Increase In Cement Content Research Articles

Will More Cement in Your Mixture Hurt You?

An old rule of thumb states that if you need more strength in a concrete mixture, just throw more cement at it. Sometimes that helped, sometimes not. Today many engineers realize that there are many other variables in a mixture that effect strength as much as, or more than, cement content. They also realize that increased cement content in a concrete mixture can lead to a number of effects that may reduce the life of the pavement. Many properties of concrete are adversely affected by over-cementing the mixture. These are discussed to help the reader understand why optimizing the cement content will help produce an efficient mixture that will meet the project requirements. By first determining the voids in the aggregate portion of the concrete mixture and then increasing that volume by an amount necessary for workability, a volume of paste can be determined that will approximate the optimum cementitious content to both maximize strength and also provide a workable mixture. Also discussed are the effects of increasing the cement content in a concrete mixture, including durability, strength, heat generation, shrinkage, set time, workability, CO2 footprint, as well as cost.

Investigating the Effect of Utilizing a Sustainable Stabilizer as a Partial Replacement of Cement on Soil Compressibility and Permeability

Desert soils present some issues that need improvement. Some of these are high permeability and collapsibility potential. These problems are due to the uniform particle size distribution and the lack of particle edges. Soil improvement is required to mitigate these issues. Cement is widely used for soil stabilization but has environmental issues since it is a significant source of CO2 emissions and requires high energy consumption. In this study, the calcined shale material is utilized as a partial replacement for cement to reduce the permeability and compressibility of soils more sustainably. The study considers three cement doses of 5%, 10%, and 15% and four calcined shale percentages of 10, 30, 50, and 70%. A series of falling head permeability and one-dimensional consolidation tests were conducted to examine the performance of cement and calcined shale as stabilizers. The results of the study indicate that the addition of 30% calcined shale as a partial replacement of cement has the most significant effect on the conductivity and compressibility of the soils. An increase in cement content decreases the permeability and compressibility of the soil due to the hydration of cement. Conversely, the conductivity and consolidation of the soil are initially decreased with an increase in the calcined shale up to 30% and then start to increase. In summary, this study reveals that the presence of CS and cement has a substantial effect on the conductivity and compressibility of the soils.

Performance Analysis of Recycled Asphalt Material Foundation Layer and Top Foundation Layer Reviewed from Primary Displacement

This study aims to determine the unconfined compressive strength of recycled materials based on variations in cement content of 1%, 3%, and 5%, as well as the percentage of emulsified asphalt. This study is urgently needed because the massive development of road infrastructure drives an increase in the need for road materials. Utilization of recycled waste from existing asphalt layers and foundation layers is an alternative sustainable and environmentally friendly material. Reusing this material is more efficient if the road damage has not reached the structural stage. Testing in the study was conducted experimentally at the Road Materials Center Laboratory, Bandung, using materials from existing asphalt layers and foundations. Testing includes physical analysis of the material, compaction to determine the optimum water content and maximum dry density, and unconfined compressive strength. The results showed that the unconfined compressive strength with cement content of 1%, 3%, and 5% were 0.70 MPa, 1.70 MPa, and 2.09 MPa, respectively, with primary displacement values ​​of 20 mm, 25.8 mm, and 24.7 mm. Meanwhile, the residual strength value decreased with increasing cement content, namely 76.3%, 66.3%, and 64.3%.

Assessment of the self-healing capacity of PVA fiber-reinforced composites by chloride permeability and stiffness recovery

This paper investigates the intrinsic ability of PVA fiber-reinforced cementitious composites to re-establish the durability properties of the uncracked state. Comparative chloride penetration tests are used as a direct measure to quantify the effect of self-healing on the chloride penetration resistance after cracking. Two different composites with cement to fly ash ratios of 1:1.5 and 1:2.0 were studied under the influence of healing periods of up to 28 days. After inducing cracks between 100 and 120 μm, samples were exposed to chlorides for 72 h and the resulting chloride penetration depth was compared to the unhealed state. Based on this procedure, a durability recovery index was proposed to quantify the material’s ability to re-establish its function as a protective layer after cracking. Results show that after 14 days of self-healing, chloride penetration through cracks was reduced between 81% and 99%. An extended healing period of 28 days leads to further reduction of the penetration depth to 84%–100%, indicating that most of the reaction takes place within the first 14 days of healing. While the stiffness recovery analysis showed that increasing cement content by 20% correlated with the formation of stronger healing products, no significant difference was found regarding crack closure.

Improvement of vibration response of a foundation resting on Salt-Encrusted Flat Soil by cement addition: a numerical investigation

ABSTRACT Excessive vibrations can negatively impact machinery performance by causing misalignment, decreased accuracy, increased wear and tear, and reduced overall operational efficiency. By conducting a numerical investigation on improving vibration response through cement addition to salt-encrusted flat soil, the study aims to enhance the performance and reliability of machine foundations, thereby optimizing machinery operation. The properties of untreated sabkha and cement-sabkha were calibrated to use in the Finite Element Method (FEM) model. The variables investigated have the thickness of cemented sabkha ratio, operation frequency, three types of subsoils (Sabkha and cemented sabkha of 5% and 10%), and vertical amplitude loading. The main findings revealed that the maximum shear modulus (Gmax) increases by 47% with a 5% to 10% increase in cement content. In addition, as the vibration’s frequency increases, the amplitude displacement is observed because the reflected waves become smaller for the foundation resting on cemented sabkha. The natural frequency rises as the thickness ratio and cement amount of cemented sabkha increase. The influence of the thickness ratio on displacement amplitude is considerable when the operation frequency is less than 20 hz. The study implies that engineers can optimize the design of machine foundations to achieve better performance and stability.

Indirect estimation of compressive strength of cement-stabilized mine tailings by using ultrasonic pulse velocity for road construction

This study proposes a correlation formula between the compressive strength, ultrasonic pulse velocity UPV, and dynamic elastic modulus of cement-stabilized mine tailings CSMT. Samples were tested in curing times (1, 7, 14, 28, and 90 days) by cement amounts (2%, 4%, 6%). The findings demonstrated that the strength and wave velocities of CSMT were enhanced due to increased cement content and extended curing periods. A regression equation with a high coefficient of determination (R-square >0.95) was developed to establish a relationship between compressive strength and ultrasonic pulse velocity UPV for tailings containing 6% cement content in both treated types. The study uncovered a strong relationship between pulse velocity and compressive strength in different CSMT mixtures. These findings indicate that UPV tests can accurately, rapidly, and without causing damage, and evaluate the compressive strength of CSMT for road paving. The results improve the advancement of environmentally friendly building materials and showcase the efficacy of non-destructive ultrasonic testing in assessing structural characteristics. The investigation has profound consequences in enhancing the quality and management of road construction industry, and the management of mining waste.

Effect of Grain Size and Porosity/Binder Index on the Unconfined Compressive Strength, Stiffness and Microstructure of Cemented Colombian Sands.

Artificial cementation of granular soils results in improved stabilization, increased stiffness, and greater mechanical strength. The porosity index and volumetric cement content η/Civa is presented as a key measure to study the evolution of different soil stabilization types. However, this index had not been previously studied or adjusted for sands in Colombia. Therefore, this study evaluates the applicability of the η/Civa index on unconfined compressive strength (qu) and stiffness (Go), complemented by microstructural analysis, in four sandy soils from Luruaco (Atlántico), Lorica (Córdoba), Medellín (Antioquia), and Bogotá D.C. The soils were stabilized with Type III Portland cement in dosages of 3%, 5%, 7%, and 9%, and subjected to UCS, ultrasound, and SEM-EDS tests after a curing period of 7 days. It was found that increasing cement content results in higher qu values for the samples, and higher molding density also leads to higher qu values. Additionally, the grain size distribution influenced the adjustment of parameter "a". In the sands from Bogotá and Lorica, with high uniformity, the value of "a" was 1.00. In contrast, mineralogy and particle shape played a predominant role in the sands from Medellín and Luruaco, where the coefficient of uniformity is higher, suggesting a possible inverse relationship between particle angularity and the value of "a".

Sustainable Pervious Concrete with Silica Fume as Cement Replacement: A Review

Pervious concrete is a unique type of concrete with high porosity that allows water to pass through. This characteristic makes it beneficial for various applications, such as stormwater management, groundwater recharge, and reduced heat island effect. However, pervious concrete typically requires more cement than conventional concrete because of its mix design. This increased cement content can be partially replaced with supplementary cementitious materials, such as silica fume. This review article investigates the influence of silica fume on the properties of pervious concrete, including the mechanical properties (compressive strength, splitting tensile strength, and flexural strength), durability (resistance to freeze–thaw cycles and abrasion), and environmental aspects. The article highlights that silica fume can improve the mechanical properties and durability of pervious concrete up to an optimal replacement level. The optimum replacement level of cement with silica fume was found to be 10%–15%. Beyond this level, the performance of pervious concrete decreases. The pervious concrete containing silica fume showed superior abrasion resistance and improved freeze–thaw resistance compared to conventional pervious concrete. In addition, incorporating silica fume in pervious concrete reduces cement usage, leading to a lower environmental impact and more sustainable construction practices. The article also analyzes the limitations of using silica fume, such as the potential for reduced workability because of its fine particle size. Overall, the review suggests that silica fume is a promising supplementary cementitious material for enhancing the performance and sustainability of pervious concrete.

Strength and deformation characteristics of waste mud–solidified soil

The treatment, disposal, and resource utilization of waste mud are challenges for engineering construction. This study investigates the road performance of waste mud–solidified soil and explains how solidifying materials influence the strength and deformation characteristics of waste mud. Unconfined compressive strength tests, consolidated undrained triaxial shear tests, resonant column tests, and consolidation compression tests were conducted to evaluate the solidification effect. The test results show that with an increase in cement content from 5 to 9%, the unconfined compressive strength of the waste mud–solidified soil increased by over 100%, the curing time was extended from 3 to 28 days, and the unconfined compressive strength increased by approximately 70%. However, an increase in initial water content from 40 to 60% reduced the unconfined compressive strength by 50%. With the increase of cement content from 5 to 9%, the cohesion and friction angles increased by approximately 78% and 24%, respectively. The initial shear modulus under dynamic shear increased by approximately 38% and the shear strain corresponding to a damping ratio decay to 70% of the initial shear modulus decreased by nearly 11%. The compression coefficient decreased by approximately 55%. Scanning electron microscopy and X-ray diffraction tests showed that a higher cement content led to the formation of more hydration reaction products, especially an increase in the content of AlPO4, which can effectively fill the pores between soil particles, enhance the bonding between soil particles, and form a skeleton with soil particles to improve compactness. Consequently, the strength of the waste mud–solidified soil increased significantly while its compressibility decreased. This study can provide data support for dynamic characteristics of waste mud solidified soil subgrade.

Comprehensive analysis of cement-stabilised dredged marine soil: Evaluating physical, microstructural, and mechanical characteristics

This study evaluates the index, microstructural, and mechanical behaviour of cement-stabilised soft soil. The marine soil dredged from Hangzhou is taken for the study. Different percentages of ordinary Portland cement (OPC)by dry mass were added to the soils during reconstitution, i.e., 5, 10, 15, and 20%. The reconstituted samples were analysed in the laboratory to determine basic properties such as moisture content, void ratio, density, specific gravity, consistency limits, and particle size distribution. The microstructures of the reconstituted samples were also evaluated through scanning electron microscopy. Results inferred a significant impact on the physical properties of the soil. An increase in cement content increases the consistency limits. Additionally, the specific gravity, plasticity index, and density of the treated soil initially decreased but increased upon further addition of cement content. The microstructure of the soil transformed from a dispersed to a flocculated structure, with larger and denser particles. The change in microstructure was also evident in the particle size distribution, with an increase in cement content leading to larger size particles. Finally, the unconfined compression test conducted on the reconstituted soil indicates a substantial enhancement in strength with higher cement content and prolonged curing periods.

Determination of Poisson’s ratio of coal gangue-based shotcrete materials using a non-contact test method

ABSTRACT Preparing shotcrete materials using coal gangue is an effective method of disposal and use of gangue solid waste, while testing the Poisson’s ratio of coal gangue-based shotcrete materials (CGSM) is an important step in evaluating the mechanical properties of such materials. Therefore, to study the evolution of the Poisson’s ratio of CGSM under different influencing factors, detailed test schemes and procedures were designed based on the non-contact test method of Poisson’s ratio. The accuracy of the non-contact test method is verified. In addition, changes in the Poisson’s ratio of CGSM under different factors were studied. Results show that the Poisson’s ratio of CGSM tends to reduce with prolonged curing. When the particle sizes of coal gangue are 0 ~ 2.5 and 2.5 ~ 5 mm, fine particles can fill interstitial voids in shotcrete materials. As the mass concentration and cement content increase, the Poisson’s ratio of CGSM gradually decreases; as the sand content rises, the Poisson’s ratio gradually increases.

Macro-micro mechanical behavior of saturated cemented sands during drained triaxial shearing

To enhance the understanding of the macro-micro mechanical behavior of cemented sands, a series of drained triaxial shearing tests were conducted on saturated cemented sands with varying cement contents and confining stresses. These tests incorporated high-performance acoustic emission (AE) monitoring and an environmental scanning electron microscope (ESEM) technique. The results yielded quantitative interpretations of macro-mechanical response, microstructural variation, and AE behaviors. Specifically, increasing cement content led to an exponential reduction in porosity (or pore area ratio) and a power increase in pore number, possibly due to the production of hydration products that segment large pores. Relationships were established among peak strength (or AE hits), cement content, and confining stress. However, AE trends diverged from those observed in peak strength due to microstructural modifications under different cement contents and their resulting differences in micromechanical behavior during shearing. General relationships between AE rate and mechanical parameters were established during the initial shearing stage, regardless of cement content and confining stress. Moreover, AE evolution efficiently characterized subtle variations in failure patterns due to its high sensitivity to failure-induced structural modifications. These contributions have the potential to establish a non-destructive field evaluation framework and provide guidelines for the efficient utilization of cemented soils in geological and geotechnical engineering applications.

Erosion Potential of Stabilized Support Layers for Concrete Pavements and Overlays

The performance of concrete pavements and overlays is highly dependent on the uniformity, durability, and stability of the underlying support layers. Erosion of support layers can lead to pavement distresses and a reduction in pavement life. A review of existing erodibility performance tests that assessed stabilized support layers was first conducted to identify and evaluate their suitability for adaptation. The Hamburg wheel tracking device (HWTD) test was selected to assess the erosion potential of asphalt and cement stabilized support layers. Field testing with distress surveys, falling weight deflectometer, and coring was completed to obtain HWTD specimens and link laboratory results to pavement performance. The HWTD test was performed on cores obtained from in-service cement and asphalt stabilized support layers, a cold in-place recycling (CIR) mixture, and cement stabilized laboratory mixtures. As expected, an increase in cement content within cement stabilized mixtures decreases the likelihood of erosion with the HWTD. Additionally, conventional asphalt stabilized base layers were highly erosion resistant. Erosion resistant cement stabilized bases (including full-depth reclamation) should target an average HWTD erosion depth ≤2 to 4 mm (0.08 to 0.16 in.) after 10,000 load cycles based on the functional classification and expected traffic volume of the pavement section. Likewise, asphalt stabilized bases (including CIR and support layers for concrete overlays) should target an average HWTD erosion depth ≤12.5 mm (0.5 in.) after 7,500 load cycles with performance grade 64 binder.

Enhancing geomechanical characteristics of calcium sulfoaluminate (CSA) cement-treated soil under low confining pressures

This study examines the efficacy of employing calcium sulfoaluminate (CSA) cement, an environmentally friendly binder, for enhancing the geomechanical characteristics of sand, particularly under low confining pressure conditions. A series of triaxial consolidated drained tests were performed on sand samples treated with varying content (5, 7, and 10%) of CSA cement and 10% ordinary Portland cement (OPC) under various low confining pressures (50, 100, 200, and 400 kPa). The test findings demonstrated the importance of cement content and confining pressure on the mode of failure, stress–strain and volumetric behavior, failure characteristics, and shear strength parameters of the treated quartz sand. After a curing period of 14 days, samples treated with 10% CSA cement exhibited a remarkable 212% increase in peak deviator stress and an 89% reduction in axial strain at failure, indicating higher initial stiffness compared to untreated samples under a 400 kPa confining pressure. Furthermore, the samples treated with 10% CSA exhibited higher peak deviator stress, initial stiffness, and strength development compared to those treated with 10% OPC. The scanning electron microscopy analysis provides insights into particle breakage and bond degradation processes, which increase with confining pressure in CSA-treated samples. Also, the mode of failure analysis reveals a transition from ductile to slightly brittle behavior with increasing cement content. Notably, the geomechanical properties of the treated material emphasized the significant impact of CSA cement on soil improvement. Thus offering a sustainable alternative for soil improvement in construction projects.

Evaluation of hydration behavior of cement-stabilized macadam via electrochemical impedance spectroscopy

Electrochemical Impedance Spectroscopy (EIS) was an important method for continuous and non-destructive monitoring of cement hydration process. The EIS, porosity and compressive strength of cement-stabilized macadam with different structures and cement content at different hydration ages were tested. By fitting the quasi-Randles equivalent circuit model, the electrochemical parameters were obtained to analyze the hydration degree and microstructure changes of materials during the hydration process. The mathematical models of electrochemical parameters and hydration parameters in skeleton dense structure, suspension dense structure and skeleton pore structure were established. The results show that the electrochemical parameters of the quist-Randles equivalent circuits model had a fine correlation with the hydration parameters of cement-stabilized macadam materials. The impedance curves of different cement-stabilized macadam structures had the same variation laws under different cement contents. As the hydration age increased, more hydration products formed and filled the internal pores of the structure, leading to the gradual formation of a dense structure in the material, further reducing the porosity and increasing the pore solution resistance RS. Meanwhile, the increase in cement content also led to a gradual increase in the compressive strength of the sample. The research results show that Rs was inversely proportional to porosity and had a good logarithmic relationship with compressive strength.

Monitoring the hardening process of cemented soil with polymer optical fibre

Cement-soil can effectively improve the mechanical characteristics of soft soil and reduce the deformation of foundations through the physical and chemical processes of cement hydration. After mixing cement with soft soil, the hydration reaction of cement consumes a certain amount of water, which leads to a decrease in the water content. The early strength of cement-soil refers to the undrained shear strength within a few hours of mixing. The initial setting time of cement-soil can reflect its early strength development. In this study, polymer optical fibre (POF) sensors are used to visually monitor the early strength of cement-soil with different cement contents; the monitoring results show that the POF sensor can effectively visualize the hydration process of cemented soil. The cement-soil hydration process is divided into three stages: the initial setting time of the cement-soil is 13-15 h, and the final is 33-41 h. Furthermore, the cement content significantly influences the initial and final setting times of cement-reinforced soil. As the cement content increases, the initial and final setting times of the cement–soil decrease. This study proposes a new method for monitoring the strength of cement-reinforced soils.

Influence of the wide range cement content on the properties of cement–treated marine soft soil and bound method of semi–solidified soil

In order to identify the upper and lower boundary cement content for modified marine soft soil (i.e., semi–solidified soils), physical, compaction, and unconfined compressive strength tests of cement–treated soils with a wide range of cement content were carried out to study their variation law of physical–compaction–mechanical properties. The test results show that cement–treated soil can be divided into uselessly treated soil, semi–solidified soil, and solidified soil with the increase of cement content. For uselessly treated soil, the treated soil cannot be compacted even after compaction delay. Cement hydration in semi–solidified soil significantly improved its physical and compaction properties. However, compaction destroyed the skeleton structure of solidified soil, resulting in lower strength than compacted semi–solidified soil. Based on the cement–soil particles–water relationship, soil particles–water transfer mechanism, cement hydration mechanism and the state of soil particles–water before and after treated, the bound method of semi–solidified soils based on cement content and moisture content ratio of untreated soil was established. The test parameters of bound method are simple, easily obtained and have small dispersion, which provides design basis and theoretical support for resource utilization of marine soft soil.

Investigation of Viscoelastic-Plastic Properties of Fresh Cemented Gangue Fly Ash Backfill Slurries

In underground filling mining, freshly prepared cemented gangue-fly ash backfill (CGFB) slurries are typically piped into the gobs. The rheological properties of backfill slurry during pipeline transportation have a direct impact on the transportation characteristics, which in turn affect pipeline blockage and wear. In this paper, the rheological behavior and viscoelastic-plastic properties of CGFB during pipeline transportation are investigated. The effects of different solid content and cement content on resistivity were tested experimentally, and their viscoelasticity and plasticity were analyzed. The results show that with the increase in solid phase content and cement content, the viscosity, yield stress, and energy storage modulus of the materials showed an increasing trend. The viscosity and yield stress of the material both increased, reaching 32.77% and 51.22%, respectively. It was found by the dynamic shear test that in the low-strain region, the material showed a more significant elastic nature of the solid, while in the high-strain region, the viscosity of the material gradually increased. Cement has a substantially lower resistivity than fly ash and gangue, and with the increase in solid concentration, the resistivity of the material shows an increasing trend. With the increase in cement content, the resistivity generally shows a decreasing trend, but it should be noted that the resistivity change trend may tend to stabilize after the cement content exceeds 12%. The study’s findings can aid in understanding the rheological properties of CGFB and its viscoelastic-plastic behavior during the underground filling and conveying process, which can provide a reference basis for research and application in related fields.

Quantitative assessment of cement bridges and voids in cement-stabilized permeable base materials using a mask R-CNN-based CT image segmentation strategy

Accurate extraction of aggregates, cement bridges, and voids in permeable cement-stabilized base materials (PCBM) is a challenging task. This paper proposed a segmentation and reconstruction paradigm for raw CT slice images using a mask regional convolutional neural network (Mask R-CNN). The results demonstrate that the proposed method effectively segments and reconstructs unclear raw CT slice images, providing a convenient and advanced tool for accurately assessing the meso-scale structures of cement bridges and voids in PCBM prepared with different combinations of cement content and compaction force. An increased cement content or compaction force results in the migration of cement paste, leading to thicker localized cement bridges and blockage of permeable pore space. This phenomenon further disrupts the homogeneous distribution of cement bridges and voids. An increased compaction force tends to elongate and flatten pore throats, while an increased cement content may clog voids, rendering them impermeable. The vertical permeability of the PCBM is significantly greater than the horizontal permeability, which should be considered during material design optimization. The proposed method could serve as a reference for microscopic analysis and structural design optimization of PCBM.

Experimental study on the evolutive shear fracture behaviour and properties of cemented paste backfill

Shear stress prevalence in in-situ cemented paste backfill (CPB) makes understanding mode-II fracture behaviour and properties vital for the mechanical stability of the backfill structure. This study delves into the effect of cement content on CPB's shear fracture behaviour and properties. Results reveal that higher cement content leads to notable changes in load-displacement characteristics under mode-II loading, including steeper pre-peak slopes, higher peak loads, smaller peak-load displacements, and minimal post-peak resistance. However, increased cement content does not linearly enhance fracture properties. Furthermore, this study proposed predictive models to capture the influence of cement content on the evolutive fracture properties.