Portland Cement Concrete Mixtures Research Articles

The impact of utilizing waste tires and plastic on concrete pavement performance and environmental benefits

ABSTRACT This study focuses on the integration of sustainable practices in construction projects by utilizing waste materials like waste plastic and rubber tires, specifically in Portland Cement Concrete (PCC) mixes. While adding plastic waste fibers (PF) has shown to enhance the performance of rigid pavements, the environmental and cost benefits are limited. On the other hand, using tire-derived aggregates (TDA) compromises the mechanical properties of PCC but offers significant environmental advantages and cost reductions. This study explores the outcomes of combining PF and TDA in PCC mixtures, assessing their impact on pavement performance through KENPAVE software, which evaluates deflections and cracking indices. Additionally, the environmental and cost effects of this combination are analyzed using the PaLATE 2.0 software, aiming to develop sustainable and economically viable rigid pavements.

Impact of Simultaneous Carbonation and Chloride Attack on Chloride Diffusion in Portland Cement Concrete Mixtures Blended with Natural Zeolite and Silica Fume

Impact of Simultaneous Carbonation and Chloride Attack on Chloride Diffusion in Portland Cement Concrete Mixtures Blended with Natural Zeolite and Silica Fume

Enhancing corrosion resistance of RC pipes using geopolymer mixes when subjected to aggressive environment

The durability of reinforced concrete (RC) pipes depends upon the corrosion resistance of the reinforcing steel and the resistance of concrete mixes against an aggressive environment. This research paper aims to compare the performance of R.C. pipes made of ordinary Portland cement (OPC) concrete mixtures with others made of two different geopolymer concrete mixes based on different ratios of granulated blast furnace slag (GBFS), fly ash (FA), and pulverized red brick (RB) subjected to three different environments, ambient, tap water (TW), and an aggressive environment, and a solution of 10% magnesium sulfates + 5% chloride (MS-CL). An accelerated corrosion setup has been applied to accelerate the corrosion process in the tested samples. The evaluation of change of compressive strength of concrete and microstructure of different mixes was investigated too. Fourier transform infrared (FTIR) spectroscopy has been studied on all pipes. Geopolymer concrete mixes based on 90% GBFS and 10% RB show better results in all cases. Geopolymer concrete mixes based on 63% GBFS, 27% FA, and 10% RB increase the concrete compressive strength in the magnesium sulfate and chloride environment by 5% compared to tap water. It can be concluded that the geopolymer concrete mixes produced of 90% GBFS and 10% RB perform well under all environments, and its microstructure shows stable behavior in an aggressive environment.

Microstructural integrity characterization of cement-based construction materials

In this paper, a new micromechanical framework to characterize the microstructural integrity and predict the effective properties of multi-phase particulate composites is presented. Within the framework, a new scalar micromechanical parameter is identified and used to derive new expressions for the effective elastic properties of particulate composites using the mean-field homogenization technique. The derived equations are then generalized for composites with multiple phase constituents. The generality of the proposed framework is demonstrated by combining the derived equations with the existing homogenization techniques such as the Mori–Tanaka method and the Generalized Maxwell’s Approach (GMA). The results show that the theory delivers consistent estimates of the effective properties of two-phase elastic composite materials. The new scalar micromechanical parameter is also used to characterize the microstructural integrity of both asphalt mixtures and Portland cement concrete. The results show that the new scalar micromechanical parameter correlates well with multiple key fundamental properties of asphalt concrete mixture, including the creep rate, the fracture energy density, the endurance limit, and the damage rate parameters. The results also show that the new micromechanical framework can be used to accurately predict the effective modulus properties of Portland cement concrete mixtures.

Sustainable concrete formulations to mitigate Alkali-Silica reaction in recycled concrete aggregates (RCA) for concrete infrastructure

The Alkali-Silica Reaction (ASR) is a Portland Cement Concrete (PCC) distress of greater relevance worldwide, and several authors have successfully mitigated ASR with improved concrete mixture formulations. These concrete mixtures are mainly associated with incorporating Supplementary Cementitious Materials (SCM), which usually involve recycled materials or co-products from other processes, thus contributing to concrete production sustainability. Due to global warming and irreversible impacts on the planet, the circular economy and sustainability concepts are now of particular concern in the cement and concrete industry. Different ways to reduce the environmental impacts of Portland cement concrete include using SCM and Recycled Concrete Aggregates (RCA) to replace natural aggregates. Despite there are no concrete structures made with RCA that have been reported showing signs of ASR, it is essential to check the potential reactivity of RCA to take the necessary corrections to use them safely. This paper includes a laboratory investigation on mitigating the ASR of RCA in PCC production by using several SCM (fly ash, slag, and silica fume) to achieve a more sustainable material, reducing the production cost and the environmental load associated. Results indicate that replacement levels of fly ash (FA, 20%), slag (SL, 40%), and silica fume (SF, 10%) were able to mitigate the alkali-silica reaction of one source of RCA successfully. The optimum dosage of RCA is suggested to be between 25 and 50% (by weight of total coarse aggregate) for mixes containing fly ash and 50–100% for silica fume and slag mixes, respectively. The work also involves a life cycle assessment (LCA) to quantify the environmental benefits depending on the SCM used and the aggregate portion replaced by RCA on PCC mixtures. SCM and RCA in concrete mixtures significantly reduced greenhouse gas (GHG) emissions and energy demand due to lower Portland cement contents.

Multiscale Characterization to Examine the Effects of Aggregate Properties on Aggregate-Paste Interphase in Cement Concrete Mixtures

AbstractThis study aims to test the effects of aggregate properties on the features of aggregate-paste interphase in portland cement concrete mixtures. The microstructural, chemical, and nanomechan...

The corrosion rate and microstructure of Portland cement and calcium aluminate cement-based concrete mixtures in outfall sewers: A comparative study

This paper presents a comparative study on the corrosion rate and microstructural characteristics of Portland cement (PC) and calcium aluminate cement (CAC) -based concrete mixtures subjected to microbially-induced sulphuric acid (biogenic H2SO4) attack for 120 months in an outfall sewer. The higher amount of the amorphous AHx within the CAC-based concrete matrix provides a higher neutralisation capacity to the attacking acid, thus giving it better performance than PC-based concrete mixtures during biogenic H2SO4 attack. In addition the results show that the biogenic corrosion rate of PC-based concrete mixtures increases with the cement content while that of CAC-based concrete mixtures decreases with the cement content.

Controlled low-strength materials for pavement foundations in road tunnels: feasibility study and recommendations

This paper presents the results obtained during a laboratory and field investigation which focused on the assessment of the feasibility of using controlled low strength materials (CLSMs) in pavement foundations of road tunnels. The CLSM considered in the study, which contained a significant amount of recycled asphalt pavement, was designed by optimizing its flowability and by considering its sensitivity to changes in cement dosage. For comparative purposes, a standard low-strength Portland cement concrete mixture was also included in the investigation. Both mixtures were produced in a Portland cement concrete batching plant and were thereafter subjected to laboratory tests for the evaluation of flowability, consistency, compressive strength, California bearing ratio and resilient modulus. Furthermore, full-scale slabs constructed with the two mixtures were subjected to plate loading tests and to the transit of a fully-loaded heavy vehicle. Obtained results indicated that both mixtures are suitable for the formation of pavement foundations since they exhibit a short-term mechanical behavior which is comparable to that of standard granular sub-base materials. However, the CLSM proved to be superior in terms of its improved flowability, easier long-term excavatability, lower production cost and enhanced sustainability. Finally, recommendations for future applications of cement-bound materials in pavement foundations were provided in the form of preliminary performance-based acceptance criteria.

Carbonation Resistance of Sustainable Concrete Using Recycled Aggregate and Supplementary Cementitious Materials

Green concrete is a recent sustainable practice in UAE that was enforced by Dubai Municipality in construction field within the emirate of Dubai to reduce the carbon foot print in construction industry and to increase the durability of the structures. This led the construction industry to reduce the usage of ordinary portland cement by replacing it with supplementary cementitious materials (SCMs) such as Grand Granulated Blast Furnace Slag (GGBS) and flyash (FA). Incorporating GGBS or FA in concrete mixtures can improve durability parameters of hardened concrete, such as resistance to water permeability, reduced water absorption and chloride penetration. This ultimately increases the structure’s service life by increasing the threshold of concrete mixture for chloride induced corrosion. On the other hand, carbonation induced corrosion to concrete is usually being ignored or forgotten generally, due its usual slow rate ingression in plain portland cement concrete mixtures. Several studies showed that incorporating some types of SCM – especially at high percentage - can reduce the concrete resistance to carbonation. Additionally and for concrete with recycled aggregate, carbonation investigation should be taken into consideration. This is since recycled aggregates are reused aggregates that are extracted from demolished structures and buildings which were already subjected to different environmental exposures and deteriorations. Unlike chloride penetration, there is no direct ASTM standard test to anticipate the concrete mixture resistance to carbonation at early ages. In this study, concrete mixtures with flyash and different recycled aggregate replacement percentages are investigated for carbonation resistance in accelerated proposed method, considering concrete mixtures’ key parameters like water-cement ratio, and total cement content. The results are analyzed to arrive to pertinent conclusions for the best utilization of sustainable concrete for carbonation resistance.

INNOVATION OF USING WASTE MATERIALS AS A REPLACEMENT OF CEMENT IN PCC

Portland cement (PC) is used in the production of Portland cement concrete (PCC) to construct many infrastructure components such as rigid pavements. This research aims at studying the effect of using common waste materials in Egypt as a replacement of PC in the production of PCC. Using waste materials in concrete production could be an effective measure in maintaining the environment, improving the properties of PCC, and reducing cost of production. Nowadays, pavement technologist and researchers had put their interests on nanotechnology. This paper outlines the innovation of using Nanotechnology-based waste materials as a replacement of PC to enhance the physical and mechanical properties of PCC. The experimental work, using waste materials such as ceramic waste (CW) and ground-granulated blast-furnace slag (GGBFS), was conducted in five phases. In phase 1 and phase 2, different rations were used for CW and GGBFS by weight of cement, respectively. In phase 3, the best three ratios of CW were used with the best ratio of GGBFS. In phase 4, different ratios of CW and GGBFS were used with a standard ratio of Un-Hydrated lime (UHL). In phase-5, various mix of CW, GGBFS and UHL were suggested based on previous results. Modified PCC mixtures were produced, tested and compared to the conventional concrete mixture. Results showed that the cost of PCC production is reduced by 34% in average comparing to the control mix.

Influence of ground pumice on compressive strength and air content of both non-air and air entrained concrete in fresh and hardened state

Study investigates the influence of ground pumice (GP) addition on compressive strength and air content of air entrained and non-air entrained concrete. Control Portland cement concrete was prepared by keeping the binder amount at 400 kg/m3 with water binder (W/B) ratio 0.45. Air entrained Portland cement concrete mixtures were also prepared by addition of 0.025%, 0.05% and 0.075% air entraining agent (AEA) dosages to control Portland cement concrete. All Portland cement concretes mixtures were modified by inclusion of 10%, 15%, 20% and 25% GP as cement replacement in mass basis, and then concretes containing ground pumice were obtained. Air contents of all fresh concretes were measured. Entrained air void area values on cut surface of hardened concrete were determined by image processing technique. Increase in air entraining agent dosage content in fresh concrete exhibited an increase not only in air content but also flow diameter value of fresh concrete. Addition of ground pumice as a cement replacement in concrete caused reduction in air content and flow diameter, however, it increased compressive strength of air entrained concrete. Compressive strength values related inversely with the air contents of fresh concrete as well as air void area values of hardened concrete computed by image processing technique. Air contents of fresh concrete and image processing void area values of hardened concrete has shown a good relationship between themselves. Image processing can be used to measure air content of hardened concrete.

Evaluation of pure and mixed modes (I/III) fracture toughness of Portland cement concrete mixtures containing reclaimed asphalt pavement

The usage of waste materials in industrial application is one of the main issues around the world. The reclaimed asphalt pavement is one of the waste materials that due to environmental and economical benefits is usually used in road construction. This research study investigates the fracture toughness of concrete mixtures containing different percentages of reclaimed asphalt pavement (i.e. 0, 15, 30 and 45%). For this, a large number of cracked disc shape specimens containing different percentages of reclaimed asphalt pavement were loaded in pure (I and III) and mixed (I/III) modes at temperatures of −25 °C, 0 °C and +25 °C. The results of this research indicate that the reclaimed asphalt pavement decreases the fracture toughness of the concrete mixture in pure and mixed modes (I/III). Meanwhile, the results show that by decreasing the temperature, the fracture toughness of the concrete mixtures containing reclaimed asphalt pavement increases.

Resonant column testing on Portland cement concrete containing recycled asphalt pavement (RAP) aggregates

This study deals with material properties of Portland cement concrete (PCC) made with aggregate that is replaced with recycled asphalt pavement (RAP). A series of PCC mixtures were produced and tested in uniaxial compression using RAP aggregate as substitute of fine and coarse natural aggregate. The main variable was the percentage content by weight of RAP aggregates in the concrete mixture. Both fresh and hardened properties of concrete were examined. Moreover, a relatively new non-destructive technique (free-free resonant column – FFRC) was used to measure concrete’s elastic modulus. The experimental results indicate that the compressive strength and the elastic modulus decrease with increasing RAP aggregate replacement, while all mixtures containing RAP aggregates remain workable. Additionally, the replacement of fine natural aggregates has a more pronounced effect on the examined properties. Finally, the FFRC can provide good estimation of elastic modulus.

Rheology of self-consolidating concrete in hot weather conditions

The rheological properties of fresh concretes incorporating various supplementary cementitious materials (SCMs) in binary and ternary blends were investigated as a function of mixing time, temperature and SCM dosage. Two types of SCMs were tested: silica fume and fly ash. Ordinary Portland cement concrete mixtures were designed with a constant water to cementitious materials ratio of 0·36 and incorporating a fixed dosage of polycarboxylate-based high-range water-reducing admixture. Self-consolidating concrete (SCC) mixtures were continuously mixed for up to 110 min using a drum mixer at different ambient temperatures (25, 30, 35 and 40°C). Rheological testing was performed using a BT2-type concrete rheometer. The relative yield stress was found to have an exponential correlation with the slump flow. The relationship between the relative yield stress and relative viscosity was investigated. The aim of this study was to gain understanding into the contribution of SCM type and dosage to mitigate the harsh effects of hot temperature and prolonged mixing on the rheology of green SCC mixtures. The findings of this study are of practical significance that can provide realistic recommendations on the use of SCMs in hot weather conditions.

Mix design formulation and evaluation of portland cement concrete paving mixtures containing reclaimed asphalt pavement

One potential solution to reduce the amounts of extra reclaimed asphalt pavement (RAP) stockpiles is to use RAP as an aggregate replacement in portland cement concrete (PCC).This study investigated whether partial replacement of virgin coarse aggregate by coarse RAP is a practically viable option to formulate PCC paving mixtures. The results showed thatreplacing virgin coarse aggregate by coarse RAP with sufficient intermediate size particles offers the benefits of achieving dense combined aggregate gradation. Measuring relevant mechanical properties followed by developing a procedure to determine optimum RAP replacement levels and guidelines and recommendations for designing PCC containing RAP were conducted and presented in this paper.

A Review on Fly Ash Based Geopolymer Rubberized Concrete

Utilization of waste materials such as waste tire rubber in the building industry can help prevent environmental pollution whilst contributing to the design of more economical buildings. Preliminary studies show that workable rubberized portland cement concrete mixtures can be made provided that appropriate percentages of tire rubber are used in such mixtures. This article provides the overview of some of published paper using tire waste rubber in portland cement concrete. The researchers mostly investigated the properties of fresh and hardened concrete. The workability, density, air content, unit weight, compressive strength, modulus of elasticity, freezing and thawing resistance, abrasion resistance and thermal properties of the waste tire rubber in concrete were discussed.

The effect of the scrap/DRI ratio on the specification of the EAF dust and its influence on mechanical properties of the concrete treated by its dust

Electric Arc Furnace Dust (EAFD) is a by-product of steel production. One of the most suitable ways to immobilize this toxic waste is adding it to the concrete mixture. According to the increasing trend of the world cost of the scarp and decreasing scrap sources, some manufacturing plants prefer to use the Direct Reduced Iron (DRI) instead of the scrap. This study investigated the characteristic of EAFD samples with different scrap/DRI ratio by XRF, XRD, SEM and BET analysis. It has been observed that zinc oxide (ZnO) content varies from 1.5 to 9.7wt% while scrap/DRI ratio increases from 0 to 0.724. The produced EAFD was added to Portland cement concrete mixture in different amounts (0, 5, 10wt%). It was found that the initial setting time of the concrete specimens was retarded by adding the EAFD with different scrap/DRI ratio. Moreover, addition of 10wt% EAFD from 0 to 0.724 scrap/DRI ratio increased the compressive strength of the concrete specimens up to 55.1MPa.

An extended chemical index model to predict the fly ash dosage necessary for mitigating alkali–silica reaction in concrete

Currently, the concrete prism test per ASTM C1293 or RILEM AAR-3 is considered the most reliable accelerated test to determine the dosage of pozzolans to suppress alkali–silica reaction (ASR) in concrete. However, the test takes 2years, which makes it impractical as a mixture design tool for new concrete construction. In the present work, a multiple nonlinear regression model is developed for predicting the fly ash dosage necessary to mitigate ASR per CPT. The model uses the oxide compositions of Portland cement and fly ash as well as the reactivity of the aggregates. Seventy-six experimental data points on CPT expansion results for plain Portland cement and fly ash-blended concrete mixtures were used to develop and evaluate the model. The model successfully predicts the fly ash required to mitigate ASR for different aggregates, cement, and fly ash combinations. The prediction errors in most cases meet ASTM C1293 multi-laboratory precision criterion.

Drying Shrinkage of Slag Blended Fly Ash Geopolymer Concrete Cured at Room Temperature

Recent studies have shown that blending of ground granulated blast furnace slag (GGBFS) with low-calcium fly ash can have significant effects on the setting and early strength development of geopolymers cured at room temperature. This paper presents the shrinkage behaviour of geopolymer concrete mixtures in which class F fly ash was replaced with 10% or 20% GGBFS and the sodium silicate to sodium hydroxide (SS/SH) ratio was either 1.5 or 2.5. Shrinkage of 4 geopolymer and 1 ordinary Portland cement (OPC) concrete mixtures cured at room temperature were studied. Comparisons are made between the shrinkage behaviours of geopolymer concretes with different mixture proportions and those of the OPC concrete. It was found that shrinkage decreased with the increase of slag content and decrease of SS/SH ratio in geopolymer concrete cured at room temperature. The shrinkage of geopolymer concrete up to the age of 180 days was found to be comparable to that of OPC concrete of similar compressive strength. Thus, shrinkage of geopolymer concrete could be reduced to values within the limit recommended in the Australian Standards for normal OPC concrete.

Chemical, Mechanical, and Durability Properties of Concrete with Local Mineral Admixtures under Sulfate Environment in Northwest China.

Over the vast Northwest China, arid desert contains high concentrations of sulfate, chloride, and other chemicals in the ground water, which poses serious challenges to infrastructure construction that routinely utilizes portland cement concrete. Rapid industrialization in the region has been generating huge amounts of mineral admixtures, such as fly ash and slags from energy and metallurgical industries. These industrial by-products would turn into waste materials if not utilized in time. The present study evaluated the suitability of utilizing local mineral admixtures in significant quantities for producing quality concrete mixtures that can withstand the harsh chemical environment without compromising the essential mechanical properties. Comprehensive chemical, mechanical, and durability tests were conducted in the laboratory to characterize the properties of the local cementitious mineral admixtures, cement mortar and portland cement concrete mixtures containing these admixtures. The results from this study indicated that the sulfate resistance of concrete was effectively improved by adding local class F fly ash and slag, or by applying sulfate resistance cement to the mixtures. It is noteworthy that concrete containing local mineral admixtures exhibited much lower permeability (in terms of chloride ion penetration) than ordinary portland cement concrete while retaining the same mechanical properties; whereas concrete mixtures made with sulfate resistance cement had significantly reduced strength and much increased chloride penetration comparing to the other mixtures. Hence, the use of local mineral admixtures in Northwest China in concrete mixtures would be beneficial to the performance of concrete, as well as to the protection of environment.