Mortar to Repair Rammed-Earth Walls’ Surfaces: Do we still Need it?

A rammed-earth technique has been echoed worldwide due to being conceived not only as an environment-friendly method of construction but also standing as an alternative method to arguably replacing cement. The technique however shows several pitfalls. One concerns the lengthy process of curing upon erecting the rammed-earth walls due to the low process of a chemical reaction occurred throughout the curing stage. A second bias followed from the slow curing and concerns the degradation accentuated at the outer wall’s texture, particularly at the edges, due to effects of the weather cycle. These drawbacks have been observed while accomplishing a funded research project. This article has at its stake remedying the above pitfalls. A natural sandy limestone shows a low percentage of calcium carbonate needed for a cohesive mixture. The method suggested here is based on an experiment that uses minerals of the fruits’ and vegetables’ waste as a binding substance. Curing time in this method has been reduced to the half. It is also suggested here that each stage has its importance, including mixing the soil particles dry and wet, compacting the moistened soil mixture, a well-made formwork and curing, towards remedying the above pitfalls.

The Dependence of Durability and Deformation of Elements of Soil Cement Composite with Carbonate White Soil Mixture on Age

The results of an experimental study of changes in strength and deformability during the period of time subjected to short-term loading of elements made of a soil-cement composite based on white soil (belozems) of carbonate composition are discussed. Research was carried out in accordance with current standards, as well as a well-known method that has been repeatedly tested earlier. To assess the experimentally established data, the results of similar studies by other authors, carried out applying elements from soil-cement based on clay soils, as well as from lightweight concrete on lithoid pumice (volcanic rock), are also presented. On the basis of the comparative analyzes of the experimentally established data, conclusions are formulated. The consideration of those may be useful both for the estimation of optimal schedules of the construction of buildings from a soil-cement composite, and for the assessment of their stress-strain state.

ACOUSTIC EXPRESS ANALYSIS OF QUALITATIVE AND QUANTITATIVE COMPOSITION OF SOILS DURING CONSTRUCTION WORKS

An express analysis of the ecological state of the soil during construction works is proposed. The algorithm is considered, which is the first approximation for describing the quality of the soil mixture, serving to build a system of operational recognition of the component composition of the soil mixture and the percentage of its main components. It is based on the analysis of the forced acoustic emission signal in the frequency domain to obtain the Fourier spectrum. From the general spectrum of the signal, consisting of a set of basic and higher (timbre) harmonics, subspectrs of significant basic harmonics corresponding to certain elements of the soil mixture are distinguished. To isolate the sub-spectra, a sequence of modal harmonics is used. The composition of the set of modal harmonics determines the qualitative composition of the soil in the first approximation.

Acclimatization of Eurycoma longifolia (Tongkat Ali) Plantlets to Ex Vitro Conditions

Eurycoma longifolia is one of the famous herbal plants with great medicinal benefits. The plant which also known as Tongkat Ali is well-known for treating erectile dysfunction and as energy booster. Tongkat Ali plantlets were produced using in vitro propagation technique to cater the demand for planting material. The development of successful acclimatization technique is prerequisite for in vitro propagation method. Acclimatization is a step to prepare the plantlets to survive and grow in different environment compare to laboratory. In this study, an attempt was made to identify the best potting media to acclimatize Tongkat Ali using glass chamber. Rooted plantlets about 2-4 cm height were used and subsequently transferred to different potting media for acclimatization i.e jiffy 7, sand, baked soil, mixture of cocoa peat and sand, sand and top soil and lastly cocoa peat and baked soil. Plantlets grown in jiffy 7 showed 100% survival followed by the mixture of cocoa peat and baked soil with 94.45% of survival. The acclimatized plantlets were transplanted into polybag and maintained in the shadehouse condition.

Numerical Simulation Study on Compression Characteristics of Gravelly Soil Mixture Based on Soft Servo Method

Because of complex mechanical properties and deformation mechanism, gravel soil mixture is an important medium of concern in the field of geotechnical engineering. Based on the continuous-discontinuous coupling algorithm formed by the structure shell elements and the particle discrete element method (PFC3D), the soft servo loading of the sample is realized, and the typical triaxial compression test data are used to calibrate mesoscale parameters. Furthermore, the numerical tests under different rock contents and confining pressure are carried out. The change rule of shear strength of mixed medium is discussed. It shows that the continuous-discontinuous coupling algorithm achieves a good effect in reflecting the deformation process. Under the mechanism of the flexible servo, the failure mode of the sample takes on drum-failure mode, and the internal of the damaged sample forms an obvious asymmetric X-shaped shear band. With the increase of stone content, the internal friction angle and cohesive force distribution of the sample have certain discreteness, but on the whole, the internal friction angle and cohesive force increase with the increase of stone content. The results can provide a reference for the parameter determination of mixed mediums such as gravel soil.

The Change of Some Food Elements in Soil Depending On Shadowing and Fertilization

Soil is one of the most important factors affecting the plant development on the basis. The method mostly applied for the purpose of accelerating the plant development and ensuring the increase in products is to increase the nutrients in the soil, namely fertilization. Fertilization ensures lots of food elements in the soil to get mixed in the soil and change the soil composition. Another factor affecting the plant growth speed and productivity is shadowing. Shadow conditions change the light receiving amounts of the plant and directly affect the plant photosynthesis speed. In addition; shadowing not only affects the dissolution and in-soil mixture speed of the fertilizers applied to the soil, but it also directly affects the humidity content of the soil. In this study, it has been aimed to determine the food element changes in the soil on the lavender individuals grown under different shadow conditions and fertilized with different fertilizers. The lavender used in the study has been selected due to the fact that it adapts to dry areas, it is abstinent in terms of soil and it is an important and income-generating medical aromatic plant. As a result of the study, it has been determined that shadowing statistically affects salt, carbon, phosphor, nitrogen and potassium and fertilization statistically affects phosphor, nitrogen, potassium, carbon and salt at least at 95% confidence level.

Chemical and Biological Enhancement Effects of Biochar on Wheat Growth and Yield under Arid Field Conditions

Nitrogen (N) losses are prevalent under South East Asia’s due to high N fertilizer inputs, but low N fertilizer use efficiency. This leaves a large quantity of reactive N at risk of loss to the environment. Biochar has been found to reduce N losses across a variety of soil types, however, there is limited data available for semi-arid climates, particularly at a field-scale. Herein we present an exploration of the biological and chemical enhancement effects observed of a cotton stalk-based biochar on wheat growth and yield under arid field conditions. The biochar was treated with urea-N and biofertilizer (bio-power) in different treatment setups. The six experimental treatments included; (i) a full N dose “recommended for wheat crops in the region” (104 kg N ha−1) as a positive control; (ii) a half N dose (52 kg N ha−1); (iii) a half N dose + biofertilizer (4.94 kg ha−1) as a soil mixture; (iv) a half N dose + biofertilizer as a seed inoculation; (v) a full N dose as broadcast + biochar (5 t ha−1) inoculated with biofertilizer; and (vi) a full N dose loaded on biochar + biofertilizer applied as a soil mixture. The half dose N application or biofertilizer addition as soil mix/seed inoculated/biochar inoculation with biofertilizer caused reduced wheat growth and yield compared to the control (conventional N fertilization). However, co-application of chemically enhanced biochar (loaded with a full N dose) and biofertilizer as soil mixture significantly increased the crop growth rate (CGR) and leaf area index (LAI). A significantly higher crop growth and canopy development led to a higher light interception and radiation use efficiency (RUE) for total dry matter (TDM) and grain yield (11% greater than control) production compared to the control. A greater grain yield, observed for the full N dose loaded on biochar + biofertilizer applied as a soil mixture, is attributed to prolonged N availability as indicated by greater plant and soil N content at harvest and different crop growth stages, respectively. The present study has improved our understanding of how the application of nitrogen loaded biochar and biofertilizer as soil mixtures can synergize to positively affect wheat growth and soil-nitrogen retention under arid environmental conditions.