Porosity Of Mortar Research Articles

Study on the micro-rheological properties of fly ash-based cement mortar

Aiming at the shortcomings of poor rheological properties and low strength of tailings filling mortar, solid waste materials such as fly ash, steel slag, and desulfurization ash were introduced to improve the filling mortar. The Response Surface Methodology (RSM) was used to design the test ratios to determine the significance of the effect of fly ash, steel slag and desulphurization ash on the physical properties of the mortar. The rheological characterization law of filling mortar was studied based on macroscopic L-tube test. The mechanism of filling mortar improvement was analyzed by Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) and other microscopic tests. The results show that the response-factor model fit regression is significant, with the highest model satisfaction at 12 % fly ash dosing, 15 % steel slag dosing, and 10 % desulfurization ash dosing. The self-flowing extension diameter of the mortar is 15.34 cm, and the 3d and 28d strengths are 0.58 MPa and 3.24 MPa, respectively. Fly ash has effectively improved the phenomenon of mortar segregation and precipitation, and the yield stress of mortar is reduced by 35.1∼64.9 % when the dosage is 8∼12 %. The fractal dimension and mortar workability are positively correlated with fly ash admixture. Fly ash incorporation will gradually consume the calcium hydroxide (CH) to generate alumina ferrite (Aft) and calcium silicate hydrate (C-S-H), which reduces mortar porosity and promotes long-term strength growth. The research results not only realized the effective utilization of solid waste resources, but also significantly improved the performance of the filler and ensured the safe production of the mine.

Ultrasonic velocity and density measurement for mortar characterization: Investigation of correlations with mortar porosity and sand grain size

Ultrasonic velocity and density measurement for mortar characterization: Investigation of correlations with mortar porosity and sand grain size

Effect of the Incorporation of Olive Tree Pruning Sawdust in the Production of Lightweight Mortars

In order to reduce energy consumption in buildings, this study used olive pruning sawdust (OTPS) instead of natural sand in the production of lightweight mortars. Different percentages of natural sand substitution were tested: 0, 10, 25, and 50% by volume of sand over 7 and 28 days of curing time. Additionally, the influence of a chemical pretreatment in an aqueous solution of calcium hydroxide on the OTPS was also evaluated to mineralize the wood before its addition to the mortar mixture. Mortars with OTPS incorporations were characterized by volumetric shrinkage, bulk density, and capillary water absorption. Mechanical behavior was tested through compression and flexural tests. The addition of this byproduct decreased bulk density and increased mortar porosity. Pretreating olive pruning sawdust with an aqueous solution of calcium hydroxide was effective for wood mineralization, resulting in physical and mechanical properties superior to mortars without pretreatment. The results showed that a maximum addition of 10% by volume of OTPS treated with calcium hydroxide solution produced lighter mortars with similar mechanical properties to the control mortar. Adding higher amounts of pretreated olive pruning (25–50% by volume) led to a more pronounced deterioration of mechanical properties.

Improvement of porosity of mortar using polyethylene glycol pre-polymer-impregnated mortar

Abstract The extreme porosity and brittleness of cement mortar, when subjected to external forces, explain its fragility and low compressive and flexural resistance. Utilizing polymers is a cheap way to address these drawbacks. In this research, cement mortar samples were improved their mechanical and physical properties using the polymer-impregnated mortar (PIM) method, where polyethylene glycol (PEG) was utilized in the impregnation process through three different methods for impregnation: vacuum technique, ultrasound technique, and immersion in PEG for 24 h. The results showed an increase in mechanical properties. PIM exhibited the highest compressive strength (CS [24.47 MPa]), flexural strength (18 MPa), and splitting tensile strength (2.082 MPa) compared with the reference specimen, which attained 1.38 MPa CS, 0.52 (MPa) flexural strength, and 1.346 MPa splitting tensile strength. Optimum mechanical properties were achieved by vacuum technique, along with the increase in bulk density. The porosity test showed a slight effect of polymer on porosity. The results of diffusion showed the greater diffusivity of the reference sample compared with the PIM samples, that is, approximately 5% weight gain after one-day immersion in water. The results of thermal conductivity exhibited the increased thermal conductivity of polymer-impregnated samples compared with the reference sample.

Influence of hybrid steel-polyacrylonitrile fibers on the mechanical toughness and freeze-thaw resistance of sulfoaluminate cement composites

Sulfoaluminate cement (SAC), an environmentally friendly low-carbon cement, is commonly applied for rapid repair and construction. However, limited studies were conducted to elevate the performance of SAC-based materials by using the hybrid fiber modification, especially the durability. This study investigated the mechanical behaviors and freeze-thaw (F-T) resistance of SAC-based materials with hybrid steel-polyacrylonitrile (PAN) fibers, as well as their enhancement mechanism characterized using X-ray computed-tomography (CT) and scanning electron microscope. The results showed that incorporating hybrid fibers remarkably increased the flexural and compressive toughness of mortars, with steel fibers contributing the most critically. The fiber hybridization also significantly enhanced the F-T resistance of mortars, with PAN fiber being the main contributor. Specifically, the use of hybrid fibers caused a 61.0% improvement in the relative dynamic elastic modulus of mortars after 300 F-T cycles. CT scanning demonstrated that incorporating PAN fibers reduced the porosity of mortars and restrained the initiation and propagation of microcracks, while uniformly and randomly distributed steel fibers interspersed between macrocracks. Morphology observation illustrated that PAN fiber addition was conducive to enhance the anchoring force of steel fiber. Accordingly, the hybrid steel-PAN fibers contributed to suppress cracking at different scales and achieved a positive hybrid effect. At last, the results of this work provide a promising design solution for SAC-based composites to achieve better toughness and frost resistance.

The Influence of Traditional Substrates on the Behaviour of Lime Mortars

ABSTRACTOne of the main functions of mortars is the protection of walls in-service conditions. Mortars, however, are associated with common pathological manifestations, which not only affect substrate strength and other properties, but also the comfort and healthiness of buildings users, being responsible for a significant fraction of rehabilitation expenses. In the last few decades, there has been a growing trend towards the rehabilitation of existing buildings instead of their demolition, not only for economic and urbanistic issues, but also for ecological and sustainability reasons due to the awareness of the limitation of available natural resources. In traditional buildings, lime-based renders (coating mortars) were the most common type of wall coating. Indeed, these renders have properties, such as low mechanical strength and stiffness and high-water vapour permeability, which are compatible with traditional substrates. However, inappropriate coating solutions, such as cement-based mortars, have been used in the rehabilitation of old buildings, leading to the development of anomalies in building walls. Nevertheless, there is an increasing awareness of the need to use coatings that are mechanical-chemical, physical and geometrical compatible with traditional substrates. Mortar characteristics, whether declared by the manufacturer, designer, or established by the user, are currently determined in the laboratory, according to applicable standards. When applied on substrates, mortars have their properties altered due to interaction with them, and various substrates influence differently the same mortar, as showed by extensive work developed in the scope of the IF MORTAR project. Thus, knowledge about in-service behaviour of mortars becomes crucial. The main aim of the research presented in this paper is to assess the behaviour of lime mortars applied on traditional substrates and to discuss how substrate properties affect mortar behaviour. In this way, there is a contribution to improve the understanding required to select materials for interventions in traditional buildings, assuring compatibility between traditional and new elements, with suitable durability. To achieve the above-mentioned aim, hydraulic lime mortars and hydrated air lime mortars, produced with two sands with different particle sizes, were applied on solid ceramic bricks and limestone slabs. These substrates were chosen because they are commonly found in traditional buildings. Physical and mechanical characterisation tests were carried out on the mortars hardened in laboratory moulds and on the mortars hardened on the substrates (after being detached). The substrates used were also characterised, as well as the aggregates and binders. The test results revealed that substrates have an impact on mortars characteristics, and this influence is greater for the more porous supports, and varies depending on the type of binder and aggregate used, being directly related to mortar porosity and pore distribution. For air lime mortars, there was an increase in the range of pores from 0.05 to 10 μm and a decrease for pores above 10 μm. The opposite occurred for hydraulic lime mortars. In addition, for air lime mortars, open porosity and water absorption by capillarity increased, in contrast to what happened to hydraulic lime mortars, the open porosity and water absorption by capillarity decreased, after applied to substrates and when subjected to standard curing. Regarding the type of aggregate, for the same ratio, the use of finer aggregates resulted in more porous mortars.

The influence of the bricks and mortar characteristics, paint, and salts on the rising damp of historic masonries through hygrothermal simulation

Rising damp is a complex phenomenon influenced by heat and moisture transfers and building characteristics. Essentially, rising damp is one of the main mechanisms of the degradation of masonry structures. In general, masonries are affected by the humidity presence due to their materials and local construction techniques. In the case of ancient Brazilian constructions, the high porosity of mortars and bricks, waterproofing lack, and the presence of salts can intensify the degradation mechanism. Thus, this paper has as the main aim to assess the influence of several factors on the rising damp in heritage masonry, such as the thickness of the bricks, the thickness and mortar composition, the type of paint, and the presence of salts. Long-term numerical analyses were performed using computational simulation in the WUFI 2D software, taking as reference the materials properties of the Luso-Brazilian of the Nosso Senhor do Bonfim Church, dating from the 18th century, located in Aracati, in the State of Ceará, Brazil. The results showed that the variation of the factors considered in this study directly influences the rising damp, except for the thickness of the mortar. This study contributes to the understanding of the factors that influence the rising damp mechanism while being helpful to support strategies for rising damp treatment on ancient buildings.

Use of biomass bottom ash as granular substitute in mortar

An experimental investigation was undertaken on the effect of biomass bottom ash (BBA) as a sand substitution in a mortar design. The objective is to characterise the physico-chemical properties of BBA and to establish a reusable proportion in cementitious composites. The aim is to provide a new way to treat these industrial waste and to reduce the consumption of non-renewable natural aggregates. First, biomass bottom ash from fluidized bed boiler are characterised by physico-chemical and mineralogical analysis. Then, they are compared to the properties of boiler sand use in the combustion process. Finally, boiler sand was substituted by BBA into mortar with a rate of 0–100% of the sand volume. The results show that incorporation of BBA does not significantly influence the hydration kinetics of the cementitious matrix. However, an enhancement of the amount of heat hydration was observed. Furthermore, the BBA substitution leads to decrease the mortar workability. In the hardened state, BBA incorporation shows an increase of mechanical properties. This finding was confirmed by a decrease of the mortar porosity. The results of this study show that there is no contraindication to the use of BBA as an aggregate for the formulation of cementitious materials.

Mechanical and microstructural properties of mortar with fine recycled aggregates

This study examines the effect of fine recycled concrete aggregate (FRCA) on the interfacial transition zone and porosity of mortars. The literature on FRCA’s effects is inconsistent, often indicating adverse impacts on workability, compressive strength, drying shrinkage, and transport properties, among others, and other times reporting the opposite. Such inconsistencies may stem from the combinations of effects of the high porosity of FRCA and the additional water sometimes added to compensate for the FRCA absorption. Attached cement paste causes a higher porosity of fine recycled concrete aggregate (FRCA) compared to fine natural aggregates. This brings more complexity to the mix design due to the difficulties in accurately determining the water absorption ratio of FRCA, often leading to inaccurate corrections of water. Overestimation of this additional water increases the porosity of the cementitious matrix. Thus, the overall effect of the inclusion of FRCA depends on which effect is more dominant. The effect of the water uptake by FRCA was analyzed by testing mixes containing different percentages of FRCA in air-dry state. A reference mortar with 45% by volume (relative to the total amount of sand) of manufactured sand and w/c ratio of 0.40 was compared with mortars with 15, 30 and 45% by volume of FRCA replacing the manufactured sand. No compensation of water due to the FRCA absorption capacity was made during the production of mortars. Measurements in fresh and hardened state were conducted, with tests for flow (0 and 30 min after mixing), bleeding, density, water absorption capacity, porosity, and compressive strength. Moreover, microstructural analyses by SEM images of thin polished samples revealed the effects of FRCA inclusion on the overall porosity and alterations of the interfacial transition zone (ITZ). Notable changes in the ITZ linked with the presence of FRCA and the water transfer between the fresh matrix and FRCA particles. The water absorption capacity of FRCA distinctively influenced mortar performance, depending on the property considered.

Effect of microwave pretreatment on mechanical behavior of concrete and aggregate recovery

Microwave heating has exhibited remarkable potential for concrete aggregate recovery due to selectivity and high efficiency. The paper aims to investigate the effect of microwave on mechanical behavior of concrete and aggregate recovery after mechanical crushing. The variations of compressive strength, elastic modulus and brittleness for concrete under different heating parameters were investigated from the macroscopic point of view and of porosity and microstructure were analyzed from the microscopic point of view. Further, the concrete fragmentation and aggregate liberated rate were evaluated following crushing. The experimental results show that hot spots occur in the central region due to the convergence of electric field in the multimode cavity. Microwaves deteriorate the microstructure of mortar and induce the growth and penetration of pores as a consequence of thermal effect and athermal effect, leading to an increase in porosity. Microwave heating results in weakened mechanical properties of concrete, including compressive strength, elastic modulus and brittleness, even at very low energy consumption. Microwave pretreatment facilitates concrete fragmentation and aggregate liberation after crushing based on the increase of mortar porosity and the weakening of interfacial transition zone. In particular, microwave power has an obvious effect on these phenomena mentioned above, and high power will promote the recovery of aggregate and fine powder. Microwave-assisted concrete recycling can be considered as an effective technique to improve the quality and recovery efficiency of aggregate.

Corrosion mechanism of recycled mortar prepared from CO2-treated hardened cement paste powder

CO2-treated recycled powder improves the mechanical properties of concrete. However, its corrosion mechanisms are not thoroughly understood. This study focused on the carbonation-induced corrosion mechanism of recycled mortar prepared from CO2-treated hardened cement paste powder (CCPP). First, the corrosion behavior of the steel reinforcement in a CCPP mortar (CCPPM) was evaluated using electrochemical and corrosion mass loss tests. Furthermore, the carbonation resistance of the CCPPM was quantified by testing the carbonation coefficient, and a corrosion model was established to predict corrosion. Finally, the microproperties of CCPPM and CCPP were investigated to reveal the corrosion mechanism. The results show that the corrosion rate of the steel reinforcement in the CCPPM is controlled by the combined effect of the concentration of OH– ions around the steel reinforcement and mortar porosity; the former plays a more critical role than the latter. Moreover, the variation in the w/c ratio of the CCPP base material had a slight effect on the compressive strength and carbonation resistance of the CCPPM and the corrosion rate of the steel reinforcement. The low concentration of OH– ions in the CCPPM increases the corrosion current density of the steel reinforcement by 15.91%–26.79%, consistent with the 10.96%–18.67% higher corrosion mass loss of the steel reinforcement embedded in the CCPPM cured for 540 days relative to that of the hardened cement paste powder mortar. Although incorporating CCPP increases the steel corrosion risk, the corrosion model developed herein demonstrates that CCPP can be used to guarantee a service life of 50 years for mortars when its replacement ratio is less than 20%.

A BEM multi-scale analysis of concrete plates in bending under static load considering microstructural effects

This study presents a BEM multi-scale modelling to analyse the bending problem of concrete plates. The concrete microstructure is represented by the Representative Volume Element (RVE), in which the mortar matrix behaviour is governed by the Mohr-Coulomb criterion, the aggregates are considered elastics and the mortar porosity is modelled by defining voids into its domain. Moreover, the microcracking process at ITZ (Interfacial Transition Zone) is modelled by defining additional cohesive-contact finite elements on interfaces between mortar and aggregates. To define the RVE microstructure and the parameters of its phases, we consider a concrete whose experimental curve in compression is known. We show that, for the same volume fraction of inclusions and voids, a RVE with reduced number of aggregates and voids can reproduce the experimental results for compression predominant regimes. But for plate bending analysis, the microstructure and mainly the modelling of the microcracking process at ITZ have enormous influence on the plate mechanical behaviour. The results are also compared to a multi-scale formulation considering the FEM (Finite Element Method) at micro-scale, showing that the proposed model is much faster than the coupled BEM/FEM model.

EFFECTS OF BAMBOO CELLULOSE MICRO-FIBERS ON MECHANICAL CHARACTERISTICS AND POROSITY OF CEMENT MORTAR

This study presents the effect of utilizing cellulose microfibers obtained through extraction from bamboo as reinforcement on mortar mixtures. The mixture proportions used in this experiment are 0.5%, 1%, 1.5%, and 2% of bamboo cellulose fiber by weight of cement as additional material in mortar mixture. It was found that the optimum compressive strength of 36.4 MPa was achieved by the sample with 1.5% of bamboo cellulose fiber as additional material with water to binder ratio of 0.5. A similar trend was also found in the result of flexural strength of mortar due to bamboo cellulose fiber addition, reaching the value of 6.31 MPa on the 28th day, which is 52% higher than the flexural strength of control mortar. From the porosity results, the percentage of mortar porosity containing micro-fibers ranged from 4.6-9.1%, lower than the porosity of control mortar, indicating that the addition of fibers led to fill in the pores, resulting in a denser cement matrix. The performances of the cellulose fiber contributed to the strength development and porosity resistance of mortar even with low volume fraction, making it a potential to be used as material building construction, for instance, masonry mortar, repair mortar, rendering mortar, joint filler, waterproof mortar, decorative mortar and for precast elements in construction. The research findings also provide new perspective on the utilization of natural cellulose fibers as a sustainable construction material.

Effect of ion chelator on water sorption and transport behavior of unsaturated mortars with high volume fly ash and blast furnace slag

This paper investigated the effect of ion chelator on water dependency of water transport and fixation in mortars with high volume of fly ash (FA) and blast furnace slag (BFS). Ion chelator (CA) as a new type of crystalline admixture could improve self-healing performance of cementitious materials by crack-healing and pore filling. The porosity of mortar was measured by vacuum saturation and pore size distribution of mortar was tested by low-field nuclear magnetic resonance (LF NMR). The water sorption of mortar was evaluated by water vapor adsorption desorption balance. The water transport of mortar with and without crack was tested by capillary water absorption. Based on the experimental results, the water distribution of capillary water absorption in mortar was calculated. Results showed that the pore structure of mortar was improved evidently by CA, and the pores (>1μm) and the total porosity in mortar containing 50 %BFS were significantly reduced. CA had no obvious effect on the water vapor diffusion coefficient of mortar, but has a significant impact on the liquid water diffusion coefficient, especially in pure cement and containing 50 % BFS mortar. The total capillary water absorption and capillary absorption coefficient of mortars were reduced by CA, especially in pure cement and containing 50 % BFS mortar. The addition of CA decreased the water penetration in mortar, the reduction rates of water penetration depth in experimental groups (with CA) at 360 min were 12.4 % (100 %OPC), 6.0 % (30 %FA), 21.3 % (50 %BFS) and 10.8 % (16 %FA 24 %BFS) compared to control group (no CA). After curing for 42d, the normalized water absorption coefficients S” of cracked M100CA and M50BFS50CA were 55.1 % and 72.0 %, respectively. Ion chelator significantly improved internal pore structure and crack healing ability of the mortar containing 50 %BFS, and then delayed the water diffusion.

Characteristics of Mortar Containing Oyster Shell as Fine Aggregate.

In this study, oyster shells were processed and classified into sizes equal to or smaller than the fine aggregate threshold, and their engineering properties and fire-resistant performance were examined. The differences in heating weight loss of oyster shell aggregate (OSAs) with different particle sizes were examined using thermogravimetric analysis (TGA). The TGA results showed indicating that the temperature at which decarboxylation reaction started depended on the OSA particle size. The porosity of mortar specimens was analyzed using mercury intrusion porosimetry (MIP). The porosity area and porosity of the OSA-containing mortar increased with decreasing particle size. Mortar fire-resistant boards with heated for 2 h in accordance with the heating conditions of KS F 2257-1(methods of fire-resistant testing for structural element—general requirements) to measure their back-side temperature. The board made with OSA2.5 exhibited 273.2 °C, which is more than 90 °C higher than the back-side temperature of the board with OSA 0.6Under. Such difference was attributed to the greater heat transfer delay caused by higher porosity, porosity area, and specific surface area in OSAs with small particle sizes. The TGA results combined with the heating test results suggested that CO2 would be generated at different temperatures in boards containing OSAs with different particle sizes because of the differences in the endothermic reaction temperature.

Effect of micron-scale pores increased by nano-SiO2 sol modification on the strength of cement mortar

Abstract A study was conducted through quantitative calculations on the correlation between the micron-scale pores and the strength of nano-SiO2 (NS) sol reinforced cement mortar. The strength, pore structure, and microstructure of NS sol modified mortar were investigated, and the mortars were made equivalent to a two-phase material comprised of pores and mortar matrix; the model was applied to conduct a quantitative analysis of the correlation between pores and the strength. According to the research results, the modification made to the mortar using the NS sol led to significantly increased early strength and the level of porosity was also increased. Furthermore, the addition of NS caused a change to the C–S–H gel morphology of cement hydration products. As revealed by the results of quantitative analysis, the addition of 1.5 and 3% NS improved the mortar matrix strength by 29.3 and 56.6%, respectively. Moreover, the ratio between the mortar strength (f c) and matrix strength index (K) exhibited a nonlinear correlation with the porosity negatively. It was thus inferred that the increase in mortar porosity inhibited the improvement of mortar strength under the influence of NS sol.

Role of recycled concrete powder as sand replacement in the properties of cement mortar

This paper investigates the properties of cement mortar containing recycled concrete powder (RCP) as sand replacement. Two types of model RCP prepared with designated water-to-cement (W/C) ratios in the laboratory, including recycled cement paste powder (RCPP) and recycled cement mortar powder (RCMP), were utilised in the mortar. The physical, mechanical and drying shrinkage properties of the mortars with various amounts of RCP were investigated, and their microstructure was characterised. The results indicate that increasing the RCP content increases the water demand and decreases the dry bulk density of mortars due to the inferior characteristics of RCP. Replacing sand by up to 10% RCPP prepared with various original W/C ratios or 20% RCMP has a negligible or slightly positive impact on the mechanical properties of mortars. This is mainly attributed to the decreased volume fraction of large capillary pores, air voids and total porosity, which overcomes the negative effects induced by RCP. Specifically, incorporating RCP can reduce the fraction of large voids through its filling effect and slightly promote hydration in mortars. Besides, the drying shrinkage of the mortars increases with the RCP replacement ratio due to the increased volume fraction of mesopores in the RCP mortars. However, an excessive amount of RCP increases the volume fraction of capillary pores and the total porosity of mortars due to the combined action of the decreased packing density and the high porousness of RCP particles, which subsequently decreases the mechanical properties and further increases the drying shrinkage of RCP mortars. In general, incorporating a proper amount of RCP as sand replacement can enhance the sustainability of mortars without compromising their mechanical properties.

Effects of pure carbonation on pore structure and water permeability of white cement mortars

The effects of carbonation on cement-based materials have drawn much attention because of its profound influences on durability performance of concrete structures. Most accelerated carbonation in lab is conducted at RH 50%–70%, which also dries out cement-based materials. The introduced drying action changes pore structure significantly, making the effects of carbonation obscure. To clarify the effects of pure carbonation, water permeability and related micro-structural characteristics are measured on mature mortars, which have been carbonated at water-saturated state. It is found that after carbonation, the porosity of mortars decreases slightly, with finer overall pore structure and lower characteristic pore size. The water permeability also decreases by roughly 40% on average. Based on the pore size distribution curves obtained through the low-field proton nuclear magnetic resonance technique, water permeability is predicted by the Katz-Thompson and Kozeny-Carman theories with satisfactory accuracy. The decrease of water permeability after carbonation agrees well with the reduced characteristic pore length, which quantitatively verifies the observed refinement of nanoscale pore structure due to pure carbonation.

Effect of recycled concrete aggregates and recycled filler on delayed ettringite formation: An experimental study compared to chemical modelling

This study investigates the development of delayed ettringite formation in concrete made of recycled concrete aggregates (RCA) and in mortars with a recycled concrete filler. Experimental results are compared to a chemical model of delayed ettringite formation by Sellier & Multon (2018). Three concretes were formulated, one with natural siliceous aggregates and two others with two different RCA. Concrete and mortar samples were screened for one year for DEF damage. Results show that RCA based concrete did not develop DEF damage, but concrete made of siliceous aggregate did. Recycled filler had a small negative effect on DEF but not as much as limestone filler. Comparison to chemical modelling, including six additional mortars from Yammine (2020), shows that the produced expansive volume cannot be directly linked to the measured expansion. The porosity of mortars and concrete plays an important role in controlling the expansion. All formulations that did exhibit large expansions had developed a maximum volume of expansive products higher than 30% of their porous volume. These results suggest a simple method to predict DEF related expansion in concrete with or without recycled concrete products.

A 3D random porous media model for cement mortar based on X-ray computed tomography

Cement-based materials are typical porous media in which the spatial pores are of vital importance to flow problems, such as chloride ion penetration. This study proposes a three-dimensional (3D) random porous media model to characterize the spatial distribution associated with the porosity in cement mortar. The proposed model addresses the random heterogeneity in material properties using a Weibull random field and an exponential correlation function. The spatial distribution data associated with the porosity of the cement mortar, including the marginal distribution of the porosity and correlation structure of the Weibull random field, are obtained via X-ray computed tomography (XCT). The results indicate that the isotropic exponential correlation function is adequate for characterizing the correlation structure of the Weibull field with a maximum correlation length of 5.7515 mm. Moreover, a comparison of the simulated and measured porosity fields suggests that the proposed model can capture the characteristics of the porosity distribution in cement mortar. Considering the correlation in the porosity leads to a larger variance in the mean porosity of the mortar in the Monte Carlo simulation (MCS). In the example, the chloride diffusion in the cement mortar is illustrated using the proposed 3D random porous media model coupled with finite element (FE) analysis. The effect of the spatial correlation of the porosity on chloride diffusion in cement mortar was discussed from a probabilistic perspective. The proposed model provides insights into considering the properties of heterogeneous materials.