Unfired Bricks Research Articles

Preparation and property of unfired brick using electrolytic manganese residue

The feasibility of making unfired brick from the EMR with some additives in laboratory experiments was investigated in this paper. The results show that the EMR can be used to produce unfired bricks meeting JC/T 422-2007 for Mu 25 non-fired rubbish gangue brick. XRD and SEM analyses indicated that C-S-H, calcite, gypsum were newly generated phases in the unfired brick and there are almost no large capillary holes in the unfired brick, which can increase the compressive strength of the brick. The leaching toxicity test demonstrated that the unfired EMR bricks samples showed significant reduction in leach ability of heavy metals compared to raw EMR.

Leachate Analysis of Heavy Metals in Cigarette Butts and Bricks Incorporated with Cigarette Butts.

Billions of cigarette butts (CBs) are discarded as litter in the environment every year worldwide. As CBs have poor biodegradability, it can take several years for them to break down while leaching toxic chemicals and heavy metals. Mohajerani et al. (2016), based on long-term research, developed a method for the recycling of CBs in fired clay bricks with promising results. This paper presents and discusses the leaching behavior of potentially hazardous metals from used, unused, and shredded used CBs, and unfired and fired clay bricks incorporating CBs. The leachate analysis was conducted according to the Australian Bottle Leaching Procedure (ABLP) for pH values 2.9, 5.0, and 9.2. The aim was to quantify the amount of heavy metals leached, determine the relationship between the metal concentration leachate, pH of the solution and condition of the sample, and examine the effect of firing on the leaching capability of bricks. The leachate results were then compared to the concentration limits for heavy metals set by the United States Environmental Protection Authority (USEPA) national primary drinking water and the Environmental Protection Authority (EPA) solid industrial waste hazard categorization thresholds to assess the suitability of fired clay bricks incorporating CBs. Metals Cu, Zn, Mn, Al, Fe, Ti, and Ba demonstrated the highest leachate concentrations for pH 2.9 and pH 5.0 for used CBs. This suggests that used CBs are more prone to leaching heavy metals in areas with highly acidic rain compared to the natural range of precipitation. The leaching behavior of fired bricks incorporating CBs was considerably lower than that for the unfired bricks due to the immobilization of heavy metals during the firing process. However, the leaching of Cr and Ni was almost completely impeded after the firing of the bricks, and more than 50% of all the tested heavy metals were hindered.

Sustainable incorporation of lime-bentonite clay composite for production of ecofriendly bricks

The global earth atmosphere is degrading due to the abundant use of fossil fuel for fulfilling the energy demands of rapidly growing economies. The conventional brick manufacturing process contributes its part by consuming energy in its firing process, which causes global warming and cardio-respiratory diseases attributed to increasing concentration of affluent greenhouse gases and hazardous particulate matter. Therefore, the proposed research aims to provide eco-friendly solutions to the stated problems by incorporating locally available powdered lime-bentonite composite in compressed and unfired bricks, whereas properties of fired bricks were examined for comparison purpose. For compressed, unfired and fired bricks, clay was replaced by 0, 5, 10, 15, and 20% of bentonite content while keeping 5% quick lime constant for each dosage level. Characterization results indicated that the calcium-rich quick lime and silica-rich bentonite being incorporated in clay bricks decreased its average particle size and optimum moisture content values, whereas increased the plasticity of lime-bentonite clay composite. Incorporation of lime-bentonite composite in compressed, unfired bricks yield the increased compressive and flexure strength, whereas reduction in water absorption and unit weight was observed. However, compressed bricks type appeared as the most desired one out of all brick types with the compressive strength value of 10.40 MPa, which satisfied the strength requirement for building code of Pakistan and ASTM specifications C62-13 for building bricks along with negligible weathering. Durability in terms of corrosion resistance of compressed bricks increased from 0.72 to 0.81 with bentonite inclusion. However, thermal conductivity reduced from 0.72 to 0.38 W/m-K comparative to conventional fired brick used in the construction industry, resulting 31.91% reduction in cooling loads and carbon footprints for B20 compressed bricks, which suggests its energy-efficient and ecofriendly nature. Conclusively, lime-bentonite compressed clay bricks provide eco-friendly, energy-efficient and sustainable options for the production of green clay bricks.

Natural radioactivity and radiological hazard of red-clay brick produced in Shangluo, China

The radiological hazard of building materials originating from clay, rock and other mineral wastes has attracted more attention because they contain natural radionuclides (226Ra, 232Th, and 40K). The activity concentration of radionuclides in red-clay brick samples obtained from three different brickyards in Shangluo, China waHs measured. Various indexes, including radium equivalent activities, Raeq, external hazard index, Hex, internal hazard index, Hin, indoor air absorbed dose rate, D, and annual effective dose, AED, of the aforementioned radionuclides in the bricks were used to assess the radiation hazard for people. The average activity concentrations of 226Ra, 232Th, and 40K were respectively 34.5 ? 1.9, 62.5 ? 2.1, and 713.7 ? 19.8 Bqkg?1 for the studied red-clay bricks. The Raeq values of the red-clay brick samples varied from 167.0 to 184.7 Bqkg?1, which are lower than the limit of 370 Bqkg?1. Moreover, the activity concentrations of natural radionuclides in unfired brick, clay and coal were also determined and the results were compared with that in the red-clay brick samples. This study shows that the red-clay bricks produced in Shangluo, China can be used safely in construction industries.

Thermal Effect on Mechanical Characteristics of Drinking Water Sludge Brick Incorporated with Rice Husk Ash

Brick is among the important construction materials and commonly manufactured from mixtures of clay or sand, lime and cement. Due to limited natural resources for raw materials and highly demand for brick in construction industry have gradually increased the market price of each unit. Therefore, alternative sources are required such utilization of drinking water sludge (DWS) and rice husk ash (RHA) are potentially used as base and/or incorporated materials for manufacturing alternative brick. In this study, the brick samples which had been developed from mixtures of DWS and RHA (D80 brick) were subjected to different firing temperatures of 300oC and 500oC. The results of this study were compared to that of unfired brick and bricks which developed from 100% DWS content (D100 brick). The result also shows the volume shrinkage significantly increased at firing temperature of 500oC and was more apparently affected the D100 brick if compared to that of D80 brick. As firing temperatures were increased, the density of both brick samples decreased with D100 brick more prominent than D80 brick. The effect of temperature on the water absorption and compressive strength clearly increased especially for the D80 bricks, respectively. The effect of temperature is closely related to the presence of rice husk ash as this organic matter destroyed at high firing temperature of 500oC. The results obtained in this study suggested that firing temperature can modify and enhance the studied mechanical characteristics.

ผลของการเผาซ้ำต่อสมบัติเชิงกลและลักษณะทางกายภาพของอิฐดินดิบทนไฟที่ใช้ก่อเตาเผาเซรามิกชนิดใช้ฟืนทางเดินลมร้อนลง

ผลของการเผาซ้ำต่อสมบัติเชิงกลและลักษณะทางกายภาพของอิฐดินดิบทนไฟที่ใช้ก่อเตาเผาเซรามิกชนิดใช้ฟืนทางเดินลมร้อนลง

Utilization Oil Based Industrial Sludge as Potential Construction Components

The aim of this study is to investigate the potential of using Wastewater Treatment sludge (WWTs) from oil-based industry as a target material for sustainable construction component. Intensive laboratory investigations were carried out to establish the best mix design for brick composition. WWTs were blended with Laterite Clay (LC) at 50:50 ratio to produce unfired bricks. These target material were stabilised using Hydrated Lime (HL), Portland cement (PC) on its own and combination of Ground granulated blast-furnace slag (GGBS), waste from metal industry, HL: GGBS and PC: GGBS both (50:50 and 70:30 ratio) at 10%, 20% and 30% stabilizer dosage. The influence of the waste addition on the compressive strength and water absorption test was investigated on brick specimens. The unfired brick were fabricated in the factory environment. The bricks that casted were wrapped in cling film and air cured for 7 and 28 days before testing. The results obtained show that the measured strength properties and water absorption of the stabilized WWTs are comparable to conventional bricks. The results suggest there is a potential of using sludge from oil based industry in view of economic and environmental concern.

The properties and formation mechanisms of eco-friendly brick building materials fabricated from low-silicon iron ore tailings

The volume of tailings discharged worldwide from iron ore smelting processes (i.e., iron ore tailings) has increased dramatically in recent years, and the disposal of this waste poses a substantial ecological threat to soil, and surface and sub-surface water. This threat can be alleviated to a large extent by employing iron ore tailings to fabricate brick building materials, while also effectively meeting the large demand for construction materials. The present paper discusses the preparation of eco-friendly bricks using fine-grained low-silica iron ore tailings and a non-cement curing agent system as the primary raw materials, and a triethanolamine hardening accelerator and a stearic acid emulsion waterproofing agent are also employed as minor components. We first evaluate the effect of the waterproofing agent content on the compressive strength and water resistance of the resulting products. In addition, the phase composition, chemical structure, and microstructure of the products are analyzed via X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy to explore the formation mechanism of the brick products. The analyses demonstrate that hydrated calcium silicate gel and ettringite formed in the curing process are strong binders. The water resistance and compressive strength of the product was optimal when the waterproofing agent and curing agent were 0.3 wt% with an initial curing temperature of 60 °C. The compressive strength and saturated compressive strength of the optimally formed brick products after curing for 28 d were 27.2 MPa and 24.3 MPa, respectively. The other physical properties and durability conform to the Chinese JC/T422-2007 standard for unfired bricks made of tailings.

The Feasibility of Using Marble Cutting Waste in a Sustainable Building Clay Industry

This study evaluates the feasibility of stabilizing clay bricks with marble cutting waste (MCW). This waste is currently discarded in huge quantities as sludge resulting from the sawing of marble blocks to slabs and the processes of disposing of grinding and polishing marble in landfills located around the marble processing factories in the Shaq El-Thoban industrial zone, Cairo governorate, Egypt, which causes negative impacts on the environment, health, and sustainable development. Experimental investigations were carried out to explore the effect of the addition of MCW in different clay–base mixes using varying percentages of up to 20% at the expense of the hydrated lime. Cement, hydrated lime, and MCW are the three types of solidification agents used, and clay and sand were also added in the formulations of the unfired clay brick specimens. Laboratory cylindrical stabilized and compressed specimens were made; then, they were cured in a humidity chamber for two weeks and four weeks. Afterwards, they were air dried, tested, and evaluated according to the Egyptian code for the building by the stabilized and compressed earth soil (ECBS, 2016). To enhance the durability of the cured specimens, transparent silicon-based paint was used. The results demonstrated that the optimum content of marble sludge waste (MCW) was 15% when used as replacement for hydrated lime in the production of stabilized clay brick. For all of the samples, the use of silicon-based paint was found to improve the strength and water resistance of the stabilized clay bricks. The use of local waste materials as a substitute for a hydrated lime binder reduces both the cost and environmental impact associated with block production.

Thermo-mechanical behavior of unfired bricks and fired bricks made from a mixture of clay soil and laterite

The objective of this paper is to determine the mechanical and thermal properties of unfired and fired clay soil bricks made from a mixture of clay soil and laterite. In this study, the physical, chemical and mineralogical characteristics of raw materials were measured. Then, experiments were carried out on six compositions of clay soil bricks prepared by adding laterite to study the effect on mechanical and thermal properties. The results obtained in this study demonstrate that clay soil brick containing 30% of laterite is the optimal mixture for both unfired and fired bricks.

Development, engineering properties and potential applications of unfired earth bricks reinforced by coal fly ash, lime and wood aggregates

The current study developed and evaluated the engineering properties of improved low-cost UEBs reinforced with various lime (L)-coal fly ash (F)-wood aggregate (W) mix ratios. The objectives were; (1) to determine the effects of lime-coal fly ash-wood aggregate mixtures on mechanical strength and water resistance properties of UEBs; and (2) to determine the comparative cost of the improved UEBs to that of the control (10% cement). Four UEBs with various lime (L)-coal fly ash (F)-wood aggregates (W) mix ratios (L4%-F16%-W1.5%; L4%-F16%-W3%; L8%-F12%-W3%; L10%-F10%-W1.5%) were fabricated and their engineering properties compared to those of unstabilised (negative control) and 10% cement stabilized (positive control) unfired earth bricks. Dry compressive strength (DCS) of UEBs stabilized by L10%-F10%-W1.5% (8.3 MPa) was significantly higher (p < 0.001) than that of 10% cement stabilized unfired bricks (7 MPa). DCS and dry density of the four UEBs conformed to the British Standards for low-density clay masonry units. DCS increased with lime-fly ash ratio according to a power function (y=−5.41x2+11.18x+2.22; r2 =0.95, p = 0.018), attaining a maximum of 8.3 MPa at a ratio of 1: 1. However, UEBs had low wet strength, but incorporation of 4% cement significantly increased (p < 0.001) the wet compressive strength of UEBs to 0.94 MPa. UEBs stabilized by 10% lime, 10% coal ash, 1.5% wood aggregates and 4% cement (L10%-F10%-W1.5%-C4%) had water absorption (15.8%) similar to that of 10% cement stabilized UEBs. Moreover, unfired earth bricks reinforced by L10%-F10%-W1.5%-C4% conformed to British Standards engineering specifications for low-density clay masonry units, while the cost was 50% lower than that of cement stabilized bricks, demonstrating the low-cost of the UEBs. In summary, the results demonstrate that improved low-cost UEBs can be developed by incorporating lime, coal fly ash and wood aggregates, but a little cement (4%) may be required to increase the wet compressive strength. Potential applications of the UEBs include, (1) internal partitioning; (2) construction of low-cost housing for low-income households in developing countries, and (3) the provision of temporary or short-term low-cost shelter for displaced persons in humanitarian emergencies.

Sustainable unfired bricks manufacturing from construction and demolition wastes

The management of construction and demolition wastes is a huge challenge for most Governments. The greatest component of such wastes is concrete and masonry fragments or remains. Among the most common approaches to valorization of such wastes is to convert them to recycled aggregates, however this may be hampered by low quality of some recycled aggregates compared to natural aggregates. This paper presents the results of experimental investigation where concrete and ceramic remains were used to partially substitute clay soil in producing unfired bricks. The bricks were then tested for mechanical strength, water absorption freeze-thaw resistance. Additionally the environmental impact of the bricks was assessed based on Life Cycle Analysis (LCA). It was established that concrete waste could be used to substitute up to 50% of the clay whereas ceramic wastes could only substitute a maximum of 30% of the clay. Blended bricks made from clay and concrete waste mixes had a lower mechanical strength than those made from clay and ceramic waste. As regards water absorption, there was no marked difference between the two blends of brick however reduction in water resistance was slightly greater in bricks containing concrete waste that in those containing ceramic wastes. Also, tests showed that freeze-thaw resistance was greater in bricks blended with concrete wastes than in those incorporating ceramic wastes. Life Cycle analyses demonstrated that it is the binder content in the mix that largely determines the environmental impact of the blended bricks. Lastly, it was demonstrated that the most desirable technical and environmental credentials of brick material mixes resulted from using the binder combination: CL-90-S+GGBS 2/8.

Utilization of Sandy Soil as the Primary Raw Material in Production of Unfired Bricks

In this study, attempts were made to use sandy soil as the main raw material in making unfired bricks. The sprayed‐cured brick specimens were tested for compressive and flexural strength, rate of water absorption, percentage of voids, bulk density, freezing/thawing, and water immersion resistance. In addition, the microstructures of the specimens were also studied using scanning electron microscope (SEM) and X‐ray diffraction (XRD) technique. The test results show that unfired brick specimens with the addition of ground‐granulated blast‐furnace slag (GGBS) tend to achieve better mechanical properties when compared with the specimens that added cement alone, with GGBS correcting particle size distribution and contributing to the pozzolanic reactions and the pore‐filling effects. The test specimens with the appropriate addition of cement, GGBS, quicklime, and gypsum are dense and show a low water absorption rate, a low percentage of voids, and an excellent freezing/thawing and water immersion resistance. The SEM observation and XRD analysis verify the formation of hydrate products C–S–H and ettringite, providing a better explanation of the mechanical and physical behavior and durability of the derived unfired bricks. The results obtained suggest that there is a technical approach for the high‐efficient comprehensive utilization of sandy soil and provide increased economic and environmental benefits.

Magnesium oxide as alternative binder for unfired clay bricks manufacturing

Replacement of fired bricks by unfired ones could be an effective way to reduce the building industry environmental footprint: Their manufacture not only requires less energy and natural resources but also generates less waste. Bricks are based on the use of an additive cementitious material in the form of a binder, usually lime or cement. Such additives have a great environmental impact owing to the high energy consumption and CO2 during in their manufacturing process. In this article experiments are carried out in order to investigate the applicability of a MgO rich industry by-product as a binder for the production of unfired clay bricks. From the experiments, the MgO was observed to show ability to enhance the mechanical properties of a clay brick in much the same way as lime does. Water absorption tests on bricks revealed the superiority of MgO over lime in enhancing the durability properties of unfired bricks. The laboratory results demonstrate the high potential of MgO based additives as alternative binders to the calcium based ones. Consequently, this offers opportunity for reducing the environmental impact associated with the use of fired clay bricks. In addition, it could allow an effective way for the valorization of MgO containing industry by-products that currently discarded to landfills.

Technical and environmental characterisation of recycled aggregate for reuse in bricks

Waste mud coming from an aggregate washing plant was formerly used as filling material for a pond, aimed at the recovery of an abandoned quarry. Once completed the filling capacity of the pond, the need for identifying a possible reuse of mud produced by the plant arose in order to avoid landfill disposal. Therefore, mud has been geometrically, physically and chemically characterised for its recovery as construction material. A variety of tests was carried out on mud samples as required by EN technical specifications and by Italian environmental standards, focusing particularly on leaching behaviour. The tested material showed satisfactory physical and chemical properties and a release of pollutants below the limits set by the Italian code. Many mix-designs for the production of unfired bricks made of waste mud, sand and straw, stabilised and non-stabilised with lime, gypsum or cement, were developed. The bricks were tested in order to evaluate mechanical properties and leaching behaviour. Mud bricks provided remarkable compressive strength, even if not suitable for structural elements. The use as interior design to minimise humidity changes and to facilitate a thermal insulation is fostered, thus strengthening the so-called green building economy.

Later, laterculus, and testa. New Perspectives on Latin brick terminology

For centuries antiquarians and archaeologists have tried to reconcile the terminology of ancient writers on architecture, such as Vitruvius, with the perceived realities of the material record. One particular issue of debate concerns the interpretation of different words for “brick” in Latin. In this paper it is argued that earlier attempts to settle this question are unsatisfactory and leave several problems unresolved. A thorough examination of literary and epigraphic sources, combined with new insights in Hellenistic brick usage, suggests that primary distinctions in Latin brick terminology were based on shape and size, rather than on a mere division between fired and unfired bricks. Thus, it is argued that later basically signified a large moulded block, but normally was used to indicate mud bricks; that laterculus changed over time from being a diminutive (a small later) to becoming the standard term for the relatively thin fired bricks of the Roman Imperial period; and that tes­ta originally and primarily signified a fragment of a roof tile (or a potsherd), but from the 1st century AD also may designate typical Roman Imperial bricks, after they have been divided into smaller, often triangular, pieces.

FABRICATION OF UNFIRED BRICKS FROM INDUSTRIAL SCHEDULED WASTE (WWTS)

Manufacturing industries produce wastes or secondary products, in which it has a direct impact to the environment. The storage of such wastes remains at the disposal would pollute the air, water resource and agricultural fields. There is a huge opportunity for recycling and it uses large quantities of wastes to minimize the environmental impact. This paper investigates the effect of utilization Wastewater Treatment sludge (WWTs) blended with Laterite Clay (LC) at 50:50 ratio to produce unfired bricks. These target materials were stabilized using Hydrated Lime (HL), Portland cement (PC) on its own and combination of Ground Granulated Blast-furnace Slag (GGBS), HL:GGBS and PC:GGBS both (50:50 and 70:30 ratio) at 10%, 20% and 30% stabilizer dosage. Compressive strength, flexural strength, thermal conductivity and toxicity characteristic leaching procedure (TCLP) test were conducted and compared with the relevant standards. It was found that it is feasible to utilize WWTs as unfired bricks from the economical and environmental point of view as it will conserve natural resource, protect the environment from waste disposal, and produce a low cost, low carbon construction components.

Appropriate structural unfired earth masonry units

Modern earth masonry utilises conventional methods of extruded fired brick manufacturing for the manufacture of unfired earth bricks. However, the bricks produced currently are not generally recommended for structural applications due to their loss of strength under elevated moisture content. In response to this loss in strength, bricks can be chemically stabilised, typically by the addition of cement or lime. However, the use of such binders typically negates the reduced environmental impact of using unfired brick, which is often the initial driver. The research presented in this paper considers the improvement in compressive strength that can be achieved through the addition of a range of pozzolanic binders as well as their associated embodied energy and carbon dioxide. This allows for a holistic comparison of material selection based on meeting the minimum structural requirements of the masonry units, while improving the embodied impact of equivalent units currently used. The study shows that an unfired brick with the addition of lime and metakaolin achieves a compressive strength of more than 6 MPa when dry and more than 1 MPa following complete saturation, while reducing the global warming potential by more than 30%. This paper demonstrates that stabilised unfired bricks can be practically viable, structurally suitable and environmentally beneficial.

Thermal conductivity of unfired earth bricks reinforced by agricultural wastes with cement and gypsum

Energy-efficiency of sustainable constructions and buildings are evaluated based upon the heating and cooling demands, but also according to the primary-energy demand, CO2 savings potential, and the ecological properties of building materials. To meet increasingly rigorous requirements, the demand for natural building materials is growing rapidly. The research objective of the here presented study is to stabilize soils with natural straw fibres to produce a composite, sustainable, non-toxic and locally sourced building material. The material appropriateness was determined by establishing the thermal conductivity of a selection of unfired earth bricks that were identified as potential new natural building materials. The thermal conductivity is an essential material characteristic to achieve the required insulation level and for market success as a new product. The earth bricks consist of soil, cement, gypsum and straw fibres. Straw was applied as fibre reinforcement for unfired bricks. Two fibre types were used: wheat and barley straw. The results indicated that the thermal conductivity of all investigated variants decreased with increasing fibre content while increasing with higher cement and gypsum contents. They also show that barley straw fibre reinforced bricks exhibited the highest thermal insulation values. The addition of fibre positively improves both, thermal and static properties.

Properties of Unfired Building Bricks Prepared from Fly Ash and Residual Rice Husk Ash

This work investigates the possibility of using fly ash (FA) and Vietnam residual rice husk ash (RHA) in producing unfired building bricks with applying densified mixture design algorithm (DMDA) method. In this research, little amount of cement was added into the mixtures as binder substitution. Unground rice husk ash (URHA), an agricultural by-product, was used as partial fine aggregate replacement (10% and 30%) in the mixtures. The solid bricks of 220×105×60 mm in size were prepared in this study. The hardened properties of the bricks were investigated including compressive strength, flexural strength and water absorption according to corresponding Vietnamese standards. Forming pressure of 35 MPa was applied to form the solid bricks in the mold. The test results show that all brick specimens obtained good mechanical properties, which were well conformed to Vietnamese standard. Compressive strength and flexural strength of the bricks were respectively in range of 13.81–22.06 MPa and 2.25–3.47 MPa. It was definitely proved many potential applications of FA and RHA in the production of unfired building bricks.