Mortar Mixes Research Articles

Enhancing the Properties of Sulfate-Resisting Cement

Sulfate-resisting cement is used in construction works when a sulfate attack is probable. This type of cement withstands sulfates due to its low C3A content. On the other hand, the decrease in the quantity of C3A leads to a reduction in the rate of early strength development. To overcome this problem, a hardening accelerator was added to the cement mix. To estimate the effect of the accelerator on some properties of hardened cement, compressive and flexural strength, and drying shrinkage tests were carried out. Four series of cement mortar mixes were made. The hardening accelerator was not added to the control series, while it was added to the others with three different percentages (of cement mass) of 0.5, 1, and 1.5%. The results revealed that the hardening accelerator enhances the compressive strength of all mortar ages while it slightly promotes flexural strength only at early ages. It was also observed that the hardening accelerator strongly inhibits the drying shrinkage strain.

Properties of cement bricks containing sago fine waste (SFW) with different water-cement ratio

Cement is a key material in the construction industry. However, this widespread use adversely affects the environment. The replacement of cement with waste materials, mainly agricultural wastes, can reduce the impact of environmental pollution and result in sustainable construction. Sago fine waste (SFW) is a fibrous residue from waste from sago milling operations where physical treatment has been made. This study used SFW as a partial cement replacement material in cement brick and the effect of adding SFW to cement brick properties. Brick samples are designed with five different percentages of 2,4,6,8, and 10% of cement replacement, including control cement brick. The mortar mix is based on a ratio of 1:3, which follows Malaysian brick production standards. For compressive strength, density, and water absorption tests, all the specimens were cured for 7 and 28 days. The strength of cement bricks was investigated based on the difference of two water-cement ratios: 0.5 and 0.6. The brick properties investigated in this study are density, water absorption and compressive strength. The experimental results show that the brick’s density, compressive strength, and water absorption decreased as the replacement percentage increased. However, it still meets the requirements of the standard for load-bearing structures. Analysis of this study is according to extensive data collection, the ideal composition for SFW in cement brick was 2% and 0.6 water-cement ratios. This demonstrates SFW’s promise as a novel pozzolanic material for producing more sustainable bricks. As a result, SFW as a cement replacement material could improve bricks’ physical and mechanical properties as curing time increases.

PROPERTIES EVALUATION OF GREEN MORTAR CONTAINING WASTE MATERIALS

The accumulation of massive waste has impacted human health and the city's appearance. As a result, there was a need to reduce waste by using by-products from industrial waste to replace cement, such as limestone, fly ash, silica fume, steel slag, and other minerals known as supplementary cementitious materials are produced environmentally and sustainably. This paper's purpose is to design a green mortar with the highest possible replacement of cement that has acceptable fresh and hardened characteristics. In this paper, three (SCMs), such as limestone powder (10%), calcined clay (0–35%), and slag (0–30%), were used to prepare ternary mixtures. The materials used in this research are available locally in Mosul, Iraq. The experimental studies were carried out for twelve mixes. The tests of flowability, flexural strength, compressive strength, dry density, ultrasonic pulse velocity, and water absorption on green mortar have been conducted. The cement was replaced 30% to 60% with a combination of ternary cement containing calcined clay, limestone, and slag in different replacement percentages than in other green mortar mixes. The results found that replacing OPC (30%), which contains 10% limestone, 10% steel slag, and 10% calcined clay, gives the highest compressive strength and flexure strength enhancement, which are 24% and 18% greater than the plain mortar after 28 days. When cement replacement was increased for ternary mixes, the result differed slightly from the plain mortar. Water absorption increased as the SCMs were increased. Dry density showed little effect.

EFFECT OF ALUMINIUM WASTE POWDER ON THE STRENGTH PROPERTIES OF CEMENT MORTAR

The cement is used as primary binding material in the field of civil engineering is undoubtedly at a higher level due to the increase in urbanization. Concrete, cement mortar, and other composite building materials are made from it. The substantial use of OPC in the field of construction industry has increased the production of CO2. This has huge negative impact on the environment and has encouraged everyone to explore and analyze practical advancement by substituting alternative waste products in concrete and mortar. Therefore, the objective of this study was to evaluate the strength performance of cement mortar containing Aluminium waste powder as a Cementitious Material. In this study, we have substituted the cement with different percentages i.e., 2.5% to 10% of Aluminium waste powder to obtain feasible mortar mix. The cubes of 50 mm size were cured for 3, 7, and 28 days, the properties of flowability, density, and compressive strength was studied. The results indicated that by increase in addition of Aluminum waste powder (AWP) flowability of mortar paste decreased, the water cement ratio was fixed as 0.50 for all type of mixes. The results indicated that the Density and Compressive Strength of Cubes cured in water, it was observed that as the % Addition of AWP increased the density and compressive strength of cubes cured were reduced. For Compressive Strength, it was found that at each designated day, the compressive strength of cubes up to 2.5% addition has given suitable value but intensely decreased at 10% addition. At 2.5% Addition Aluminium waste powder on 28th day test it was noticed that it has greater value of compressive strength for all % of addition.

Cow Dung Ash in Mortar: An Experimental Study

This study investigated the impact of using cow dung ash (CDA) as a partial replacement for ordinary Portland cement (OPC) in mortar. Mortar mixes are prepared by replacing OPC with CDA at varying levels: 5%, 10%, 15%, 20%, 25%, and 30%. The chemical composition of CDA shows that it is composed primarily of SiO2, Al2O3, and Fe2O3, with a significant amount of loss of ignition. The workability, hardened properties, and microstructure of CDA-containing mortars are also analyzed. The increasing CDA content in mortar reduces workability and, beyond 5%, it causes high water absorption due to CDA’s porous nature and unremoved organic compounds. This impacts the density and compressive strength of the hardened mortar as well as compromising its homogeneous characteristics. When using 5% CDA, the bulk density and compressive strength of the mortar are comparable to those of the control mixes. Nonetheless, as the proportion of CDA increases, both the bulk density and compressive strength of the mortar diminish. The thermal stability of mortar mixes with 10%, 20%, and 30% CDA is unaffected at temperatures between 500 °C and 600 °C. The Fourier-transform infrared spectroscopy (FTIR) analysis reveals the presence of unreacted particles and wide stretched C–S–H gels in the mortar samples. In general, the results suggest that CDA can be utilized as a substitute for OPC at a ratio of up to 10% in the manufacturing of mortar and can serve as a feasible alternative cementitious material.

A Neural Network-Based Prediction of Superplasticizers Effect on the Workability and Compressive Characteristics of Portland Pozzolana Cement-Based Mortars

Portland Pozzolana Cement (PPC) mortars are predominantly employed in plastering works to achieve better workability, superior surface finish, and higher fineness to offer better cohesion with fine aggregates than the ordinary Portland cement (OPC) mortars. To achieve high performance in the cement mortar similar to cement concrete, the addition of a superplasticizer is recommended. The present study investigates the impact of addition of sulphonated naphthalene formaldehyde- (SNF)-based (0.5%, 0.6%, 0.7%, and 0.8%) and lignosulphate- (LS)-based (0.2%, 0.3%, 0.4%, and 0.5%) superplasticizers on the workability and compressive strength characteristics of PPC mortars. Plastering mortars of ratio 1 : 4 were prepared with natural sand and manufacturing sand (M sand) as fine aggregates. A flow table test was conducted on all the mortar mix proportions, and the effects of the inclusion of superplasticizers on flow properties were recorded at different time intervals (0, 30, 60, 90, and 120 minutes). PPC mortar cubes were prepared, cured, and examined to assess the inclusion of chemical admixtures on compressive strength at different ages (1, 3, 7, 14, and 28 days). The experimental findings from the workability and compressive strength of PPC mortars were analyzed, and the corresponding results were predicted using artificial intelligence. Experimental investigations demonstrated that the desired flow characteristics and higher compressive strength results were achieved from a 0.7% dosage of ligno-based superplasticizer. The predicted workability and compressive strength results at various ages acquired by implementing an Artificial Neural Network (ANN) were found to be in close agreement with the experimental results.

Flexural behavior, porosity, and water absorption of CO2-cured amorphous metallic-fiber-reinforced belite-rich cement composites

The present study aims to scrutinize the flexural behavior and engineering properties of beams reinforced with amorphous metallic fiber (AMF) at varying dosages (0%, 0.25%, 0.50%, and 0.75% AMF according to the volume of mortar) and lengths (5 mm, 10 mm, 15 mm, and 20 mm). A total of fourteen mortar mixes, i.e., seven mixes for water curing (immersed in fresh tap water) and seven mixes for carbonation curing (60% relative humidity, 20 °C, and 10% CO2 concentration) were considered. The load–deflection behavior, flexural strength, pore structures, voids, and water absorption of the beams were investigated. The outcomes were justified with the mix containing 0.5% steel fiber (SF) and a length of approximately 20 mm. The results reveal that the load–deflection behavior and flexural strength were dramatically augmented for the beams with AMF as compared to the control beam (fiber-free beam), and the difference was more pronounced with an increase in both the dosage and the length of the AMF. Greater flexural strength with a lower deflection at failure was registered for the beam with AMF compared to that with SF. The voids and water absorption increased with an increase in the dosage and length of the AMF compared to the control specimen. It was also revealed that the carbonation-cured beams exhibited lower load–deflection behavior and lower flexural strength than those cured in water due to the substantially increased number of voids and greater water absorption driven by the better-connected pores. This study demonstrates that 0.50% AMF with a length of 20 mm can be used in cement-based materials due to the outstanding performance among all mixes.

Synergistic effect of nano silica on carbonation resistance of multi-blended cementitious mortar

Confiscation of alkaline buffer in a blended cementitious system surges the risk of carbonation. Understanding the carbonation mechanism and kinetics of multi-blended cementitious systems in correspondence to microstructural properties is the need of the hour. In this context, the change in the microstructure of binary, ternary, and quaternary blended cementitious mortar mix comprising of fly ash or/and ultra-fine fly ash or/and nano-silica upon accelerated carbonation (3.5% CO2; 70% RH) was studied. All multi-blended mixes were proportioned using modified Andreasen and Andersen particle packing theory. Permeable porosity and carbonation parameters such as carbonation depth, rate of change in compressive strength, and carbonation shrinkage were measured. Further, qualitative/quantitative estimation of carbonation phases was done using characterization techniques such as TGA and FTIR. In control mix with solely OPC, the reaction of CO2 with calcium-bearing phases showed chemo-mechanical changes leading to 18% improvement in strength at 30 days of exposure. The optimized multi-blended cementitious systems with nano-silica exhibited higher resistance to carbonation kinetics. Phase assemblages quantified through TGA within depth of carbonation imply a negligible concentration of portlandite (CH). However, mixes without nano-silica exhibited a significant reduction in bound water content associated with C–S–H/AFt/AFm phases and intensified the precipitation of calcium carbonate (CaCO3) phase. Asymmetric stretching band of C–O–C at 1424 cm−1 corresponding to calcite phase measured using FTIR validates the outcomes of TGA.

Self-stabilisation of high-temperature calcined electrolytic manganese residue in mortar

High temperature calcination and mechanical ball milling are the most effective methods for increasing the volcanic ash activity of electrolytic manganese residues (EMR) and pretreating hazardous substances (NH3-N and Mn2+). In this study, the effects of different calcination temperatures (200, 400, 600, 800, and 1000 °C) and different EMR dosages (10, 15, and 20 %) on the mechanical properties, microscopic properties, and leaching toxicity of mortar were investigated. The results showed that the compressive strength of the prepared mortar mixture at different ages increased by 13.14 % to 24.5 % at a calcination temperature of 800 °C and dosage of 10 % EMR. Microscopic tests were performed to characterise the distribution of ettringite and calcium silicate hydrate gels on the surface of the mixed mortar. X-ray photoelectron spectroscopy and leaching toxicity analysis revealed the presence of EMR in the form of CaSiO3, MnO(OH)2, and M−NH4+. The leaching toxicity of Mn2+ and NH3-N in the EMR-blended mortar was significantly lower than the emission standards. The use of EMR in construction materials assists in resource utilisation and environmental protection.

Cracking of limestone calcined clay blended concrete and mortar under restrained shrinkage

This work is investigating restrained shrinkage induced early age cracking of limestone calcined clay (LC) blended concrete and mortar. A series of ring tests was conducted on LC blended concretes with 44% replacement of General Purpose (GP) cement and reference GP cement-only concretes. In addition, autogenous shrinkage and total shrinkage of concretes, mortars, and pastes were monitored to investigate the effect of the addition of LC on the different shrinkages and subsequent restrained shrinkage induced cracking. Results showed that LC blended concrete cracked earlier than the control mixes due to a high stress rate which is a function of the shrinkage of the restrained concrete ring. However, the autogenous shrinkage of concrete, rather than the total shrinkage, significantly influenced the early age cracking of LC blends. The ratio (total/autogenous) of shrinkage rates was proportional to the time to cracking for all mixes. The dependency of cracking on early-age autogenous shrinkage was further corroborated by the ring test results using LC blended mortar mixes considering various replacement levels ranging from 14% to 59%. Less early-age autogenous shrinkage in the LC blend with 59% replacement contributed to delayed cracking compared to other mortar mixes.

Self-healing of cement mortar with partial replacement of cement with silica fume

Many attempts are being made to use alternative building materials for sustainable construction practices. Huge research work being conducted to identify materials which can be partially replaced by cement. Here we tried to use silica fume & pseudomonas fluorescens as a partial replacement of cement which is having capability of self-healing in cement mortar. Efforts has been made to develop resources with minimal use of fossil fuel based on non-renewable resources which has negative impact on environment. Hence reducing ecological disturbances making biologically efficient. Many industries have been exploring way for variety of bacterial properties to introduce in construction line. Cracks occurring in cement mortar will result into the decrease in its durability property. Hence there is a great demand for effective yet eco-friendly alternative technique for reducing cracks in cement mortar. Reduction of cost can be achieved by bacterial self-healing cement mortar in terms of damage spotting and maintenance of cement mortar. This project presents effect of the bacteria (pseudomonas fluorescens) on strength and durability properties of sustainable cement mortar. Optimized bacterial concentrations of 107 cells/ml and 108 cells/ml were used for designing of mortar mix proportions. Silica fume is added at 5%, 10%, 15%, 20%, and 25% by weight of cement for replacing of cement in the 1:3 cement mortar mix. Compressive strength, split tensile strength and flexural strength tests were performed on mortar cubes at the age of 7 & 28 days. The obtained results are evident that, addition of pseudomonas fluorescens bacteria in mortar mix will enhance the mechanical and durability properties in cement mortar.

Mineralogical, pozzolanic and microscopic characterization of dolomite mine overburden

Waste generated during the cutting and processing of stones is a severe environmental problem. Using waste materials in civil engineering applications is beneficial for sustainable construction practices. The stone industry generates a very high quantity of overburden during mining processes. This overburden is discarded as its composition is not similar to that in the pure state. This study aims to characterize the dolomite mine overburden in its native state. This characterization is based on mineralogical, pozzolanic and microscopic characteristics of dolomite overburden. The mineralogical characterization was done using XRD and XRF analysis. XRD tests showed the presence of dolomite [CaMg(CO3)2] and Silica Oxide (SiO2) in significant compositions. The predominant presence of 30.54 % of Calcium Oxide (CaO), 18.71 % Silica Oxide (SiO2) and 7.6 % of (MgO) was determined by XRF analysis. Frattini and Strength Activity Index (SAI) tests were performed to check the presence of pozzolanic properties in the material. Frattini test results showed the non-pozzolanic/inert nature of overburden. The inert nature of dolomite overburden was confirmed by SAI test results. The modified mix failed to fulfill the criteria of 75 % and 85 % strength of the control mix after 7 and 28 days of curing. The microscopic analysis was carried out by SEM analysis. SEM images showed the irregular shape and rough surface texture of dolomite overburden. The pozzolanic characterization proves that the dolomite mine overburdened can't be used as a cementitious material. Its application can be tested for filler material or as a replacement for coarse/fine aggregates in concrete and mortar mixes. It can also be tested as filler material in bituminous mixes or stabilizing agent in soil stabilization.

Study for the development of flyash and GGBS-based alkali activated foam concrete

This research project focuses on developing sustainable mix proportions for foam concrete with densities ranging from 1200 kg/m3 to 1400 kg/m3, suitable for use as a structural material. To achieve this, the study uses pre-formed foam of a specific density added to the mortar mix, with aluminium oxide powder as a foaming agent and a 12.5 molarity sodium hydroxide solution to densify the foam. To make the foam concrete sustainable, industrial waste products such as ultrafine GGBS and fly ash are added as partial replacements, and the study examines the qualities of the material in both fresh and hardened states by varying the amounts of GGBS, fly ash, and additives used. By examining the air-void-strength relationship of foam concrete with a compressive strength of 5.5 MPa, the study achieves a better understanding of the material's properties and how to achieve greater compressive strength by adjusting the amount of ultrafine GGBS and fly ash in the mix. In conclusion, this research project offers a sustainable solution for foam concrete as a structural material by utilising industrial waste products and exploring the material's qualities in both fresh and hardened states.

The effect of temperature and sulphate attack on ternary blended self-compacting concrete

In this paper, self-compacting concrete was prepared by modifying cement content of the conventional concrete mix. The substantial cementitious materials like fly ash, metakaolin and ground granulated blast furnace slag are used to partially replace the cement. The substitution amount of fly ash, metakaolin are 15%, 5% (fixed) and GGBS is used by 20%, 30% and 40% of cement to get three various SCC mixes. For both M25 and M40 grade concrete followed the same pattern and produced S25A, S25B, S25C, S40A, S40B and S40C. The mechanical properties of concrete like flexural and split tensile strength along with compressive strength at the age of 7, 14, and 28 days for all blends mixes. Specimens were immersed into 5% sodium Sulphate and 5% magnesium Sulphate solutions, and compressive strength was conducted on the specimens at 3, 7 and 28 days. Based on the mechanical properties and sulphate resistance of all the mixes S25C and S40C are selected for the temperature effect on mortar mix related to that concrete. The mortar specimens of S25C and S40C were tested for various elevated temperatures such as 250 °C, 450 °C to 650 °C for a period of 1 h. After that, the specimens were cooled in quenched and air-cooled condition.

RILEM TC 277-LHS report: How hot are hot-lime-mixed mortars? A review

It is believed that many historic mortars were made using hot-lime mixing techniques. They are back in use today, and their good qualities are often praised, including being more compatible and a better match with historic fabrics. This paper studies the methods of producing hot-lime mortars and putties. It discusses the variables that determine the properties of the resultant mortars such as slaking and calcination, and compares hot-lime mortars with their equivalent putties, and with factory-produced calcium lime and hydraulic lime mortars. The paper concludes that the most important variable that governs the properties of hot-lime mixed mortars is the quantity of water used for slaking, because it determines the temperature reached during slaking which makes the resultant Ca(OH)2 vary from a fairly large size to extremely small, hence producing mortars with different properties. Based on scientific and historic evidence, it is concluded that the best method for hot-lime mixing is dry-slaking (sand-slaking) with long storage, because it combines a high slaking temperature (that reduces particle size and increases the surface area of the hydrate), with gradual slaking (that lowers volume expansion and crack development) and long storage (to ensure complete slaking hence no expansion cracks). Many historic mortars were probably hot-lime mixed. However, it is practically impossible to recreate them today due to the different limestones, kilns, calcination regimes and slaking/storage methods used in the past. Hydraulic and magnesian quicklimes were used historically for hot-mixing. In contrast, most of the factory quicklimes used today are purer limes with higher free lime content and a greater reactivity. Therefore, a hot-lime mix made with a factory-produced quicklime may not be more authentic or compatible than a natural hydraulic lime –NHL– mortar designed to suit a specific fabric and application. To ensure quality mortars that can be consistently repeated, a hot-lime mixing specification should contain both the process and the materials including: type of slaking (dry/wet); amount of water used; mixing details and the time at which it takes place; storage time and at what stage does it occur. To control the slaking temperature, the right amount of water should be established (according to free lime content) by trial which will also inform on the amount of yield and hence allow proportioning. With careful site work and specification, high-quality, compatible mortars can be made with both NHLs and hot-lime mixing. However hot-lime mixing requires more time and logistics, closer care and a more complicated specification.

Effects of electric arc furnace slag powder and fly ash within ternary waste blend on performance of concrete

Recently, research on utilising industrial and natural waste has advanced owing to their environmental concerns, including soil and groundwater contamination. Most such waste possess zero or low commercial value, yet it is stored, occupying large storage yards. Iron and steel factories and quarries worldwide produce large amounts of waste annually. This study used three types of steel mill waste (electric arc furnace slag powder, fly ash and steel sludge and natural waste from quarries limestone dust, marble dust, and recycled glass powder) as supplementary cementitious materials with the aim of producing an economical and environmentally friendly ternary waste binder. To determine the appropriate waste blend compounds of mixes, the study was conducted in three stages. First, waste mortars were used to mix, tests of mortars properties were conducted, and the properties of the mix were compared with those of a control mortar mix. Second, concrete was mixed from the waste blend with the most suitable properties. Finally, durability tests on the concrete were performed. Ternary residue having 4.5% SP, 10% FA, and 4.5% SS with 18% replacement of cement and that having 3.75% SP, 7.5% FA, and 3.75% LD with 15% replacement of cement achieved the requirements of concrete and improved the compressive strength and durability towards sulfate and chloride attack, including impermeability and resistance.

Alkali-activated slag & fly ash as sustainable alternatives to OPC: Sorptivity and strength development characteristics of mortar

One approach to decreasing the environmental footprint of the construction industry is to replace ordinary Portland cement (OPC) with recycled slag and fly ash activated using alkaline materials. This article presents the outcomes of an experimental study that evaluated water absorption characteristics and strength development of mortar that uses blends of alkali-activated ASTM class F slag and fly ash binders. Mortar mixes were developed using three binder combinations: 100% slag and no fly ash (S1F0), 75% slag + 25% fly ash (S3F1), and 50% slag + 50% fly ash (S1F1). Slag and fly ash binders were activated using NaOH solution with molarity ranging from 10 mol/L to 16 mol/L mixed with sodium silicate solution. Two sets of samples were created, one set was immersed in an acidic medium after casting, which represented a closed environment, and the second was left in the lab exposed to air until the test day. For mortar cured in a closed system, the highest strength development during the first seven days after casting occurred in S1F0 mortar followed by S3F1, then S1F1. The observation indicates strength development is dominated by the fast reactivity of slag during the first 7 days. The pattern is similar for all NaOH activator concentrations evaluated in this study. Mortar samples with high slag content (S1F0 and S3F1) that were cured in air experienced a decrease in strength during the 28–90 day curing phase as the strength at the age of 90 days decreased relative to the strength at 28 days. However, S1F1 gained strength during the 28–90 day phase when NaOH molarity was the highest (16 mol/L). This is due to the dissolution and activation of fly ash at high solution alkalinity which contributed to the continued increase in strength. A strong linear correlation between the square root of time (t0.5) and water absorption existed in all activated mortars evaluated in the study, except for mortar samples prepared using NaOH with high concentration and the highest ratio of Na2SiO3/NaOH. Therefore, alkali-activated slag-based mortars share similar water capillary absorption characteristics with conventional cement-based mortar. It was found that increasing the NaOH concentration increases the global warming potential (gwp) and that the mix with the least environmental impact was the S1F1 developed using the lowest NaOH concentration of 10 mol/L and 50% fly ash.

Study on the effect of plant extracts as low carbon green admixtures on the performance of cement mortar

The pollution of the environment by chemical admixtures for cement and concrete and the carbon emission in the production of cement and other concrete raw materials have attracted increasing attention from scholars. In order to improve the physical and mechanical properties of cement, eliminate pollution and reduce carbon emission, this paper uses natural plant extracts (cactus sativus extract and mulberry leaf extract) as admixtures to make cement mortar. The consistency, water absorption, compressive strength, flexural strength, chloride ion penetration resistance and microstructure of the mortar were tested and analyzed, the effects of different admixtures of natural plant extracts on the physical and mechanical properties of cement mortar were investigated. The results show that the consistency of the cement mortar was increasing with the increase of the admixture of cactus sativus extract and mulberry leaf extract; the admixture of cactus sativus extract and mulberry leaf extract did not change the hydration reaction and hydration products. When the admixture amount was lower, the extracts could promote the hydration reaction, improve the internal crystal morphology and generate more C-S-H, thus improving the physical and mechanical properties of cement mortar. The physical and mechanical properties of the cement mortar were optimized when the amount of mulberry leaf extract was 0.15% of the cement mass, and the overall performance was improved more compared with that of cactus extract. With the increase of amount of admixture, the viscosity of the system increases due to plant extracts, and the air bubbles formed during mortar mixing cannot be discharged and form micro-pores inside, resulting in the reduction of physical and mechanical properties. As a low carbon green admixture, plant extract is worthy of further research and promotion.

Use of high ductile mortar mixing method for the enhancement of flexural fracture behaviour of steel filler mortar

The use of steel fillers enhances the flexural behaviour of mortar and concrete. However, it makes it more difficult to disperse them uniformly and coat them firmly in the mortar/concrete with the conventional mixing method while using them at higher content. In this method, steel fillers are generally mixed after the mixing of mortar with a full part of water. In the high ductile mortar mixing method, the viscous mortar was first prepared with the first part of the water and then the steel fillers were mixed. Its workability was increased in the final stage of mixing with the second part of the water. The mixture proportion of the base mortar was similar to that used for the production of the permanent formwork (W/C = 30% and W = 206 kg/m3). The content of steel filler (0, 1.5%, and 2.5%) was by volume of the mortar and it was used as part of the sand. The distribution and coating condition of steel filler was better in the second mixing method. It was made possible due to the strong kneading and lapping action within the viscous mortar. The flexural strength was increased by 28.7% with less variation. It was a 241% increase from that of plain mortar and only a 165% increase was with the conventional mixing method. The high ductile mortar mixing method enhanced the flexural strength, deflection, rigidity, flexural performance, and fracture energy of steel filler mortar more than that of the conventional mixing method. This result contributes to reducing the thickness of permanent steel filler mortar formwork as well as of other structures enabling easier transportation and erection work. Moreover, it also helps to reduce the overall cost of the steel filler mortar structures.

Characterization of Ceramic and Concrete Wastes from CDW as Secondary Raw Materials for Mortar Applications

The construction sector uses high quantities of raw materials and consequently the demolition sector generates huge amounts of waste. Envisioning the future of the construction sector, new Circular Economy Business Models should be implemented to contribute to the development of the sector. These Business Models will be based on innovative recycling techniques able to provide the technical requirements of the construction materials. This work aims to valorize ceramic and concrete wastes as aggregates for the mortar manufacturing. The chemical composition of these materials with high proportion of silica and very low quantities of sulfates makes them appropriate for their application. The wastes were previously crushed to the required particle size (6mm). The crushed ceramic waste presents an important fines proportion, which will increase the water consumption in the mortar mixes.