Lightweight Mortars Research Articles

Composite Mortars Produced with Wood Waste from Demolition: Assessment of New Compounds with Enhanced Thermal Properties

AbstractIn this study, wood waste from demolition was used by replacing natural aggregate for developing lightweight mortars. Many domestic buildings in the historical city centers of Spain have wo...

폐 발포폴리스티렌과 발포폴리스티렌 비드를 활용한 경량 모르타르의 특성

본 논문에서는 발포폴리스티렌 비드 (EPB)와 폐 발포폴리스티렌 (WEP)의 대체율에 따른 경량 모르타르의 기초 특성을 평가였다. EPB 및 WEP를 이용한 경량 모르타르의 기초 특성으로서 단위용적중량, 압축 강도, 휨강도, 흡수율, 열전도율 및 폴리스티렌 (EPB 및 WEP) 분포를 분석하였다. 그 결과 경량 모르타르는 WEP의 대체율이 증가할수록 단위용적중량, 압축 강도, 휨강도, 흡수율 및 열전도율은 증가하고, 폴리스틸렌 면적 분포는 감소하였다. This study presents an evaluation of basic properties of light weight mortar with expanded polystyrene bead(EPB) and waste expanded polystyrene(WEP) by varying replacement rations. In order to evaluate the basic properties of the light weight mortar with EPB and WEP, unit weight, compressive strength, flexural strength, water absorption ratio, thermal conductivity and distribution of polystyrene (EPB and WEP) in hardened mortar were performed. As a result, unit volume, compressive strength, bending strength, water absorption and thermal conductivity of light weight mortar were increased, but area distribution of polystyrene decreased with increasing the replacement ratio of WEP.

Properties of hydrophobised lightweight mortars with expanded cork

The article evaluates the efficiency of surface hydrophobisation based on organosilicon compounds. The subject of the study involved expanded cork mortars produced from Quercus Suber oak. Surface hydrophobisation was carried out by means of: a solution of methyl-silicone resin with high VOC content, aqueous emulsion from methyl-silicone resin in potassium hydroxide and low-molecular alkyl-alkoxy-silane in an organic solvent. The basic mechanical and physical parameters were investigated in this paper. The following parameters were studied: compression strength, tensile strength, density, open and total porosity, absorbability, water vapour diffusion capacity, vapour-permeability, capillary water absorption coefficient, frost resistance, resistance to sodium sulphate corrosion, surface free energy (SFE), thermal conductivity coefficient. The contact zone, micro-structure, and decomposition of polysiloxane gel in the mortars were presented on the basis of a scanning electron microscope (SEM) research. The mortar characterized by the greatest porosity exhibits the highest absorptivity. The mortar with sand is the tightest; its absorptivity is almost three times lower than the one of a mortar without sand. The mortar C2S with sand has the highest resistance. All considered samples exhibited good resistance to salt crystallization after 15 cycles. The mortars subjected to hydrophobisation showed virtually no damages following the frost resistance test, whereas the mortar samples with 20% cork and lime content were badly damaged and suffered a 14% weight loss. The contact angle and SFE determine the wetting and adhesion properties of mortars. The latter can be modified by means of cork and sand additions.

Bubble stabilisation improves strength of lightweight mortars

Lightweight foamed mortars are produced through the addition of foaming agents into the cement blend, so that voids of different sizes are formed within the matrix, reducing the density of the material and therefore also its weight. However, the increased porosity of these materials usually compromises their mechanical strength, limiting their application as a structural material. Modern infrastructure demands high-strength lightweight concrete formulations that can be adjusted to develop more ambitious projects, both in design and application. In this study, lightweight pastes and mortars were produced using Portland cement blended with fly ash and silica fume, with varying water contents, and foamed using aluminium metal powder. To stabilise the bubbles produced through oxidation of the aluminium metal, polyethylene glycol was added to the mixes, and proved effective in yielding more uniform bubbles than were observed in the samples with no added stabiliser. This led to improvements in both the bulk density and compressive strength of the materials produced according to this new methodology.

Mechanical behavior of mortar reinforced with sawdust waste

Compressive strength, density and dynamic elastic modulus of mortar reinforced with wood sawdust wastes (WSW) were investigated. Additions of 0, 0.5, 1 and 3% by weight of (WSW) were used. The mechanical influence of sawdust was followed after 7, 30 and 90 days of curing. Scanning electron microscope (SEM) was used to characterize the morphology of the composites and to find the adhesion behavior of sawdust. The results show that compressive strength increases with sawdust content up to 0.5%. Using sawdust content larger than 1%, produces mortars with an excessive loss of compressive strength, especially for 3% of WSW. Lightweight mortar was obtained only for 3% of WSW reaching a compressive strength of almost 25MPa after 90 days of curing. According to SEM results, a good adhesion was originated for 0.5 and 1% of WSW and for all WSW percentages used a positive effect on the post-cracking behavior was found.

Thermal Conductivity and Compressive Strength of Lightweight Mortar Utilizing Pumice Breccia as Fine Aggregate

Pumice Breccia is a natural material which is available in a vast deposit of volume in Indonesia, especially in Yogyakarta area. The main characteristics of this type of rock are lightweight and having low thermal conductivity. Pumice breccia utilization is expected to support the implementation of green building concept by minimizing electrical power needs that may be required for setting the room temperature (air conditioning system). The aim of this study is to evaluate the effect of pumice breccia utilization as fine aggregate in various compositions on the thermal conductivity and compressive strength of the mortar. This study conducted using the experimental method to determine the thermal conductivity and compressive strength of each variation of the mortar. Two (2) types of mortar were investigated in this research. The first type is normal mortar using sand as the fine aggregate with mixture compositions variations of 1 Pc (Portland Cement):4 Ns (Sand), 1 Pc:6 Ns, and 1 Pc:8 Ns, which are labeled as MN1, MN2, and MN3. The second type of mortar is pumice breccia mortar that utilizing pumice breccia material as fine aggregate with mixture compositions variations of 1 Pc (Portland Cement):4 Pb (Pumice Breccia), 1 Pc:6 Pb and 1 Pc:8 Pb, named as MP1, MP2, and MP3. All composition of mortar mixtures is prepared based on the volume ratio. Test results show by using the Pumice Breccia as fine aggregate in the mortar mixtures, the thermal conductivity of the normal mortar can be reduced nearly considerably. Even though, the reduction in compressive strength is observed in all the compositions of mortar mixtures, based on SNI 03-6882-2002, still the Pumice Breccia based mortar can be classified into the type-O mortar that can be used for partition walls, protective and decorative purposes.

Lightweight aggregates from waste materials: Reappraisal of expansion behavior and prediction schemes for bloating

There is a growing concern on lightweight aggregates (LWA) for recycling of waste materials: this manufacturing technology is considered a flexible tool to make it possible the conversion of large amounts of residues into building products. The main challenge for this purpose is the control on the technological behavior during firing of waste-bearing batches. The target is engineering the sintering and expansion of LWA in order to tailor bulk density, mechanical strength and water absorption on various possible applications (e.g., structural and non-structural lightweight concretes, lightweight mortars, filtration substrates, floriculture). The prediction of the aggregate expansion – and hence the batch design – is usually carried out utilizing the Riley’s and/or Cougny’s schemes, which are based on the bulk chemical composition of clay bodies. However, collecting the literature data on waste-based LWA and plotting them in the Riley’s and Cougny’s diagrams, no reliable discrimination turns out between expanding and non-expanding batches. In the same way, the attempt to modify the Riley’s and Cougny’s parameters, including elements present in wastes but not in natural raw materials, was unsuccessful. From this standpoint, a new approach to assess the batch expandability was developed through a deeper comprehension of mechanisms acting on sintering and expansion of LWA. A specific characterization protocol was set up, entailing hot-stage microscopy and determination of phase composition and microstructure. This implies a paradigm shift from batch (chemical composition) to vitreous phase (amount, chemical composition, and viscosity at high temperature). The vitreous phase plays a key-role for bloating, microstructure and physical properties of LWA. A working example is presented about new LWA based on waste glasses, ceramic tile polishing sludge and clay raw materials.

Characterization of lightweight mortars containing wood processing by-products waste

In this study wood processing by-products were used by replacing natural sand for producing lightweight mortars. Manufacturers of wood products and furniture generate sawdust and pieces of side-cuts from a log to rectangular shapes. These are also produced by cutting, drilling, and milling operations when a wood piece is cut either from wood logs or while preparing finished products. Saw dust is often collected in filter bags or dust collectors. Three different percentages of substitution of natural sand were tried: 2.5%, 5%, and 10% by volume of the sand. Wood by-products were always pre-soaked in water and sometimes in calcium hydroxide aqueous solution in order to obtain wood mineralization before addition to the mortar mixture. Mortars containing wood by-products were characterized by means of compression and bending tests, drying shrinkage, resistance to water vapour permeability, water capillary absorption, and thermal conductivity measurements.Results obtained showed that a maximum dosage of 5% wood by-products should be used in order to avoid an excessive loss of mortar mechanical strength, and due to the reduction of thermal conductivity of about 25%. On the other hand, if a water reducing admixture is added, adequate mechanical performance can be obtained even with 10% wood by-products.

Investigation on the use of foamed plastic waste as natural aggregates replacement in lightweight mortar

Abstract The large growth of plastic consumption and consequently of plastic waste, requires new forms of recycling, avoiding landfill disposal. Polymeric aggregates obtained from recycled materials are often used for the production of lightweight mortars whose properties are widely reported in the literature. In this work, a new kind of polymeric aggregates with a particular set of properties are used to replace natural sand in the preparation of lightweight mortars. In particular, starting from end of waste materials, a process of extrusion-melt foaming was applied to produce polymeric particles characterized by high porosity and surface roughness. The process also allowed to tailor the particles size in order to accurately substitute natural sand particle size distribution in the mortar samples. Natural quartz sand was replaced by artificial aggregates at two volume fractions (10 and 25%) both in saturated and unsaturated conditions. Moreover, two different w/c ratios were investigated (0.45 and 0.50). The high porosity and rough surface of foamed aggregates resulted in a good adhesion with the cement paste. SEM investigations revealed the presence of interlocking positions onto aggregates surface and an ITZ very similar to that between natural aggregates and cement paste. At increasing sand replacement a reduction of mortar consistency was observed and, as expected, also a mechanical properties decrease. The use of artificial plastic aggregates, obtained by foam extrusion process, provides some advantages: reduction of natural sand consumption, use of plastic waste otherwise not used, decrease of structures dead-weight and improved aggregates/cement paste ITZ.

Lightweight masonry mortars made with expanded clay and recycled aggregates

One of the most extensive applications of recycled construction and demolition waste is as recycled aggregate in substitution of natural aggregate. An application for the fine fraction is investigated in this study by preparing lightweight mortars with different types of fine recycled aggregate from concrete waste and rubble. The properties of the materials are evaluated by means of physical and chemical characterization, their mechanical properties are tested, and the economic viability of the final product evaluated. In conclusion, despite the significant differences noted between the lightweight mortars and those incorporating natural aggregates, the former remain a technically and economically viable alternative.

Evaluation of strength of mortar using different saw waste with sand and model development

In this study saw wastes of wood, rattan and bamboo were used in mortar as a partial replacement of fine aggregate at different proportion. The variation of strength with time, density and water absorption, modulus of elasticity, and poisons ratio were identified. The test result was verified with the standard of mortar strength. Comparing to sand, being lighter in weight the above mentioned saw wastes decreased the weight of mortar. It can be considered as a new possibility of producing lightweight mortar as a building material. The test values were checked/verified using Artificial Neural Network (ANN). Also multivariable equations were generated to predict the strength of mortar. Finally it was seen that prediction using ANN has closer position with the test result instead of the equations.

Estimation of thermophysical properties of lightweight mortars made of wood shavings and expanded polystyrene beads using a hybrid algorithm

Over the past few decades, buildings energy consumption has risen seriously due to the growth of population and to the increase demand of comfort in indoor environment. Thus, the use of low thermal conductivities building materials and the development of powerful techniques to determine their thermal properties are receiving greater attention. To this end, lightweight mortar samples made with different percentage of polystyrene beads and wood shavings have been prepared and thermally characterized. To determine the thermal properties of these lightened mortar samples, an inverse problem based on a hybrid algorithm combining a genetic algorithm and the Nelder–Mead simplex algorithm has been implemented. The experimental bench using the boxes method has been used in transitory state. The implemented hybrid algorithm is used to minimize an objective function which represents the gap between a measured temperature and a calculated one. The obtained results demonstrate that the thermal conductivities and the densities of the elaborated samples have been improved until 71% and until 36%, respectively. Thus, energy consumption in buildings is expected to decrease. In addition the replacement of a percentage of cement by wood shavings and polystyrene beads leads to a reduction of the total produced energy and in CO2 emission. Furthermore, results show that the implemented hybrid algorithm has the ability to correlated parameters and the efficiency to combine convergence speed and accuracy of results.

A new lightweight support for the restoration and presentation of a large Roman mosaic

Abstract This paper presents a new technique employed in the construction of a lightweight backing for the Roman floor mosaic XIII.8 from Emona (Ljubljana, Slovenia). The rather large mosaic did not remain in situ but was instead lifted in 1997 before being restored and reassembled during a long and demanding conservation process between 2013 and 2014. Due to the size of the mosaic and subsequent demands associated with its presentation, as well as the need for easy handling when carrying and assembling the restored fragments, a necessity arose to develop a lightweight, compatible and easily removable support. Hence with an investigation of mechanical properties of lightweight mortars based on natural hydraulic lime was carried out. A low mortar density was obtained via the use of a lightweight aggregate composed of recycled glass beads. Conservation–restoration processes included documentation, cleaning, application of the new support, retouching and reassembly of the mosaic fragments.

Gas Generation from Incinerator Bottom Ash: Potential Aerating Agent for Lightweight Concrete Production

AbstractIncinerator bottom ash (IBA) has great potential to be utilized for civil engineering applications. This paper is to investigate the characteristic of gas generation from IBA and to study the potential of IBA as an aerating agent. Results show the aeration capacity of IBA used in this study is approximately 1% that of pure aluminum powder by mass. Finer particles, higher alkali molarity, and higher reaction temperature encourage the reaction and more gas is generated per gram of IBA. Type of alkaline solution does not seem to be an important factor for gas generation from IBA. Several exemplary lightweight mortars were produced by incorporating IBA as an aerating agent. It is highly plausible IBA can be used as an aerating agent to replace pure aluminum powder in the production of aerated concrete.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA).

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

Effect of Biomass Waste Materials as Unconventional Aggregates in Multifunctional Mortars for Indoor Application

In order to decrease energy consumption in buildings, a new way to recycle materials coming from biomasses waste in mortars was studied. For this purpose, mortars with water/cement equal to 0.5 by weight and aggregate/cement equal to 3.5 by volume were considered. Cement was replaced by hydraulic lime and sand was substituted with two different types of spruce sawdust shavings (as it is and roasted), biomass bottom ash and biomass fly ash. The results show that mortar prepared with cement has obviously a better mechanical strength and 60% lower capillary water absorption. All unconventional aggregates increase the total porosity of lime mortars. Moreover, biomass fly ash and both spruce sawdust shavings based mortars can be classified as lightweight mortar. Regardless of porosity and lightness, biomass bottom ash improves up to 150% the mechanical performance of lime-based mortars. Concerning durability, bio-based lime mortars show in general nearly twice higher capillary water absorption with respect to the sand lime mortars whit the exception of spruce sawdust shavings and biomass bottom ash. Mortars can be classified as permeable to water vapour. As it is and roasted spruce sawdust shavings are able to increase three and two times the capacity of the mortar to be a hygroscopic buffer in terms of MBV values.

Mechanical Characteristics of Lightweight Mortars on Small-Scale Samples

Abstract Occasionally, in laboratory conditions, it can be advantageous to use small-scale specimens, e.g., when the amount of available material is limited or expensive or when there are space limitations. The characteristics of any tested material such as concrete or mortar are affected by the specimens’ size; therefore it is important to consider this effect when estimating the properties of these materials. Despite the extensive studies about the effect of the specimens’ size in concrete, there is a shortage of information about this matter in mortars. This study presented the effects of specimens’ size on the mechanical properties of cement-based lightweight mortars. These included the compressive strength and flexural strength, bulk density, dynamic Young’s modulus, and ultrasonic pulse velocity. For this purpose, statistical analyses were conducted in order to correlate test values from standard samples and small-scale samples and to analyze the feasibility of estimating the mechanical strength from non-destructive tests on small-scale samples. In order to facilitate the production of small-scale specimens, an alternative mixing method was also tested. The results obtained show correlation factors around 0.9, which was found suitable to estimate the mechanical characteristics by using small-scale samples instead of standard specimens. The correlations obtained from the relationships between the results of mechanical strength and non-destructive tests were also evaluated.

Effect of Using Recycled Instead of Virgin EPS in Lightweight Mortars

Performances of structural, moderate and heat insulating lightweight mortars manufactured by replacing sand volume with virgin or recycled expanded polystyrene (EPS) are compared. At the same dosage, replacing virgin EPS with recycled one improves the mechanical performance of mortars without a significant variation in capillary water absorption and water vapour permeability. Recycled EPS mortars have lower thermal insulation properties than those manufactured with a virgin one, but this can be counteracted by increasing the percentage of EPS. To obtain mortars with a certain thermal insulating capacity, an economical saving over than 25% can be reached by using recycled EPS.

Reuse of wood waste for lightweight mortars

Reuse of wood waste for lightweight mortars

Resistance of coal bottom ash mortar against the coupled deterioration of carbonation and chloride penetration

This paper investigated the resistance of bottom ash mortar against the coupled deterioration of carbonation and chloride penetration. To evaluate the resistance of the mortar, a comparative study was conducted with variables of ordinary mortar, lightweight mortar using expanded shale, fly ash cement mortar, and slag cement mortar. Test results showed that a combination of carbonation and chloride penetration accelerated the rate of chloride penetration into the mortar regardless of the mortar type. The replacement of sand with bottom ash moderated the penetration depth of chloride under coupled-deterioration environments, while the overall penetrated-chloride contents showed no significant differences. It can be concluded in a coupled-deterioration environment that the chloride resistance of the bottom ash mortar was greater than that of both ordinary mortar and lightweight mortar. The type of cement paste on the surface of a carbonated mortar had a governing impact on the chloride penetration.