Suitable Mix Proportion Research Articles

Use of recycled concrete aggregates in stabilization of black cotton soil

The long-term performance of a pavement structure depends on its structural integrity and the stability of its underlying soils. The properties of black cotton (BC) soils are known to adversely affect the performance of pavement. BC soil is creating a lot of problems in constructing the pavements on it because of its low California bearing ratio (CBR) and high swelling potential behavior. Black cotton soil possesses poor strength, high swelling and shrinkage behavior on exposure to moisture. Pavements on BC soil require stabilization. Soil stabilization is a process utilized for improving the properties of undesirable weak soil. Stabilization of subgrade soil by chemical, thermal or mechanical techniques is very common practice and too expensive. Therefore, in this study, an attempt has been made to stabilize the BC soil subgrade by recycled concrete aggregate (RCA). The RCA are the waste aggregates obtained from demolition of concrete structure buildings, road, and bridges. The main aim of this study is to know the suitability of RCA waste as a stabilizer for BC soil in the construction of flexible pavements. In this investigation, properties of RCA and BC soil are evaluated, RCA is mixed in different proportions with the BC soil, and their influence on the CBR value and compaction curve are studied. Seven mixes (100% BC soil, 90% BC soil + 10% RCA, 80% BC soil + 20% RCA, 70% BC soil + 30% RCA, 60% BC soil + 40% RCA, 50% BC soil + 50% RCA, 40% BC soil + 60% RCA) are tested for CBR value in order to find the proportion which gives maximum CBR value. Based on the results, it is observed that for the BC soil used in this study, mix containing 60% BC soil and 40% RCA is the suitable mix proportion for the stabilization. For this proportion of mix, the CBR value increased from 3.53% to 11.2%. This accounts to 3.2 times increase in the CBR value, whereas the optimum moisture content (OMC) decreased from 27% to 22% and maximum dry density (MDD) increased from 1.22 gm/cm3 to 1.45 gm/cm3. Hence 60% BC soil and 40% RCA can be used to stabilize the given soil.

Mechanical Behavior of Compression-Compacted Dry Concrete Paver Blocks Making Use of Sea Sand and Seawater

Dry concrete is a kind of concrete whose fresh mixture has almost no flowability and is widely used in the production of small-size unreinforced compression-compacted concrete blocks in plants. Considering the shortage of natural river sand and freshwater for concrete production, this study proposes that sea sand and seawater can be directly used in the manufacture of compression-compacted dry concrete paver blocks. The idea was verified in the laboratory to find suitable mix proportions and forming pressure, which are two key parameters for the production of paver blocks. Furthermore, the effect of sea sand replacement ratio and seawater replacement ratio is investigated, where compression and flexural tensile tests were conducted on lab-made paver blocks at different ages. The experimental results reveal that both the compressive and flexural tensile strengths of paver blocks increased when sea sand and seawater were adopted. It is finally suggested that sea sand and seawater are suitable for the production of unreinforced paver blocks with enhanced mechanical performance.

Mechanical Properties and Optimal Mix Design of Phosphogypsum Cement Mineral Admixture Foam Light Soil

With the rapid growth of road transportation, the increase in road subgrade and pavement diseases has become a pressing issue, requiring the development of cost-effective filling materials that meet both strength and economic requirements. Foam lightweight soil, as a novel construction material, offers excellent characteristics such as adjustability in density and strength, high fluidity, and self-supporting capabilities. It has been widely utilized in various engineering applications, including road subgrade backfilling and retaining wall fillings. However, the conventional application of foam lightweight soil, predominantly cement-based, has raised concerns about pollution and high energy consumption due to large cement dosages. To address this issue, this study proposes the integration of phosphogypsum, a byproduct of wet-process phosphoric acid production, into foam lightweight soil. Phosphogypsum has a significant annual discharge and accumulation, but its comprehensive utilization rate remains relatively low. The research investigates the combination of phosphogypsum and foam lightweight soil by introducing mineral admixtures such as microsilica and slag powder to improve early strength development and reduce the influence of fluoride impurities on early strength. The optimal mix proportions for two types of foam lightweight soil, namely phosphogypsum cement microsilica foam (PGCF) and phosphogypsum cement slag powder foam (PGCS), were determined based on single-factor tests. The key parameters considered for optimization were water–binder ratio, foam content, and phosphogypsum dosage. The findings indicate that both PGCF and PGCS foam lightweight soil possess superior mechanical properties and thermal conductivity. By incorporating phosphogypsum into the mix, the early strength development of foam lightweight soil is effectively improved. Moreover, with suitable mix proportions, the maximum phosphogypsum dosage can be achieved, demonstrating potential economic and environmental benefits. In conclusion, this research provides valuable insights into the effective utilization of phosphogypsum in foam lightweight soil, offering a promising solution for the challenges associated with phosphogypsum disposal and the demand for sustainable construction materials in highway engineering.

Gravity Blind Backfilling of Abandoned Underground Mine Voids Using Suitable Mix Proportion of Fill Materials and Method of Filling

Gravity Blind Backfilling of Abandoned Underground Mine Voids Using Suitable Mix Proportion of Fill Materials and Method of Filling

Prediction of HFRC compressive strength using HS-based SIRMs connected fuzzy inference system

A single input rule modules (SIRMs)-connected Fuzzy Inference System optimized by Harmony Search model is used to predict compressive strength for steel-polypropylene hybrid fiber reinforced concrete (HFRC). The proposed model is evaluated using a dataset with 114 real experimental steel-polypropylene data gathered from literature. 82 data (72% of the total data) were used in training the model. Predictions from the model for both training and testing datasets achieve coefficient of determination more than 0.96 with root-mean-square error (RMSE) less than 2.40 MPa. These results show that the proposed model gave accurate and reliable predictions of steel-polypropylene HFRC compressive strengths. The predictions from neural networks model gave accuracy with coefficient of determination more than 0.89 with RMSE 3.89 MPa, while predictions from the multiple regression analysis model achieve accuracy with coefficient of determination 0.95 with RMSE 2.59 MPa. The proposed model gave better accuracy for testing dataset, when compared to neural networks model. Comparison with multiple regression analysis model showed that the proposed model gave better predictions for training and testing datasets. These results show that the proposed model can be used for HFRC mix design in deciding a suitable mix proportion for HFRC.

Durability properties of cement – saw dust ash (SDA) blended self compacting concrete (SCC)

This paper report the durability properties of self-compacting concrete (SCC) modified with Saw dust ash (SDA) exposed to an aggressive media. Saw dust ash (SDA) was used to partially replace OPC in SCC at 0 - 30%. A number of trials mixes were conducted to obtain grade 40 SCC, with a suitable mix proportion varied at 5, 10, 15, 20, 25 and 30 % by weight of the binder as OPC replacement in SCC. Constant water to binder ratio of 0.37 with water reducing admixtures was used in all the mixtures. The research reveals that SDA enhanced the resistance of SCC against Na2SO4 attack at 5% replacement but performed poorly in H2SO4. The water absorption of SCC decreases with an increase in SDA content. The resistance of SDA-SCC to elevated temperature is reduced with an increase in SDA content. The compressive strength of the SDA-SCC decreases with the age of exposure in an aggressive media. The SEM result revealed the presence of crystal like spikes of SDA particles, which may contribute significantly to the high surface area of the ash particles and results in a porous structure at an early age.

Seismic response investigation and analytical model of light polymer material-filled CFS shear walls

The light polymer material (LPM), prepared with suitable mix proportion and physical method, is a type of low-carbon and environmental-friendly material. Recently, the LPM is developed as structural material for cold-formed steel (CFS) structures to cover the shortages of traditional CFS shear wall. In this paper, material properties of gypsum-based and cement-based LPM including compressive strength, elastic modulus and thermal property were explored by tests. Experimental results demonstrate that LPM exhibits excellent thermal insulation, and the thermal insulation and compressive strength of LPM satisfy the demand of bearing capacity and thermal insulation property of shear walls. To explore the effect of LPM on seismic response and failure modes of CFS shear walls, three specimens are manufactured and tested under cyclic loading. The existence of LPM in CFS shear wall would restrain the failure of wall studs to some extent. Due to the restriction effect of LPM on wall studs and self-drilling screws and the bond-slip performance between LPM and studs, the shear walls exhibit better seismic behavior than traditional CFS shear walls. At last, a modified equivalent bracing model is employed to predict the lateral stiffness of LPM-filled CFS shear walls considering the effect of filling materials, rib lath, and sheathing. The lateral stiffness obtained by the proposed method is compared to the experimental results in this paper and other researches, and the proposed model is proved to supply a conservative result which is safe to be adopted in the design and application of the LPM-filled CFS shear wall.

Reactive Powder Concrete with Composite Fibres

Reactive Powder Concrete (RPC) is a composite material characterised with high strength and durability. Reactive powder concrete is a type of concrete which is made without coarse aggregate, contains cement, river sand, micro silica, super plasticizer and composite fibres with low water cement ratio. RPC can attain high strength characteristics with the addition of fibres. In this project we cast Reactive Powder Concrete specimens of suitable mix proportions by trial and error method and tested its compressive strength, tensile strength and flexural strength characteristics. In order to increase the strength of RPC we have adopted hot water curing at 90°C for 24 hours. Hence, rapid hydration of cementitious materials increases the strength of RPC.

Workability and compressive strength properties of normal weight concrete using high dosage of fly ash as cement replacement

This study evaluates the workability and compressive strength properties of normal weight concrete (NWC) using high dosage of fly ash cement replacement. The goal is to find the suitable mix proportion of G40 NWC and to study the slump-loss at different interval time with fly ash replacement up to 60%. The strength properties of NWC were investigated using rebound hammer test as non-destructive and compressive strength test for verifying it. The acceptable mix proportion for fly ash replacement was then investigated using laboratory experiments. For strength properties of NWC, the samples were tested for 3, 7, 14 and 28 days. Results indicate that the inclusion of fly ash as partial cement replacement improves the workability of NWC concrete. The slump-loss of NWC with fly ash increases and it delays the setting time of fresh concrete. The strength of concrete reduces with an increment of fly ash. The strength measured using non-destructive test is lower when compared to compressive strength test. The results demonstrate that the replacement of cement with fly ash in concrete is beneficial and the targeted strength of concrete will achieve with time.

Mix Design and Mechanical Properties of High-Performance Pervious Concrete.

The mechanical properties of traditional pervious concrete are insufficient, which limits its application. In view of the imperfections of traditional permeable concrete in mechanics, this paper aimed to find a suitable material composition that can be used as a feasible mix design of high-performance pervious concrete, to essentially improve its mechanical properties. Based on the view that concrete is a two-phase material, in order to understand the rheological properties of the matrix, it was subjected to a rheological test, and then the filler aggregate was uniformly incorporated into the aforementioned matrix to further explore the composition and properties of the resulting pervious concrete. For the matrix, the orthogonal array employed was L16(45), which consisted of five factors, each with four levels. Base on the fluidity and compressive strength of the tested matrix, three groups of suitable matrixes mix proportions were selected to serve as the matrix type for pervious concrete mix proportion design. Then, an orthogonal array L9(34), which consisted of four controllable three-level factors, was adopted in the pervious concrete. The parameters investigated included the coarse aggregate size, fine aggregate content, matrix type, and aggregate-to-binder ratio. The test results demonstrate that the key factors affecting the compressive strength of the matrix and the pervious concrete were closely related to the cementitious material. In the matrix, the proportion of the cementitious material was the most important factor, while in the pervious concrete, the type of matrix was the most important factor.

Development of high workability grout on semi rigid wearing course

A composite pavement known as semi rigid wearing course is made by incorporating high workability fluid grout into a high porosity of porous asphalt skeleton. This fluid grout is particularly designed to have the consistency workability of water with high early and 28 – day strength. It is critical to maintain its high fluidity so it can flow through air voids while simultaneously generate high compressive strength with minimal porosity. The aim of this study is to investigate the influence of a known pozzolanic material towards the properties of fluid grout. A wide range of mix trials was formulated with various proportions of chemical and mineral admixtures. The fresh and hardened grout underwent flow cone and compressive test for its workability and strength determination respectively. The results obtained show that the combination of a known pozzolanic material and a known chemical admixture is possible to improve the fluidity of grout and strength when suitable and conducive mix proportions attained.

Effect of Fibre Content on Mechanical Behavior of Slurry Infiltrated Fibrous Concrete

Cement mortar or slurry is an essential material for production of Slurry Infiltrated Fibrous Concrete (SIFCON) structural components. However, there have been limited technical data available for deciding a suitable mix proportions and water cement ratio. For achieving a good quality of mortar mix or slurry with specific strength requirement and satisfactory level of workability for proper infiltration ability of cement slurry fibrebed. The preliminary study was carried out to select suitable mix and W/C from various mixes (1:1, 1:1.5 &1:2) and W/C (0.4, 0.45 & 0.5)on fresh and hardened properties of cement mortar. The optimum mix proportion and water cement ratio were obtained on workability (flow table test) and compressive strength of cement mortar are found to be as 1:1 and 0.40 respectively for fabrication of SIFCON. The main focus of this investigation on the behaviour of SIFCON contains various volume fraction of fibre content with an optimum mix(1:1) and W/C (0.4) under static loading. Hooked end steel fiber length of 30mm and tensile strength of 1050MPais used throughout the entire investigations. Cubes of 100 x 100 x 100mm for compressive strength and cylinders of 100mm diameter and 200mm height for split tensile strength were cast and tested at 3, 7 and 28 days. For flexural strength, three SIFCON beams of length 1200mm and cross section of 100mmx 200mm were cast and tested at 28 days under three point bending. The parameters like fracture energy, load deflection response, split tensile strength and compressive strength were found and compared the results with conventional mix. The test results observed that the strength performances were greatly improved due to addition of fibre by volume fraction in SIFCON matrix. Also developed the regression model from the experimental results to estimate the compressive and split tensile strength and compared the predicted values with the experimental values.

Effect of a new type of high-strength lightweight foamed concrete on seismic performance of cold-formed steel shear walls

High-strength lightweight foamed concrete (HLFC), as a new type of load-bearing structural material, was developed using suitable mix proportion and physical method in this study. Material properties of HLFC with dry density of 500 kg/m3 and 700 kg/m3 were studied by a series of tests. To investigate the effect of HLFC on seismic behavior of cold-formed steel (CFS) shear walls, three shear wall specimens were fabricated and tested under in-plane cycle loading. The effects of HLFC on failure mode, load-bearing capacity, ductility, stiffness degradation and energy dissipation capacity of the walls were analyzed. Test results indicated that HLFC with density grade of A05 and A07 exhibit higher compressive strength and better thermal insulation than conventional foamed concrete. Furthermore, the compressive strength and thermal insulation of HLFC meets the requirements of both the load-bearing capacity and thermal insulation property of shear walls. Moreover, the use of HLFC in CFS shear wall changes failure mode of the walls from local failure to shear failure. Due to compressive strength of HLFC, restriction effect of HLFC on steel frame and bond-slip behavior between HLFC and studs, HLFC-filled CFS shear walls are superior to conventional CFS shear wall in terms of load-bearing capacity, ductility, stiffness and energy dissipation capacity. Finally, based on shear strength of the HLFC-filled CFS shear walls, the existing formula proposed by the standard CNS 383-16 is suitable for predicting the shear strength of HLFC-filled CFS shear walls, and the differences between the experimental and calculated results were within 10%.

DESIGNED OF CONCRETE DISTRIBUTOR LEVEL B15 WITH MEDICAL GLASS AGGREGATES AND CRUSHED SAND

The project has built and found suitable mix proportion for compacted glassconcrete, corresponding to Soundness B15 of normal concrete by laboratory method. The experimental gradations were used 5% or 10% cement content with the control (witnessing) gradation. The results of the study: finding the suitable components to create glass-concrete, using glass aggregate and grinded sand for the same Soundness as B15; Handling medical-glass-bottles and contributing to handle the local scarcity of sand, making a new construction product that is highly applicable in practice. However, for more efficient use, additional tests of tensile strength and other related properties must be carried out.

Geopolymerized self-compacting mud concrete masonry units

This study was conducted to develop an alternative method of utilizing fly ash as an alternative stabilizer to build affordable earth masonry units named “mud concrete blocks”. Mud concrete masonry block is a novel invention in which the mud helps to self-compact the mixture to reduce the production of energy content. This study uses fly ash from electric power generating plant with an alkaline solution made of Sodium hydroxide and Sodium chloride. Different combinations of mixtures (fly ash, sodium chloride, sodium hydroxide and soil) were taken into consideration to study a suitable mix design. And compressive strength was tested to understand each mix suitability.Results of this study have manifested that suitable mix is to use Fly Ash 20% of the dry weight of soil, Sodium hydroxide 5% and Sodium Chloride 2% of the total dry weight. The suitable water ratio is 15%–20% of the dry weight. And then the suitable soil mix proportion was developed. It was found that the soil mix proportion of Gravel 10–20% (sieve size 4.25 mm ≤ gravel≤ 20 mm) range of (35%–45%), the Sand 70–80% (sieve size 0.425 mm ≤ sand ≤4.25 mm) proportion of (60%–70%) and Fine ≤10% (≤sieve size 0.425 mm) content of 5% makes the best mix to develop. Scanning electron microscope images were taken to understand the geo polymerized fly ash bond result on the total strength of the soil mixture.

Mechanical properties of green structural concrete with ultrahigh-volume fly ash

Using a high dosage of fly ash in concrete is an effective approach to control the heat release rate, reduce the material cost and enhance the sustainability. However, ultrahigh-volume fly ash (UHVFA) concrete, with fly ash replacing over 60% of the binder by weight, often exhibits low compressive strength at an early stage, which limits the material to non-structural or semi-structural applications. Though different approaches have been proposed to increase the strength, the efficacy of some of the methods is debatable, because of the high energy consumption and/or low cost-benefit ratio. This study aims to increase the compressive strength of UHVFA concrete by the simple and practical method of reducing the water/binder ratio while adding super-plasticizers to maintain workability. Mortar samples were used to explore the influence of silica fume, and Portland cement was replaced with fly ash at five different percentages (20%, 40%, 60%, 80% and 98%). Mechanical properties up to 360-day age were recorded, and the cementing efficiency factor of the fly ash was studied. With a suitable mix proportion, even with 80% of the binder replaced by fly ash, the compressive strength of the mortar and concrete can reach over 40MPa at 7-day age, and over 60MPa at 28-day age. Compared to commercial Grade 45 concrete, the proposed green structural concrete shows a reduction in CO2 emission of around 70%, a reduction in embodied energy of more than 60%, and a reduction in material cost of 15%.

Mix Proportions of High Flowable Early Strength Mortar for Emergency Repair of Damaged Road Base in Rural Area

Recently, due to the climate changes, the frequency and severity of natural disasters such as torrential rain have become more significant worldwide. In South Korea, there are number of summer typhoons and localized torrential downpour every year and these cause severe damages onto a residential area and road networks. More than 70% of the land of Korean peninsula is a mountainous area and thus damages onto road networks result in serious harm to daily lives especially in a rural area by isolating residents from networks. Therefore, there is a strong demand on the immediate and emergency repair technology for the collapsed road networks. This study develops an emergency repair technique for damaged road base where the damaged road base can be packed with gravels and then the pores or open-gaps of the packed gravels can be filled with high flowable mortar that develops strength in an early age. The aim of this research study was to find the suitable mix proportions of high flowable early strength mortar. Throughout the experimental work, study was done on two stage mix variables, where in the 1st stage, W/C ratio and high range water reducer was considered whereas in the 2nd stage cost effective early strength cement was used for the mix-design. With various variables in mix proportions, compressive strength and flow capacity were investigated. Finally from those experimental study, optimum mix proportions of the high flowable early strength mortar was found. The hardened materials composited with gravels and mortars can be used as a permanent road base with no need for compaction thereafter.

PERVIOUS CONCRETE WITH BOTTM ASH AND COPPER SLAG

Pervious concrete is a porous concrete with voids which has no fine aggregates in it thereby facilitating the drainage of rain and storm water. The interconnected porosity of the porous concrete facilitates runoff from paved areas thereby preventing water logging which causes discomfort to passengers on roads. Moreover the rough surface of the pervious concrete prevents skidding of vehicles and it has also been reported that it absorbs sound and minimizes the deposition of fine dust on the pavement surface. This type of concrete has been successfully used in pavement and parking lots. Several researchers have optimized the proportion of aggregate that can be used in pervious concrete in order to achieve maximum permeability. But as the void content increases the strength of the concrete is reduced. Pervious concrete can be designed by using little or no sand thereby proportioning the concrete to have considerable voids. The binder content is very minimum sufficient enough to just coat and bind the aggregate particles together. The coarse aggregate used can be of single gradation or gap graded to facilitate the formation of voids which are interconnected. Approximately 20 to 30% voids are present in the hardened concrete and research has shown that flow rate of 0.25 to 0.38 cm/sec can be achieved if the gradation of aggregate is designed with gap graded aggregate. The disadvantage of the pervious concrete is its low strength compared to conventional concrete. But it has been tested and reported that it has the sufficient strength that can take up the vehicle load and other loads for many other applications. This paper discusses about the suitable mix proportion for the pervious concrete that uses copper slag and bottom ash as fine aggregate and properties of the concrete in terms of strength and durability.

Effect of Different Parameters on Properties of Multiwalled Carbon Nanotube-Reinforced Cement Composites

The exceptional mechanical properties of carbon nanotube (CNT) such as high strength, elastic modulus and aspect ratio. reflect its potential to be used as reinforcements in cementitious materials. Nanotubes can be distributed on much finer scale and can act as bridge across void spaces and cracks. This in turn improves the overall mechanical properties of the composite. However, there are certain issues that need to be considered while producing CNT cement composites. With this end in view, an attempt has been made to summarize the effect of different parameters on properties of CNT-reinforced cementitious composites through interpretation of results obtained from a comprehensive study. Different sizes and dosage rates of MWNT were used to conduct parametric study. In addition, untreated and surface-treated commercially available MWNTs were used to make composites. Sonication was done for dispersion of nanotubes within cement matrix. An appropriate mixing technique was suggested after conducting a parametric study by varying the amplitude and time of sonication. In some cases, polycarboxylate-based superplasticizer was used as surfactant to disperse MWNTs in aqueous medium. It was observed that surface treatment of nanotubes and utilization of superplasticizer as surfactant enhance their solubility within water. It was also found that proper dispersion and dosage rates of MWNT have significant effect on composite behavior. A suitable mix proportion in terms of MWNT dosage rate, MWNT size and plasticizer proportion has been found. Moreover, it was suggested that flow values of composite paste is a good indicator of stability of the mix.

Compressive Strength Index of Different Types of Light Weight Plastic Aggregate Concrete

The study on potential usage of industrial waste products and other wastes in the concrete is going on globally. In this study an attempt has been carried out to explore the utilization of plastic wastes in concrete. Four different types of Light Weight Plastic Aggregates (LWPA) are prepared from the non-recyclable plastic bags of size 20-40μ thick by heating on a container at 120-150 oC. 100% replacement of Natural Aggregate (NA) with different types of LWPA is carried out, based on trail mix a suitable mix proportion was arrived. The compressive strength and Ultrasonic Pulse Velocity (UPV) tests for different types of plastic aggregate and conventional aggregate concrete are carried and outcomes are analyzed. The replacement of NA with LWPA reduces the density of the concrete and overcome the double issue of safe disposal and raw material shortage of non-recyclable plastic wastes. Keywords: Compressive Strength, Density, Light Weight Plastic Aggregate, Non-Recyclable Plastic