrove forests and in rhizophore plantings of 2004 and poorly developed laterite soil in cultural cenoses of 2007 and 2013 and in the littoral zone. These two groups have differences in the soil texture depending on the time of stand formation. The total amount of gravel, aleurite, and silt in the first group of soils is higher than that in the second group. The concentrations of nutrients (phosphorus and nitrogen content) in the soil of mangrove forests is quite high, though it gradually decreases from the soil of natural mangrove forests to the littoral zone. In order to effectively prevent erosion of soils and improve their physical and chemical properties, artificial mangrove forests should continuously be grown along the coast lines of the Nha Trang Bay in the Khanh Hoa province, Vietnam. For citation: Phan T.H., Kovyazin V.F., Zvonareva S.S., Nguyen T.H.T., Nguyen T.L. Physical and Chemical Soil Properties of Mangrove Forests in Vietnam. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 9–21. DOI: 10.37482/0536-1036-2021-5-9-21

Efficient Loading of Mano Mn Particles On Calcined Laterite Soil (Lt-nMn) For Higher Removal of As(III) Ions From Groundwater: Adsorption And Eco-Scale Analysis

Occurrence of arsenic in the groundwater has become a cause for concern in many countries. The presence of As(III) species in the groundwater had been one of the biggest challenges for the water workers especially in the south east Asian countries. Nano based adsorption techniques are gaining attention among researchers for the removal of arsenic ions. However, synthesis of nano-adsorbents is a costly affair. Therefore, the present study utilized the cheap and readily available laterite soil as a base material for nano coating. Nano sized manganese (nMn) particles were synthesized by chemical reduction method and later coated on calcined laterite (Lt-nMn). Coating with 0.1 M nMn provided the best As(III) removal efficiency. The prepared material was characterised for its morphological and surface properties. Phase analysis using XRD (X-ray diffraction) showed the presence of zero valent manganese species, which assisted in adsorption. Adsorption studies were conceded by selecting the different affecting parameters such as contact time, concentration, dose, temperature, and pH. Very high removal in less time regime led to the investigation of the oxidation mechanism. Phosphate and sulphate anions insignificantly reduced the removal efficiency. Langmuir model for the sorption isotherms and pseudo-second order kinetic model for the sorption kinetics symbolized the experimental data. Sustainability studies in terms of eco-scaling and cost analysis were performed for the applied method of production of the nano materials. Adsorber design analysis was also conducted to estimate the required amount of Lt-nMn particles for achieving the desired equilibrium As(III) concentration.