Mix Design Parameters Research Articles

Evaluation of the HMA performance using combined effects of marble waste dust filler and superpave aggregate gradation

ABSTRACT During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial sector that produces huge waste. Thus, the main purpose of this study is to evaluate the combined effects of marble waste dust filler and Superpave aggregate gradation on the performance of HMA. Based on the Marshall Mix design, seventy-two (72) specimens were produced from three below-restricted zone (BRZ) of Superpave gradation (BRZ4, BRZ5, & BRZ6) by using the 0.45 power chart. The design gradation obtained to be BRZ5 with 4.96% OBC with corresponding values 9.13 KN of stability, 2.96 mm of flow, 73.51% of VFA, 15.73% of VMA, 2.308 gm/cm3, of bulk density and 4% of air void. The crushed stone dust filler was partially replaced by Marble Waste Dust filler (under No. 200 sieve) at replacement rate of (1%, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5%) by keeping design gradation and OBC constant. The test showed satisfactory results. The Marshall mix design parameters of all mixtures are within specification limit under international and local specifications. Marble waste dust filler when blended with a BRZ of Superpave gradation indicated a substantial effect on Marshall stability with 10.18 KN value at 3% MWD filler content.

Characteristics of metakaolin-based geopolymer concrete for different mix design parameters

Geopolymer is emerging as a potential alternative material to the ordinary Portland cement (OPC) owing to its energy efficiency and environmental protection. However, the effect of the mix design parameters on the behavior of geopolymer concrete (GPC) produced using local metakaolin (MK) is not well established. This paper presents findings from a comprehensive experimental program to study the effect of various mix design parameters on the properties of fresh and hardened MK-based GPC. Seventeen mixes were cast in four groups to investigate the effect of four parameters, including sodium silicate to sodium hydroxide ratio, alkaline solids to MK ratio, aggregate content, and water to solids ratio on the properties of GPC. The investigated properties included workability, density (wet and dry), development of compressive strength with age, splitting tensile strength, ultrasonic pulse velocity, water absorption, and horizontal abrasion resistance. Besides, two reference OPC concrete mixes, equivalent to two MK-based geopolymer mixes, were tested for the sake of comparison. The test results were helpful in developing a better understanding of the behavior of MK-based GPC. Some useful models are proposed for predicting workability, splitting tensile strength, water absorption, and weight loss in abrasion for MK-based GPC. The test results were supplemented and confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis performed on some selected GPC mixes.

Experimental approach on a moving formwork

In a slipforming process, concrete is continuously poured and the formwork simultaneously raised so that the older concrete on the bottom supports the fresher on the top after a few hours of hydration. The objective of the present study is to examine the evolution of the concrete/formwork interface at very early age.An experimental device was designed to measure the evolution of the friction at this interface during the first hydration period. With cement hydration and thus water consumption, pore water pressure decreases and creates suction, which could increase granular stress on the formwork. The role of pore water pressure on formwork friction is investigated. The effect of mix-design parameter such as air content is described. Finally, a model that is able to predict the friction force at very early age (up to the initial setting time) is proposed.

Effects of Compositional and Physico – Chemical Mix Design Parameters on Properties of Fly Ash Geopolymer Mortars

The present experimental study investigated the effects of mix design parameters on workability and compressive strength of fly ash geopolymer (FA – GPC) mortars. Observed effects of the compositional parameters comprising SiO2/FA, Na2O/FA and H2O/FA mass ratios, were inter – linked with those of the physico – chemical mix parameters namely:– the concentration of sodium hydroxide solution, ratio of sodium silicate to sodium hydroxide, and the alkali activator to raw material ratio. In the preparation of mortars, low calcium (Class F) FA was activated using a combined solution of sodium hydroxide and sodium silicate, and mixed with fine aggregate at the aggregate to FA ratio of 2.25. Altogether, seventy – two (72) mortar mixtures were prepared by varying the values of compositional parameters. It was found that the SiO2/FA ratio of 0.08 to 0.11, Na2O/FA ratio of 0.05 to 0.08, and H2O/FA ratio of 0.32 to 0.37, are the optimum ranges that gave the best workability values and compressive strength results, depending on the H2O/FA ratio. In mix design, the various values of compositional parameters are obtained by appropriately combining the aforementioned physico – chemical parameters.

Robotic spray coating of self-sensing metakaolin geopolymer for concrete monitoring

Sensors and new materials can support optimised concrete maintenance, and produce the data needed to justify new, low carbon structural designs. While these technologies are affordable, the process of manual installation in a construction context comes with acute and unfamiliar risks to productivity, personnel safety, and confidence in the quality of workmanship. The installation of smart materials using robotics could address some of these issues, but there are few proofs-of-concept at the time of writing. Here, we present a robotically controlled process for spray coating geopolymers — a class of self-sensing concrete repair materials. By tuning mix design, robotic toolpaths and spray dispenser parameters, we show reliable and automated spray coating of 250 mm2 patches in a laboratory setting. The cured geopolymer has a compressive strength of 20 MPa, and a bond strength to the concrete substrate of 0.5 MPa. Electrical interrogation of patches, via a set of four electrodes, produces strain and temperature measurements of the underlying concrete substrate with resolutions of 1 με and 0.2 °C, respectively. This demonstration multifunctional material deposition using robotics is a step towards remote, traceable, and low-risk technology deployment across civil engineering sectors. This could support more widespread adoption of novel concrete health monitoring and repair systems in future.

Influence of Critical Parameters of Mix Proportions on Properties of MK-Based Geopolymer Concrete

Conventional Portland cement concrete has been extensively used in the past century due to its superior performance compared to other building materials. Recognizing the environmental impact of cement composites and global pressure toward implementation of sustainable construction materials, geopolymer concrete has been introduced as a potential alternative to conventional cement concrete. This study investigates the properties of metakaolin-based geopolymer concrete by employing various mix design parameters based on locally sourced materials. The test results reported herein comprised 16 mixes divided into three groups to understand the influence of various parameters on the workability and compressive strength of the concrete and hence optimizing the mix proportions. The outcome of this research provided insights into the curing conditions, curing age, sodium hydroxide molarity, sodium silicate content, molar ratios of the mix, and aggregate water absorption effect on the geopolymer concrete behavior. A model is proposed for deciding the water to solids ratio based on the total aggregate percentage for workable geopolymer mixes. In order to produce MK-based geopolymer concrete for structural applications, thresholds are proposed for the three molar ratios, namely sodium oxide to silicon oxide, sodium oxide to aluminum oxide, and water to sodium oxide ratios.

A Novel Durability Based Concrete Mix Design Using Supplementary Cementitious Materials and Modified Aggregate Band Gradation

This study focuses on proposing a novel mix design method giving emphasis to the durability of concrete and replacing cement with supplementary cementitious materials (SCMs) at certain percentages. It also includes band gradation of aggregate that merges fine and coarse aggregates to result in a single well-packed combined gradation. Two replacement levels (20% and 35%) of fly ash and three replacement percentages (20%, 65% and 90%) of slag by weight of cement were used to prepare a significant number of concrete mixes. Compressive strength, workability and durability of the prepared mixes were determined. Rapid Chloride Permeability Test (RCPT) was carried out for measuring durability of concrete. From the prepared mixes, it was possible to achieve 90-day RCPT value as low as 216-coulomb and 28-day compressive strength up to 46.5 MPa. Several contour plots were developed correlating the three mix design parameters (compressive strength, slump and durability) with cement and water contents. Finally, using the plotted contours, a mix design process has been organized into five simple steps that can easily be followed in order to proportion an optimized ratio of cement, aggregate and SCMs for preparing durable and economical concrete mixes.

Prediction of Marshall Mix Design Parameters in Flexible Pavements Using Genetic Programming

The mix design of asphalt concrete is usually accomplished in the Iranian ministry of road and transportation according to the Marshall method. Marshall mix design parameters are a function of grading and properties of aggregates, amount and type of bitumen in asphalt mixtures. Therefore, in order to determine these parameters and the optimum bitumen content, many samples with different compounds and conditions must be manufactured and tested in the laboratory, a process that requires considerable time and cost. Accordingly, the necessity of using new and advanced methods for the design and quality control of asphalt mixtures is becoming more and more evident. Therefore, in this study, a genetic programming simulation method was employed to predict the Marshall mix design parameters of asphalt mixtures. Also, multiple linear regression models were adopted as the base model to evaluate the models presented by the genetic programming method. The models proposed here predict the Marshall mix design parameters based on parameters such as the index of aggregate particle shape and texture, the amount and viscosity of the bitumen. The results demonstrated that the proposed methods are more efficient than the costly laboratory method, and genetic programming models with minimal error (identified in this study with RMSE and MAE parameters) and correlation coefficients > 0.9 can predict relatively accurate Marshall mix design parameters.

Non-destructive prediction of strength of concrete made by lightweight recycled aggregates and nickel slag

The aim of this research was to develop an equation to predict the compressive strength of concrete in terms of ultrasonic pulse velocity (UPV) and concrete mix design parameters. A wide range of concrete samples were prepared with varying water-cement ratio and density. The variation of density was achieved by using lightweight recycled coarse aggregate, and high density nickel slag aggregate as fine aggregate. The influences of water-cement ratio and density on the compressive strength were evaluated. In addition, the relationships between density and water-cement ratio with the UPV were also studied. A statistical analysis was then conducted, and a simplified equation was proposed to non-destructively predict the compressive strength of concrete in terms of UPV, water-cement ratio and density. Finally, the equation was validated by comparing with the experimental data collected from various published literature. The results show that the proposed equation could predict the compressive strengths of this study and those from previous literature with an overall coefficient of determination (R2) of 0.88.

A Durable Concrete Mix Design Approach using Combined Aggregate Gradation Bands and Rice Husk Ash Based Blended Cement

This study proposes a new concrete mix design procedure that incorporates durability as an integrated design parameter. Rice husk ash (RHA) was used as supplementary cementitious materials (SCM) with pozzolanic characteristics to enhance durability. Moreover, utilization of RHA as SCM also solves the problem of its disposal in rice producing countries. Two combined aggregate gradation bands were used to develop the proposed mix design since those were proved to perform well in the mix and the resulting concrete exhibited insignificant variation in fresh and hardened properties. It was found that RHA incorporation within cement significantly reduced the permeability of resulting concrete. Consequently, concrete mixes with intended durability could be designed through addition of RHA. A number of contour plots, representing correlations between different design parameters, were generated to be used in different steps of the proposed mix design. Finally, concrete mix prepared following the new mix design approach showed satisfactory validation with respect to targeted design parameters. Thereby, the uniqueness of the proposed mix design of this study lies in the fact that it uses improved aggregate band gradations, utilizes RHA as SCM, takes durability as a mix design parameter and provides sustainable solution to concrete construction in rice producing developing countries like Bangladesh.

Prediction of Properties of Concrete Cured Under Hot Weather Using Multivariate Regression and ANN Models

Concreting in hot weather poses special problems, and the properties of concrete are significantly influenced by mix parameters, construction practices and environmental conditions. In this study, mix design parameters, casting temperature and curing conditions were varied to study the mechanical properties and durability characteristics with the ultimate aim of developing models relating the concrete properties and the experimental parameters. The effect of w/c ratio (0.3 to 0.45), in situ concrete temperature (25 to 45 °C) and curing method (ponding, covering with wet burlap or applying curing compound followed by curing under laboratory or field conditions) was assessed by measuring compressive strength (f′c), split tensile strength (ft), pulse velocity (PV) and depth of water penetration (WP) up to 180 days. Prediction models were developed utilizing quadratic regression models and artificial neural networks (ANNs). The regression models indicated that moist curing, in situ concrete temperature and curing period have a positive impact on the strength parameters and PV, while the former two variables had a negative effect on the WP. The w/c ratio had a significant positive impact on the WP. The concrete properties predicted by ANN models were more accurate than those predicted by regression models. A combined ANN model, developed for predicting strength and PV simultaneously, had a better correlation coefficient compared to ANN models developed for each variable separately. The developed models are expected to assist concrete technologists in the selection of appropriate concrete mixture parameters to obtain concrete with desired properties under hot weather conditions.

Combined effect of binder type and target mix-design parameters in delaying corrosion initiation time of concrete

Ingress of chloride ions is the prime determinant for inducing corrosion damage to marine Reinforced Concrete (RC) structures and subsequent lowered service life. Being attributable to high inherent permeability of concrete, chloride ions ingress can be hindered by appropriate selection of binder types and mix design parameters as means of safeguarding durability concerns while ensuring desired target strength and workability. Commercially available Portland Composite Cement (PCC) consists of general blends of different Supplementary Cementitious Materials (SCM) without any particular regard for durability and there is no proper guideline available to determine the ideal proportion or type of SCM for different mix design requirements. Hence, a comprehensive study is essential in inferring the ideal type and proportion of SCM for a range of common mix design parameters in marine environment. A study has, thereby, been conducted on local concrete mixes, designed for different strengths, with different proportions of fly-ash or slag as SCM for a wide range of water cement (w/c) ratios and target slump values. An overall comparison of both Corrosion Initiation Time (CIT) and compressive strength of each mix has also been evaluated. It has been evident that fly-ash, as SCM, has been significantly effective in enhancing CIT values of concrete mixes, although it affects compressive strength. A considerable effect of target slump range on CIT values has also been observed in the study. Furthermore, generalized graphs have been generated with CIT and strength values for each of the mix parameters with an aim to develop a quantitative guideline to tailor mix designs with ideal SCM selection while maintaining an optimum balance between desired strength, workability and durability concerns in marine environment.

Predicting the Permeability of Pervious Concrete Based on the Beetle Antennae Search Algorithm and Random Forest Model

Pervious concrete is an environmentally friendly material that improves water permeability, skid resistance, and sound absorption characteristics. Permeability is the most important functional performance for the pervious concrete while limited studies have been conducted to predict permeability based on mix‐design parameters. This study proposed a method to combine the beetle antennae search (BAS) and random forest (RF) algorithm to predict the permeability of pervious concrete. Based on the 36 samples designed in the laboratory and 4 key influencing variables, the permeability of pervious concrete can be obtained by varying mix‐design parameters by RF. BAS algorithm was used to tune the hyperparameters of RF, which were then verified by the so‐called 10‐fold cross‐validation. Furthermore, the model to combine the BAS and RF was validated by the correlation parameters. The results showed that the hyperparameters of RF can be tuned by the BAS efficiently; the BAS can combine the conventional RF algorithm to construct the evolved model to predict the permeability of pervious concrete; the cement/aggregate ratio was the most significant variable to determine the permeability, followed by the coarse aggregate proportions.

Prediction of engineering properties of fly ash-based geopolymer using artificial neural networks

Fly ash-based geopolymer has been studied extensively in recent years due to its comparable properties to Portland cement and its environmental benefits. However, the uncertainty and complexity of design parameters, such as the SiO2/Na2O mole ratio in alkaline solution, the alkaline solution concentration in liquid phase, and the liquid-to-fly ash mass ratio (L/F), have made it very difficult to create a systematic approach for geopolymer mix design. These mix design parameters, along with fly ash properties and curing conditions (temperature and time), significantly influence key properties of the material, such as setting time and compressive strength. In this study, an artificial neural network (ANN) was used to develop models for predicting the key properties of high-calcium fly ash-based geopolymer according to its mix design parameters. The correlations between experimental measurements and ANN model predictions of setting time, compressive strength, and heat of geopolymerization were established based on the results of tests on 36, 273, and 72 geopolymer mixes, respectively. The results show that the correlations between the experimental measurements and ANN model predictions of the properties studied are all strong. ANN modeling was found to be a suitable computing method to analyze the effects of design parameters on geopolymer properties and showed that L/F exhibited the greatest effect on setting time, alkaline solution concentration had the greatest influence on compressive strength, and a mole ratio larger than 1.5 significantly impacted heat at the geopolymerization peak. The developed ANN models can be used as guidance for mix design of high-calcium fly ash geopolymer in engineering applications.

Use of incinerated ashes as aggregate in concrete: a compressive strength model

Municipal solid waste, described as household waste, and sewage sludge, arising from wastewater treatment, are produced in large quantities around the world. Incineration plays a key role in the management of these materials, although the process leaves behind residual ashes: municipal incinerated bottom ash and sewage sludge ash, respectively. This paper examines the use of these ashes as aggregate in concrete, focusing specifically on developing a model to estimate the compressive strength of the concrete. The data used in this work have been obtained from a comprehensive search of the globally published literature. The strength model, focusing on 28 d results, has been developed using a regression analysis approach, with the renowned Abram's law as the foundation. The validated model demonstrated that, with favourable ash properties and mix design parameters, compressive strength results close to the control can be targeted with the use of the ashes as a low content aggregate component.

Utilization of waste rubber fiber considering modification in strength reduction factor and its effect on the behavior of concrete

Abstract In this Study, the improvisation on mix design and the analysis of the strength of rubberized concrete is carried out. The carbon fiber is cut in the prescribed ratio and used for the partial replacement of coarse aggregates. The carbon fibers were mixed with the concrete to form a Rubberized concrete. To obtain a rubberized concrete mixture, all mix design parameters were kept constant as given by the IS-456 method except for the coarse aggregate constituents. The coarse aggregate of the concrete was replaced by 5%, 10%, 15%, 20% and 25% of its weight. The fine aggregate was sieved using 2.36 mm in order to pass through the holes of the carbon fiber to make a strong contact with the cement matrix. From some experimental results of compressive strength testing it was observed that both plain and rubberized concrete developing similar strength over the curing period as expected. For all concrete mixtures, the rate of compressive strength developed was high between 7 and 14 days and slow between 14 and 28 days. Also, it was noted that irrespective of the curing period, there was a systematic reduction in compressive strength with increasing rubber content of the composite. Some experimental investigations observed that a high percentage of carbon fiber mixed cylinders took a longer time to crackdown because of the elastic nature of the fibers when bearing the loading. Moreover, it was observed that the above said rubberized concrete did not exhibit brittle failure under compression or split tension.

Determination of moisture damage mechanism in asphalt mixtures using thermodynamic and mix design parameters

The shortcoming of the available laboratory methods for determining the moisture susceptibility of asphalt mixtures has led researchers to think about providing new methods based on effective parameters on moisture damage process. Accordingly, this research is an attempt to provide a prediction model using thermodynamic and mix design parameters that can predict and analyze the performance of asphalt mix against moisture. T he results of this study indicate that the use of anti-stripping additives can generally improve the performance of asphalt mixtures against moisture; however, the type and percentage of these additives should be determined according to the type of aggregate, the type of bitumen and the properties of the mixing plan of the asphalt mix. Based on the proposed model, it can be stated that an increase in cohesion free energy, adhesion free energy, aggregate wettability by bitumen, surface area of aggregates, and apparent asphalt film thickness on the aggregate surface improve the moisture resistance of mixtures. On the other hand, debonding energy, saturation percentage, and permeability negatively affect the asphalt mixture’s resistance to moisture damage.

Natural radioactivity of barite concrete shields containing commonly used supplementary materials

The recycling of hazardous materials within new composites has a sustainable importance as it contributes on the reduction of high radionuclide concentrations. In this study, the effect of cementitious materials i.e. viscosity modifier, silica fume and fly ash on the 226Ra, 232Th and 40K activity levels of barite concrete shields was researched by using different mixing compositions in terms of binder content, w/b ratio and the amount of supplementary cementitious materials. In comparison to cement, silica fume and fly ash used in the production of concrete shields were found to have significantly higher activity levels of 40K, as well as 226Ra, 232Th and 40K, respectively. The 226Ra, 232Th and 40K activity levels of concrete shields range between 2.2 and 20.7 Bq kg−1; 2.6 and 7.0 Bq kg−1; 51.5 and 89.3 Bq kg−1, respectively. These activity values were found similar or less than those of building materials in the world. These satisfactory results are mostly caused by the barite source which has lower radioactivity levels. The concrete mixture details used in the study caused significant variation in the natural radioactivity of barite concrete shields. The introduction of silica fume which has high 40K activity levels and fly ash with high 226Ra, 232Th and 40K activity levels compared to cement and barite aggregate, significantly increased the radiological hazard parameters, although all results were found to be below the limits recommended by international reports. In conclusion, 226Ra activity levels of the concrete shields were significantly increased (up to 8.4 times) by the variation of mix design parameters used in comparison with concrete mixtures that have the least 226Ra activity level. The 232Th and 40K activity levels were as well increased in relatively less amounts (1.7 and 0.73 times higher, respectively).

Production of geopolymer composites by using different alkaline solution/material ratio

This study reports an experimental program to optimize mix design parameters of fly ash-based geopolymer engineering composites. Fly ash (FA) supplied from Çatalağzı Thermal Power Plant (Zonguldak, Turkey) and Rilem Cembureau Standard Sand were used together with a constant ratio of 0.50 for producing geopolymer. In the first step, two different alkaline solution/material ratio (FA+standard sand) (L/M) were determined as 0.20 and 0.40, respectively. After that, sodium silicate ((Na2SiO3) and 12M sodium hydroxide (NaOH) were utilized at a ratio of 1, 2, and 3, respectively. 6 mixtures obtained by using different design parameters were cured at 70 °C for 24 hours, respectively, and then they were stored at room temperature until testing age. While the physical properties of the samples were measured by the bulk density and water absorption tests at 28 days, mechanical properties were tested via the compressive and flexural strength tests at 90 days, respectively.The results indicated that the highest compressive strength for geopolymer materials was found as 36.5 MPa in the mixture produced with the ratios of L/M=0.2 and Na2SiO3/NaOH=2 (by weight). However, less alkali reaction caused by using excessive activator solutions decreased the strength characteristics of geopolymer.

On the Compaction Characteristics of Soil-Lime Mixtures

Aim of the present note is to contribute to the optimization of the mix-design procedure of lime treated soils with particular reference to compaction characteristics. Seven soils with different plasticity characteristics and clay fractions are included in the experimental program, different amounts of quicklime and hydrated lime were added to the soils by wet mixing and then Standard Proctor compaction was carried out at different water contents in order to study the effect of lime treatment on compaction characteristics. Microstructural investigation was developed by means of scanning electron microscope. A general decrease in the maximum dry unit weight was observed together with a flattening of the Proctor curve. Also optimum water content changes due to lime addition. A factor that takes into account these modifications was defined and compared for several mix designs. Good correlations (confirmed by Fisher’s statistical test) between this factor and clay fractions of the soil to be treated were derived for 5% hydrated lime added. In addition, useful directions were retrieved analysing experimental results for soils treated with different types of lime in different proportions. Results contribute to have a preliminary idea of the effective mix design parameters, knowing the soil to be treated, helping, in this way, in possibly reducing the number of tests in the design phase.