Sand-lime Brick Research Articles

Silicate brick production using anhydrite raw material

Purpose: The aim of this work is to substantiate recycling of anhydrite raw materials for the production of silicate products and the development of methods for preparing source materials, compositions and process modes.Methodology/approach: Selection and research of basic materials, methods of their preparation for the production of silicate products; justification of process methods and assessment of quality parameters of materials with the required properties.Research findings: The possibility of utilizing acid fluoride during the synthesis of calcareous-siliceous binder used to produce silicate bricks during autoclave processing. The obtained sand-lime brick samples possess the following physical and mechanical properties: 1750 to 1900 kg/m3 average density, 10 to 12.5 MPa compressive strength, 16 or 17 % water absorption. The samples meet the requirements for sand-lime bricks, namely strength, density, water absorption and correspond to grades 100 and 125.Practical implications: The process modes of autoclaving are detected and the main operational characteristics of sand-lime brick are determined. Methods proposed for preparing raw materials and process conditions of silicate wall materials allow solving environmental problems and saving natural limestone raw materials.Novelty: Sand-lime brick production is based on anhydrite raw materials; suggested dependencies make it possible to control the composition and properties of silicate materials.

Sensor-based characterization of construction and demolition waste at high occupancy densities using synthetic training data and deep learning.

Sensor-based monitoring of construction and demolition waste (CDW) streams plays an important role in recycling (RC). Extracted knowledge about the composition of a material stream helps identifying RC paths, optimizing processing plants and form the basis for sorting. To enable economical use, it is necessary to ensure robust detection of individual objects even with high material throughput. Conventional algorithms struggle with resulting high occupancy densities and object overlap, making deep learning object detection methods more promising. In this study, different deep learning architectures for object detection (Region-based CNN/Region-based Convolutional Neural Network (Faster R-CNN), You only look once (YOLOv3), Single Shot MultiBox Detector (SSD)) are investigated with respect to their suitability for CDW characterization. A mixture of brick and sand-lime brick is considered as an exemplary waste stream. Particular attention is paid to detection performance with increasing occupancy density and particle overlap. A method for the generation of synthetic training images is presented, which avoids time-consuming manual labelling. By testing the models trained on synthetic data on real images, the success of the method is demonstrated. Requirements for synthetic training data composition, potential improvements and simplifications of different architecture approaches are discussed based on the characteristic of the detection task. In addition, the required inference time of the presented models is investigated to ensure their suitability for use under real-time conditions.

CO2-curing of carbon-reducing slag-based masonry bricks at elevated pressures in pre-industrial scale

The production of masonry bricks consumes enormous amounts of resources and causes high CO2 emissions. Most of the CO2 emissions are due to the use of hydraulic binders. We substitute conventional binders by different slag types that are a secondary-product of the steel industry to produce masonry bricks and perform CO2-curing. The scale-up from laboratory to pre-industrial scale including a lifecycle assessment (LCA) is focused. Literature values of the global warming potential (GWP) of sand-lime bricks serve as reference for the LCA. All slag-based CO2-cured bricks reach compressive strengths (24 to −49 MPa) higher than those of sand-lime bricks (12 to −20 MPa). The optimal curing parameters are 15 bar, 50 °C and 6 h. For these process conditions, autoclaves of the sand-lime brick industry can be modified for the usage of CO2. The LCA shows a CO2-saving potential of 337 kgCO2,eq/m3brick by carbonation process, compared to the conventional sand-lime bricks. CO2-curing of slag-based bricks has great potential for industrial implementation.

Sorption isotherm measurements for porous materials: A new hygroscopic method

The water sorption of materials can significantly affect their durability. While a wide range of techniques has been already introduced and implemented to measure the sorption behavior of materials, obtaining high-resolution data to describe the water sorption isotherm is still a challenging task. This is especially the case for materials with a complex sorption behavior such as concrete for which the pore structure is very complicated. The level of complexity increases when chloride is present in such structures. In this study, a hygroscopic technique is introduced to measure the sorption behavior of porous materials. By this technique, the sorption isotherm can be obtained by injecting water with a high level of control into a controlled environment where a sample is positioned. The amount of water can be added in steps resulting in high-resolution data for the sorption properties of the sample. The technique is evaluated for two porous materials: Portland cement mortar and sand-lime brick. The results are extensively compared with similar measured data available in the literature. In addition, the performance of the technique is evaluated for porous materials with initial chloride content. The results show that the present technique allows for obtaining high-resolution data in desirable ranges that is essential for materials with complicated pore structures.

Determination of standard characteristics of recycled crushed aggregate from crushed sand-lime brick and prospects of its application

Introduction. Construction enterprises can adversely affect the environment during the extraction of natural raw materials, as well as during the reconstruction, overhaul, and demolition of buildings. The manufacturing of construction materials, the actual erection, and maintenance of various buildings and structures comprise highly material- and energy-intensive processes characterized by waste generation, which need to be disposed. In developed countries, recycling wastes as a commercial commodity represents the preferable way of recovering concrete, reinforced concrete, and masonry (brick) waste. In this regard, the disposal of construction waste (including waste from sand-lime brick and brickwork) is becoming increasingly important.Aim. In this work, the grain-size distribution, strength, and bulk density of recycled crushed aggregate from crushed sand-lime bricks (open stone mix) and brickwork (containing mortar) were determined and compared, and the prospects of its use as aggregates in the production of general-purpose concrete were identified.Materials and methods. Recycled crushed aggregate from crushed sand-lime bricks (open stone mix) and brickwork (containing mortar) was used for the studies. The recycled crushed aggregate was tested as per GOST 8269.0-97, its characteristics were evaluated as per GOST 8267-93.Results. This work shows the correlation between the bulk density, grain-size distribution, and crushing capacity of recycled crushed aggregate produced by crushing fragments of brickwork (containing mortar) and sand-lime bricks (open stone mix).Conclusions. It is shown that recycled crushed aggregate obtained by crushing fragments of brickwork (containing mortar) and sand-lime bricks (open stone mix) are suitable (along with crushed stone from sedimentary and metamorphic rocks) for use as a coarse aggregate in the production of general-purpose concrete. It is shown that it is necessary to carry out comprehensive experimental work in order to develop a new GOST, which will improve the recycling of sand-lime bricks, as well as structures and products based on them following the end of their operation lifetime, and allow high-quality ready-to-use construction material to be obtained.

Experimental study of the processes of dynamic energy absorption of sand-lime brick

The data obtained as a result of dynamic tests of sand-lime brick samples were used to estimate its energy intensity. The experiments were carried out according the Kolsky method using a split Hopkinson bar. The graphs of the specific energy absorption of sand-lime brick were obtained at different deformation rates as a result of the numerical integration of dynamic deformation diagrams. In addition, dependences characterizing the growth of energy characteristics with an increase of the strain rate are plotted. Comparison of the studied properties of sand-lime brick with same properties of other brittle media is carried out.

Loss factor measurement and indications for nonlinearities in sound insulation

The loss factor is often determined in building acoustics by measuring the structure-borne reverberation time. To do this, elements under test are excited either by a hammer or by a shaker. In several experiments with sand-lime brick walls, measured loss factors turned out to be significantly larger when hammer excitation was used instead of shaker excitation. A thorough investigation of this effect was then performed using hammer blows of different strengths and a 250-kg shaker. This way, forces are in the same order of magnitude for both excitations. Measurement results lead to the conclusion that large forces may create a nonlinear structural response. The nonlinearity is observed for a sand-lime brick wall without plastering but not for a lightweight composite wall and also not for a monolithic concrete wall. The assumption of nonlinear behaviour is furthermore supported by an additional investigation where alarm pistol shots were used to excite a sand-lime brick wall with very large airborne sound pressure levels. The airborne sound insulation of the wall turned out to be nonlinear, that is, it increased with increasing sending room levels.

Heat and Moisture Transport and Storage Parameters of Bricks Affected by the Environment

The effect of external environment on heat and moisture transport and storage properties of the traditional fired clay brick, sand–lime brick and highly perforated ceramic block commonly used in the Czech Republic and on their hygrothermal performance in building envelopes is analyzed by a combination of experimental and computational techniques. The experimental measurements of thermal, hygric and basic physical parameters are carried out in the reference state and after a 3-year exposure of the bricks to real climatic conditions of the city of Prague. The obtained results showed that after 3 years of weathering the porosity of the analyzed bricks increased up to five percentage points which led to an increase in liquid and gaseous moisture transport parameters and a decrease in thermal conductivity. Computational modeling of hygrothermal performance of building envelopes made of the studied bricks was done using both reference and weather-affected data. The simulated results indicated an improvement in the annual energy balances and a decrease in the time-of-wetness functions as a result of the use of data obtained after the 3-year exposure to the environment. The effects of weathering on both heat and moisture transport and storage parameters of the analyzed bricks and on their hygrothermal performance were found significant despite the occurrence of warm winters in the time period of 2012–2015 when the brick specimens were exposed to the environment.

Evaluation of dampness-induced strength reduction of calcium silicate blocks

Due to its numerous technical advantages as well as health benefits, sand-lime brick is increasingly used in the construction of brick walls, especially in residential buildings. Unfortunately, the occurrence of damp leads to a sharp deterioration of the technical properties of the material and the environmental conditions inside the building. Given the importance of this issue, an attempt was made to diagnose the extent of dampness variability of the main hygrothermal and strength characteristics of calcium silicate products. The study involved the basic material properties (density in dry and water-saturated conditions), moisture-related properties (capillary adsorption coefficient and sorptivity), thermal coefficients (thermal conductivity and volumetric heat capacity) as well as mechanical properties (compressive strength). This article describes diagnostic studies that were conducted to assess the extent of the effect of dampness on the strength of sand-lime products. In order to render the diagnosis more comprehensive and to include a wider range of silicate blocks available on the market, it was decided to examine three groups of silicate blocks (strength class 15, 20 and 25) obtained from three different factories. It was demonstrated that for all the examined groups dampness caused a significant decrease in compressive strength ranging from about 30% to about 40%.

Advanced Rating Method of Airborne Sound Insulation

This paper describes an advanced calculation scheme based on the loudness level linked to the specific fluctuation strength yielding a weighted normalized loudness level difference as a single number value. This advanced rating method is a useful tool investigating airborne sound insulation. Evidence has been presented that a simple level difference is not a suitable method to exhibit the effects of a given signal to the airborne sound insulation. Additionally, while using a weighted normalized loudness level difference, the effect of different test signals results in a significant influence in the single number value. By analyzing the difference between the standard airborne sound insulation value and the weighted normalized loudness level difference, the sound pressure level that is transmitted through a partition is demonstrated to contain important details concerning the subjective assessment. This study supports findings in the literature that airborne sound insulation performance is significantly dependent on what type of sound signal is used. This paper investigates six different thicknesses of a sand-lime brick using five different sound samples. The study indicates that no single number value can be modeled at this time in relation to a certain construction to fulfill comparable results related to a hearing sensation.

Plasma technologies application for building materials surface modification

Low temperature arc plasma was used to process building surface materials, such as silicate brick, sand lime brick, concrete and wood. It was shown that building surface materials modification with low temperature plasma positively affects frost resistance, water permeability and chemical resistance with high adhesion strength. Short time plasma processing is rather economical than traditional processing thermic methods. Plasma processing makes wood surface uniquely waterproof and gives high operational properties, dimensional and geometrical stability. It also increases compression resistance and decreases inner tensions level in material.

Determination of Microstructure and Phase Composition of Sand-Lime Brick after Autoclaving Process

The mass for sand-lime products consists of fully organic components: silica sand, quicklime and water. Depending on the proportions of ingredients used, admixtures and additives, the degree of fragmentation of the sand, and autoclaving temperatures different hydrated calcium silicates structures can arise. In autoclaved sand-lime products the following phases can be found mostly: C-S-H (I), C-S-H (II), 11A tobermorite, xonotlite and C2SH (A). Using a scanning electron microscope, the internal structure of “white brick”(common name of sand-lime products) was observed and the phase composition was examined by X-ray diffractometry. Pore size distribution was described using the most universal and most common method of analysis of the porosity of building materials – Mercury Intrusion Porosimetry. An additional component to the standard ingredients of traditional sand-lime products, lithium water glass was used. Three series of samples in the rectangular shape with dimensions 40 x 40 x 160 [mm] were prepared. The study of standard samples, with the content of 0.5% and 5.0% additives was performed in a Kielce University of Technology laboratories.

Boronizing Process of 45 Carbon Steel Mold for Fabricating Sand-Lime Brick

Boronizing Process of 45 Carbon Steel Mold for Fabricating Sand-Lime Brick

Aspects for a cleaner production approach for coal and biomass use as a decentralized energy source in southern Brazil

Biomass and coal are two vastly available energy sources that have been under-utilized for thermoelectric generation within the available energy matrix in Brazil, considering that the southern region has an excellent potential for the use of biomass as a decentralized energy source and the Brazilian coal reserves are totally distributed in this region. So, this paper makes an analysis concerning the use of the southern Brazilian coal together with the biomass available in the same region through a cleaner production approach in order to decrease the generation of solid wastes – ashes – and produce atmospheric emissions on a more environmental friendly way through a decentralized energy generation system. A review on the possibility of using the coal ash – from its cofiring with wood wastes and the use of limestone for desulfurization – as a low-cost material for the production of sand lime bricks is evaluated. Then, results obtained from tests that technologically evaluated the use of those fuels on a bubbling fluidized bed are presented. Finally, the economical possibility of developing an integrated system for energy production, carbon crediting and production of building materials using the cofiring of biomass and coal with limestone addition in Small Thermal Power Plants is assessed. The results showed a good possibility for the increment of biomass use in the southern Brazilian region and the data obtained from combustion tests are already sufficient to support the launch of definitive projects to provide steam generation from renewable sources on a decentralized way. The revision reveals that the Brazilian ash composition is prone to react with the high CaO content in wood ashes and the limestone addition can be adjusted for the production of a suitable composition for the direct use on sand lime brick production. This integrated system proposed has the possibility of having annual revenue about US$ 1,105,000.00.

Experiment Study of Optimal Combination of Strength for Mortar and Block of Autoclaved Sand-Lime Brick Masonry

In order to write Hunan province engineering construction local standard named" Technical specification for autoclaved sand-lime brick masonry building ",the author has finished a series of fundamental mechanical properties experiments on autoclaved sand-lime brick masonry such as material character experiment, shear strength experiment , bending tensile strength experiment. By analysis on experimental data, the author found a startling regularity: there is a feature of optimal combination of strength for mortar and block of autoclaved sand-lime brick masonry.

Utilization of copper tailing for autoclaved sand–lime brick

The influences of the batch ingredients and the autoclaving processes on the properties of autoclaved sand–lime brick from low SiO 2 content copper tailing were studied. The results show that the copper tailing with low content of SiO 2 can be used to produce autoclaved sand–lime bricks meeting GB11945-1999 for Mu 15 sand–lime brick, if only the proportion of the copper tailing in the brick batch does not exceed 50% (% by mass) and appropriate proportions of river sand and sand powder are added to compensate for the low SiO 2 content. XRD and SEM analyses show that the main hydrothermal reaction products in the brick are 0.9 nm, 1.1 nm and 1.4 nm tobermorite phases, and the andradite in the copper tailing nearly does not take part in the autoclaving reaction.

Factors affecting the radiation dose to inhabitants in a small new housing-estate in the Netherlands

A survey has been made of the radiation exposure of inhabitants in a small new housing estate in the Netherlands, where 101 houses are built at about the same time, but according to nine different designs. The objective of this study was to determine which dwelling characteristics affect the indoor radon concentrations and the absorbed dose in air. Both components were examined separately for a period of one year in the crawl space, the living room and a first-floor bedroom, using passive tracketched and thermoluminescence detectors, respectively. The calculated effective dose to the inhabitants ranges from 0.5 to 1.3 mSv per year, depending on the design. The houses at the low end of this range are characterised by a timber frame construction with an air-tight concrete ground floor, with the remaining floors made of timber and with flue gas desulphurization gypsum inner walls. Designs constructed according to a corresponding ‘conventional’ building method (concrete floors, cavity walls made of brick and sand-lime brick), show almost equal radon concentrations and dose rates. The results indicate that the design has a more pronounced influence on the radiation burden than the habits and preferences of its occupants.

THE ANALYSIS OF SPEED AND PRESSURE OF WIND IN RAINY WEATHER/VĖJO SLĖGIO IR JO GREIČIO KITIMO LYJANT ANALIZĖ

It is not enough to investigate only the effect of wind on buildings, because deterioration of exterior surfaces of buildings is caused by wind and moisture together. A considerable part of rain gets into the exterior surface of enclosure, penetrates deep down and destroys the material of surface layer. The rain passes through enclosure construction and its surface layer due to wind pressure, through joints of the elements and cracks caused by improper transportation as well as by an inaccurate assembling. At present, new multilayer constructional elements are used for building envelope having numerous assembling seams, therefore, the combined influence of rain and wind becomes rather dangerous. It was established that the wind velocity during the rain is one of the main reasons predetermining moisture penetration into protective-decorative walls made of sand-lime brick with split surface, on concrete-lime mortar, according to the analysis of combined influence of the climate by research data [4]. The total effect of rain and wind on the humidity condition of exterior layers is described. Distribution of real wind velocity was estimated according to the data of the last 10 years. It was found that in Kaunas the average wind velocity increases from 3,4 m/s when the rain is absent up to 4,3 m/s and in Vilnius—the average wind velocity increases from 2,9 m/s when the rain is absent up to 3,7 m/s with an increase of approximately 26%, while in Klaipeda the average wind velocity increases from 3,6 m/s when the rain is absent up to 5,1 m/s with an increase of approximately 42%. On the base of the investigations carried out the suggestion is proposed to use the maximum and mean wind velocity values at the rain for estimating the effect of wind to the moisture behaviour in building elements.

THE ANALYSIS OF SPEED AND PRESSURE OF WIND IN RAINY WEATHER

Summary It is not enough to investigate only the effect of wind on buildings, because deterioration of exterior surfaces of buildings is caused by wind and moisture together. A considerable part of rain gets into the exterior surface of enclosure, penetrates deep down and destroys the material of surface layer. The rain passes through enclosure construction and its surface layer due to wind pressure, through joints of the elements and cracks caused by improper transportation as well as by an inaccurate assembling. At present, new multilayer constructional elements are used for building envelope having numerous assembling seams, therefore, the combined influence of rain and wind becomes rather dangerous. It was established that the wind velocity during the rain is one of the main reasons predetermining moisture penetration into protective-decorative walls made of sand-lime brick with split surface, on concrete-lime mortar, according to the analysis of combined influence of the climate by research data [4]....

Investigation of dielectric properties of brick materials as a function of moisture and salt content using a microwave impulse technique at very high frequencies

A pulsed microwave method using a frequency range of about 7 GHz has been developed based on the principle of the pulsed radar method. This method is employed for the non-destructive quantitative determination of the moisture content and distribution in brickwork. The measurements are more precise than previous measurements that have used frequencies below 1 GHz. Owing to the shorter wavelength and the higher absorption coefficient of water in this frequency region, both real and imaginary parts of the complex dielectric properties are measured with a higher accuracy. The expected non-linear relationship between the dielectric properties of several building materials and their moisture content and salt concentration (NaCl) requires calibration measurements. Therefore, systematic measurements on brick material, like sand-lime brick, solid brick, hollow brick and porous concrete, have been carried out. The results are demonstrated and compared with actual theoretical models.