Water-cement Ratio Of Concrete Research Articles

Strength prediction of seawater sea sand concrete based on artificial neural network in python

Based on the artificial neural network method, the nonlinear mapping between the 28d compressive strength of seawater sea sand concrete and concrete water-cement ratio, cement content, and the sand ratio was established in Python. The results showed that with reasonable network settings, the fitting of the model training was good, and the prediction results were satisfactory. The mean relative error of prediction results was 3.16%, and the correlation coefficient was 0.974. Therefore, it is possible to use an artificial neural network to set up a compressive strength prediction model for seawater sea sand concrete. Compared with the traditional mix design method, the artificial neural network design method can decrease the number of mixing proportion adjustments and reduce the waste of labor, time, and materials.

Durability life prediction of RC piles subjected to localized corrosion in chloride environments

In this study, an analytical model for evaluating the durability life of reinforced concrete (RC) piles subjected to localized corrosion under chloride attack is proposed. The localized corrosion process is divided into three stages, and a predictive method is presented to predict the durability life of the pile by calculating the time of each stage. The time of each stage is determined based on the chloride diffusion model, the pitting corrosion model and the crack propagation model. The effects of the water-cement ratio, concrete cover thickness, pile concrete quality, relative humidity, chloride threshold level, pitting factor, corrosion current density and initial surface chloride ion concentration on the various stages of localized corrosion and the durability life of the pile are investigated. The analysis results show that the effects of the water-cement ratio and concrete cover thickness on the durability life of the pile are the most significant in the corrosion initiation stage. The durability life is increased by a reasonable choice of both concrete water-cement ratio and concrete cover thickness with constant concrete quality. The durability life of the pile increases with increasing concrete cover thickness, concrete quality, chloride threshold value and limit crack width, while it decreases with increasing water-cement ratio, relative humidity, corrosion current density and initial surface chloride concentration. The influence of the pitting factor is minimal and is mainly in the pit nucleation stage.

METHODS OF CELLULAR CONCRETE PRODUCTION USING FLY ASH

Abstract. An analysis of modern capital construction state shows that the material and technical base of the construction industry does not allow the production of effective building materials and products in the required quantity without due consideration of the economic burden on the environment, and now significant financial costs are required to restore the ecological balance of the natural zone. Power plant fly ash is a man-made raw material for many industries, which is utilized up to 92% in dry form and is of practical interest in the production of effective thermal insulation building materials and products as a filler and an aggregate. In view of the instability of the chemical and mineralogical composition, the content of raw fuel, as well as the pozzolanic activity, the study of the profitability of the production of pozzolanic cements and concretes based on them was carried out, with an increase in sulfate resistance, corrosion resistance of the aggregate while preventing thermal cracking. The expediency of autoclaved gas-ash-slag concretes production with the use of cement with high content of highly basic minerals ‒ alite and tricalcium aluminate is proved. The technology of obtaining ash-alkaline cellular concrete using ash-removal and alkaline component is given. The economic efficiency of cellular ash-containing concretes is justified by the replacement of sand with ash, a 1.2-1.5-fold reduction in lime consumption compared to lime-sand concrete and a reduction of approximately 2 times the capital costs for extraction and processing of raw materials. Comparative physical and mechanical parameters of autoclave and non-autoclave aerated concrete products are given. The process of manufacturing products by vibro-vacuuming and vibratory compaction of ash concrete is presented. The strength data of vacuum concrete are given, which are 30-40% higher than that of vibro- compacted concrete from a rigid mixture. The investigated value of shrinkage as a result of the water-reducing effect of ash, provides a decrease in the water-cement ratio of concrete. Autoclaved and non-autoclaved aerated concrete can compete with such an effective thermal insulation material as mineral wool. They are more effective materials for low-rise and frame housing construction than traditional brick and concrete.

Analysis of the Influence of Water-cement Ratio on Concrete Strength

In this paper, the main strength of the relationship between water-cement ratio and concrete, and it uses the contrast test of different water cement ratio, finally, it gets the regular change between water cement ratio and concrete strength. The test results show that: cement. when the ratio of large stone: small stone: water: admixture is 340: 618: 1009: 433: 139: 6.8, the water-cement ratio of concrete is within the range of 0.371-0.479. The concrete strength of the sample decreases with the increase of the water-cement ratio. Finally, the relationship between the concrete strength and the water-cement ratio is obtained by fitting.

Using Ultrasonic Pulse Velocity Test to Assess the Effect of Water-Cement Ratio on the Compressive Strength of Concrete

This study aims to find the effect of water-cement ratio on the compressive strength of concrete by using ultrasonic pulse velocity test (UPVT). Over 230 standard cube specimens were used in this study, with dimensions of 150mm, and concrete cubes were cured in water at 20 °C. Also, the specimens used in the study were made of concrete with varied water-cement ratio contents from 0.48 to 0.59. The specimens were taken from Diyarbakir-Turkey concrete centers and tested at the structure and material science lab, civil engineering, faculty of engineering from Dicle University. The UPV measurement and compressive strength tests were carried out at the concrete age of 28 days. Their UPV and compressive strength ranged between (3.89-4.66km/s) and (17.74-40.56MPa) respectively. The experimental results showed that although the UPV and the compressive strength of concrete are related, also, the UPV and compressive strength have a relation with the rate of the water-cement ratio of concrete.

Sustainable utilization of granite cutting waste in high strength concrete

The excessive consumption of river sand as a construction material has led to its acute scarcity. Researchers across the globe have attempted to utilize waste of copper slag, rubber tyre, recycled glass, pond ash, foundry sand, plastic, stone etc. as a partial or complete substitute of river sand in concrete. The present study investigates the feasibility of using granite cutting waste (GCW) as a partial substitute of river sand in high strength concrete based on strength, durability & microstructural attributes. Eighteen concrete mixes were cast at 0.30, 0.35 and 0.40 water cement ratios (w/c) by substituting 0%, 10%, 25%, 40%, 55% and 70% river sand by GCW. The concrete mixes were tested for compressive, flexural strength, abrasive resistance, permeability, water absorption, carbonation, corrosion and microstructure; changes in morphology and hydration were also studied. Test results suggested that 25–40% river sand can be substituted by the GCW with a favourable influence on the investigated parameters. The optimum amount of GCW to be used in concrete depends significantly upon water-cement ratio of concrete.

염해환경에서의 RC보의 허용 균열폭 산정에 관한 연구

Deterioration of reinforced concrete structures in corrosive environment is tend to be accelerated due to ingress of aggressive ion such as chloride ion. Chloride-induced corrosion is affected by various factors such as cover concrete qualities, width of existing cracks, and cover depth of concrete. However, the allowable crack width of RC structure in design code does not consider the concrete material properties and conditions of construction except the cover depth. In this paper, an equation for allowable crack width is proposed to consider the cover concrete quality, crack width, and cover depth. Crack width, cover depth, and water-cement ratio of concrete are selected as influencing factors on corrosion of reinforcement for rapid chloride tests. From test results, the relationships between the factors and corrosion are derived. Finally, the equation for allowable crack width is derived in terms of concrete compressive strength and cover depth. The presented equation is verified by comparative calculations with design code variables.

再生細骨材を用いたコンクリートの構造用コンクリートへの適用 : 原モルタルの性質が再生細骨材および再生コンクリートの品質に及ぼす影響

The original concrete to be used for the production of recycled aggregate is basically composed of the original aggregate and the original mortar, and, if the original aggregate has sound properties, the quality of the recycled aggregate depends on the property of the original mortar to a large extent. In addition, it is said that the degree of deterioration in the quality of the recycled fine aggregate is larger than that of the recycled coarse aggregate. Therefore, when the recycled fine aggregate or the concrete prepared using it is applied to the structural concrete, it becomes imperative to make a proper estimation of the effects of the properties of the original mortar as to their qualities prior to setting various mix design conditions. From this point of view, this paper presents a series of experiments which analyze recycled fine aggregate and recycled aggregate concrete as given below. 1. 12 types of original concrete were prepared using 3 types of original aggregate having different strengths, shapes and surface characteristics, and changing the water-cement ratio of the original mortar in 4 levels of 35%, 45%, 55% and 65%, respectively. Then, 16 types ofrecycled fine aggregate were made by manufacturing the prepared original concrete using 2 types of crushing methods. 2. The amounts of the original mortar contained in 16 types of recycled fine aggregate were estimated, and the tests on their various physical properties were carried out to clarify the relationship between them. 3. From among the above-mentioned 16 types of recycled fine aggregate, 6 types, which were made using the same type of original aggregate and the original mortar of different strengths, and by different methods to crush the original concrete, were selected. Using these 6 types of recycled fine aggregate, 48 types of recycled concrete having a different replacement ratio of recycled fine aggregate and a different water-cement ratio of concrete were produced to investigate the effects of the amount of the original mortar contained in each recycled fine aggregate and its properties on the quality of the recycled aggregate concrete. Much valuable information regarding useful results pertaining to the mix design of the recycled aggregate concrete to be produced using the recycled fine aggregate was obtained through these experiments and the analysis described above.

A study on moisture diffusion in drying and drying shrinkage of concrete

It is the purpose of this paper to clarify the behavior of moisture existing in concrete as drying occurs, and the relationship between moisture loss and drying shrinkage. Assuming that the behavior of moisture existing in concrete when drying was governed by nonlinear diffusion equation, the diffusion coefficient was expressed as a function of the moisture content by the experiment. The surface factor was also determined by the experiment. The relationship between diffusion coefficient or surface factor and the water-cement ratio of concrete were given. It was shown that the shrinkage strain was closely related to moisture loss.

Study of a Method of Immediate Estimation of Concrete Strength

The method of immediate estimation of concrete strength using rapid hardening process is a method which can estimate concrete strength within about 1.5 hr after getting a sample from fresh concrete by means of compression test of rapidly hardened specimens. The rapidly hardened strength of specimens can be obtained by using the combination of the addition of accelerator and the high temperature curing. The strength of rapidly hardened mortar specimens which are obtained by wet-screening of concrete is clearly dependent on the water-cement ratio of concrete. Thus, there is a high correlation between the 28-day strength of concrete and the strength of rapidly hardened mortar specimen. The coefficient of variation of the ratio of estimated strength at 1.5 hr to the actual 28-day strength of normal concretes was about 10 percent regardless of the brand of ordinary portland cement used in the laboratory test. Practicability of this method was ascertained at the field test using a portable curing chamber and a compressive test apparatus. /Author/

1021 コンクリート洗イ試験による現場コンクリートの水比変動について(材料・施工)

1021 コンクリート洗イ試験による現場コンクリートの水比変動について(材料・施工)