Self-leveling Mortar Research Articles

Effect of phosphorus impurities on sulfoaluminate cement-modified gypsum-based self-leveling mortar and improvement method

The preparation of gypsum-based self-leveling mortar (GSLM) from solid waste-derived sulfoaluminate cement-modified hemihydrate gypsum is an effective path to enhance its mechanical properties. However, the phosphorus impurities in phosphogypsum (PG) still pose a challenge to the hemihydrate gypsum & sulfoaluminate cement composite system. To evaluate the impact of phosphorus impurities and develop targeted removal strategies, this study first assessed the effects of different types of phosphorus impurities on the mechanical properties and hydration characteristics of the GSLM. Then, a method of pretreating PG with carbide slag (CS) was proposed, and the removal efficiency and mechanism of phosphorus were examined by ICP-OES and XPS testing. The results indicated that the soluble phosphorus impurities severely inhibit the hydration of both CŜH0.5 and C4A3Ŝ, leading to a most notable reduced mechanical performance. The sequence of inhibitory action was as follows: H3PO4 >> Ca(H2PO4)2·H2O > CaHPO4·2H2O > Ca3(PO4)2. CS could effectively immobilize the soluble phosphorus in PG. The pretreatment by CS notably enhanced the hydration degree of the GSLM by converting soluble phosphorus into Ca3(PO4)2 beforehand. In addition, the alkaline environment provided by CS promoted the ettringite formation. When the CS content approaches 3%, a PG-based GSLM with good performances meeting the G20 standard requirements of GSLM can be prepared.

A Study on the Performance of Self-Leveling Mortar Utilizing Tungsten Tailings as the Aggregate

A significant quantity of tailings is produced during the development of different metal mines in China. In particular, fine-grained tailings pose challenges to the sustainable development of the mining industry. This study examines the utilization of finely ground tungsten tailings as a replacement for natural aggregates in self-leveling mortar (SLM). The study examined the impact of the aggregate-cement ratio, cement mix ratio, and varying substitution levels of different grain sizes of tungsten tailings on the flow properties, mechanical properties, and dimensional change rate of SLM. Additionally, the role of tungsten tailings in SLM was analyzed using XRD, FTIR, and SEM methods. The findings demonstrated that the utilization of sulphoaluminate cement (SAC) had a notable impact on improving the initial strength of the SLM. Additionally, a high aggregate-cement ratio negatively affected the fluidity of the SLM. The doping of tungsten tailings improved the grading relationship of the SLM. Substituting tungsten tailings of 38–75 μm grain size for natural aggregates in the preparation of SLM did not have a negative impact on its performance. In fact, substituting 60% tungsten tailings had a positive effect on the 28-day mechanical properties of the SLM. The compressive and flexural strengths of the SLM after 28 days were 26.53 MPa and 9.06 MPa, respectively, which were enhanced by 18.81% and 26% compared to the control group (C0). According to the environmental leaching test, SLM can effectively fix the heavy metal ions in tungsten tailings, and the leaching concentration of heavy metals is significantly reduced after long-term curing. The doping of finely fragmented tungsten tailings accelerated the process of hydration, resulting in the creation of hydrocalcium zeolite crystals in the latter phases of hydration. Furthermore, an increase in tailings substitution resulted in the production of a greater amount of hydration products, specifically C-S-H gels.

Effect of Mineral Admixtures on Physical, Mechanical, and Microstructural Properties of Flue Gas Desulfurization Gypsum-Based Self-Leveling Mortar.

The production of flue gas desulfurization gypsum poses a serious threat to the environment. Thus, utilizing gypsum-based self-leveling mortar (GSLM) stands out as a promising and effective approach to address the issue. β-hemihydrate gypsum, cement, polycarboxylate superplasticizer, hydroxypropyl methyl cellulose ether (HPMC), retarder, and defoamer were used to prepare GSLM. The impact of mineral admixtures (steel slag (SS), silica fume (SF), and fly ash (FA)) on the physical, mechanical, and microstructural properties of GSLM was examined through hydration heat, X-ray diffractometry (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) analyses. The GSLM benchmark mix ratio was determined as follows: 94% of desulfurization building gypsum, 6% of cement, 0.638% each of water reducer and retarder, 0.085% each of HPMC and defoamer (calculated additive ratio relative to gypsum), and 0.54 water-to-cement ratio. Although the initial fluidity decreased in the GSLM slurry with silica fume, there was minimal change in 30 min fluidity. Notably, at an SS content of 16%, the GSLM exhibited optimal flexural strength (6.6 MPa) and compressive strength (20.4 MPa). Hydration heat, XRD, and Raman analyses revealed that a small portion of SS actively participated in the hydration reaction, while the remaining SS served as a filler.

DEVELOPMENT OF A SELF-LEVELING FLY ASH-SLAG GEOPOLYMER MORTAR

Exponential growth in the world population and increase in demand for concrete are pressing researchers and scientists to find sustainable alternative materials for Portland cement and natural aggregates. Self-leveling mortar is extensively used in construction applications, such as floor leveling, repair, resurfacing, or adhesion. Yet, limited research has been carried out on enhancing this material’s sustainability. This paper aims to produce a geopolymer mortar produced with fly-ash (FA), ground granulated blast furnace slag (BFS), and desert dune sand. Geopolymer mortar samples were produced with different binder-to-sand (B:S), FA-to-slag (FA:BFS), and alkali-activator solution-to-binder (AAS/B) ratios. Alkaline solution was blended with sodium silicate and sodium hydroxide with a molarity of 8 M (ratio of 1.5). Fresh and hardened properties of the developed self-leveling mortars were assessed. Experimental results showed that the flow, initial and final setting time, and 7-and 14-day compressive strength were in respective ranges of 17.3-40.3 cm, 21-155 minutes, 42-221 minutes, 6.0-70.3 MPa, and 5.2-78.7 MPa. Furthermore, an increase in FA:BFS, B:S, and AAS/B ratios enhanced flowability and prolonged setting time but reduced compressive strength at both ages. These research findings advocate the use of a self-leveling, cement-free geopolymer mortar to be utilized in various buildings and repair applications.

DEVELOPMENT OF A SELF-LEVELING FLY ASH-SLAG GEOPOLYMER MORTAR

Exponential growth in the world population and increase in demand for concrete are pressing researchers and scientists to find sustainable alternative materials for Portland cement and natural aggregates. Self-leveling mortar is extensively used in construction applications, such as floor leveling, repair, resurfacing, or adhesion. Yet, limited research has been carried out on enhancing this material’s sustainability. This paper aims to produce a geopolymer mortar produced with fly-ash (FA), ground granulated blast furnace slag (BFS), and desert dune sand. Geopolymer mortar samples were produced with different binder-to-sand (B:S), FA-to-slag (FA:BFS), and alkali-activator solution-to-binder (AAS/B) ratios. Alkaline solution was blended with sodium silicate and sodium hydroxide with a molarity of 8 M (ratio of 1.5). Fresh and hardened properties of the developed self-leveling mortars were assessed. Experimental results showed that the flow, initial and final setting time, and 7-and 14-day compressive strength were in respective ranges of 17.3-40.3 cm, 21-155 minutes, 42-221 minutes, 6.0-70.3 MPa, and 5.2-78.7 MPa. Furthermore, an increase in FA:BFS, B:S, and AAS/B ratios enhanced flowability and prolonged setting time but reduced compressive strength at both ages. These research findings advocate the use of a self-leveling, cement-free geopolymer mortar to be utilized in various buildings and repair applications.

High value-added utilization of desulfurized building gypsum as self-leveling mortar: the comprehensive effect of cement.

The utilization of desulfurized building gypsum as raw material for gypsum-based self-leveling mortar (GSL) is limited by its low strength and poor water resistance. The objective of this study is to enhance comprehensive properties of GSL and prepare qualified desulfurized building gypsum-based self-leveling mortar that can be effectively applied in practical engineering projects. The influence of cement on water consumption rate of initial fluidity (W/M ratio), fluidity, setting time, mechanical strength, and water resistance of GSL were evaluated. Additionally, rheological parameter, heat of hydration, crystal morphology, and pore structure were also analyzed. Cement significantly improved the fluidity of slurry. Moreover, the compressive strength and softening coefficient of GSL reached 20.6MPa and 0.56 at 10% cement, respectively. Furthermore, cement reduced the 30-min-fluidity loss and improved fludity by reducing the yield stress and increasing the plastic viscosity of screed. The transformation of hydration kinetics of GSL could be due to Ca2+ and OH- released by cement, thus resulting in the shortening of initial setting time and the prolongation of the interval between initial and final setting time. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) showed that CSH gel and AFt crystal would generate on the surface of CaSO4·2H2O crystal, making the structure more compact. Mercury intrusion porosimetry (MIP) indicated that cement greatly reduced the porosity through the water reduction effect in the early stage and continuous hydration in the later stage. The continuous hydration of cement also increased the shrinkage rate. This work was expected to provide reference for promoting the application of desulfurized building gypsum as the high value-added screed.

Red mud modified phosphogypsum based self-leveling mortar: Hydration mechanism, heavy metal migration law and spatial distribution characteristics

In the production processes of phosphoric acid and alumina, chemical enterprises generate solid waste such as red mud (RM), phosphogypsum (PG), and fly ash (FA). The environmentally friendly utilization of these waste materials is of crucial significance. Therefore, this study focuses on investigating the impact of collaborative modification using diverse solid wastes on the macroscopic properties and internal microstructure of self-leveling mortar. Through a careful selection process, the optimal ratio for red mud and phosphogypsum self-leveling mortar(RPSM) has been identified during the research. This study not only provides substantial support for the effective utilization of solid waste but also contributes to the improvement of overall performance and structural characteristics of the mortar. Based on this, the hydration characteristics, leaching patterns, and spatial distribution characteristics of heavy metals in RPSM were evaluated. The research revealed that the optimal ratios of RM, PG, FA, PC, river sand, and heavy calcium carbonate powder in RPSM were 20.7%, 13.8%, 17.1%, 13.8%, 17.3%, and 17.3%, respectively. Under a water-binder ratio of 0.18, the flexural and compressive strength of the mortar specimens after 14 d of curing can reach 4.3 and 31.6 MPa. Through comprehensive analysis and discussion of the performance, microstructure, and dynamics of the hydration process of RPSM, the main processes of mortar hydration were elucidated. Environmental risk assessments indicated no environmental risks from heavy metals in RPSM. Human health risk assessment suggested carcinogenic risks from Cr and Cd in RPSM through oral exposure, leading to restrictions on the content of characteristic heavy metals in different application scenarios. Furthermore, fitting results of the release kinetics of heavy metals indicated that the leaching of heavy metals in RPSM can be well fitted with kinetic models, allowing the determination of the optimal safe age of RPSM containing harmful heavy metals. Finally, using interpolation and vertical distribution simulation by software such as ArcGIS, the spatial distribution characteristics of heavy metals in RPSM during use were analyzed. The research can supply fundamental academic support for the recycling of solid wastes like RM and the control of environmental risks associated with heavy metal leaching in building materials.

Modification mechanism, heavy metal coupling and ecological security risk assessment of phosphogypsum utilization in self-leveling mortar

Few researches on high efficiency modified phosphogypsum (MPG) and its resource utilization in bulding materials. This article investigated the effects of different lower temperatures and drying times on the thermodynamic modification mechanism of macroscopic performance and microscopic structure of MPG, and investigates its application in phosphogypsum-based self-leveling mortars (PBSLM). Then, the coupling mechanism of characteristic heavy metals in the modification process (original-modification-hydration) was discussed, and the safety evaluation was conducted on the content of heavy metal elements in the sample. Data from microscopic analysis showed that with the increase of temperature and drying time, the strength of MPG blocks and the decomposition rate of dihydrate gypsum crystal both increased, while the particle size decreased. The degree of crystal decomposition becomes more complete as the temperature rises if the holding time remains constant. As well as, the MPG at 180 °C/7 h, 195 °C/7 h/10 h met the Chinese standard of “Calcined gypsum” (GB/T9776). The heavy metal elements in MPG decreased obviously, caused by the substitution solid solution formed by Ca2+ and Fe3+ and heavy metal ions and the adsorption of calcium sulfate hemihydrate crystals. After hydration of MPG, As and Cd increased slightly because dicalcium phosphate was insoluble in water and soluble in acid, and iron oxide reduced and dissolved Cd. Then, the ecological hazards of heavy metals in hydrated MPG after hydration were evaluated. The results showed that there was no environmental safety problem in the hydrated MPG, but the As and Cr elements in it had an acceptable carcinogenic risk through oral intake. Based on ensuring the safety of MPG, MPG powder was used in PBSLM. The research demonstrates that the basic mechanical properties of the PBSLM produced, when the MPG powder content is 330 g, and cement is 40 g are the best. The heavy metal aqueous solution's leaching amount is lower than China's national standard limit value. (30min fluidity, 24 h-flexural and compressive strength were 154 mm, 5.7 MPa and 10.6 MPa). Finally, based on this research, a set of general evaluation system for safe utilization of solid waste was established according to national standards. This provides theoretical support for the research of heavy metal in PG at low temperature and the ways of harmless and resource utilization.

Reuse of by-product gypsum with solid wastes-derived sulfoaluminate cement modification for the preparation of self-leveling mortar and influence mechanism of H3PO4

Preparing beta-hemihydrate gypsum and then using it for gypsum-based self-leveling mortar (GSLM) in building engineering is one of the promising approaches to consume by-product gypsum such as flue gas desulfurization gypsum and phosphogypsum. In order to overcome the deficiencies of low mechanical strengths and large fluidity loss of beta-hemihydrate gypsum, solid wastes-derived sulfoaluminate cement (WSAC) was used to modify beta-hemihydrate gypsum and prepare GSLM in this work. The effects of various additives on the fluidity and setting characteristics of GSLM prepared using WSAC-modified beta-hemihydrate flue gas desulfurization gypsum was firstly studied, and an optimal formula was obtained. The WSAC-enhanced GSLM had good mechanical performance due to the well-connected structure of the hydration products gypsum and ettringite. However, the hydration speed and degree of GSLM prepared using WSAC-modified beta-hemihydrate phosphogypsum were seriously weakened by phosphorus impurities, which resulted in poor mechanical performance. PO43- would react with Ca2+ and Al3+ dissolved from ye'elimite in WSAC to form CaHPO4·2H2O and AlPO4 precipitates, which seriously inhibited ettringite formation. This negative effect was found mainly acting on the hydration of WSAC and could last until later hydration.

Effect of limestone powder on properties of self-leveling mortar

Mixing limestone powder (LP) in the self-leveling mortar (SLM) can not only solve the problems of LP waste randomly piled up and secondary utilization of resources, but also reduce the raw material cost of SLM and have excellent mechanical properties. The effect of replacing fly ash (FA) with LP and replacing cement with LP after completely replacing FA on fluidity and strength of SLM are studied. The microstructure of SLM is measured by mercury intrusion porosimetry and scanning electron microscope. The results show that the initial fluidity and the 20-min fluidity of SLM decrease gradually with the increase of LP content. The strength of SLM increases and then decreases with the increase of LP replacing FA, and the strength is the highest when the addition of LP is 40%. When LP replaces cement after completely replacing FA, the strength of SLM decreases with the increase of displacement. Excessive LP can greatly damage the mechanical properties of SLM. The appropriate content of LP can improve the microstructure of SLM and promote the formation of hydration products, which is helpful to reduce the porosity and thus improves the structure density. This may be due to the chemical reaction and the microfiller effect of LP.

Effect of Chemical Admixtures on the Working Performance and Mechanical Properties of Cement-Based Self-Leveling Mortar

In this work, the effect of cellulose ether (CE), tartaric acid (TA), and polycarboxylate superplasticizer (PCE) on the working performance and mechanical properties of cement-based self-leveling mortar is investigated. According to the orthogonal experiment analysis, TA is identified as the most influential factor affecting the working performance, as indicated by factors such as fluidity, fluidity loss, and viscosity. Upon conducting a comprehensive assessment of the working performance and mechanical properties, the optimal parameters are found to be CE = 0.6 wt.‰, TA = 0.5 wt.‰, and PCE = 2.0 wt.‰. A univariate test highlights that that the working performance improves with the higher TA dosages. Specifically, the exponential reduction of fluidity loss corresponds with an increased TA content. Regarding the mechanical properties of cement-based self-leveling mortar, the compressive and flexural strength exhibit enhancement when the TA dosage remains below 0.4 wt.‰ at the early stage, implying that TA has some influence on the hydration process. Impressively, the 1 d compressive and flexural strengths surpass 7 MPa and 2 MPa, respectively, ensuring the viability of subsequent construction activities. Through an analysis of hydration heat, the effect mechanism of TA on the cement-based self-leveling mortar is derived. The result shows that the addition of TA decelerates the hydration process within the initial 10 h, followed by acceleration in the subsequent 20 h to 30 h. Consequently, this delayed formation of the early hydration product, ettringite, contributes to a more porous structure in the slurry, with low friction leading to a better working performance. A large number of hydration products, such as alumina gel and calcium–silicon–hydrate gel, presented in the hardened paste results in the good mechanical properties at 1 d. This study may lay a foundation for the optimization of the dosage of chemical admixtures in the self-leveling mortar and high-performance cement-based materials, and also impart valuable insights for practical applications extending to the realm of building construction and decoration.

Improving industrial drying process of recycled fine aggregates as a means of carbonation to improve the mechanical properties and plastic shrinkage of self-leveling mortar

Industrial drying and carbonation of recycled fine aggregates (RFA) is a highly efficient carbonation method, in which the high temperature and carbon sources generated by drying are utilized to improve the quality of RFA and reduce CO2 emissions. However, there are deficiency analyses in the terms of temperature control and the replenishment of moisture or CO2, during drying process, resulting in the barrier of industrialization application. In this study, physical and mechanical properties of RFA before and after accelerated carbonation treatment were tested and evaluated in different high-temperature drying environments. The results showed that under drying and carbonation at 100 °C, the RFA treated for 2 h demonstrate the best carbonation rate, with three times higher than that of the standard accelerated carbonation. Furthermore, mortars consisted of carbonated recycled fine aggregates (CRFA) show significant improvement in both mechanical properties (compressive and flexural strength increased by 69% and 31%, respectively) and workability. The relationship between physical properties and the performance has been actively explored. The linear relationship between the properties of the fine aggregate and the mortar’s impedance parameters and compressive strength is evident. Noted that, this study proposes an innovative method for industrial drying and carbonating recycled fine aggregates.

Study on the influence mechanism of water reducing agent on the properties of anhydrite-based self-leveling mortar

Gypsum-based self-leveling has been widely used for its good construction performance and economy. This paper investigated the influence mechanisms of three kinds of water-reducing agents (WRAs) on the properties of anhydrite-based self-leveling floor screeds (ASLF) through macroscopic performance characterization, rheological model fitting, TG-DSC, MIP, SEM, et al. The outcomes conducted that the types, densities, and lengths of the side chain groups of the WRAs had diverse effects on the hardening, rheological parameters, and crystal morphology of ASLF. In descending order, the influence was PCE > SMF > SNF. The anionic groups of PCE affected the crystal growth by adsorbing on the dominant surface of CaSO4·2H2O and reducing the crystal length-diameter ratio. Simultaneously, with the increase of PCE content, the steric resistance effect increased, and the thickness of the surface water film layer increased, resulting in a decrease in the final viscosity and yield strength. ASLF is a power-law fluid that fits the Hershel-Bulkle (H-B) model well. Compared with PCE, the hydration and hardening characteristics of ASLF mixed with SMF and SNF were similar, and the influence was smaller, but a larger amount was required to ensure flowability. The pore size distribution of ASLF-hardened bodies mixed with various superplasticizers was similar. The hardening properties of ASLF were investigated using a variety of methods in this study. Various types of WRAs were investigated for their effects on the hydration and hardening of anhydrite, providing important reference information for ASLF preparation and production.

Producing a gypsum-based self-leveling mortar for subfloor modified by polycarboxylate admixture (PCE)

Self-leveling mortar is a layer applied on a surface without the need for thickening. This type of mortar has large fluidity and is often cement-based, with low productivity. The production of a self-leveling gypsum-based mortar provides shorter execution times, as well as better thermal and acoustic properties and eliminates the need for expansion joints in large areas. This article aims to develop a gypsum-based mortar with self-leveling properties for application in the subfloor layer. In this sense, water/gypsum ratios of 0.45, 0.475, and 0.5 were used, in addition to plaster/sand ratios of 1:1 and 1:0.5 for each consistency. The content of superplasticizer additive (PCE) was adjusted to consistency suitable for self-leveling through the fluidity test. The set of mortars were characterized by considering tests of fluidity, enthalpy of hydration, setting times, compressive and flexural strength, and experiments of scanning electron microscopy (SEM). The results revealed that the PCE increased the setting times, reduced the water content, and modified the crystalline structure of the dihydrate. Finally, the mortar with water/gypsum ratio of 0.5, gypsum/sand ratio 1: 0.5 and 1% PCE presented satisfactory properties, with the exception of setting times.

Porcelain waste from electrical insulators in self-leveling mortar: Materials characterization and properties

The addition of waste in building materials is a technical and economical alternative for modern construction. Self-leveling mortar (SLM) is a material used in floors because it is able to flow and fill a base area without using extra energy. The present studied SLMs using porcelain insulator waste (PIW) as partial and total sand replacement. Different methods were used to characterize the PIW (e.g. X-ray fluorescence, X-ray diffraction (XRD), and pozzolanic activity index) and tests were made in SLMs in fresh and hardened states. XRD results revealed that PIW presented pozzolanic characteristics and increased the compressive strength of mortars. Tests also not verified alkali-aggregate reaction (AAR) when PIW was added. SLMs containing PIW presented compressive and flexural strengths of 24.11 MPa and 7.07 MPa, respectively. The spread diameter reached values found in the literature.

The Properties and Durability of Self-Leveling and Thixotropic Mortars with Recycled Sand

In recent decades, relevant environmental and economic reasons have driven an increasing interest in using a large amount of recycled aggregate in replacement of natural ones to produce mortar and concrete. The present study aims to investigate the effect of substituting 100% of natural sand with recycled aggregate on fresh properties, mechanical properties, and the durability of a thixotropic and a self-leveling mortar. Recycled aggregate was characterized using X-ray diffractometry and energy-dispersive X-ray spectroscopy. Its morphology was investigated using scanning electron microscopy and automated morphological imaging. Recycled aggregate mortars showed a moderate decline in initial workability, as well as higher shrinkage and porosity than the control ones. The compressive strength of self-leveling mortars produced with recycled aggregate was only 6% lower than mortars produced with natural sand. The gap increased to 40% in the case of thixotropic mortars. The self-leveling recycled aggregate mortar showed equivalent resistance to freeze–thaw cycles and better sulfate resistance than the control one. The thixotropic recycled aggregate mortar showed comparable sulphate resistance and only slightly lower resistance to freeze–thaw cycles than the control one. Their capacity to relief stresses, due to hydraulic pressures and the formation of expansive products, arises from their higher porosity. Thermal stability of the prepared mortars, after a curing period of 90 days, up to 700 °C, was also investigated. A significant decrease in ultrasonic pulse velocity is observed in the 200–400 °C interval for all the mortars, due to the dehydration–dehydroxylation of calcium silicate hydrate. The overall decline in the strength of both the recycled aggregate mortars was comparable to the control ones. The results reported in the present investigation suggest that the selection of high-quality recycled aggregate helps to obtain good-quality mortars when a large amount of natural sand is replaced.

Preparation of Self-leveling Mortar Based on Anhydrite-II Phosphogypsum

The construction material from anhydrite-II phosphogypsum is dense in structure and has good water resistance. But its disadvantages are low hydration activity and long setting time. In this work, anhydrite-II phosphogypsum is modified by adding a composite activator, which is made of sulfuric acid modified steel slag, β-hemihydrate gypsum and calcium aluminate cement. With this, the hydration rate of anhydrite-II phosphogypsum is clearly increased and setting time shortened. The performance of self leveling mortar prepared is as per JC/T 1023-2021, with softening coefficient of 0.8.

Ternary system Portland cement-calcium aluminate cement-calcium sulfate applied to self-leveling mortar: a literature review

The modernization of building systems is increasingly demanding products that improve efficiency during their processing. The development of self-leveling mortars for the regularization of flooring is a consequence of this evolution. The high contents of binder and water to obtain self-flowing property, plus the application of thin layers over large areas, make this type of mortar susceptible to high shrinkage levels. Thus, the ternary system Portland cement-calcium aluminate cement-calcium sulfate (OPC-CAC-CaSO4) is a viable solution for shrinkage compensation. The expansion mechanism based on ettringite formation aims to prevent the mortar from cracking. Considering its complexity and that international literature is still limited (while Brazilian is null), this article presents a literature review that covers diverse aspects related to the application of the system OPC-CAC-CaSO4. The influence of raw materials and mix proportions on rheological behavior, reaction kinetics, development of strength, and length change are discussed.

Influence of Redispersible Powder on Properties of Self-Leveling Mortar of Ternary Cementitious System.

The self-leveling mortar (SLM) of a ternary cementitious system with different dosages of redispersible powder (RP) with ordinary Portland cement (OPC), sulfoaluminate cement (SAC), and calcium sulfate (CS) as cementitious materials was investigated with regard to fluidity, bond strength, shrinkage rate, abrasion resistance, flexural strength, and compressive strength. The performance parameters obtained from the experimental test for SLM were weighted values calculated with an analytic hierarchy process (AHP). The comprehensive index of performance was evaluated on the basis of a weighted-sum method, and the optimal dosage of RP was determined according to the comprehensive index. The experimental results demonstrated that the fluidity of SLM decreased with the increase in RP dosage at the beginning but then increased thereafter and decreased rapidly as the dosage went beyond 3.0%. The addition of RP resulted in a significant improvement in bond strength (of SLM), reduction in the shrinkage rate, abrasion loss, early flexural strength and compressive strength, and resistance to cracking. The properties of SLM with 3.0% RP can meet the requirements of the industrial standard for cementitious self-leveling floor mortar. Compared with the SLM without RP, the bond strength of SLM with 3.0% RP was increased by 46.7%, while the shrinkage rate and abrasion loss were reduced by 50% and 71.9% respectively. The weighted values of fluidity, compressive strength, flexural strength, stability, cohesiveness, and abrasion resistance were 0.422, 0.196, 0.196, 0.089, 0.058, and 0.039, respectively. A higher value of the comprehensive index generally denotes a better performance. The comprehensive index of SLM with 3.0% RP was the highest.

Properties of self-leveling mortars incorporating a high-volume of sugar cane bagasse ash as partial Portland cement replacement

Self-leveling mortar (SLM) is a special mortar that can flow and fill under its own weight without the need for any compaction energy. To meet these characteristics and to ensure their stability (no segregation and exudation) these mortars require, in addition to proper mixing design and the use of water reducing assets, a large quantity of fines or viscosity modifying additives, which raises the cost for the production. The use of industrial by products such as sugar-cane bagasse ash (SCBA) is an interesting alternative because they are lower cost materials and act as viscosity modifying agent, providing improvements in the rheological, physical and mechanical properties for SLM. Thus, the influence of SCBA on the rheological, physical and mechanical properties of cement-based and limestone filler (LF) mortars will be investigate in this research. The mortars were produced with a water/binder (cement + LF + SCBA) volumetric ratio of 0.85 and 15%, 20%, 25% and 30% Portland cement (PC) replacement by SCBA. An experimental study was conducted to evaluate the effects of SCBA incorporation on the properties of fresh (viscosity, flowability and filling ability) and hardened mortars (flexural strength, compressive strength, dynamic modulus of elasticity, bond strength and water absorption by capillarity). The results show that the rheological, physical and mechanical behavior of mortars was improved, especially for contents of up to 25% replacement of PC by SCBA. For higher contents, the performance of SLM was reduced.