In situ seismic testing of a reinforced autoclaved aerated concrete building

Surface wastewater is consideredas effluents, which are formed on the surface of urbanized areas. Stormwater treatment is performed out using a variety of filters: sand, grass. Wastewater penetration into the deeper layers is called hydraulic conductivity. After evaluation of the hydraulic conductivity, it is possible to determine the ability of the investigated fillers to entrap the stormwater flow. The hydraulic conductivity tests can indicate which fillers of stormwater filters may influence the more effective stormwater cleaning. Four stormwater filters were tested: crushed autoclaved aerated concrete filter; crushed autoclaved aerated concrete with Meadow grass (Poa pratensis) layer; silica sand filter with Meadow grass (Poa pratensis) layer; silica sand filter. Under in-situ conditions hydraulic conductivity in filters is investigated using Constant-head method. Mathematical modeling program Hydrus-1D presentsthe changes of hydraulic conductivity in each filler layer of the filter. Assessed hydraulic conductivity in filters under in-situ conditions hasn‘t changed only in crushed autoclaved aerated concrete filter (30 000 mm/d). The smallest hydraulic conductivity in filters under in-situ conditions was estimated in silica sand filter with Meadow grass (Poa pratensis) layer, here it was equal to 209.3 mm/d.With mathematical modeling program Hydrus-1D it was found that the hydraulic conductivity in each filter decreases, depending on the depth of filler in the filter. Paviršinėmis nuotekomis laikomos tokios, kurios susidaro ant urbanizuotos teritorijos paviršiaus. Paviršinių nuotekų valymas atliekamas taikant įvairius filtrus – smėlio, augalinius. Nuotekų skverbimasis į gilesnius sluoksnius vadinamas hidrauliniu laidumu. Įvertinus hidraulinį laidumą galima nustatyti tiriamų filtro užpildų gebėjimą sulaikyti atitekėjusių paviršinių nuotekų srautą filtro užpilduose. Atlikus hidraulinio laidumo tyrimus, galima nustatyti, kurie paviršinių nuotekų filtro užpildai gali lemti efektyvesnį paviršinių nuotekų išvalymą. Tiriami keturi paviršinių nuotekų filtrai: smulkinto autoklavinio akytojo betono filtras; smulkinto autoklavinio akytojo betono ir pievinės miglės dangos filtras; kvarcinio smėlio filtras su pievinės miglės danga; kvarcinio smėlio filtras. Natūrinėmis sąlygomis hidraulinio laidumo tyrimas atliekamas, taikant Constant-Head metodą. Matematinio modeliavimo programa Hydrus-1D pateikiama, kaip kinta hidraulinis laidumas kiekviename filtro užpildo sluoksnyje. Nustatytas hidraulinis laidumas filtruose natūrinėmis sąlygomis nekito smulkinto autoklavinio akytojo betono filtre (30 000 mm/d). Mažiausias hidraulinis laidumas natūrinėmis sąlygomis nustatytas kvarcinio smėlio filtre su pievinės miglės (Poa pratensis) augalinės dangos sluoksniu, čia jis nustatytas 209,3 mm/d. Matematinio modeliavimo programa Hydrus-1D nustatyta, kad hidraulinis laidumas filtruose mažėja priklausomai nuo filtro užpildo gylio.

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Development of an in situ X-ray diffraction system for hydrothermal reactions and its application to autoclaved aerated concrete formation

Powder Diffraction ◽

10.1154/1.3583565 ◽

2011 ◽

Vol 26 (2) ◽

pp. 126-128 ◽

Cited By ~ 1

Author(s):

J. Kikuma ◽

M. Tsunashima ◽

T. Ishikawa ◽

S. Matsuno ◽

A. Ogawa ◽

...

Keyword(s):

Structural Changes ◽

Hydrothermal Reaction ◽

Photon Counting ◽

Phase Evolution ◽

High Energy ◽

Array Detector ◽

X Rays ◽

Autoclaved Aerated Concrete ◽

Aerated Concrete

An in situ time-resolved XRD system for hydrothermal reaction has been developed in order to investigate the phase evolution during autoclave process in autoclaved aerated concrete (AAC) formation. The system includes a novel autoclave cell for transmission XRD with thin beryllium windows, a two-dimensional photon-counting pixel array detector, and uses high energy X-rays from a synchrotron radiation source. The temperature and pressure inside the cell are extremely stable during hydrothermal reaction over the course of several hours. The system was utilized for the formation reaction of AAC. Phase evolution was clearly observed, including several intermediate phases, and detailed information on the structural changes during the hydrothermal reaction were obtained.

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In Situ X-ray Diffraction at High Temperatures: Formation of Ca2SiO4 and Ternesite in Recycled Autoclaved Aerated Concrete

Minerals ◽

10.3390/min11080789 ◽

2021 ◽

Vol 11 (8) ◽

pp. 789

Author(s):

Angela Ullrich ◽

Krassimir Garbev ◽

Britta Bergfeldt

Keyword(s):

Room Temperature ◽

X Ray Diffraction ◽

Sulfate Content ◽

In Situ Xrd ◽

Autoclaved Aerated Concrete ◽

Thermal Expansion Coefficients ◽

Slow Quench ◽

Aerated Concrete ◽

Heating Up

This study provides an insight into possible recycling processes for autoclaved aerated concrete (AAC) at low temperatures (<1000 °C). Belite binders were synthesized from wastes of AAC by the addition of CaCO3 and adaption of the molar CaO/SiO2 (C/S ratio) in the range of 2 to 2.5. An in situ XRD study performed during heating up to 1000 °C and subsequent quenching to room temperature evidenced the formation of ternesite besides C2S in sulfate-containing systems. Several factors influencing the reaction kinetics and the evolution of the phase composition were investigated thoroughly. Increased sulfate content and dwelling time during heating increase the ternesite content and promote the formation of highly crystalline α’H-C2S. The C/S-ratio of the starting materials has to be adjusted to the sulfate content in order to prevent the formation of ternesite at the expense of C2S. Ternesite remains stable during quenching to room temperature or even increases in amount, except in cases of very low cooling rates or high residual quartz contents (C/S-ratio ≤ 2). Temperature and range of α’H-C2S to β-C2S phase transition on quenching strongly depend on the cooling rate. The onset temperature for β-C2S formation varies between 540 °C (slow quench) and 450 °C (fast quench). Thermal expansion coefficients of ternesite are calculated showing similarity with C2S. The incorporation of CaSO4 modules in the structure switches the direction of maximum compression.

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