Cement Grade Research Articles

Influence of wet grinded slag on the hydration of phosphogypsum-slag based cement and its application in backfill tailings

Phosphogypsum-slag based cement (PSBC) has a great potential in tailings backfill because of low cost and CO2 emission in comparison with Portland cement. However, slow early hydration was often observed, and this problem was generally solved by adding cement clinker, which could provide alkalinity to hasten the hydration of ground granulated blast furnace slag (GGBS). In this study, GGBS by wet grinding (i.e., WGGBS) was used to partially replace raw GGBS in PSBC, with intent to promote the early hydration and cementitious performance in backfill tailings. Results showed that 60 % replacement ratio of GGBS by WGGBS enhanced the 3 d compressive strength by 507 %, and that for a 28 d was 45 MPa, which meet the strength requirement of 42.5 grade cement; besides, its carbon emission was only 5 % of that of cement. Due to the high reactivity of WGGBS at the early age, pH of PSBC system was promoted, and this hastened dissolution of GGBS and formation of hydrates. This was the reason for the significant increase in early compressive strength. Moreover, with the continuous hydration of PSBC, the hydrates were produced, and the microstructure was densified over time, leading to the increase in later compressive strength. It seemed that the PSBC with WGGBS showed an excellent cementitious performance in iron tailings filling. Under the condition of 1:10 wt ratio of cementitious material to iron tailings, 28 d compressive strength of PSBC with WGGBS was up to 3.1 MPa, while that for cement was only 0.8 MPa.

Corrosion of Reinforcement in HVFA Concrete

bstract: Concrete is a composite material composed of fine aggregate and coarse aggregate bonded together with cement that hardens over time. Concrete is one of the most frequently used building materials. Water cement ratio plays an important role which influences various properties such as workability, strength and durability. In concrete cement is main concrete material.The use of fly ash as an addictive material, as replacement of cement. The most important benefit is reduced permeability to water and chemicals. Properly cured concrete made with fly ash creates a denser product because the size of pores is reduced. This increases strength and reduces permeability and corrosion. For concrete mixes 43 grade of ordinary Portland cement and class F type Fly ash is concrete cubes are casted with varying percentage of fly ash and ultrafine fly ash. Three types of percentage is used as replacement of cement with fly ash. For replacement 40% ,50% and 60% fly ash is used. The size of cubes is 150mm x 150mm x150mm.Water/cement ratio 0.36 and Four types of percentage of Ultra fine fly ash is added such as 6%,8%,10% and 12%. Test is carried out after 7 days and 28 days of curing period. The tests conducted on concrete specimens are compressive strength. Results show that the addition of 6 wt.% UFFA significantly improved the early age and later age compressive strengths of HVFA concretes. The HVFA concrete containing 50% fly ash and 6% UFFA exhibited higher corrosion resistance properties. The results also indicate the effectiveness of UFFA in producing high packing density and in accelerating the pozzolanic activity to produce more C–S–H gel by consuming calcium hydroxide (CH) in HVFA concretes.

Influence of Grades of Cement on Strength of Concrete as per IS 10262-2019

Abstract: Concrete is the most used material in the world for construction. As we know Cement is the major constituent of concrete which is produced by natural raw materials like limestone rock, clay and chalk etc. Cement is produced in various grades and types used for construction according to the requirement. According to various grades used the strength of the concrete is influenced. The present investigation deals with the development of mix design of concrete using the IS 10262 - 2019. The study mainly focuses on the discussion of strength characteristics of concrete when various grades of cements used with reduction of 5% & 10% to understand if the concrete reaches the required target strength. It also focuses on understanding as to which grade of cement would be able to reach the required strength with less cement content. Compression test and Split Tensile test were conducted for strength analysis. The research evaluates the variation in Mix Design Guidelines between IS 10262-2009 & IS 10262-2019; strength factors of hardened concrete, by using various grades of cement at different percentages for M30 grade concrete at different ages. From this study it can be concluded that, 53 grade gives the better compressive strength with lesser amount of cement content, hence it is suggested that 53 grade cement can be used wherever bulk or mass concreting is done or concrete is produced

Assessment of Altawseea Ordinary Portland Cement Northern Iraq: Mineralogy, Microstructure, and Hydration

The current study is an assessment of the Al-Tawsseea Cement Plant, located in the northwest of Iraq, Nineveh. This plant produces Ordinary Portland Cement grade 42.5R according to the I.Q.S No(5)/2019. Ordinary Portland Cement was chosen to determine the mineralogy using X-Ray Diffraction and Scanning Electron Microscope before and after hydration. Physical tests were carried out such as the Fineness Test (Blain) ( 331.4) M2/Kg, Soundness Test (Autoclave) 0.1% Compressive Strength Test (2 Days 22.35 N/mm2 and after 28 Days 47.81 N/mm2) and Setting Time Test (Initial 150 Min and Final 3:10 Hours) and all the physical tests are within the requirements of limits according to I.Q.S No(5)/2019. XRD analyses revealed that the studied cement is composed of alite, belite, ferrite, and aluminate which indicate good burning and cooling processes, while after hydration the paste is composed of CSH, CH, and Ettringite. The Scaning Electron Microscope showed that the studied Ordinary Portland Cement microstructure, characterized by an intensive intergrowth of hypidiomorphic crystals and belite (spherical to oval shape) is less but bigger than alite. After hydration, the microstructure became dense and calcium-silicate hydrate (C-S-H ) formed a lathe-like shape fill the pores of the cement paste and gave the paste hardness and good compressive strength. The pore diameters in studied Ordinary Portland Cement are ranging from 9.9 to more than 15.9 µm. They look like circular or irregular shape and are randomly distributed which decrease the density, and compressive strength of the paste. According to the results of the physical test and mineralogy microstructure, we can say that it is possible to raise the grade of Ordinary Portland Cement of the Al-Tawseea Cement Plant ( 42.5R) by increasing the proportion of calcium in the raw materials mixture within the specification. This will lead to an increase in the value of LSF and the C3S which is responsible for increasing hardness or compressive strength.

Development of Portland Limestone Cement (PLC) in India using different composition of cement and marginal grade limestone: A sustainable approach

In this study, Portland Limestone Cement (PLC) was synthesized by inter-grinding method Portland clinker (PC) with two grades of limestone individually; Cement grade (LS-CG) and Marginal grade (LS-MG) at varying dosages of 0, 10, 15, 20, and 30% by weight, along with a fixed amount (5% by weight) of Gypsum-GYP. It was found that the growth of finer and wider particles was enhanced by increasing both grades of limestone (LS-CG and LS-MG). However, as Limestone per cent exceeded up to 30% in PLC, the normal consistency and specific gravity decreased in the PLC. Investigations suggested that PLC blends with up to 20% addition of LS-CG and LS-MG have qualified the specifications stipulated for blended cement in India as per the Bureau of Indian Standards. It was also observed that the compressive strength of PLC was found to be strongly associated with the 5.5 μm and 3.27 μm particles of PLC. This research suggests that LS-MG can be used to produce PLC.

Prediction compressive strength of cement-based mortar containing metakaolin using explainable Categorical Gradient Boosting model

Although machine learning models have been employed for the compressive strength (CS) of cement-based mortar containing metakaolin, it is difficult to understand how they work due to “black-box” nature. In order to explain the involved mechanism, Categorical Gradient Boosting (CatBoost) model with feature importance, feature interaction, partial dependence plot (PDP) and SHapley Additive exPlanations (SHAP) is proposed in this paper. A dataset consisting of 424 samples with six input variables is used to build the CatBoost model, which has optimal performance by tuning a set of seven hyper-parameters using sequential model-based optimization. Five quantitative measures (R2, MAE, RMSE, a10-, a20-index) are employed to evaluate the accuracy and the obtained results are superior to the previous study. It is from feature importance that the most significant input variable involving the CS is water-to-binder ratio, followed by age of specimen and cement grade. The strongest feature interaction is between water-to-binder ratio and metakaolin. A comprehensive parametric study is carried out via SHAP and PDP to investigate the effects of all input variables on the CS of cement-based mortar.

A Comparative Analysis of Machine Learning Models in Prediction of Mortar Compressive Strength

Predicting the mechanical properties of cement-based mortars is essential in understanding the life and functioning of structures. Machine learning (ML) algorithms in this regard can be especially useful in prediction scenarios. In this paper, a comprehensive comparison of nine ML algorithms, i.e., linear regression (LR), random forest regression (RFR), support vector regression (SVR), AdaBoost regression (ABR), multi-layer perceptron (MLP), gradient boosting regression (GBR), decision tree regression (DT), hist gradient boosting regression (hGBR) and XGBoost regression (XGB), is carried out. A multi-attribute decision making method called TOPSIS (technique for order of preference by similarity to ideal solution) is used to select the best ML metamodel. A large dataset on cement-based mortars consisting of 424 sample points is used. The compressive strength of cement-based mortars is predicted based on six input parameters, i.e., the age of specimen (AS), the cement grade (CG), the metakaolin-to-total-binder ratio (MK/B), the water-to-binder ratio (W/B), the superplasticizer-to-binder ratio (SP) and the binder-to-sand ratio (B/S). XGBoost regression is found to be the best ML metamodel while simple metamodels like linear regression (LR) are found to be insufficient in handling the non-linearity in the process. This mapping of the compressive strength of mortars using ML techniques will be helpful for practitioners and researchers in identifying suitable mortar mixes.

Prediction of Marshall Test Results for Dense Glasphalt Mixtures Using Artificial Neural Networks

Asphalt mixture comprising waste glass as an aggregate is referred to as “glasphalt”. Limited studies have been oriented to investigate the Marshall test results of dense-graded glasphalt mixes considering a wide range of variables. This study aims to utilize the artificial neural networks (ANNs) to develop predictive models for Marshall stability and Marshall flow of dense glasphalt mixes based on a large experimental database collected from the literature. Eight independent variables covering the material and mix properties were utilized as inputs in the models. The proposed models resulted in an experimental-to-predicted ratio of 1.00 and 1.00, coefficient of variation of 8.6% and 8.7%, RMSE of 1.63 kN and 0.54 mm, and R-squared of 93.6% and 85.7% for the glasphalt stability and flow models, respectively. Comprehensive parametric analyses have been conducted to further validate the models by investigating the sensitivity of their parameters to the predicted stability and flow values. The analyses revealed some desirable design values that could be considered for a better performance of dense glasphalt mixes. The results indicate that 4% is the desired design air void content of glasphalt mixes. High stability value can be achieved for glasphalt mixes containing a crushed aggregate of 12.5 mm maximum size and 50% glass cullet of 4.75 mm maximum size. Lower viscosity asphalt binder would provide uniformly compacted mixes. Furthermore, glasphalt flow increases as the maximum size of ingredient particles, the penetration grade of asphalt cement, asphalt cement content, and VMA% increase.

ASSESSMENT OF COMPRESSIVE STRENGTH OF CONCRETE PRODUCED WITH FINE AGGREGATE FROM DIFFERENT LOCATIONS IN KADUNA STATE

Building Collapse from failure of structures has been a major concern for researchers today. This is traceable to several factors, one of which is the quality of the materials used during construction, as the quality of concrete is known to depend on the type of cement, water and aggregates used. Since coarse and fine aggregates occupy up to 70-75% of the concrete volume, it is necessary that the quality of aggregates be astutely ascertained. The objective of this research is to establish the best locations of fine aggregate in Kaduna state in order to facilitate its selection for construction purposes. A prescribed mix of 0.55/1:1.5:3 targeting a concrete of grade C20 was adopted for 100 x 100 x 100mm cubes. This research examined the engineering properties of fine aggregate which are used in concrete works in Kaduna. Fifteen sources from the three senatorial districts in Kaduna (Kaduna North, Kaduna South and Kaduna Central) were identified from which fine aggregate samples were collected and transported to the Nigerian Defence Academy, Afaka, for examination. The test results revealed that the specific gravity of the samples falls between 2.34 and 2.85 and fineness modulus between 2.36 and 3.3. The compressive strength after curing for 7 days varies between 18.5 N/mm2 and 26.4 N/mm2, and after 28 days curing varies between 23.3 N/mm2 and 30.1 N/mm2 all for same prescribed mix, cement grade and coarse aggregate type. Concrete produced with fine aggregate from Kaduna South L.G shows the highest strength after 28 days while the concrete from Kajuru L.G has the lowest compressive strength after 28 days.

Towards Sustainable Construction Materials: A Comparative Study of Prediction Models for Green Concrete with Metakaolin

Cement-based materials are widely used in transportation, construction, national defense, and other fields, due to their excellent properties. High performance, low energy consumption, and environmental protection are essential directions for the sustainable development of cement-based materials. To alleviate the environmental pressure caused by carbon emissions in cement production, this paper studies cement-based materials containing metakaolin by a comparison of prediction models for the compressive strength. To more accurately evaluate the compressive strength of metakaolin cement-based materials, this paper compares the prediction effects of four models, namely, support vector machine (SVM), decision tree (DT), k-nearest neighbor (KNN), and random forest (RF), with hyperparameters optimized by the Firefly Algorithm (FA) to study the compressive strength of cement-based materials containing metakaolin. The results demonstrated that the RF model showed the optimized prediction effect considering the lowest RSME value and the highest R value among the hybrid models for predicting metakaolin cement-based materials’ compressive strength. The importance test showed that the cement grade and the water-to-binder ratio greatly influence the compressive strength of cement-based materials with metakaolin compared to the other design parameters.

An investigation of the influence of various types of cement on the physicochemical properties of autoclaved aerated concrete

Introduction. The article addresses the influence of various types of cement on the physicochemical properties of the aerated concrete mix and finished products that have D600 density and are manufactured according to the impact technology. The study is aimed at improving the rheological properties of the mix and the operational parameters of autoclaved aerated concrete (AAC). The authors study a reduction in the “carbon footprint” of AAC CEM II. The aim of the study is to improve the physicochemical properties of the aerated concrete mix to stabilize the AAC production process and increase the strength-density ratio of the ultimate product.
 
 Materials and methods. To analyze the influence of various types of cement on AAC, trial batches were manufactured. The following grades of cement were used in testing: CEM I 52.5 N, CEM I 42.5B, PC 500-D0-N, CEM II/A-M (S-I) 42.5N, CEM II/A-L 42.5N, CEM II/A-L 42.5B. Chemical and mineralogical compositions of cements were identified as factors affecting the rheological properties of the aerated concrete mix. The properties of the aerated concrete mix were evaluated against the following parameters: consistency identified using the Southard viscosimeter, mix boiling point, boiling time, plastic strength, and cutting temperature. Final properties of products were evaluated against such parameters as strength and density. The flow was measured using the Southard viscosimeter; the value of plastic strength was identified using the penetrometer. The strength and density of ACC were identified pursuant to GOST (State Standard) 10180-2012 and GOST 12730.5-2018.
 
 Results. The authors have identified dependences between changes in the rheological properties of the mix, operational parameters of AAC and the mineralogical composition of cement. The authors present graphs describing dependencies between plastic strength and the C3A content, plastic strength and the MgO content, ultimate strength and the MgO content, strength and the C3S content; density and the C3S + C4AF content. A graph describing the effect of limestone and slag additives on the mix consistency is presented. The authors describe the way the amount of alkaline oxides in cement affects the ultimate strength of AAC. The types of defects caused by particular types of cement have been identified. The cement, having the highest value of the strength-density ratio, has been selected.
 
 Conclusions. It is shown that the cement, containing limestone and slag additives, cannot deteriorate any physicochemical or operational characteristics of AAC. The use of CEM II reduces the cost of production and the “carbon footprint”.

Towards sustainable concrete: Cement replacement using Egyptian cornstalk ash

The environmental impact of cement production has fostered several attempts for cement replacement within the concrete industry especially using agricultural wastes. More specifically, several agricultural waste ashes have shown good pozzolanic reaction that works in favor of concrete production. On the other side, cornstalk is considered one of the widely available bi-products in Egypt that produces heavy pollution from its dumping. However, limited research has been presented on the applicability of using cornstalk ash as cement replacement for concrete production. As such, this study investigates the feasibility of producing cornstalk ash from the Egyptian stock and its applicability as a partial replacement for cement in concrete production. Three different cement replacement ratios (by weight) have been tested, 5 %, 10 %, and 15 %, and the results of fresh (workability) and hardened (compressive, flexural, and splitting strength) properties are reported. Moreover, the influence of changing the cement grade along with the cornstalk ash replacement on the short- and long-term compressive strength has been investigated. Finally, the impact of using cornstalk ash as cement replacement on permeability has been investigated as an indication of the expected durability behavior. The presented work is considered a gate opener for sustainable applications of different agricultural wastes produced in Egypt.

Concrete as a factor in reinforced concrete buildings collapse in Burundi

Introduction. This paper presents the results of the assessment in-situ of the involvement of the concrete in the collapse of reinforced concrete buildings in Burundi.Materials and Methods. The study consisted in the identification of the compressive strengths of the concrete structural elements of the reinforced concrete buildings under study. The compressive strengths were identified on the columns, beams and slabs using an industrial SCHMIDT 2000 sclerometer according to the protocol described in NF EN 12504-2(2003). Seventeen (17) three-storey buildings under construction were studied. For each building involved in the study, the reinforced concrete bearing elements of the first floor were studied. The results obtained were classified according to the cement grades (32.5) and (42.5) that were used in the studied buildings. A comparison of the compressive strengths obtained in-situ was established in relation to the normative values according to the cement grade used. The reliability of the obtained results was confirmed by the correlation between the results obtained in the laboratory conditions on the reinforced concrete experimental samples.Results. This study showed that in Burundi up to 100% of collapses are caused by privately built structures. It was proved that the compressive strengths of 100% of the columns, 82% of the beams and 82% of the slabs that were made with a low-grade cement (32.5) had compressive strengths lower than the normative value (25MPa). In addition, the compressive strengths of 50% of the columns, 50% of the beams and 84% of the slabs made with a high-grade cement (42.5) were also proved to have compressive strengths lower than the normative values (35MPa).Discussion and conclusion. In this study, the reliability of the results obtained by sclerometer test in-situ on the reinforced concrete buildings has been proved. Concrete has been shown to be a factor in the collapse of privately built reinforced concrete buildings in Burundi. Low-grade cement was observed to have a high impact in the collapse of reinforced concrete structures than the high-grade one. Therefore, as a recommendation, the process of building reinforced concrete buildings in Burundi needs to be regulated and controlled.

Prediction of the Compressive Strength for Cement-Based Materials with Metakaolin Based on the Hybrid Machine Learning Method

Cement-based materials are widely used in construction engineering because of their excellent properties. With the continuous improvement of the functional requirements of building infrastructure, the performance requirements of cement-based materials are becoming higher and higher. As an important property of cement-based materials, compressive strength is of great significance to its research. In this study, a Random Forests (RF) and Firefly Algorithm (FA) hybrid machine learning model was proposed to predict the compressive strength of metakaolin cement-based materials. The database containing five input parameters (cement grade, water to binder ratio, cement-sand ratio, metakaolin to binder ratio, and superplasticizer) based on 361 samples was employed for the prediction. In this model, FA was used to optimize the hyperparameters, and RF was used to predict the compressive strength of metakaolin cement-based materials. The reliability of the hybrid model was verified by comparing the predicted and actual values of the dataset. The importance of five variables was also evaluated, and the results showed the cement grade has the greatest influence on the compressive strength of metakaolin cement-based materials, followed by the water-binder ratio.

The Mechanical Behavior of Self-Compacting Concrete SCC Samples Locally Produce

The main objectives of this research were to obtain a locally self-compacting concrete SCC, a modern concrete with a high property, that enables it to pass and flow through the structural elements and within the steel bars under its own weight only. which was produced and tested in the reinforced concrete laboratory, using local materials in its composition. The mixtures showed no separation or accumulation of the concrete mixture, which enables us to use it in the construction, restoration and structural strengthen at the lowest costs of production. Three concrete mixtures have been produced using three grades of cement (550, 500 and 450-475 kg/m3), using three types of chemical plasticizers, which has been coded as (3500, NN, and S) and two plasticizers ratios (2%, and 2.5%) of the cement weight, verified by the experiments of the fresh properties of the concrete mixture, determination of the cylindrical strength at the age of 28 days, and the measurement of the stress-strain(ϭ, ξ) for the tested samples. It was found that the self-compacting concrete mixture with cement grade (550kg/m3) using the chemical plasticizer (3500) at (2%) ratio of cement weight, gave the best properties at a water/cement (W/C) ratio of (0.39), with relatively high concrete strength.

Evaluation of the Effects of Nigerian Portland-Limestone Cement Grades on the Strength of Concrete

The influence of Nigerian Portland-Limestone cement grades on the strength of concrete was investigated in this study. Three cement grades of 32.5R, 42.5R and 42.5N were adopted. A constant mix design ratio of 1:2:4 with a varying water-cement ratio of 0.4, 0.5, and 0.6 was used. All of the constituents of concrete were calculated using the mass of a concrete cube specimen of 150mm x 150mm x 150mm. A total of 135 cube specimens were cast and cured for 3, 7, 14, 21 and 28 days accordingly in order to determine the compressive strength of the concrete. The results obtained show that concrete cube specimens produced with Portland-Limestone cement grade 42.5N had the optimum compressive strength on the 28th day of curing in each water-cement ratio. However, the optimum compressive strength on the 7th day of curing in each water-cement ratio was obtained in the concrete cube specimens produced with Portland-Limestone cement grade 42.5R. The results also show that concrete produced from cement grade 32.5 will generally produce more workable but weaker concrete than concrete produced from cement grade 42.5, irrespective of the water-cement ratio. Finally, it was concluded that the compressive strength of concrete is inversely proportional to all the water-cement ratios used in this study, irrespective of the grade of cement.

Strength Evaluation and Durability on Addition of Nanosilica in M30 Grade Concrete

Abstract: Nano technology plays a very vital role in all the areas of research. The incorporation of nano materials in concrete offers many advantages and improves the workability, the strength and durability properties of concrete. In this study an attempt has been made to carry out an experimental investigation on concrete in which cement was replaced with nano sized cement. Nano-silica has a unique advantage in the potential pozzolanic-reaction with cement hydration products over other nanoparticles. Addition of Nano-silica is known to redefine pore size and distribution which would alter the durability of the concrete. Ordinary Portland cement of 53 grade was ground in a ball grinding mill to produce nano cement. . Nano technology is an emerging field of interest for civil engineering utility. A few of the nano substances presently used in concrete, nano-silica very own greater pozzolanic nature. It has the functionality to react with the unfastened lime inside the route of the cement hydration and bureaucracy extra C-S-H gel giving strength, impermeability and durability to concrete. Present paper investigates the effects of addition of nano silica in normal strength of concrete. The present research deals with Partial alternative cement through nano silica powder as partial replacements in concrete at associate with various materials like OPC53 grade cement, fine aggregate, coarse aggregate to check their suitability for making concrete. The mix proportions of concrete were modified as micro silica (5%, 7.5%, 10%, 15%) and nano silica (1%, 1.5%, 2%, 2.5%) as partial replacement of cement. The cubes were cast by replacing Specimens were cast as per mix design and the tests are conducted after proper curing, the tests are compressive strength of cubes (150mm x 150mm x 150mm) and split tensile strength of cylinders (150mm x 300mm). The results had been compared with the outcomes of concrete specimens with 0% of nano silica. Keywords: M30 grade, nano silica, Nano technology,pozzolanic-reaction

Preparation of belite–sulphoaluminate cement using phosphate rock acid-insoluble residue

In the phosphorous–sulfur two-step process involved in the clean production of phosphoric acid, the acidolysis of phosphate rock yields a solid filter phosphate rock acid-insoluble residue (PAIR). Herein, belite–sulfoaluminate cement is prepared using the PAIR as the main silica source to promote the residue resource utilization. The PAIR has practical feasibility for belite–sulfoaluminate cement preparation. Preparation conditions comprising the basicity coefficient of the raw meal of 1.187, clinker calcination temperature of 1200 °C, and the holding time for clinker calcination of 1.0 h are employed. Under these conditions, calcium sulfoaluminate and dicalcium silicate, the main mineral phases of the clinker, are fully formed, exhibiting contents close to the theoretical design value. The high amounts of fluorine and phosphorus in the PAIR reduce the clinker sintering temperature by 50 °C–150 °C and activate the clinker mineral phase. The maximum ɑ′ dicalcium silicate content in the clinker is 20.233%. The hydration and mechanical properties of the prepared belite–sulfoaluminate cement are better than those of commercial 42.5 grade cement. Moreover, its 28-day compressive strength can reach 64 MPa.

Study on Strength Enhancement Factors of Cement‐Stabilized Recycled Aggregate

With the rapid development and urbanization, huge amounts of construction and demolition (C & D) waste are produced. In order to protect the environment and conserve natural resources, promoting renewable materials, with C & D waste as raw materials, is imperative. However, the poor mechanical properties of recycled aggregate hinder its applicability in projects. In this study, two kinds of recycled aggregates, that is, concrete and brick slag, were strengthened with polyvinyl alcohol (PVA) solution, and the optimal strengthening time and soaking concentration were determined. Recycled mixed aggregate and brick slag were designed with two kinds of graded recycled aggregate. Recycled cement‐stabilized crushed stone specimens were prepared for a 7‐day unconfined compression and freeze‐thaw cycle test. The results showed that the recycled aggregate strength was improved to a certain extent, while the improvement of brick slag aggregate was more pronounced. The recycled mixture with less cement‐stabilized brick slag can be used for the base course of heavy traffic secondary highways before strengthening. Cement‐stabilized unreinforced brick slag has shown low strength, so it is not suitable to be used as a base on heavy traffic roads. The strengthened cement‐stabilized recycled mixture and cement‐stabilized brick slag could meet the requirements of heavy traffic class I and class II highways, respectively. When the cement grade, dosage, and grading type were kept the same, the strength of cement‐stabilized crushed stone prepared with larger aggregates was slightly lower. After the freeze‐thaw cyclic test, the strength loss of the recycled stable gravel was low, and its durability did not significantly improve after the reinforcement of recycled aggregate.

Torsional performance of reinforced concrete beam with carbon fiber and aramid fiber laminates

In the presented research paper, investigated the torsional performance of reinforced concrete beams with light emissions grade of cement utilizing Carbon fiber and its relative investigation with aramid fiber, for its torsional conduct, utilizing both exploratory and insightful strategies. A distinctive example of its strips folded over RC beams and the torsional conduct of these restrengthened beams is considered. Carbon fiber (CF) is utilized as outside support. Reinforced concrete beam retrofitted with CF tried for torsional disappointment utilizing lever arms exposed to torque. The beams have dimensions of 150mm in width and 200mm in depth and 1 m long, as planned according to IS456-2000. Three bars are intended for a twist. Steel has a stronger ultimate strength but a lower density than aramid FRP, as well as being easier to install and requiring no interim support until it reaches its full strength. The impact of various sorts and designs of CF on the initial stage of breaking load, extreme load conveying limit, and disappointment method of the beam are thought about and its relative examination utilizing finite element programming with aramid fiber gives a better outcome for additional investigation.