scholarly journals PROPOSAL OF PROCEDURE FOR IDENTIFICATION OF MENÉTREY–WILLAM (M-W-3) PLASTICITY SURFACE OF HOMOGENEOUS AND HOLLOW MASONRY UNITS

2019 ◽  
Vol 11 (2) ◽  
pp. 40-49 ◽  
Author(s):  
Radosław Jasiński
Keyword(s):  
Calcium Silicate ◽  
Test Stand ◽  
Statistical Analyses ◽  
Triaxial Tests ◽  
Autoclaved Aerated Concrete ◽  
Custom Made ◽  
Aerated Concrete ◽  
Masonry Units ◽  
Elliptical Function

The article presents the author’s proposal to determine the parameters of the Mentérey–Willam (M-W-3) plasticity surface of the homogeneous masonry elements made of autoclaved aerated concrete (AAC) and vertically hollow calcium-silicate (Ca-Si) masonry units. The uniaxial and triaxial tests of AAC samples in a standard Hoek’s cell was performed while the hollow units made of silicate were tested on a custom-made test stand. By performing statistical analyses, the shape of the meridians of the surface was determined, and then the eccentricity e of the elliptical function was identified.

scholarly journals Behaviour of Autoclaved Aerated Concrete Blocks using Alkali-Resistant Glass Fibre as Additive

2020 ◽  
Vol 8 (6) ◽  
pp. 3508-3513
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Glass Fibre ◽  
Physical And Mechanical Properties ◽  
Slight Variation ◽  
Average Value ◽  
Autoclaved Aerated Concrete ◽  
Concrete Blocks ◽  
Aerated Concrete ◽  
Masonry Units

Autoclaved aerated concrete (AAC) blocks are the lightweight and green concrete blocks that are composed of cement, fly ash, lime, gypsum and aluminium powder. Depending on its density AAC consists of up to 80% of air by volume. Due to their low density and lightweight Autoclaved aerated concrete blocks exhibit so many favourable physical properties that these have got attention from all around the globe. Due to these enhanced properties Autoclaved aerated concrete blocks are extensively used as masonry units in all types of construction. On one hand AAC blocks have no comparison with other types of masonry units in terms of physical properties but on other hand AAC blocks are found to have low compressive strength relatively. In this study an attempt has been made to study the influence of Alkali-Resistant Glass Fibre additive on the physical and mechanical properties of Autoclaved aerated concrete blocks. Four sets of samples were cast and named as A, B, C and D with the fibre additive contents as 0%, 0.1%, 0.2% and 0.3% respectively (by dry weight of all the ingredients).Each sample set consisted of three specimens and the average value of the three samples were taken. For example, the average value of the three specimens- A1 , A2 , and A3 was taken as A and so on. Fibre additive influenced the aeration process of Autoclaved aerated concrete by increasing the rising/aeration time by 8%. The investigated fibre additive increases the compressive strength by 0%, 10%, 24% and 13.8% respectively to the added fibre contents of 0%, 0.1%, 0.2%, and 0.3% respectively. The optimal content of Alkali-Resistant Glass Fibre additive to be added for obtaining the highest compressive strength is 0.2%. Further investigations have shown a slight variation in density (about 0.2%) between the normal and modified Autoclaved aerated concrete blocks.

scholarly journals Comparison of Influence of Superficial Strengthening with FRCM System and Kind of Mortar Type on Shear Strength of Autoclaved Aerated Concrete Masonry

2021 ◽  
Vol 1203 (2) ◽  
pp. 022052
Author(s):  
Łukasz Drobiec ◽  
Radosław Jasiński ◽  
Wojciech Mazur ◽  
Remigiusz Jokiel
Keyword(s):  
Shear Strength ◽  
Cement Matrix ◽  
Angle Of Internal Friction ◽  
Autoclaved Aerated Concrete ◽  
Concrete Masonry ◽  
Test Elements ◽  
Aerated Concrete ◽  
The Individual ◽  
Two Sides ◽  
Masonry Units

Abstract This paper describes a comparison of results from testing shear strength of autoclaved aerated concrete (AAC) walls strengthened with superficial strengthening with the results of tests of walls made of various types of joints and mortar. The initial and characteristic shear strength and the angle of internal friction were compared. The test elements were made using two types of mortars, three types of joints, and two methods of reinforcement. The models were made using masonry units in the SOLBET OPTIMAL system. SOLBET 0.1 mortar, intended for thin joints, as well as SOLBET SMART polyurethane adhesive were used. Typical joints with a width equal to the thickness of the wall, shell bedded joints and joints without mortar were made. Models with typical joints were also tested as reinforced on one and two sides with the FRCM system, using the mineral cement matrix PBO-MX GOLD MASONRY and the PBO-MESH GOLD 22/22 mesh. A total of 56 models were tested in accordance with the requirements of PN-EN 1052-3: 2004. A significant influence of with superficial strengthening as well as the type of mortar and the construction of joints on the individual parameters of shear strength was demonstrated.

Ergonomic evaluation of masons laying concrete masonry units and autoclaved aerated concrete

2010 ◽  
Vol 41 (3) ◽  
pp. 477-483 ◽  
Author(s):  
Jennifer A. Hess ◽  
Laurel Kincl ◽  
Tal Amasay ◽  
Peter Wolfe
Keyword(s):  
Autoclaved Aerated Concrete ◽  
Concrete Masonry ◽  
Aerated Concrete ◽  
Masonry Units ◽  
Ergonomic Evaluation

scholarly journals Comparison of Masonry Homogenization Methods – Macromodelling and Micromodeling of Walls Behaviour Made of Autoclaved Aerated Concrete Masonry Units

2021 ◽  
Vol 1203 (2) ◽  
pp. 022033
Author(s):  
Radosław Jasiński ◽  
Krzysztof Grzyb
Keyword(s):  
Compressive Strength ◽  
Boundary Surface ◽  
Calibration Coefficient ◽  
Compression Phase ◽  
Plastic Model ◽  
Advantages And Disadvantages ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Contact Surfaces ◽  
Masonry Units

Abstract The adopted method of empirical homogenization strictly determines the degree of faithful reproduction of the masonry structure's work in terms of the analysis of cracking forces, destructive forces, and the mechanism of structure destruction. The high level of detail of the numerical model may make it impossible to perform calculations and predict internal forces for larger structures or entire buildings. The study aims to compare two different masonry homogenization techniques and determine the advantages and disadvantages of the adopted methods. The concept of a micromodel, in which the contact of two materials - a masonry unit and a mortar, was simulated using contact elements in the interface planes and a macromodel in which the wall was modelled as a homogeneous, isotropic material, omitting contact surfaces. The analysis subjects were standard wall models made of autoclaved aerated concrete (AAC) masonry units in axial and diagonal compression tests. In the numerical calculations, the elasto-plastic model with degradation implemented. The Menetrey William boundary surface describes the compression phase, and the Rankine criterion determines the tensile phase. In the axially compressed walls, the relations of forces and vertical and horizontal deformations compared, and in the shear walls, the forces and values of strain angles analyzed. In both models, the mechanisms of wall destruction and scratching were considered. The initial parameters of the elasto-plastic model derived from the results of wall tests using various model validation techniques. The calibration coefficient was used in the micromodel, determined as the quotient of the wall's compressive strength and masonry unit's compressive strength. The fracture energy value was also corrected. In the macromodel, the masonry's modulus of elasticity and the tensile strength value calibrated. Calculations based on the micromodel were consistent with the test results at the relative error level of 2%. The observed damage and scratches to the walls after the tests were consistent with the numerical projection. The macromodel calculations showed the convergence of the results in scratch morphology, scratching and destructive forces. The most significant differences occurred in shear deformations. The macromodelling approach allowed for capturing the wall's global tendency to deteriorate without opening the contact surfaces locally (cohesive cracks), as is the case during the tests.

scholarly journals Study of the influence of the secondary raw materials on microstructure and properties of calcium silicate composite

2019 ◽  
Author(s):  
Jana Húšťavová ◽  
Vít Černý ◽  
Rostislav Drochytka
Keyword(s):  
Calcium Silicate ◽  
Raw Materials ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Autoclaved Aerated Concrete ◽  
Secondary Raw Materials ◽  
Aerated Concrete ◽  
The Difference ◽  
Positive Effect

Calcium silicate composites are a widely used building material, especially autoclaved aerated concrete or sand-lime bricks. The physico-mechanical properties of these materials depend on their microstructure. Microstructure is characterized by the content of crystalline calcium silicate compounds that arise during autoclaving. This is in particular the tobermorite mineral, which carries the mechanical strength of the composite. This paper focuses on the influence of secondary raw materials on properties and microstructure of the calcium silicate composite. Secondary raw materials were selected as slag from the combustion of lignite and ground glass. Mixtures of composites were selected with respect to the required C/S molar ratio of 0.73. The hydrothermal treatment was carried out at a temperature of 190 °C and a residence time of 4, 8 and 16 hours. The microstructure of calcium silicate composites and autoclaved aerated concrete was studied. The use of slag resulted in an increase in the intensity of the diffraction line of tobermorite by X-ray diffraction analysis as well as the use of glass. The difference was particularly evident in the shape of the tobermorite crystals. Long strong crystals were detected in the sample with slag, while the sample with glass exhibited low tobermorite leaves. Porous structure of autoclaved aerated concrete with slag was uniform, unlike samples with glass. Both materials have a positive effect on the increase in compressive strengths of the samples.

scholarly journals Research of Influences of Bed Loints Reinforcements on Strength and Deformability of Masonry Shear Walls

2019 ◽  
Author(s):  
Radosław Jasiński
Keyword(s):  
Calcium Silicate ◽  
Construction Materials ◽  
Shear Walls ◽  
Horizontal Shear ◽  
Wall Stiffness ◽  
Steel Bars ◽  
Aerated Concrete ◽  
The Impact ◽  
Steel Trusses ◽  
Masonry Units

The area of Central and Eastern Europe, and thus Poland, is not exposed to effects of seismic actions. Any possible tremors can be caused by coal or copper mining. Wind, rheological effects, the impact of other objects or a non-uniform substrate are the predominant types of loading included in calculations for stiffening walls. The majority of buildings in Poland, as in most other European countries, are low, medium-high brick buildings. Some traditional materials, like solid brick (>10% of construction materials market) are still used. But autoclaved aerated concrete (AAC) and cement-sand calcium-silicate (Ca-Si) elements with thin joints are prevailing (>70% of the market) on the Polish market. Adding reinforcement only to bed joints in a wall is a satisfactory solution (in addition to confining) for seismic actions occurring in Poland that improves ULS and SLS. This paper presents results from our own tests on testing horizontal shear walls without reinforcement and with different types of reinforcement. This discussion includes 51 walls made of solid brick (CB) reinforced with steel bars and steel trusses, results from tests on 15 walls made of calcium-silicate (Ca-Si) and AAC masonry units reinforced with steel trusses and plastic meshes. Taking into account our own tests and those conducted by other authors, empirical relationships were determined on the basis of more than 90 walls. They are applicable to design and construction phase to determine the likely effect of reinforcement on cracking stress that damage shear deformation and wall stiffness.

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