Inhibition Studies of Expansion Damage in Medium-Low Reactivity Limestone by Fly Ash.

Expansion damage in medium-low reactivity dolomite limestone poses significant challenges in construction and engineering projects. This study investigates the potential of fly ash in inhibiting expansion damage in such limestone formations based on RILEM AAR-5 method. Through a series of laboratory experiments, various proportions of fly ash instead of cement, respectively, were prepared and subjected to varying alkali content conditions immersion tests to simulate expansion conditions. The expansion rates and extents were monitored and compared between pure limestone samples and those mixed with different proportions of fly ash. Additionally, scanning electron microscopy (SEM) analysis was employed to investigate the microstructure of the dolomite limestone-fly ash mixtures to understand the inhibition mechanisms. Results indicate that fly ash demonstrates promising inhibitory effects on expansion damage in medium-low reactivity dolomite limestone across the addition of 40% fly ash and alkali content of 0.70%. The reaction products are calcite, brucite, and a mixture of Mg-Si-Al phases and the reaction area is within 100 µm from the boundary when the cement alkali content is 1.50% without any fly ash. However, no reaction products were found at the boundary after adding 40% fly ash when lowering the cement alkali content to 0.70%. This research contributes to a better understanding of the interaction between fly ash and dolomite limestone in inhibiting expansion damage, providing valuable insights for engineering applications.

The Importance of Liming with an Appropriate Liming Material: Long-Term Experience with a Typic Palexerult.

Aluminium phytotoxicity is considered the main limiting factor for crop productivity in agricultural acid soils. Liming is a common practice used to improve acidic soil properties, but an appropriate liming material is essential for both agricultural productivity and environmental sustainability. A long-term field experiment with two liming amendments (dolomitic limestone and limestone) was developed during 10 years to determine the changes in soil acidity and assess the effects on crop (rye) yields. Although the adverse effects of the soil acidity conditions were alleviated with both amendments tested, dolomitic limestone was the most effective in the short- and long-term period. In terms of the saturation of exchange complex, dolomitic limestone had a better efficiency, likely based on its rate of dissolution. No significant changes in soil organic matter and exchangeable potassium levels between the treatments tested were found. Both liming materials significantly increased the rye total biomass, but interestingly, significant correlations were showed between tissue levels of magnesium and biomass production, but not between the latter and calcium. The increases in rye biomass production compared with control soils at the end of the research were the following: dolomitic limestone, 47%, and limestone, 32%. A link between an increase in magnesium bioavailability and biomass production was found, as well as between magnesium rye content and total, spike and stem biomass. Hence, it could conceivably be hypothesized that since magnesium is crucial for the transport of assimilates from source leaves to sink organs, alleviating its deficiency leads to avoiding the reducing growth rate of sink organs. Although further investigations are needed to gain a better understanding of liming on the biological, chemical and physical soil properties in the long term, our research provides support for the conceptual premise that an appropriate selection of liming material is crucial for the productivity of acid soils.

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation.

Natural dolomitic limestone (NDL) is employed as a heterogeneous green catalyst for the synthesis of medicinally valuable benzimidazoles, dihydropyrimidinones, and highly functionalized pyridines via C-N, C-C, and C-S bond formations in a mixture of ethanol and H2O under ultrasound irradiation. The catalyst is characterized by XRD, FTIR, Raman spectroscopy, SEM, and EDAX analysis. The main advantages of this methodology include the wide substrate scope, cleaner reaction profile, short reaction times, and excellent isolated yields. The products do not require chromatographic purification, and the catalyst can be reused seven times. Therefore, the catalyst is a greener alternative for the synthesis of the above N-heterocycles compared to the existing reported catalysts.

Use of cassava wastewater treated anaerobically with alkaline agents as fertilizer for maize (Zea mays L)

The wastewater of the processing of cassava's flour (manipueira) was submitted to the anaerobic treatment in two phases: acidogenic and methanogenic. In the acidogenic phase, the wastewater was stabilized with NaOH (ASH) and with limestone (ASL). After that, both stabilized effluents were treated by a methanogenic reactor. Then, the effluent of the methanogenic reactor was used as fertilizer on maize in the initial growth stage (30 days), cultivated in pots in a greenhouse. The treatments were T1: control without urea addition (only N from soil); T2: NPK (2.2 g of urea with 45 percent of N); T3: ASH (84 mL.kg soil-1); T4: ASL (102 mL.kg soil-1); T5: double dose ASH (168 mL.kg soil-1) and T6: double dose ASL (204 mL.kg soil-1). Each treatment was composed by 4 plants/pot in five repetitions. It was observed that all the treatments with stabilized wastewater had favorable effect to the soil pH (> than 7.5) and basis saturation (V percent) in the soil around to 90 percent. The performances of nitrogen absorption by the maize plants were 64, 54, 80 and 78 percent for T3, T4, T5 and T6, respectively.

A água residuária do processamento de farinha de mandioca (manipueira) foi submetida ao tratamento anaeróbio em duas fases: acidogênica e metanogênica. Na fase acidogênica, a água residuária foi estabilizada com NaOH (ASH) e com calcário (ASL). Em seguida, ambos efluentes estabilizados foram tratados por um reator metanogênico. Então, o efluente do reator metanogênico foi usado como fertilizante no milho no estádio inicial de crescimento (30 dias) cultivado em vaso em casa de vegetação. Os tratamentos foram T1: controle sem uréia (somente N do solo); T2: NPK (2,2 g de uréia com 45 por cento de N); T3: ASH (84 mL.kg solo-1); T4: ASL (102 mL.kg solo-1); T5: dose dupla de ASH (168 mL.kg solo-1) e T6: dose dupla de ASL (204 mL.kg solo-1). Cada tratamento foi composto por 4 plantas/vaso com 5 repetições. Foi observado que todos os tratamentos com á água residuária estabilizada tiveram efeitos favoráveis ao pH do solo (> que 7,5) e saturação de bases (V por cento) no solo ao redor de 90 por cento. A eficiência de absorção de nitrogênio pelas plantas foram 64 por cento, 54 por cento, 80 por cento e 78 por cento para T3, T4, T5 e T6, respectivamente.

Koeleria macrantha: performance and distribution in relation to soil and plant calcium and magnesium.

• The reported sensitivity of Koeleria macrantha (Poaceae) to soil magnesium, resulting in its absence from South Wales dolomitic limestone, was examined here in relation to varying ionic Ca to Mg ratios, and by cultivation in different limestone soils. • In a growth cabinet experiment, shoot and root Ca and Mg concentration and dry weight yield were determined for five edaphically varied populations of K. macrantha grown from tillers, over a range of Ca : Mg concentrations. The influence of relative concentrations of other nutrients was also investigated. In addition, K. macrantha plants were cultivated on Carboniferous, Magnesian and dolomitic limestone soils. • Total plant Ca: Mg ranged from 0.3 to > 20 mille-equivalents. Optimal substrate ratios (from 25 : 1 to 0.1 : 1), and response to different concentrations of nutrients varied between the populations. Cultivation on dolomitic limestone soil produced the highest yields. • The adverse effect on yields of all populations with low substrate Ca: Mg was much lower than predicted. Results suggest K. macrantha has a higher substrate Mg tolerance than other members of the Poaceae: its reported absence from the South Wales dolomitic limestone is unlikely to be due to soil magnesium sensitivity.