Characteristics Of Volcanic Ash Research Articles

Effect of Volcanic Ash and Natural Pozzolana on mechanical properties of sustainable cement concrete: A comprehensive review

Environmental degradation is on the rise due to escalating pollution caused by raw material depletion and the increasing demand for concrete products. Consequently, researchers and scientists have dedicated significant efforts towards developing sustainable, eco-friendly concrete using renewable materials. Among these materials, Volcanic Ash (VA) and other Natural Pozzolana (NP) types have emerged as promising Supplementary Cementitious Materials (SCMs). VA and NP types play a crucial role in reducing costs, energy consumption, and environmental impacts associated with cement production. Thus, it is imperative to investigate the characteristics of VA and NP and their influence on the performance of concrete and cement mortar. This paper presents a comprehensive review of previous studies examining the effect of VA and other NP types on the mechanical properties of concrete while evaluating their chemical, physical, and microstructure characteristics. The findings from these studies indicate that the properties of concrete primarily depend on the characteristics and quantities of NP employed. Notably, silica dioxide (SiO2) comprises the predominant component in VA compositions. In most cases, an increase in VA and NP content within concrete mixtures leads to a reduction in strength. Finally, recommendations and suggestions for future research are provided to enhance concrete properties and achieve the development of sustainable construction materials.

Effect of long-term different fertilization on bacterial community structures and diversity in citrus orchard soil of volcanic ash.

This study was conducted to assess bacterial species richness, diversity and community distribution according to different fertilization regimes for 16 years in citrus orchard soil of volcanic ash. Soil samples were collected and analyzed from Compost (cattle manure, 2,000 kg/10a), 1/2 NPK+compost (14-20-14+2,000 kg/10a), NPK+compost (28-40-28+2,000 kg/10a), NPK (28-40-28 kg/10a), 3 NPK (84-120-84 kg/10a), and Control (no fertilization) plot which have been managed in the same manners with compost and different amount of chemical fertilization. The range of pyrosequencing reads and OTUs were 4,687-7,330 and 1,790-3,695, respectively. Species richness estimates such as Ace, Chao1, and Shannon index were higher in 1/2 NPK+compost than other treatments, which were 15,202, 9,112, 7.7, respectively. Dominant bacterial groups at level of phylum were Proteobacteria, Acidobacteria, and Actinobacteria. Those were occupied at 70.9% in 1/2 NPK+compost. Dominant bacterial groups at level of genus were Pseudolabrys, Bradyrhizobium, and Acidobacteria. Those were distributed at 14.4% of a total of bacteria in Compost. Soil pH displayed significantly closely related to bacterial species richness estimates such as Ace, Chao1 (p<0.05) and Shannon index (p<0.01). However, it showed the negative correlation with exchangeable aluminum contents (p<0.05). In conclusion, diversity of bacterial community in citrus orchard soil was affected by fertilization management, soil pH changes and characteristics of volcanic ash.

화산재입자의 고유 광학특성이 원격탐사 복사량에 미치는 민감도 분석

화산재입자의 굴절률과 산란 같은 고유 광학 특성으로 결정되는 분광학적 신호는 원격탐사 센서를 통하여 측정될 수 있지만, 화산 폭발 이후 생성된 화산재입자의 성분에 대한 굴절률에 관한 정보는 매우 제한적이었다. 따라서, 화산재입자의 원격탐사의 강건성을 개선하기 위하여 화산재입자와 복사전달 과정의 상호작용에 대한 정확한 이해가 필요하다. 본 연구에서는 화산재 주요 성분으로 알려진 화산성 안산암과 부석에 대한 입자 소산계수, 산란 위상함수, 비대칭 계수, 단산란 알베도 값을 정량화 하였다. 이러한 화산재입자의 고유 광학 특성값은 복사전달모델의 입력자료로 이용하여 다양한 에어러솔 광학두께(<TEX>${\tau}$</TEX>) 및 기하조건에서 원격탐사 센서(인공위성과 지상관측용)가 측정하는 이론적인 복사량과 화산재입자 특성의 관계를 분석하였다. 복사전달모델 분석결과, 대기권 최상층부에서 <TEX>${\tau}$</TEX> 에 대한 복사량의 변화율의 평균값은 안산암의 경우 부석보다 6배 정도 크게 나타났다. 지표에서 이러한 변화율은 <TEX>${\tau}$</TEX> <1인 경우 양의 상관관계를 보이지만, <TEX>${\tau}$</TEX> >1인 경우에는 음의 상관관계를 보였다. 그러나, 적외선 영역인 11 <TEX>${\mu}m$</TEX> 에서는 차이가 매우 적게 나타났으며, 여기서 발생하는 복사량의 오차범위는 광학두께가 증가할수록 커지는 양상을 보이며, 다항 회귀함수로 표현될 수 있다. 이러한 결과는 원격 탐사 관측자료를 이용한 화산재 관측에 있어서 화산재의 정량적 분석에 도움이 될 것이다. Volcanic ash (VA) can be estimated by remote sensing sensors through their spectral signatures determined by the inherent optical property (IOP) including complex refractive index and the scattering properties. Until now, a very limited range of VA refractive indices has been reported and the VA from each volcanic eruption has a different composition. To improve the robustness of VA remote sensing, there is a need to understanding of VA - radiation interactions. In this study, we calculated extinction coefficient, scattering phase function, asymmetry factor, and single scattering albedo which show different values between andesite and pumice. Then, IOPs were used to analyze the relationship between theoretical remote sensed radiation calculated by radiative transfer model under various aerosol optical thickness (<TEX>${\tau}$</TEX>) and sun-sensor geometries and characteristics of VA. It was found that the mean rate of change of radiance at top of atmosphere versus <TEX>${\tau}$</TEX> is six times larger than in radiance values at 0.55 <TEX>${\mu}m$</TEX>. At the surface, positive correlation dominates when <TEX>${\tau}$</TEX> <1, but negative correlation dominates when <TEX>${\tau}$</TEX> >1. However, radiance differences between andesite and pumice at 11 <TEX>${\mu}m$</TEX> are very small. These differences between two VA types are expressed as the polynomial regression functions and that increase as VA optical thickness increases. Finally, these results would allow VA to be better characterized by remote sensing sensors.

Fresh, Mechanical, and Durability Characteristics of Self-Consolidating Concrete Incorporating Volcanic Ash

Self-consolidating concrete (SCC) is known for its excellent deformability, high resistance to segregation, and use in congested reinforced concrete structures characterized by difficult casting conditions without applying vibration. The use of known mineral admixtures such as fly ash and slag cement has proved very effective in the production of nonexpensive SCC with satisfactory fresh and hardened properties. However, the use of volcanic ash (VA) in SCC is new and can provide low cost SCC. This paper presents fresh, mechanical, and durability characteristics of VA based SCC mixtures (VA-SCCs). VA-SCCs are developed by varying water-to-binder ratio, percentages of VA as cement replacement, and dosages of superplasticizer (SP). Mix design parameters are optimized to achieve minimum use of SP and optimum use of VA. The fresh concrete properties are determined from slump flow, V-funnel flow time, bleeding, air content, and segregation tests. The mechanical properties and durability characteristics such as compressive strength, freezing-thawing resistance, rapid chloride permeability, surface scaling resistance, and drying shrinkage are determined to evaluate the performance of VA-SCCs. The study produces encouraging results and confirms the production of satisfactory VA based SCC mixtures with acceptable properties. VA-SCCs having a minimum strength of 15 MPa (requirement for some structural concrete applications) can be obtained by replacing up to 50% (by mass) of cement by VA. Development of nonexpensive and environmental friendly VA-SCC with acceptable strength and durability characteristics (as illustrated in this study) is extremely helpful for the sustainable development and rehabilitation of volcanic disaster areas around the world.

Characteristics of volcanic ash and natural lime based stabilized clayey soils

Clayey soils are stabilized with various percentages of volcanic ash (VA), finely ground natural lime (NL), Portland cement, and their combinations. The influence of stabilizers and their combinations is evaluated through standard Proctor compaction, unconfined compressive strength, splitting tensile strength, modulus of elasticity, and California bearing ratio (CBR) tests. The durability of stabilized soil mixtures is judged based on drying shrinkage and the influence of water immersion on strength. Correlations between compressive strength, modulus of elasticity, and CBR are also established. Stabilized soil mixtures can be used in various constructions, including road pavements and low-cost housing.Key words: soil stabilization, volcanic ash, natural lime, mechanical properties, durability.