Optimization Of Mix Proportion Research Articles

Durability Evaluation of Concrete in Cold and Arid Regions Based on Grey Relational Theory

Aiming at the outstanding problem of concrete durability in cold and arid regions, the Datonghe‐Qingwangchuan Diversion Project in Gansu Province, China, was used as a typical research area, and erosion products were determined by field sampling and laboratory XRD analysis. Three durability evaluation indices, namely, the mass loss rate, relative dynamic elastic modulus (RDEM), and compressive strength loss rate, were measured via indoor accelerated testing. Based on grey relational theory, a concrete durability evaluation model was constructed. The critical failure values of the three evaluation indices were introduced as a set of data to optimize the model and determine the grey relational degree of each group of concrete specimens under different working conditions. The results show that using the test results and the optimized grey relational analysis evaluation model, the concrete specimens mixed with an air‐entraining agent have strong resistance to composite erosion. The durability of concrete specimens with an air‐entraining agent content of 0.016% and fly ash content of 15% is better, and a high content (30%) of fly ash accelerates the damage of concrete specimens. The model calculations are consistent with the test results. This method can solve the problem of the durability of concrete specimens in the whole test cycle not being fully evaluated. The results of the study provide useful references for concrete mix proportion optimization and durability evaluation problems.

Optimization of Mix Proportion of Self-compacting Concrete Based on Single Fluid Model

The study aims to optimize the mix proportion of self-compacting concrete according to the workability and compressive strength. Firstly, based on computational fluid dynamics, the flowability and filling ability of self-compacting concrete were simulated by the single-fluid model to verify the single-fluid model. And then, the simulation of casting a pre-cambered composite beam was carried out. In the end, the mix proportion was optimized considering the filling ability and the compressive strength of self-compacting concrete. The results showed that increasing sand rate can improve the workability and decrease the rheological parameters of self-compacting concrete. The mixture with a 45% sand ratio in the case of 3% silica fume alone or 43% sand ratio in the case of 30% granulated blast furnace slag and 3% silica fume had adequate filling ability and excellent long term compressive strength. Moreover, the model can be used to simulate the filling ability and passing capacity of self-compacting concrete and the maximum error between the simulation results and the actual measured value is 4.80%. When the concrete mixture is considered to be uniform, namely, without considering the effect of the aggregates, the single-fluid model can simulate the casting of self-compacting concrete.

Prediction of optimal ranges of mix ratio of self-compacting mortars (SCMs) based on response surface method (RSM)

The influences of constituents on the rheological and mechanical properties of self-compacting mortars and efficient mix proportion optimization are two key issues in the design of self-compacting mortars (SCMs). Due to the lack of specifications of the mix design, a wider range of variable optimization can provide great feasibility to meet wider requirements of rheological and hardening properties of SCMs. In this study, response surface methodology (RSM) was adopted to systematically investigate on the independent and interactive effects of fly ash (FA), silica fume (SF), sand-binder ratio (s/b) and water-binder ratio (w/b) on the rheological and mechanical properties of SCMs. A total of 30 SCMs mixes were formulated by using the Central Composite Design (CCD) method to determine the contents of the four variables at 5 levels, e.g., FA range from 0 to 30%, SF ranged from 0 to 16%, sand-binder ratio varied from 1.0 to 1.4 and water-binder ratio from 0.34 to 0.38. The results showed that these four variables and their partial interactions have significant influences on the rheological and mechanical properties of SCMs, especially SF and sand-to-binder ratio. The prediction of the optimal range of variables in multi-response optimization was developed and validated. The result showed that the contents of FA, SF, s/b, w/b ranging in 10–20%, 6–10%, 1.1–1.2, 0.35–0.36 respectively leaded a better workability and greater compressive strength of SCMs.

Study on Mix Proportion Optimization of C50 High Strength Concrete

With the progress of engineering technology, C50 high-strength coagulation came into being for the needs of actual engineering. This research mainly focuses on the selection of cement varieties and admixtures of C 50 high-strength concrete, so as to realize the optimization research of the mix ratio of C 50 high-strength concrete. The results show that ordinary P.O 42.5 and fly ash admixture can increase the mechanical performance of concrete. However, the concrete compressive strength with the mixed admixture of fly ash and mineral powder is even lower than that without any admixture. On the premise of meeting actual engineering needs, the optimization of the mix ratio of high-strength concrete can not only achieve sustainable development, but also save investment in project economic costs.

Optimization of mix proportions for high performance concrete using TOPSIS method

Optimization of mix proportions for high performance concrete using TOPSIS method

Development of Fly Ash-GGBS based Self Compacting Geo-Polymer Concrete with and without Steel Fibres

The present work is focussed on the optimization of mix proportions to satisfy the self-compatibility requirements as per EFNARC [march 2006] guidelines and to assess the mechanical properties of concrete made out from these industrial by-products adding partially with GGBS in cement called self compacting concrete (SCC) and concrete made with (GGBS+Fly ash) named as Self Compacting Geo-polymer Concrete (SCGPC) and concrete made with incorporation of steel fibers for the optimized SCGPC mix named as Self-Compacting Geo-Polymer Fibre Reinforced Concrete (SCGPFRC) mixes were prepared. The fresh properties, as well as the hardened properties, were studied. The physical durability was also studied with the abrasion resistance test. The fresh properties of SCGPC were better than SCC and SCGPFRC. Although there is a slight decrease in strength for SCGPC, when compared to conventional concrete(100% cement) and SCC, but it fulfill the strength requirements by achieving the target strength. With the introduction of fibres to the SCGPC, the flexural strength and split tensile strength of SCGPFRC is significantly increased when compared to SCGPC mixes. It can be inferred that at fiber content of 1.5% (SCGPFRC2) the value of flexural strength and split tensile strength was found to be increased by 15.73% and 40.72% respectively.

Optimization of mix proportion of alkali-activated slag mortars prepared with seawater and coral sand

To effectively utilize marine resources and promote sustainable development in the construction industry, an innovative building material, namely, alkali-activated slag mortars prepared with seawater and coral sand (SC-AAMs), was proposed in this paper, and its workability, setting time, compressive strength, flexural strength, and drying shrinkage were studied. The effects of the modulus of sodium silicate (Ms), Na2O-to-binder (N/B) ratio by weight, replacement ratio of the coral sand for sea sand (Rs), and water-to-binder (W/B) ratio were considered using the Taguchi orthogonal experimental design method. The experimental results indicated that an increased alkali activator modulus and alkaline contents improved the compressive and flexural strengths, however, resulting in a decreased setting time and an increased drying shrinkage. According to the results from the aforementioned orthogonal experiments, the optimum mixtures for SC-AAMs were determined to be an Ms = 1.2, a N/B = 4%, a W/B = 0.45, and a Rs = 100%. Then, the microstructure and crystalline phases in the SC-AAMs prepared with this optimum mix proportion were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively, and the cement mortar mixed by seawater and coral sand was selected as the reference. It can be concluded that the utilization of the alkali-activated materials changed the reaction hydrate products of the mortars and improved the interfacial microstructures between the coral sand and slurry. In addition, the existence of the coral sand reduced the drying shrinkage of the AAMs due to the self-curing effect inside the coral aggregate.

Experimental Research on Durability of Fly Ash Pavement Concrete and Mix Proportion Optimization

This paper focused on the optimization of the C40 fly ash concrete pavement, which was considered as a measure to accelerate the consumption of industrial solid wastes such as fly ash, committing to the goal of zero waste. By comparing with three groups of ordinary mix proportion, the performances (e.g., mechanical properties, durability, and brittle property) of the optimized mix proportion were evaluated via multiple mechanical and physical tests. Their air voids’ structure was characterized by the BJH method (a method to calculate pore size described by Barrett, Joyner, and Halenda), and the results were combined with the road performances of concrete to analyze the formation mechanism of high durability of optimized fly ash pavement concrete. As for the experimental results for the optimized, its 28 d compressive strength peaked at 50.8 MPa together with corresponding 28 d flexural strength at 8.2 MPa, which indicated a favorable mechanical performance for wide application in pavement construction. Except for the mechanical properties, the better durability indicators obtained after optimization also provided a more compact pore structure for the optimized. The raw materials and construction technology of the two kinds of pavements were compared. Promoting the use of optimized fly ash pavement concrete can break the situation of the asphalt pavement monopolizing heavy‐haul highway and greatly reduce the industrial wastes which can be used as raw materials in the production of cement, such as blast furnace slag and fly ash. It was proved that the optimized fly ash concrete pavement can be used to replace the asphalt pavement under the premise of achieving the same working performances.

Optimization of Mix Proportions for Novel Dry Stack Interlocking Concrete Blocks Using ANN

This paper proposes novel concrete interlocking blocks made of fly ash and GGBS which are an alternative for the conventional concrete blocks. The artificial neural network (ANN) technique is used to estimate the mechanical strength of interlocking blocks and is verified with experimental investigation. The ANN model is based on the Levenberg–Marquardt principle which is executed using MATLAB. The inputs are given in the percentage ratio of cement: fly ash: crushed stone aggregate (FA): coarse aggregate (CA) for the process of learning, testing, and validation. The selected model is subjected to several trials in terms of mean square error, containing 4 input, 2 sets of 10 hidden layers, and one output components. In this study, a total of 2600 blocks of different mixes were tested as per IS 2185‐1 (2005) to assess 3, 7, 14, 21, and 28 days’ strength. The experimental investigations were carried out in two phases. In the first phase, experimental investigations to identify the optimum mix proportions of cement, aggregate, fly ash, and ground granulated blast furnace slag to achieve desired compressive strength was carried out. In the second phase, the identified mix proportions were analysed using ANN to predict the compressive strength of interlocking blocks. The results indicate that the proposed ANN model developed to determine the mechanical strength and cost of interlocking blocks has excellent prediction ability.

Experimental Study on the Workability and Stability of Steel Slag Self-Compacting Concrete

There is important application value and economic value in exploring the potential use of steel slag to prepare self-compacting concrete (SCC) and make full use of solid waste resources. In this paper, steel slag self-compacting concrete (SSCC) with relatively ideal workability is prepared by using steel slag instead of natural fine aggregate based on mix proportion optimization and SSCC performance research. The filling ability, passing ability and resistance segregation were tested to evaluate the workability of SSCC. The results show that when the content of steel slag sand is 20%, the workability performance of SSCC is similar to that of SCC with natural aggregates. When the content of steel slag sand is less than 60%, the performance of SSCC can also meet the workability requirements after adjusting the amount of raw materials.

Experimental studies and microstructure analysis for ultra high-performance reactive powder concrete

In this paper, the strengthening mechanism of curing temperature, fine aggregate gradation, reactive materials, water reducer type, dosage and types of fibers on the microstructures and mechanical properties of Ultra-high-Performance Concrete (UHPC) was analyzed in detail by means of microstructure analysis using Scanning Electron Microscope (SEM) and mechanical tests. Based on the mechanical tests and analysis of the microstructure, a new optimal mix proportion of UHPC was also developed by considering the economic benefits. It is found that the gradation of UHPC fine aggregate can achieve the densest stacking state gradation after the optimization of mix proportion. Gradation Optimization promotes UHPC to be hydrated step by step. A large amount of hydrated calcium silicate (C-S-H) gel and a small amount of crystal produced in the early hydration phase together form the original structure of the concrete. The initial hydration products consume a large amount of Ca (OH)2 to produce C-S-H and other cementitious substances by so called Secondary Hydration Reaction, the C-S-H can further catalyst hydration. It is also found that the low water-cement ratio can reduce porosity and improve the compactness and compressive strength of UHPC microstructure. The fibers can effectively delay the appearance and development of micro-cracks in the concrete matrix, help to improve the toughness, ductility and flexural properties of UHPC, and avoid brittle failure. High temperature curing is beneficial to the formation of cementitious substances with lower calcium-silicate ratio (C/S) and catalyst the occurrence of secondary hydration reaction.

Study on Mix Proportion Optimization of Manufactured Sand RPC and Design Method of Steel Fiber Content under Different Curing Methods.

This study investigated four factors (water/binder ratio, silica fume, fly ash, and sand/binder ratio) using the orthogonal experimental design method to prepare the mix proportions of a manufactured sand reactive powder concrete (RPC) matrix to determine the optimal matrix mix proportions. On this basis, we assessed the compressive and splitting tensile strengths of different steel fiber contents under natural, standard, and compound curing conditions to develop an economical and reasonable RPC for various engineering requirements. A calculation method for the RPC strength of the steel fiber contents was evaluated. The results showed that the optimum steel fiber content for manufactured sand RPC is 4% under natural, standard, and compound curing conditions. Compared with standard curing, compound curing can improve the early strength of manufactured sand RPC but only has a small effect on the enhancement of late strength. Although the strength of natural curing is slightly lower than that of standard curing, it basically meets project requirements and is beneficial for practical applications. The calculation formula of 28-day compressive and splitting tensile strengths of manufactured sand RPC steel fiber at 0%–4% is proposed to meet the different engineering requirements and the flexible selection of steel fiber content.

Investigating and optimizing the mix proportion of sustainable phosphate-based rapid repairing material

For solid waste disposal and cement consumption reduction, sustainable phosphate-based rapid repairing materials (sust-MPC) were prepared with MgO-containing by-products (LG-MgO) and circulating fluidized bed (CFB) fly ash. The effects of various mix proportions on the fluidity, setting time and mechanical properties of sust-MPC were investigated. Based on that, mix proportion optimization procedure has been developed according to the multi-objective comprehensively considering. The results showed that the MgO to KDP ratio (M/P) was the most influential parameter on the fluidity, whereas the Borax dosage (B/MPF) and Water-to-binder ratio (W/MPF) were the dominant factors on the setting time and 1-h mechanical properties, respectively. Yet, the effect of CFB fly ash addition (CFB/MPF) was relatively small. Finally, the performance comparisons of sust-MPC and conventional MPC were carried out. Examined properties included basic properties, adhesion strength and microstructure, etc. Overall, sust-MPC has shown a better behavior. These positive results indicated that sust-MPC could be a promising alternative in developing sustainable construction material and waste management as well.

Thermal and mechanical properties of high-performance fiber-reinforced cementitious composites after exposure to high temperatures

This paper investigates residual thermal and mechanical properties of high-performance fiber-reinforced cementitious composites (HPFRCCs) proportioned with high-volume fly ash after exposure to 200, 400, 600, and 800°C. The investigated thermal and mechanical properties include the thermal conductivity, specific heat, compressive strength, tensile strength, tensile ductility, and density. The effects of five mix proportioning variables on the material properties are evaluated, which include the water-to-binder ratio (0.24–0.36 by mass), sand-to-binder ratio (0.36–0.66 by mass), fly ash content (60%–75% by mass), polyvinyl alcohol fiber content (1.5%–2.2% by volume), and superplasticizer content (0.10%–0.15% by mass). Experimental results reveal significant dependence of the residual thermal and mechanical properties on temperature and the mix proportion, which can be attributed to a series of chemical and physical reactions that occur at elevated temperatures. This study can facilitate optimization of mix proportions of HPFRCCs for enhanced thermal and mechanical performance in fire or high temperature applications.

Experiments and Optimization of Mix Proportions for Cement Paste Backfill Materials with Extra-Fine Unclassified Tailings

To produce effective cement paste backfill materials at iron mines technologically and economically, orthogonal experiments of mix proportions with extra-fine unclassified tailings were carried out. The results of the range analysis showed that the sensitivity of influential factors to the slurry slump is sequentially mass concentration, tailing/rock ratio, and cement/(tailing+rock) ratio. The sensitivity to bleeding rate, concretion time and 28-day uniaxial compressive strength is sequentially mass concentration, cement/(tailing+rock) ratio and tailing/rock ratio. Relationships of paste properties and influential factors can be demonstrated with regression analysis. Additionally, the optimal mix proportion for cement paste backfill was obtained with 78% mass concentration, 7:3 tailing/rock ratio and 1:25 cement/(tailing+rock) ratio. The slump, bleeding rate, concretion time and R28 of the optimal mixture are 25.2 cm, 8.77%, 20.9 h and 1.29 MPa, respectively. The experimental results show a feasible way to produce the industry standard backfilling materials.

Carbon trading opportunities from tannery solid waste: a case study

The leather industry has gained high socioeconomic relevance in India and contributes significantly to the economy and export growth. Nearly 2000 tanneries operate throughout India, with a total processing capacity of 700,000 t/y of raw hides or skins. In the present study, co-digestion experiments were carried out using fleshings (a tannery process solid waste) along with the primary and secondary sludge generated during treatment of tannery wastewater. The significance of optimization of mix proportion of substrates was ascertained. For the total processing capacity of 700,000 t/a from the Indian tanning industry, the potential for bioenergy generation and greenhouse gas emission reductions was estimated at 52.15 × 106 kWh/y and 0.3 × 106 t CO2-eq/y, respectively. There is a vast scope for the Indian tanning industry to benefit from tapping of bioenergy and carbon credits under the clean development mechanism.

Multi Objective Optimization of Mix Proportion for a Sustainable Construction Material

The rapid industrialization and urbanization resulted in large quantity of waste generation and in turn, environmental degradation. Recycling of solid waste into a sustainable construction material with optimum mix proportion is the global need to reduce its adverse environmental impacts. The present paper aimed at optimization of the mix proportion for designing the sustainable material. Sugarcane bagasse ash (SBA) was identified as the principal raw material over the study area. It was used further in combination with quarry dust (QD), and lime (L) for various proportions to develop the sustainable bricks. In all 35 compositions for SBA-QD-L bricks were developed and Physico-mechanical properties were evaluated using standard laboratory tests as per Indian standards. A statistical cubical regression model was formulated for compressive strength of brick as a function of mix proportion using XLSTAT software. To achieve the criteria of sustainability, constraints were developed in terms of achieving maximum compressive strength and minimum embodied energy. A multi objective non-linear optimization model was formulated and optimum mix proportion was obtained using software LINGO. The optimum value of compressive strength and embodied energy predicted by this model was 5.44MPa and 2.32MJ. The embodied energy was estimated to be 47% and 5% lower than the conventional burnt clay and fly ash bricks. A cost analysis was also carried out between optimum composition of SBA-QD-L bricks and commercially available fly ash bricks. The percentage reduction in the cost was found to be 49% and 58% as compared to the fly ash and burnt clay bricks.

Study on the Mix Proportion Design of C30 Supersulphated Phosphogysum-Slag Cement (SSC) Concrete

supersulphated phosphogysum-slag cement (SSC) is a newly developed non-burned cementitious material. It’s mixed and ground with 40%-50% phosphogypsum, 40%-50% ground granulated blast-furnace slag (GGBFS), 2% steel slag and 4% portland cement clinker. But the component of SSC differs greatly from that of Portland cement, there is few application researches about the SSC. In order to realize resourceful utilization of phosphogypsum, the mix proportion design method of SSC are studied. The mix proportion design method for C30 are systematically studied and a design optimization was carried out. According to the design regulations of mix proportion of ordinary concrete and the characteristics of SSC, the C30 high flowing concrete is prepared, and the optimum water-cement ratio is obtained based on revised Bowromi formula. According to the mix proportion optimization design, the 28d strength of SSC is up to 38.5MPa.

Enhancement of biogas generation during co-digestion of tannery solid wastes through optimization of mix proportions of substrates

Tanneries in India face the twin problems of managing process solid waste and treatment of effluent plant sludge. The present study covered (i) significance of optimization of mix proportions of substrates i.e., fleshings (F) and the primary sludge (PS) and secondary sludge (SS) generated during treatment of tannery wastewater (ii) residence time during co-digestion for enhancement of biogas generation and (iii) digestate analysis. Maximum biogas generation of 385 mL/g of VSadded was observed for the mix proportion of 1.00:2.70:0.30 (F:PS:SS) and a residence time of 45 days during co-digestion of tannery solid wastes. Biogas generation was enhanced by increasing the proportion of PS to SS. After digestion, secondary metabolites i.e., primary, secondary, and tertiary alcohols, amino acids, methane, and ammonia were observed from FT-IR analysis. The exothermic reaction was observed at around 175 °C and when C/N ratio of digestate was around 8.0.

Concreting Control Technology of Mass Foundation Slab

We analyze the unfavorable factors of mass foundation slab construction during high temperature climate and list the key points of quality control of construction. Then we lay down safe and reasonable temperature control scheme on the basis of selection of concrete material, optimization of mix proportion and theoretical calculation of temperature field. Finally, the constructors carry out the scheme strictly to prevent the temperature crack of mass concrete block and the construction quality is ensured.