Strength Of Cement Mortar Research Articles

Monitoring the Early Strength Development of Cement Mortar with Piezoelectric Transducers Based on Eigenfrequency Analysis Method

Monitoring the early strength formation process of cement is of great importance for structural construction management and safety. In this study, we investigated the relationship between the eigenfrequency and the early strength development of cement mortar. Embedded piezoceramic-based smart aggregates recorded the early strength of cement mortar. An eigenfrequency analysis model demonstrated the relationship between strength and frequency. Experiments were performed by using piezoelectric transducers to monitor the early strength formation process during the testing period. Three types of specimens with different strength grades were tested, and the early strength formation processes were recorded. The experimental results demonstrate that cement mortar strength has a good linear relationship with the resonance frequency, and the average square of the correlation coefficient is greater than 0.98. The results show that structural health monitoring technology is a feasible method of assessing structural safety conditions and has a broad market in the structural construction industry.

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.

Effect of Binary and Ternary Binders on Flow and Strength of Cement Mortar

This paper reports the results of laboratory work on the flow and strength of cement mortars containing binary and ternary blends of portland cement, silica fume (SF), Class C fly ash (CFA) and Class F fly ash (FFA). The cement was partially replaced with 20 and 40 wt.% of fly ash (FA) and 5 wt.% of SF as binary mixtures. Besides, the ternary mixtures contained 15%FA+5%SF and 35%FA+5%SF in place of 20% and 40% cement respectively. Both fly ashes were used in the ternary mixtures, thus, 4 mixtures containing ternary binders were prepared. Two sets of mortar mixtures having either same flow or same water/binder (W/B) ratio as those of the control mixture (containing no mineral admixture) were investigated. In total, 15 mortar mixtures were taken into constitution in the present study. The flow of mixtures was measured immediately after casting. In addition, the 7-and 28-day flexural and compressive strength of the mortar mixtures were determined. The use of SF in binary mixtures with constant W/B ratio provided the highest compressive strength (68 MPa). In ternary mixtures the use of 20%FA+5%SF mixture with constant W/B ratio showed the highest 28-day compressive strength (65 MPa). Among the mixtures with constant W/B ratio, ternary mixtures showed the lowest flow values. Besides, in the mixtures with constant flow, once again, the ternary mixtures had the highest W/B ratio. Both in binary and ternary specimens, the mixtures prepared with FFA had a higher flow than that of the CFA mixtures.

Rapid regeneration cement-stabilized macadam: Preparation, mechanical properties, and dry shrinkage performance

Based on the mechanical strength and dry shrinkage of cement mortar, the early strength anti-cracking materials ZFP (mixture of single early strength agents Z1 and Z3 and expansion agent P) and ZSP (mixture of single early strength agents Z1, Z2, and Z3 and expansion agent P) are optimized. Using waste cement-stabilized macadam in road base maintenance as an aggregate, rapid regeneration cement-stabilized macadam containing early strength anti-cracking materials with different contents was prepared, and the mechanical properties and dry shrinkage performances were tested. The early strength anti-cracking mechanism of rapidly regenerated cement-stabilized macadam with different ZSP contents was explored via microscopic experiments. The results show that ZFP and ZSP have an optimal mixing ratio, which makes the setting time, mechanical properties, and dry shrinkage of cement mortar the best. The 2 d compressive strength of rapidly regenerated cement-stabilized macadam containing 8% ZSP was 6.23 MPa, while the 3 d compressive strength of the rapid regeneration cement-stabilized macadam containing 7% ZFP was 6.14 MPa, and the corresponding dry shrinkage coefficients were 91.6% and 11.2% lower than those of the control group, respectively. The chlorine salt, sulfate, and organic amine in ZSP react with calcium hydroxide, which accelerates the hydration process of cement and improves the early strength of rapidly regenerated cement-stabilized macadam. Hydration products, such as expansive sulfuraluminate and chloroaluminate produced by cement hydration in rapidly regenerated cement-stabilized macadam and calcium oxide in ZSP, inhibit early dry shrinkage cracking.

Microstructure, chemical compositions, and soft computing models to evaluate the influence of silicon dioxide and calcium oxide on the compressive strength of cement mortar modified with cement kiln dust

Cement kilnsare used for thepyroprocessingstage of the manufacture ofPortlandand other types of hydrauliccement. Calcium carbonatereacts withsilica-bearing minerals to form a mixture ofcalcium silicates. Over a billion tons of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improving kiln dust efficiency has been the central concern of cement manufacturing technology. Emissions from cement kilns are a significant source ofgreenhouse gas emissions, accounting for around 2.5% of non-natural carbon emissions worldwide. This study evaluated the effect of the primary two components of CKD, such as SiO2 and CaO, on the long-term compressive strength of cement-based mortar up to 360 days of curing. For that purpose, 167 data of cement-based mortar samples modified with CKD were collected from literature and analyzed. Water to binder ratio (w) ranged from 0.34 to 0.76, CKD content ranged from 0 to 50% (dry weight of cement), different CaO and SiO2 of CKD and cement ranged from 17.64 to 25.45%, and 51.45 to 65.57%, respectively. Several soft computing models were used to predict the compressive strength of the cement-mortar modified with CKD. It was revealed from the modeling results that are increasing both SiO2 and CaO contents (%) resulted in increasing the compressive strength of the mortar. Based on the sensitivity analysis, the curing time is the most influential parameter in the compressive strength prediction of cement-based mortar modified with CKD.

Dynamic behavior of carbon nanotubes and basalt fiber reinforced coral sand cement mortar at high strain rates

This study investigated the dynamic mechanical behavior of basalt fiber (BF) and carbon nanotube (CNT) reinforced coral sand cement (CSC) mortars. Based on the Split Hopkinson Pressure Bar (SHPB) tests and micro analysis, the stress–strain behavior, and failure mode of the CNT and fiber reinforced CSC specimens were quantitatively analyzed. The quantitative relationships among the dissipated energy density, impact air pressure, dynamic compressive strength, and incident energy were explored. Furthermore, the reinforcement effect of a glass fiber reinforced polymer (GFRP) tube on the BF reinforced specimens and CNTs reinforced specimens was also evaluated. It was found that the dynamic compressive strength and toughness of coral sand cement mortar were enhanced by CNT and BF with the maximum strength growth rate up to 106% and 73%, respectively. There was an optimal fiber content for the BF reinforced specimens and the CNTs reinforced specimens at a specific condition. In this study, the optimal fiber content of CNT and BF was 0.04% and 0.3%, respectively. The BF reinforced specimens and CNTs reinforced specimens hooped with GFRP tubes showed a significant improvement of dynamic compressive strength compared with those without GFRP tubes, with the maximum strength increase rate of up to 168% and 130%, respectively.

Study on Mechanical Properties of Polycaprolactone Modified Cement-Based Material

With the continuous development of economy, engineering construction is developing towards deep high-stress area, and the problems of large-deformation engineering are becoming more and more serious. Anchoring grouting is a very effective support reinforcement method. The anchoring grouting materials used in the project are mainly cement paste and cement mortar. The characteristics of the grouting material have a decisive influence on the grouting effect. However, it is difficult for the existing grouting materials to satisfy the requirements of strength and deformation at the same time, and improvement is urgently needed. Polycaprolactone (PCL) is an organic polymer material of good engineering properties, including high ductility, good stability and strong impact resistance. In this paper, PCL was added as an auxiliary additive to cement-based materials innovatively, and the mechanical test and micro-test of PCL-cement-based materials were carried out. The results show that adding PCL can significantly increase the compressive strength of cement paste. By adjusting the content of PCL, the strength and ductility of cement mortar can be effectively improved. When the content of PCL is 15%, ideal high performance cement mortar material can be obtained. Anchor grouting is a very effective reinforcement and support method.

Resource utilization of slag from desulphurization and slag skimming: A comprehensive recycling process of all components

In order to make the slag from desulphurization and slag skimming (SDSS) to be comprehensively recycled and utilized, a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS, meanwhile to apply the remaining slag tailings as cement admixture. From this process, three iron-rich products were recovered in stages by clean gravity - magnetic separation, slag tailings were left. Slag powder was prepared by ultrafine grinding of slag tailings. The stability, setting time and cement mortar strength of the slag tailings cements (STC) which were mixed with Portland cement and slag powder were studied respectively. The results showed that a proper overall performance still could be obtained at the slag powder content of 30%. Chemical composition analysis, X-ray diffraction (XRD) analysis, metallographic microscope and scanning electron microscope (SEM) analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process. The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate (C2S) and tricalcium silicate (C3S) in the slag tailings make the addition of slag powder into the Portland cement feasible.

Hydration mechanisms and mechanical properties of pumice substituted cementitious binder

This paper reports the hydration production, micro structuring, and compressive strength results of Portland cement–pumice systems. The compressive strengths of cement mortars examined on the 2nd, 7th, 28th, and 90th days in the first stage. In the second step, hydration mechanisms of cement paste samples containing 0%, 10%, and 20% pumice at the 2nd, 7th, 28th, and 90th ages were determined by SEM, FT–IR, XRD, and DTA/TGA. In addition, the chemical, physical, molecular, mineralogical characterizations of the pumice and Portland cement were detected. Water demand, setting time, and volume expansion of paste samples with standard cement tests were determined. The XRD and TGA results prove that the pumice–containing cement displays a high hydration degree on the 90th day and will continue to hydrate. Furthermore, on the 90th day, the chemically bound water content in 10P paste is the same as that in Portland cement. Moreover, SEM images reveal that the usage of pumice results in a much denser microstructure as the hydration age increases. The results showed that pumice has lower pozzolanic activity in the early period and yet the compressive strength increases with time.

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.

Effect of CNT-COOH Addition on the Compressive Strength, Chloride Resistance, and Microstructure of Cement Mortar

This work evaluated the effect of multiwalled carboxyl carbon nanotube (CNT-COOH), upon cement mortar. In order to obtain a homogeneous suspension, the CNT-COOH was dispersed in distilled water, and it then underwent an ultrasonication treatment. Samples of cement mortar were prepared with varying the additions of this suspension at 0.01%, 0.05%, and 0.10% by weight of the cement. These samples were tested in compression and for chloride migration in terms of diffusion coefficient. An increase in the CNT-COOH content led to an increase in the compressive strength. While there was an increase in the chloride diffusion coefficient up to 0.05% weight fraction, higher dosage led to a drop in the chloride diffusion coefficient with a further increase in the compressive strength. Using mercury intrusion porosimetry (MIP), it is shown that at a weight fraction of 0.10%, CNT-COOH effects a pore-size refinement by eliminating macropores (≥50 nm) and a 34% reduction in porosity. The (scanning electron microscopy) SEM and (X-ray diffraction) XRD analyses confirm that CNT-COOH leads to mature hydration products, nucleation effect, and a refined microstructure.

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)

Interactive Effects of Admixtures on the Compressive Strength Development of Portland Cement Mortars

The interaction effects of four chlorine-free admixtures such as calcium formate (CF), triethanolamine, (TEA), triisopropanolamine (TIPA), and sodium sulfate (SS) on the compressive strength development of Portland cement mortars were investigated based on the design of experiment (DoE). The results showed that both the addition of CF and SS contributed significantly to the strength of cement mortars at early curing age. However, the interaction of CF and SS could hinder their respective positive effect on the strength of cement at 1 d. At later curing ages, CF was still beneficial in improving the late strength of cement, but SS had a negative effect on the strength of cement at 28 d. A negative effect of TIPA on the strength of cement was found at 3 d. However, the positive interactive effect of TIPA and CF was sufficient to offset the negative effect of TIPA on the strength of mortars at 3 d if the dosage of CF exceeded 2%. In addition, TEA had a positive influence on 7 d strength until a turning point was reached and the optimum dosage of TEA was approximately 0.013%.

Properties of 3D-Printed Polymer Fiber-Reinforced Mortars: A Review.

The engineering applications and related research of fiber-reinforced cement and geopolymer mortar composites are becoming more and more extensive. These reinforced fibers include not only traditional steel fibers and carbon fibers, but also synthetic polymer fibers and natural polymer fibers. Polymer fiber has good mechanical properties, good bonding performance with cement and geopolymer mortars, and excellent performance of cracking resistance and reinforcement. In this paper, representative organic synthetic polymer fibers, such as polypropylene, polyethylene and polyvinyl alcohol, are selected to explore their effects on the flow properties, thixotropic properties and printing time interval of fresh 3D-printed cement and geopolymer mortars. At the same time, the influence of mechanical properties, such as the compressive strength, flexural strength and interlaminar bonding strength of 3D-printed cement and geopolymer mortars after hardening, is also analyzed. Finally, the effect of polymer fiber on the anisotropy of 3D-printed mortars is summarized briefly. The existing problems of 3D-printed cement and polymer mortars are summarized, and the development trend of polymer fiber reinforced 3D-printed mortars is prospected.

Effects of incorporating large quantities of copper tailings with various particle sizes on the strength and pore structure of cement-based materials

Although it is estimated that approximately 300 million tons of copper tailing is produced in China annually, only about 8.2% of this byproduct is reused. Therefore, to promote natural material sustainability, and value-added utilization of copper tailings in China, tailings from Hubei (HT) and Jiangxi (JT) were explored as replacement materials for the fine natural aggregate. The water/cement ratio was fixed at 0.50, and various proportions of fine aggregate were replaced (0%, 30%, 50%, 70%, and 100%). The size distribution of the tailings particles was as follows: HT (1.18 to 0.15 mm) and JT (0.60 to 0.15 mm). This study was made to match the size distribution of the tailings with that of the fine aggregate it replaced. The mechanical properties and pore structure were assessed using the methylene blue test, flexural tensile strength test, compressive strength test, absorption test, fluidity test, mercury intrusion porosimetry (MIP) test, and scanning electron microscopy (SEM). The control group (without tailings) presented the highest flexural strength but the lowest compressive strength. The experiment group achieved the highest flexural and compressive strength under 50% HT content or 70% JT content. Overall, MIP results show that inclusions in tailings tend to reduce “harmless pores” (pores < 20 nm). SEM observations at 7 days revealed that unreacted tailings particles filled the macropores between fine aggregate and paste. Observations at 28 days revealed fewer unreacted tailings particles. The finer tailings particles reacted with calcium hydroxide in cement to form hydrated calcium silicate gel and fill pores, thereby enhancing the strength of cement mortar.

Recycled Non-Biodegradable polyethylene terephthalate waste as fine aggregate in fly ash geopolymer and cement mortars

In this study, the use of recycled non-biodegradable polyethylene terephthalate (PET) waste as a fine aggregate in fly ash geopolymer mortar was examined. PET waste was used to replace 0%, 10%, 20%, 30%, and 40% by volume of natural fine aggregate for preparing geopolymer mortar. The flow, density, porosity, water absorption, ultrasonic pulse velocity (UPV), thermal conductivity, and strengths of the mortars were tested and compared with those of ordinary Portland cement (OPC) mortar. The results showed that the mechanical properties of the geopolymer mortar deteriorated with an increase in the amount of PET waste. The compressive strength decreased from 42.7 to 12.8 MPa with increasing PET content from 0 to 40% for geopolymer mortars and decreased from 49.5 to 22.5 MPa with increasing PET content from 0 to 20% for cement mortars. However, the ratio of flexural strength to compressive strength of geopolymer and cement mortars containing PET waste tended to improve. In addition, the density and thermal conductivity were significantly reduced with increasing PET content; ranging from 1585 to 2020 kg/m3 and 0.6329 to 1.3116 W/m.K, respectively for geopolymer mortar and from 1763 to 2042 kg/m3 and 1.181 to 2.0030 W/m.K, respectively for cement mortar. The reduction of density and thermal conductivity in both types of mortar could be used to reduce self-weight and improve thermal performance.

Investigating the Mechanical Properties and Durability of Metakaolin-Incorporated Mortar by Different Curing Methods.

In this paper, the traditional, silicate-based Portland cement (PC) was employed as the control to explore the impact of adding varying amounts of metakaolin (MK) on the mechanical properties of cement mortar. In fact, as a mineral admixture, metakaolin (MK) has the ability to significantly improve the early strength and sulfate resistance of cement mortar in traditional, silicate-based Portland cement (PC). In addition to this, the performance of Portland cement mortar is greatly affected by the curing mode. The previous research mainly stays in the intermittent curing and alkaline excitation mode, and there are few studies on the influence of relatively humidity on it. Moreover, the paper investigated the impact of four different curing methods about humidity on the mechanical properties and sulfate resistance. The results show that the best content of metakaolin in Portland cement is 10% (M10), and the best curing method is 95% humidity in the first three days followed by 60% humidity in the later period (3#). Based on previous literature that suggests that adding MK thickens water film layer on the surface of mortar, the mechanism of MK increasing the early strength of cement was analyzed. The compressive strength of the Portland cement containing 10% MK (M10) after 1 day curing is 3.18 times that of pristine PC mortar, and is comparable if PC is cured for three days under the same curing conditions. The traditional PC mortar is highly dependent on the wet curing time, and normally requires a curing time of at least seven days. However, the incorporation of MK can greatly reduce the sensitivity of Portland cement to water; MK cement mortar with only three days wet curing (3#M10) can reach 49.12 MPa after 28 days, which can greatly shorten the otherwise lengthy wet curing time. Lastly, the cement specimens with MK also demonstrated excellent resistance against sulfate corrosion. The work will provide a strong theoretical basis for the early demolding of cement products in construction projects. At the same time, this study can also provide a theoretical reference for the construction of climate drought and saline land areas, which has great reference value.

Investigation of Mechanochemically Treated Municipal Solid Waste Incineration Fly Ash as Replacement for Cement

Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste in China because of the leachable toxic heavy metals and high concentrations of chlorides and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). Currently, the main treatment method is still landfilling after chemical treatment or cement solidification, and an effective approach to realize fly ash utilization is still lacking. In the present work, the fly ash was firstly water-washed to remove the soluble chlorine salts, which can improve the performance of the produced cement mortar in later work. Mechanochemical pre-treatment was adopted to destroy the PCDD/Fs and improve the heavy metals’ stabilization. The results show that 75% of PCDD/Fs can be degraded and that most of the heavy metals are stabilized. After the mechanochemical pre-treatment, the average particle size of the fly ash decreases to 2–5 μm, which is beneficial for promoting the activation energy and accelerating the hydration process in cement mortar production. The compressive and flexural strengths of the fly ash cement mortar improve to 6.2 MPa and 32.4 MPa, respectively, when 35% of the OPC is replaced by treated fly ash. The similarity in the 3-day and 28-day strength with or without the addition of the treated ash shows the light influence of the fly ash addition. Thus, the mechanochemical process can stabilize the heavy metals and activate the fly ash, allowing it to partly substitute ordinary Portland cement in building materials, such as cement raw materials and concrete.

STUDY THE EFFECT OF ADDITION GLENIUM 51AND SILICA FUME ON THE MECHANICAL AND PHYSICAL PROPERTIES OF ORDINARY PORTLAND CEMENT

This research includes a study of the effect of adding Glenium 51 polymer and silica fume on the mechanical and physical properties, which included compressive, flexural and tensile strength of cement mortar and comparing the results with reference cement mortar. Glenium 51 and silica fume were added in different weight ratios as a percentage of the cement weight, and the results showed increase in compressive strength, flexural and tensile strength. All experiments were conducted with different temperatures of 7C°, 20C°, 55C° respectively to demonstrates the effect of different temperatures on cement strength and the polymers behaviour and the results showed that the compressive, flexural and tensile strength of the cement mortar reached its maximum value at the temperature of 20 C° for the moulds and there is increase in the compressive, flexural and tensile strength after adding the additives in all temperature. The values of the compressive and tensile strength used the standard specimens at the age of (2&amp; 28 ) days.

Variation of Critical Water Pressure for Hydraulic Fracturing in Cement Mortar under Sulfate Attack.

Hydraulic fracturing may be induced easily in a cement-based structure in a sulfate-rich environment, which threatens engineering safety. In order to investigate the evolution of critical water pressure, a series of hydraulic fracturing tests and splitting tensile strength tests on the cement mortar under different sulfate-exposure periods are performed. The critical water pressure of the cement mortar under sulfate attack experiences an initial increase stage and a subsequent decrease stage. A stress intensity factor is modified by two proposed damage variables which are crack length and fracture stress. Then, the relationship between the critical water pressure and the tensile strength is established. Moreover, an evolution model of the critical water pressure is proposed, which reveals that the matrix tensile strength and porosity of cement mortar strongly affect the critical water pressure evolution. Additionally, an empirical formula is suggested to describe the critical water pressure evolution of the cement mortar under sulfate attack, and its validity is verified by experimental results.