Behavior Of Cement Mortar Research Articles

Thermal and structural properties of cement mortar embedded with hybrid nanocomposite based phase change nanocapsules for building application

A novel Cu-TiO2 Hybrid Nanocomposites adsorbed Nanoencapsulated Phase Change Material (HNNP) was developed. The current research work aims to develop PCM-based cement mortar used as plastering material with increased Energy Utilization Efficiency. The work addresses the poor thermal conductivity of the polymer based shell material (melamine) by adsorbing Cu-TiO2 hybrid nanocomposites on the nanocapsule (HN). The HNNP capsules are capable of freezing and melting at a temperature of 24.02 °C and 25.76 °C, with latent heat of 146.71 J/g and 144.46 J/g respectively. The phase change temperatures of HNNP are in the human comfort temperature zone. The adsorption of HN over nanoencapsulated PCM (NP) has greatly enhanced the thermal conductivity by 137.19% over NP. The HNNP exhibited excellent thermal stability and thermal reliability. Furthermore, the behaviour of the cement mortar in terms of thermal conductivity and compressive strength was studied by dispersing NP and the HNNP capsules. The maximum inclusion of HNNP in the cement mortar greatly enhanced its thermal conductivity, whereas the behaviour of cement mortar with NP inclusion, was contrary, resulting in reduced thermal conductivity. The compressive strength was reduced with the increased percentage of both NP and HNNP capsules in the cement mortar. Albeit, the compressive strength was reduced due to the maximum inclusion of NP and HNNP in the cement mortar, the resulted compressive strength is acceptable for plastering material. From the above stated results, the HNNP is a viable candidate, having a great potential for cooling needs in buildings.

Microstructure tests, flow, and mechanical behavior of polymerized cement mortar

The influence of two types of polymeric admixture on the stress–strain (σ-ε) behavior of cement mortar is discussed in this article. The characteristics of cement mortars modified with two types of polymeric admixtures containing 0.20 percent (% wt.) were investigated. For early age (1 day) and 28-day curing periods, the σ-ε behavior of modified cement mortar with polymeric admixtures was investigated. Depending on the polymeric structure and content, adding polymeric admixture reduced the water/cement ratio (w/c) by 14.5 to 25.5 %. When 0.20 % of polymeric admixture was added to cement mortar, the compression strength improved by 72 % to 153 %. The cement mortar samples became brittle as the polymeric admixtures content increased. The amorphous gel fills the spaces between cement particles and sand particles, decreasing voids and porosity and improving the density of the cement mortar. To forecast the connection of the modified cement mortar with polymer, the nonlinear Vipulanandan p-q equation was used, and it was compared to the Farazdaghi- Harris-YD and Sinusoidal models. The compressive stress–strain models were evaluated using statistical methods, and nonlinear approaches were utilized to predict compressive strength as a function of water/cement ratio, curing age, and polymer quantity. The less complicated model, the Vipulanandan p-q model, already has a smaller sum of squares than the other two models. Therefore, the Vipulanandan p-q model is the best one.

Influence of Taheri Consciousness Bond Field on the Crystallization and Strength of Cement Mortar (Concrete)

In this study, the behavior of cement mortar under the Consciousness Bond Field was investigated. Taheri Consciousness Fields (TCFs) were founded and introduced by Mohammad Ali Taheri as new Fields more than four decades ago. These Fields are neither material nor energetic. Therefore, they do not have the quantity, but they have direct effects on both matter and energy. In other words, although TCFs cannot be directly measured, we can investigate their effects indirectly through various reproducible experiments. In all tests of this research, type II cement and standard sand were used. The samples preparation and their strength measurement were done under the ISIR 393 standard, and each group includes 3 prism samples. Three series of experiments were performed with a number of different groups, in each series one group was as control and the others were under Consciousness Bond Field. Series 1 included five groups of cement sand mortar. Compressive and flexural strengths were measured at 7, 28, and 42 days of age. Series 2 included four groups of cement sand mortar which were measured at 7, 28, and 42 days of age. Series 3 included four groups of cement sand mortar made exactly according to the above-said condition. And strength was measured at 7, 28, 42, and 90 days of age. Due to the results received from FT-IR (Fourier-transform infrared spectroscopy), SEM (Scanning electron microscopy), XRF (X-Ray Fluorescence), and XRD (X-ray Diffraction), the growth trend of the strength of the samples under the Consciousness Bond Field were more significant than the control samples. The results of other analyzes showed that the abundance of chemical compounds containing calcium (CaCO3 from 20 to 80% and Ca3SiO5 from 25 to 75%) in the samples under the Consciousness Bond Field at 90 days was higher than the control. While silicon-containing compounds were higher in control samples at the same age. Sodium (Na), Potassium (K), and Phosphorus (P) were reduced by approximately (an average of 30%) in samples under Consciousness Bond Field at 90 days, while the abundance of Aluminum and Calcium was increased (about 7% on average). Differences in the appearance and chemical composition of the crystals, including the amount of ettringite formation in the samples under the Consciousness Bond Field, were observable in SEM imaging.

Behaviour of cement mortar containing Iron waste powder as substitute for sand

The effect of replacing the fine aggregate (sand) with iron waste powder was studied. Four mixes of cement mortar with iron waste powder were prepared; two of these groups were prepared without adding SBR (Styrene-butadiene rubbers); while the others were prepared with SBR. These groups were allowed to cure for (7 and 28) days. Each of them consists of iron waste powder with 850μm as partial replacing of sand (10, 20, 30%) by weight. The results show an enhancement of strength for each group after measuring the compressive strength and flexural strength. Otherwise the properties (dry density, porosity and water absorption) were improved too. The best results of compressive strength and flexural strength were (32.66 Mpa, 5.0232 Mpa) at 20% without SBR and 30% with SBR, respectively. The lowest result of dry density were (2109.20 Kg/m3) at 10% with SBR, and the water absorption and porosity were (5.05%, 11.06%) at 20% with SBR. It was concluded that the iron waste powder can be utilized as partial replacer of sand with modifying the properties of cement mortar.

Effect of Main Factors on Fracture Mode of Mortar, A Graphical Study

One of the most effective ways to identify the concrete properties is to understand further about the cement mortar, which is a mixture of cement paste and fine aggregate. In order to identify the behavior of cement mortar, all required materials including cement, fine aggregate, water as well as the different ratios of each material should beinvestigated. The main objective of this research is to study the effectiveness of main parameters of mortar on the fracture mode and related factors. Specifically 26 mixing designs of flexural mortar with three cement strength classes (32.5, 42.5 and 52.5 MPa), three water to cement (W/C) ratios (0.25, 0.3 and 0.35) and three sand to cement (S/C) ratios (2.5, 2.75 and 3) were first prepared. The prepared samples were then tested using a stress-strain apparatus. Some pictures were finally taken from the fracture surfaces to investigate the mode and angle of fractures. The results indicated that any change in the main parameters of mortar changes the fracture mode and the fracture angle.

Influence of the Nanomaterials of Kaolin Content on the Chloride Permeability of Cement Mortar

This study investigated the influence of nanokaolin content on the behavior of cement mortar at various curing ages. The fluidity, chloride permeability, bending and compressive strength of cement mortar with various nanokaolin additives were examined. The addition of 0%, 1%, 2%, 3%, 4%, 5% and 6% nanokaolin were taken into consideration. The results showed that the addition of nanokaolin decreases the fluidity of cement mortar, and the fluidity the cement mortar decreases with the increase of nanokaolin additives. It is obtained that the addition of nanokaolin increases both the bending and compressive strength of cement mortar, and with the increase of nanokaolin additives, the bending and compressive strength of cement mortar increase. The addition of 4% nanokaolin can result in a significant low chloride permeability of cement mortar among the seven dosages. The chloride diffusion coefficient of the mortar with the addition of 4% nanokaolin was decreased by 18.93%, 12.68% and 31.05% at 7, 14 and 28 curing days, respectively.

The effect of elevated temperature on the properties of cement mortars containing nanosilica and heavyweight aggregates

In this contribution the effect of nanosilica (NS) on the behavior of cement mortars containing quartz aggregate and two types of heavyweight aggregates (magnetite and barite) exposed to elevated temperature will be investigated. The cement mortars have been modified with nanosilica in quantities of 1%, 2%, 3%, 4% and 5% (by weight of cement). The samples were exposed to the elevated temperatures of 200°C, 400°C, 600°C and 800°C, respectively. The mass loss, flexural and compressive strength of the cooled specimens were determined. Additionally, by means of scanning electron microscopy (SEM) and optical microscopy the structure defects have been determined.The results clearly demonstrate that there is an optimal nanosilica content, in the cement mortar containing quartz and magnetite aggregate, improving the thermal resistance and preventing the crack extension (especially in the range of 200–400°C). However, the study has also shown that cement mortars containing barite aggregate tend to crack and exhibit spalling as a result of low thermal resistance of the aggregate.

Influence of cement/sand ratio on behavior of cement mortar

Purpose – The purpose of this paper is to investigate the influence of cement/sand ratio on behaviour of cement mortar. Design/methodology/approach – Literature review was used to confirm that the cement/sand ratio have influence on the mortar strength and that its influence is not very studied. The literature points out also that the constitutive model of mortar is very important in the structural design of masonry but it has not been investigated much. Findings – The results of study allow to forecast the mortar strength by the cement/sand ratio when the water/cement ratio is fixed (0.50). Besides, the obtained experimental results allow defining a constitutive model for sand mortar. Research limitations/implications – Other experiments would be proper to extend the research field. Practical implications – The findings are of particular importance to mix design of cement mortar and to structural design of masonry. In fact, for mortar in the practices, there are no constitutive equations to use in the structural calculation, and so, normally the engineers use the constitutive equations of concrete (very rough). The idea is to find constitutive equations that, using simple and economic tests, allow to engineers to model more correctly the realty. Originality/value – There are few studies which try to investigate the relationship between the behaviour of cement mortar and cement/sand ratio, as well as to study constitutive model of cement mortar. This paper contributes to bridging that gap.

Influence of Recycled Aggregate on the Rheological Behavior of Cement Mortar

In this work it was studied the influence of recycled fine aggregate obtained from construction and demolition waste (CDW) on the rheological properties of Portland cement mortars. The CDW was initially separate in their main constituents (mortar, ceramic and concrete debris) at the laboratory and then grinded separately to the sand size in order to generate more homogeneous fine aggregates. The characterization of the natural and recycled sands was carried out through physical tests, X-ray diffraction, scanning electron microscopy (SEM), and image analysis (shape and texture description parameters). A conventional mortar and three mortars containing recycled sands were produced with a sand/cement ratio of 4 and consistency index of 255±5 mm. The consistency was kept constant by ranging the water-cement ratio from 0.58 to 1.14. The rheological study was performed using a rotating viscometer to obtain torque-rotation ratio and to calculate the yield stress and plastic viscosity. The results indicate that the presence of recycled aggregate causes a lowering of both yield stress and plastic viscosity with respect to the mortar containing natural aggregate.

Physical Properties and Mechanical Behavior of Cement Mortars Containing Waste Tire Rubber Particles

The physical properties and mechanical behavior of cement mortars containing waste tire rubber particles (WTRP) were studied. Several mortar mixtures were prepared by replacing quartz sand with 100% of WTRP and by using cement content of 150, 200, 250, 300, 350 and 400 kg/m3 respectively. Results indicated that dry bulk densities of the mortars containing WTRP were all less than 1000 kg/m3. The mortars had a certain hydrophobic property. The 28 d compressive strengths of the mortars were 0.59~2.29 MPa and the thermal conductivity values were 0.096~0.152 W/(m.K) increased with the cement content increasing. So, the mortars containing WTRP can be used as thermal insulating material.

Physical and Chemical Influence of Polyacrylate Latex on Cement Mortars

In this research, the physical and chemical influence of polyacrylate (PA) latex on cement-based materials were studied using polymer modified mortars with polymer/cement (P/C) ratios of 0%, 5% and 10%. Physically, the mechanical performance of PA latex modified mortars was investigated with compression toughness energy and bending strength. Further more, a comparison of the pore structure and porosity between PA latex modified and unmodified mortars was conducted. The chemical reactions between PA polymer and cement hydrates were clarified with thermogravimetric (TG) analysis. It can be concluded from this research that PA polymer can refine the pore structure of cement mortars and link the cement hydration products together chemically. While, at the same time, PA latex addition can cause air entrainment which will weaken the physical behavior of cement mortars. So there is an optimum P/C ratio to achieve the best mechanical properties. And in this research, the optimum P/C ratio is 5%.

Research on Mechanical Behaviour of Cement Mortar with High-Volume Coal Gangue

With the fast development of modern industry, the fact that coal dominates the main energy structure will not change for a long time. While the output of coal gangue has accounted for 15%~20% in that of coal. Therefore, coal gangue has become one of the greatest contributions to industrially discharged solid waste in China currently. Nowadays the comprehensive utilization ratio is less than 20%, so there is so much room for the activity and comprehensive utilization of coal gangue. In this article, coal gangue in Tongchuan stimulated by thermal, mechanical and chemical activation has been used as supplementary gelatinize material in cement. The optimal activated ways and technological parameter have been selected by the test of strength, fluidity, water requirement for normal consistency of cement paste, and stability. Also XRD and SEM are used to discuss the change of microstructure which has taken place in activated coal gangue preliminarily.

Properties of cement mortars containing clinoptilolite as a supplementary cementitious material

This paper presents a study of the properties and behavior of cement mortar with clinoptilolite which is one of the most common zeolite minerals found in nature. Six mortar mixtures were prepared by replacing the Portland cement with 0%, 5%, 10%, 15%, 20% and 30% clinoptilolite by weight. Test results showed that water demand, soundness and setting times of the cement pastes increased with the increase of clinoptilolite content. Compressive and flexural strength of the mortars containing clinoptilolite were higher than the control mixture. Dry unit weight of the mortars with clinoptilolite was lower than the control mortar. Clinoptilolite replacement decreased water absorption and porosity of the mortars. The control mortar showed less durability to carbonation compared to the mortars made with clinoptilolite at the end of carbonation tests. Freeze–thaw resistance of the mortars containing 5% clinoptilolite was higher than control mortar. The effect of clinoptilolite incorporation on high-temperature resistance seemed to be dependent on amount of clinoptilolite, temperature level, and the cooling method.

Mechanical and durability properties of cement mortar with Algerian natural pozzolana

This paper presents a study of the properties and behaviour of cement mortar with natural pozzolana from Algeria. The effect of level of addition of natural pozzolana (0, 10, 20, 30, and 40%) on the mechanical properties of mortars at different ages as well as the effect of curing environment and the period of initial curing on the mechanical properties were investigated. The performance of natural pozzolana cement exposed to three aggressive solutions (acids, sulphate, and chloride) is also analysed. The results indicate that the strength of pozzolanic cement is lower than that of plain Portland cement at early ages, but can reach the same order of strength at longer curing periods. The enhancement of the resistance to acid and sulphate attack as well as to chloride ion penetration of natural pozzolanic cement is also demonstrated.

Behaviour of cement mortars containing an industrial waste from aluminium refining: Stability in Ca(OH) 2 solutions

The physical and chemical interaction between a solid industrial waste from aluminium refining and saturated Ca(OH) 2 solution, as well as the effects of substituting siliceous sand for the waste on the physical and mechanical properties of mortars were studied. The waste is a solid that contains reactive alumina capable of combining with the calcium hydroxide. These reactions result in stable and insoluble compounds. This alumina, together with the halite (also present in the waste composition), chemically react with a saturated solution of Ca(OH) 2, giving as a main reaction product the so-called Friedel's salt (Ca 4Al 2Cl 2O 6 · 10H 2O). Strätlingite and Si-hydrogarnets were among other products detected. The waste has a high specific surface area. The cement/waste mixtures therefore require a higher quantity of mixing water than cement/sand mixtures. The result is a decrease of the mechanical strengths and an increase of the total porosity. However, a decrease of the average size of the pores occurs, which can have a positive effect on the durability of the final material.

Effect of embedded steel on the compressive damage behavior of cement mortar

Steel embedded in cement mortar in the uniaxial compressive stress direction was found to decrease by 80% the compressive longitudinal strain at a given stress and increase by 300% the tensile transverse strain at a given longitudinal strain. The former effect is due to longitudinal confinement of mortar by steel. The latter is due to debonding at the steel-mortar interface.

Experimental study of the microstructural influence of the strain-softening behavior of cement mortar

The influence of sand grain size on the bridging stress-crack opening displacement curve has been investigated by the Post Fracture Tensile (PFT) testing technique. The PFT method is a well-established technique used in studies of wake-toughened ceramic systems. This method isolates and characterizes the role of microstructure in the development of closure stresses in the process zone. The critical stress was found to be higher for the coarse-grained specimen, but there was no influence of the sand grain size on the critical crack opening displacement. The stress-displacement curves, grain size distribution data, and SEM observation of the fracture surfaces suggest that the coarse sand grains are not very efficient in bridging the crack front and consequently give a negligible contribution to the load sharing event in the wake zone.

Behavior of Cement-Mortars Under Various Contingencies of Use. With a Brief Discussion of Certain Tests, ETC

Behavior of Cement-Mortars Under Various Contingencies of Use. With a Brief Discussion of Certain Tests, ETC