Compressive Strength Of Cement Mortar Research Articles

Hybrid MARS-, MEP-, and ANN-based prediction for modeling the compressive strength of cement mortar with various sand size and clay mineral metakaolin content

Hybrid MARS-, MEP-, and ANN-based prediction for modeling the compressive strength of cement mortar with various sand size and clay mineral metakaolin content

The Effect of Variation Calcination Temperature of Polystyrene/Tetrahydrofuran (PS/THF) Hydrophobic Layers on Contact Angle and The Compressive Strength of Cement Mortar

Infrastructure development in Indonesia continues to increase, this can be seen from the increasing number of buildings and housing. The house is an important building for humans, one of the important parts of the house is the walls made of bricks and covered with plaster. Its function, which can be used as plaster on walls, makes the authors use mortar as a sample in this study. The drawback is that the existing mortar is easy to grab because it absorbs water. Therefore, the author wants to make a waterproof mortar by providing a hydrophobic layer. This study aims to obtain the optimum value of the contact angle and compressive strength by varying the temperature as the independent variable used, namely 30°C, 60°C, 90°C, 120°C and 150°C. The results showed that the optimal contact angle was 120.7053° with a compressive strength of 258.19 kg/cm2. The temperature calcination relationship with the contact angle and compressive strength of mortar, is the higher the temperature. The temperature relationship with the contact angle and compressive strength of cement mortar is higher than the temperature.

Partial Replacement of Municipal Incinerated Bottom Ash and PET Pellets as Fine Aggregate in Cement Mortars.

The objective of this study was to examine the optimal mixing ratio of municipal incinerated bottom ash (MIBA) and PET pellets used as a partial replacement of fine aggregates in the manufacture of cement mortars. As a partial replacement for sand, 15 mortar specimens were prepared by mixing 0%, 10%, 20%, 30%, and 40% municipal incinerated bottom ash (MIBA) (A) and 0%, 10%, and 20% PET pellets (P) in 5 cm × 5 cm × 5 cm cube molds. The cement/aggregate ratio was 1:3, and the water/cement ratio was 0.5 for all specimens. The results showed that the compressive strength of cement mortars decreased when increasing the amount of MIBA and PET pellets. The mortar specimens with 10% PET pellets achieved the highest compressive strength (49.53 MPa), whereas the mortar specimens with 40% MIBA and 20% PET pellets achieved the lowest compressive strength (24.44 MPa). Based on this finding, replacing 10% and 20% sand in cement mortar with only MIBA or only PET pellets could result in compressive strengths ranging from 46.00 MPa to 49.53 MPa.

Physical and Strength Properties of Cements Manufactured in Bangladesh: A Case Study

This study investigates the physical qualities and strength properties of representative cements manufactured by different brands in Bangladesh. The physical and strength properties such as normal consistency, initial and final setting time, density, specific gravity, fineness, and compressive strength of cement mortars as well as concrete cylinders were investigated experimentally. Using CEM II/B-M type cement, a total of 300 test specimens are prepared to determine those parameters. In this case study, specimens were prepared from ten different representative cement industries of Bangladesh and tested as per ASTM specifications. The experimental result shows that the physical and strength parameters of nearly all the representative cement samples are within the ASTM recommended ranges that ultimately proofs the quality of Bangladeshi Cement. The relationship between mortar and concrete strengths from the same batch of cement has also been investigated. Besides, a regression analysis has been conducted to find relationships between the concrete strength and their age of curing. The influence of initial and final setting times on concrete strength is also investigated. This study also provides the relationships between compressive strengths, between mortar and concrete cylinders at different ages. These age dependencies of concrete strength will help to predict the actual concrete strength at the early age of curing which may ensure faster construction work.

Dextrins as Green and Biodegradable Modifiers of Physicochemical Properties of Cement Composites

Growing interest in the use of natural organic compounds in the production of green concrete with the use of plasticizers has been particularly noticeable in the literature of recent decades. Starch is an attractive material due to its abundance, the low cost of sourcing it, and its biodegradability, biocompatibility, and susceptibility to modification. The objective of the study was to evaluate the effect of starch hydrolysate additives on the physicochemical properties of cement composites and concrete. Compressive strength tests and cement slurry rheology measurements were carried out for water–cement ratios from 0.40 to 0.50 and for amounts of added dextrin from 0.0 to 0.7% in relation to the cement weight. The dextrins used were characterized in terms of their viscosity, polymerisation degree, and surface activity in air/water systems. Conducted research indicates that even the minimum content of dextrin increases the fluidization of cement mixes (the flow diameter increased by 67.5% compared with the mixture without the admixture), enables the reduction of mixing water, and contributes to the compressive strength of cement mortars. A further decrease in the w/c ratio to the value of 0.40 resulted in an increase in the strength value of up to 67.9 MPa, which provided a 40% increase in strength. The degree of the polymerisation of added dextrin is seen as having an effect on the physical parameters of the cement mortar; the shorter the polymer chain of the studied dextrin, the more packed the adsorbent layer, and the greater the flow diameter of the cement mortar.

Microstructure and chemical characterizations with soft computing models to evaluate the influence of calcium oxide and silicon dioxide in the fly ash and cement kiln dust on the compressive strength of cement mortar

Environmental issues are raised from the global warming due to raised Carbon Dioxide (CO2) emissions of factories worldwide. Cement manufacturing is highly energy- and emissions-intensive because of the extreme heat required to produce it. Producing a ton of cement requires 4.7 million British Thermal Units (BTU) of energy, equivalent to about 400 pounds of coal, and generates nearly a ton of CO2. Therefore, it is necessary to reduce cement production; as a result, it contributes to solving those issues. This study investigates the effect of two major chemical compositions in the CKD and FA on the long-term compressive strength of cement mortar, especially their Calcium Oxide (CaO) and Silicon Dioxide (SiO2) contents; furthermore, their chemical, mineralogical, and microstructure are compared. In addition, 228 data for FA-modified cement mortar and 167 data for CKD-modified cement mortar were collected from previous literature and used to develop predictive models to forecast the compressive strength of cement mortar modified with CKD and FA. The dataset contained different mix proportions of the cement mortar, such as curing times, various SiO2 (%), CaO (%), water/cement ratio (w/c), and curing times up to 90 days. The result of the Multi expression programming (MEP), full quadratic (FQ), Nonlinear regression (NLR), and artificial neural network (ANN) models were used to quantify the effect of CaO and SiO2. The short-term compressive strength of cement mortar modified with fly ash (from 1 to 28 days) decreases with increasing the fly ash content, while the long-term compressive strength (from 28 to 90 days) increases by up to 15% replacement of cement with fly ash. However, the compressive strength of the cement kiln dust modified-cement mortar decreases with increasing the cement kiln dust content. The sensitivity evaluation discovered that the most influential parameter for predicting compressive of the cement mortar modified with CKD and modified with FA is the curing time.

Theoretical models to evaluate the effect of SiO2 and CaO contents on the long-term compressive strength of cement mortar modified with cement kiln dust (CKD)

Theoretical models to evaluate the effect of SiO2 and CaO contents on the long-term compressive strength of cement mortar modified with cement kiln dust (CKD)

Effect of mixed fibers on fly ash-based geopolymer resistance against carbonation

In this study, the resistance of mixed fiber reinforced fly ash-based geopolymer incorporated with different polyvinyl alcohol (PVA) fibers and modified multi-walled carbon nanotubes (MWCNTs) against carbonation was analyzed using the accelerated carbonation test. The resistance enhancing effects of modified geopolymer were investigated using the carbonation depth and compressive strength tests. Meanwhile, X-ray diffraction(XRD), Fourier transforms infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP), and field emission scanning electron microscopy(FE-SEM) were used to evaluate the mineralogical phases, geopolymerization process, micropore structures, and microscopic morphologies, respectively. The experimental results showed that the resistance of geopolymer against carbonation decreased compared to that of cement mortar. However, the incorporation of an appropriate amount of modified MWCNTs and PVA fibers can enhance the resistance of the geopolymer against carbonation. Moreover, accelerated carbonation decreases the compressive strength of geopolymers while increasing the corresponding compressive strength of cement mortars. The addition of an appropriate amount of modified MWCNTs and PVA fibers can enhance the compressive strength of geopolymers. The resistance of the modified geopolymer against carbonation is best when incorporated with 0.10% modified MWCNTs and 2.00% PVA fibers. After carbonation, the microstructure of the modified geopolymer becomes loose. Moreover, accelerated carbonation decreased the porosity of the modified geopolymer and increased the proportion of harmful pores.

Preparation, thermal and structural properties of n-octadecane/melamine formaldehyde nanocapsules embedded cement mortar for energy storage application in buildings

Phase change materials (PCM) integrated into building fabrics plays an important role in achieving energy efficiency in buildings through thermal energy storage. The incorporation of nanotechnology-based heat storage materials into building fabric materials are becoming increasingly popular in recent times. From this perspective, a novel nanoencapsulated PCM (NePCM) embedded cement mortar was developed and its thermal energy storage and structural properties were investigated, experimentally. In-situ polymerization technique was used to prepare the nanocapsule containing n-Octadecane as the PCM and melamine formaldehyde as the shell material. The particle size analysis results reveal that the size of NePCM ranged from 76 nm to 530 nm. The NePCM resulted in an appreciable encapsulation efficiency of 60.14 % with a melting temperature and latent heat of fusion of 26.01 °C and 122.24 kJ/kg, respectively. The NePCM exhibited good chemical and thermal stability. The pure PCM and the NePCM were embedded into cement mortar with varying proportions for the preparation of cube specimens and based on which a comparative study was performed. During curing the cube specimens for 28 days, leakage of the pure PCM from the cement mortar was noticed to some extent. On the other hand, no leakage issues were found in the NePCM embedded cement mortar, as a result of the shell material which protected the PCM from leaking. The PCM and NePCM embedded cement mortar cube specimens exhibited an excellent compressive strength of 56.8 MPa and 48.16 MPa, respectively. However, by increasing to 6 wt% of PCM content in cement mortar, the cube samples of PCM embedded cement mortar compressive strength was reduced to 44.41 %. Thus, the developed NePCM with improved thermal and structural properties can achieve enhanced energy storage and passive cooling in buildings without sacrificing the structural stability.

Creep and Shrinkage Behaviour of Disintegrated and Non-Disintegrated Cement Mortar.

One way to prevent cement from ending up in landfills after its shelf life is to regain its activity and reuse it as a binder. As has been discovered, milling by planetary ball mill is not effective. Grinding by collision is considered a more efficient way to refine brittle material and, in the case of cement, to regain its activity. There has been considerable research regarding the partial replacement of cement using disintegrated cement in mortar or concrete in the past few decades. This article determines and compares the creep and shrinkage properties of cement mortar specimens made from old disintegrated, old non-disintegrated, and new non-disintegrated Portland cement. The tests show that the creep strains for old disintegrated and old non-disintegrated cement mortars are close, within a 2% margin of each other. However, the creep strains for new non-disintegrated cement mortar are 30% lower. Shrinkage for old disintegrated and non-disintegrated cement mortar is 20% lower than for new non-disintegrated cement mortar. The research shows that disintegration is a viable procedure to make old cement suitable for structural application from a long-term property standpoint. Additionally, it increases cement mortar compressive strength by 49% if the cement is disintegrated together with sand.

Mechanical strengths, drying shrinkage and pore structure of cement mortars with hydroxyethyl methyl cellulose

This paper aims at investigating the long-term mechanical strengths and drying shrinkage, as well as pore structure of cement mortars with hydroxyethyl methyl cellulose (HEMC). The results show that the 3-d flexural strength and compressive strength of cement mortars tend to decrease with the HEMC content increasing. At 28 d to 360 d, the strengths keep decreasing with the HEMC content increasing at 0–1%, and then increase from the minimum value with the HEMC content increasing at 1–3%, still being much lower than those of the control (0% HEMC). Throughout the curing age, both the tensile bond strength and the drying shrinkage value gradually increase with the HEMC content, to be nearly twice at 3% HEMC than those of the control. HEMC significantly delays the 3-d hydration of cement pastes, but has negligible retardation effect on the hydration after 28 d, to bring the similar late hydration degree of cement pastes with HEMC or not. With the HEMC content increasing in the range of 0–1%, incorporating HEMC brings the sharp increase of macro pores, large capillary pores and porosity, and decreases the interconnected pores to bring many more closed pores. Further increasing the HEMC content to 3%, macro pores and porosity decrease, large capillary pores slightly increase and interconnected pores have a negligible change. Obviously, the understanding on the performance development of cement mortars with HEMC is conducive to the better application of HEMC in dry-mix mortars to meet different requirements.

Potential utilization of municipal solid waste incineration ashes as sand replacement for developing sustainable cementitious binder

This paper investigates the ability of recycling the municipality solid waste incineration (MSWI) ashes as sand replacement in cementitious binder production. Two types of MSWI ashes were considered in this study including fly ash and bottom ash. The ashes were characterized, and then incorporated into the mixes as sand replacement with different ratios: 0%, 10%, 20%, and 30%. Comprehensive experimental work was conducted to investigate the mechanical strengths, workability, density, water absorption, thermal conductivity, thermal stability, chemical composition, and heavy metals content of the prepared binders. The results reflected the ability of producing sustainable cementitious binder with low dosage of MSWI ashes (up to 10%) as sand replacement with good mechanical properties, and accepted workability, water absorption, and thermal stability. Partially substitution of sand with MSWI ashes enhanced the early (3-day) compressive strength of cement mortar. Optimum enhancements of 16% and 45% were achieved at 10% and 20% replacement ratios in the case of mortar with MSWIFA and MSWIBA, respectively. Using the MSWI ashes as sand replacement resulted in better compressive strength of the mortar compared to the common approach of using it as cement replacement. However, the chemical composition analysis showed the presence of heavy metals in the hydration products of the binder. The mobility and leaching of these metals should be taken into consideration before any possible application of these materials.

Influence of Mechanical and Mineralogical Activation of Biomass Fly Ash on the Compressive Strength Development of Cement Mortars.

Biomass combustion is a significant new source of green energy in the European Union. The adequate utilization of byproducts created during that process is a growing challenge for the energy industry. Biomass fly ash could be used in cement composite production after appropriate activation of that material. This study had been conducted to assess the usefulness of mechanical and physical activation methods (grinding and sieving), as well as activation through the addition of active silica in the form of silica fume, as potential methods with which to activate biomass fly ash. Setting time, compressive strength, water absorption and bulk density tests were performed on fresh and hardened mortar. While all activation methods influenced the compressive strength development of cement mortar with fly ash, sieving of the biomass fly ash enhanced the early compressive strength of cement mortar. The use of active silica in the form of silica fume ensured higher compressive strength results than those of control specimens throughout the entire measurement period.

Effects of seawater and undesalted sea sand on the hydration products, mechanical properties and microstructures of cement mortar

The effects of seawater and undesalted sea sand on the early-age hydration, mechanical performance, water absorption, leaching behavior and hydration products of Portland cement mortars with only sea sand, seawater, or both seawater and sea sand were fundamentally investigated in this study. The results show that the salts content in sea sand could accelerate the hydration reaction and increase the early-stage compressive strength, while the physical properties of sea sand have an adverse effect on the strength development, leading to the compressive strength of cement mortar with only sea sand lower than the ones with demineralized water and river sand. The addition of seawater could significantly accelerate the hydration due to its high salts content, which could compensate for the side effect of sea sand and make the cement mortar with seawater and sea sand with the highest compressive strength. The chloride, sulphate and magnesium ions in seawater and/or sea sand may lead to the phase changes of cement mortars. The chloride and sulphate ions in seawater and sea sand reacted with tricalcium aluminate (C3A) and the hydrated product of Portlandite to form much more Friedel’s/Kuzel’s salts and ettringite. Moreover, the magnesium ions primarily in seawater generated magnesium hydroxide (Mg(OH)2) and magnesium silicate hydrate (M−S−H) formation by replacing the Ca2+ and decalcification of calcium silicate hydrate (C-S-H). The substitute of seawater also can make the Si/Ca ratio of the C-S-H (Cl) be increased from the range of 0.2–0.4 to 0.6–1.2 respectively. Therefore, utilization of seawater and undesalted sea sand in concrete production provides a sustainable way to solve the shortage of natural freshwater and river sand.

Surface-treated carbon nanotubes in cement composites: Dispersion, mechanical properties and microstructure

In order to achieve good dispersibility and strong interfacial bonding strength in cement-based composites, multi-walled carbon nanotubes (MWCNTs) were chemically modified by low-temperature plasma. Specifically, pristine MWCNTs (p-CNTs), carboxyl functionalized MWCNTs (c-CNTs) and low-temperature plasma modified MWCNTs (m-CNTs) were incorporated in cement matrix for further reinforcement. The results show that the plasma treatment can efficiently form large amounts of oxygen-containing functional groups on the surface of MWCNTs. The m-CNTs in combination with polycarboxylate superplasticizer show favorable dispersion stability in water, especially in cement pore solution, and exhibit more positive effects on mechanical behavior of cement composites. With the addition of 0.1 wt% m-CNTs, the flexural strength and compressive strength of cement mortars were increased by 37.1% and 17.4%, respectively. Microscopic examination shows that the well-dispersed c-CNTs and m-CNTs exhibit more effective crack-bridging behavior in cement matrix. Mercury intrusion porosimeter analysis verifies m-CNTs can bring about lower porosity and improve pore size distribution for cement composites, which is closely correlated with mechanical test results. This work paves an effective way to further use MWCNTs as nano-reinforcing materials in cement composites.

Producing cement mortars through implementing cement replacement

Cement mortars have been recognised as one of the most important and effective binding materials. The main materials that can be used in cement mortars are sand and Portland cement. The implementation of natural materials in the production process of cement mortars has many negative environmental effects including energy consumption production of various pollutants. Scientific research highlighted that the implementation of wasted materials as cementitious materials has large potential environmentally and economically. The present research study aims to assess the compressive strength of cement mortars that contain replacement Cementous materials that are cement kiln dust and silica fume. The compressive strength of the developed mortars was examined after 7 and 28 days of curing. The findings extracted from the specimens that contain cement replacement have been compared to the specimens of cement mortar having only cement. The findings revealed that mixtures that contain cement kiln dust and silica fume have less compressive strength than mixtures of ordinary Portland cement only. Moreover, a lesser compressive strength was obtained with a greater cement kiln dust content. Samples with reduced replacement at various curing times have higher compressive strength values.

Mix proportion design method of recycled brick aggregate concrete based on aggregate skeleton theory

Due to the specific gravity of recycled brick aggregate (RBA) is less than that of natural aggregate (NA), the traditional mix proportion design of concrete can not be used. The purpose of this study is to propose a new mix proportion design method, which is suitable for recycled brick aggregate concrete (RBAC) or lightweight aggregate concrete. In this test, RBA volume fraction, sand volume fraction and water/cement ratio were considered; calculation formula of paste thickness on coated aggregate was established; calculation model of RBAC compressive strength was established, in which RBA volume fraction, the compressive strength of cement mortar and water/cement ratio were considered; mix proportion design method of RBAC based on aggregate skeleton theory was established. The results show that: when the volume fraction of RBA is between 44% and 47%, and the total volume fraction of RBA and sand is about 70%, the compressive strength of RBAC reaches the maximum; when the volume fraction of RBA is between 40% and 50%, the skeleton contribution strength of RBA is greater than that of cement mortar. When sand/cement ratio is about between 0.35 and 2.1, the sand skeleton contribution strength is higher. When the volume fraction of RBA is between 40% and 50%, the actual average paste thickness on coated coarse aggregate (APTCCA) is between 10.04 mm and 5.86 mm and the APTCCA simulated by PFC3D software is between 9.21 mm and 5.75 mm. In the compressive strength calculation model of RBAC, the relative errors of the predicted values are concentrated within 10%, the average relative error is 0.53%, and the correlation coefficient between the predicted values and the test values is 0.96; Compared with ACI 211.2 and ACI 211.6, the mix proportion design method proposed in this paper is to mix more RBA and less sand and cement in concrete mix proportion under the condition of ensuring concrete strength and slump, which is beneficial to protect the environment.

Effect of Using Flue-Gas Desulfurization Gypsum and Water Treatment Sludge on Compressive Strength of Cement Mortar

Ordinary Portland cement (OPC) is a material that is widely used in construction. The production of OPC creates large amounts of carbon dioxide. Mortar is one of the building materials that uses cement as the main ingredient, including the use of natural sand as a fine aggregate. Therefore, to reduce the use of cement and natural materials, flue-gas desulfurization (FGD) gypsum was used instead of OPC, and water treatment sludge (WTS) was used instead of fine sand to create cement mortar. This research used both materials as ingredients in the production of cement mortar and helped to reduce waste in the environment. The objective is to study the suitable ratios of FGD gypsum and WTS in the production of cement mortar. As for the binder, FGD gypsum was used instead of OPC at 0%, 10%, 20%, 30%, and 40%. Instead of fine sand, WTS was used at 0%, 5%, 10%, and 15%. The cement mortar was tested after 7 days for compressive strength. It was found that the cement mortar made with increased ratios of FGD gypsum and WTS decreased in compressive strength.

Improvement of Flexural and Compressive Strength of Cement Mortar by Graphene Nanoplatelets

Background: In order to provide space for improving the durability of engineering structures by enhancing strength, the addition of nanomaterials has become a research trend in recent years. Graphene and its derivatives have unique properties and have been used in certain fields, which has also stimulated continuous and in-depth research on whether it can improve structural strength. Objective: This paper investigates the mechanical properties and mechanism of cement-based materials reinforced by Graphene Nanoplatelets (GNPs). Methods: Macroscopically, the flexural strength and compressive strengths of cement mortar were tested. Microscopically, the structure and composition were characterized and analyzed by SEM, EDS, and XRD. Results: The results show that the mechanical properties of modified cement mortar are directly related to the GNPs content. When the GNPs content is 0.04wt%, the flexural and compressive strength can still be increased by 12.8% and 33.9% after 28 d. Furthermore, the appropriate content of GNPs dispersed in the cement matrix played a role in promoting cement hydration. The interconnection with hydration products further reduces cracks and pores so that the cement composites form a denser microstructure. Conclusion: The results obtained above would provide references for understanding the reinforcement mechanism of GNPs.

Experimental Investigation on Compressive Strength of Cement Mortar by Rice Husk Ash and Jute Fiber

Experimental Investigation on Compressive Strength of Cement Mortar by Rice Husk Ash and Jute Fiber