Concrete Water Research Articles

Utilization of Prior Information in Neural Network Training for Improving 28-Day Concrete Strength Prediction

AbstractA concrete mix design aims to obtain the optimal proportions of concrete ingredients, including cement, water, sand, coarse aggregates, and admixtures. Neural networks (NNs) have been widel...

Dynamic response of cylindrical water storage tanks made byECC compared to normal concrete

In this paper, the dynamic behaviour and seismic damages of concrete cylindrical water storage tanks are investigated. Furthermore, by modeling the reservoirs, using normal concrete and engineered cementitious composite (ECC), the effects of ECC on reducing the seismic damages of reservoirs are investigated. For this purpose, ANSYS software is used to perform the nonlinear dynamic analysis of the tanks and different parameters including the hoop force and bending moment of the wall and cracking or crushing of the concrete were examined. According to the results, the relationships and criteria provided in the ACI standard for design of tanks are recommended to be revised in certain parts. Unlike the normal concrete tanks, in those made of ECC, concrete fracture is not observed and the crack width remains very small at a level that is not problematic. Finally, the use of ECC in cylindrical water storage tanks is suggested as a strategy for reducing the seismic vulnerability of this type of hydraulic structures.

Bacterial from wawolesea hot springs: crack sealing application to concrete

Concrete is one of the most widely used construction materials for infrastructure, but concrete has the disadvantage of being easy to crack. One of the factors that influence concrete cracks is rain water, because water can enter and seep into the pores. Several studies have been carried out to overcome the cracking of concrete structures; one of them is the addition of bacteria that have calcium carbonate precipitating activity. Calcium carbonate from bacterial metabolism can closed on cracked concrete surfaces. This method is commonly called Microbial Induced Calcite Precipitation (MICP). The source of bacteria in this study is bacteria at Wawalosea hot springs from the limestone mountain. The research is healing of cracks in concrete compare by bacteria MICP and MICP immobilization using alginate-chitin. The results showed that the concrete made with the addition of MICP isolates as much as 1.6x108 cells / mL had a greater compressive strength than the concrete without the addition of isolates. The value of compressive strength and absorbency of concrete water with the addition of MICP isolates has a compressive strength of 25.78 Mpa and addition imobilization MICP has 18 Mpa. So when compared to concrete without the addition of isolates and concrete with the addition of MICP isolates, the value of concrete compressive strength occurred at 100%.

Evaluation of Prospective Use of Existed CFRP-Strengthened Concrete Pipes in Forest Areas: Assessment of Their Structural Stability and Possible Re-Use

Forest traffic networks receive considerable structural stress from supporting heavy vehicles and machinery. Usually, in forest areas, artificial waterways are constructed on the side of the road and feature open constructions, so that solid materials blocking the waterways may be easily cleared. The use of closed bridges at vehicle crossing points, though infrequent, necessitates the use of installing closed water pipelines of large diameters. However, these closed, reinforced concrete (RC) water pipelines suffer structural damage over time. Here, we propose the strengthening of existed old concrete pipes using sheets of carbon fiber reinforced polymer (CFRP) at increasing levels. The assessment of the results, which were conducted in ABAQUS, is done in light of the stress tests and suggests that the use of a simple, cost-effective method, such as the installation of composite materials, can potentially increase the structural strength of these pipes and allow their re-use for forest roads.

Concretes Made of Magnesium–Silicate Rocks

At present, there is a shortage of high-quality feedstock to produce widely used building materials—concretes. Depletion of natural resources and growing restrictions on their extraction, in connection with environmental protection, necessitate the search for an equivalent replacement for conventional raw materials. Magnesium–silicate rocks are a waste of the mining industry. We researched the possibility of using these rocks as coarse and fine aggregates in heavy concrete production. Following the requirements of the national standards, we studied the physical and mechanical characteristics of the obtained material. It was found that the strength of concrete, made of magnesium–silicate rock coarse aggregate, at the age of 28 days of hardening is within 28 MPa, while the strength of the control sample is 27.3 MPa. Replacing quartz sand with dunite sand also leads to an increase in concrete strength (~4%). Complete replacement of aggregates facilitates an increase in strength by 15–20% than the control sample. At the same time, the density of the obtained materials becomes higher. Concretes have a dense structure that affects their quality. Concrete water absorption is within 6%. The fluxing coefficient is 0.85–0.87. The application of magnesium–silicate rocks in concrete production enables the complete replacement of conventional aggregates with mining waste without reducing the quality of the obtained materials. Furthermore, the issues of environmental protection in mineral deposit development are being addressed.

Durability performance of pervious concrete containing rice husk ash and calcium carbide: A response surface methodology approach

Pervious concrete is a special type of concrete used for stormwater management due to its high porosity and permeability. However, the large pores in pervious concrete resulted to its low mechanical strength. Moreover, the emissions of greenhouse gases from Portland cement (PC) production are high and contribute to climate changes leading to climate change. Calcium carbide waste (CCW) and rice husk ash (RHA) were used as supplementary cementitious material to partially replace Portland cement by 5%, 10 %, 15 %, and 20 %. Response Surface Methodology was used to design the experiments and develop models for predicting the water absorption and permeability of PC. The properties of the developed pervious concrete like water permeability and water absorption were investigated. The most vital property of the pervious concrete is water-permeability. The result findings showed that both RHA and CCW have negative effect on the durability of PC, with RHA having the worst effect. The RSM models developed showed a high degree of correlation between the variables and the responses. The optimized variables which give the best durability performance was a combination of 0% RHA and 5% CCW having the following properties, water permeability between 0.96 cm/s and water absorption of 4.338 %. The developed models can be used for predicting the permeability and water absorption capacity of pervious concrete.

Seismic Performance of Elevated Reinforced Concrete Water Tanks

Most of the codal provisions used worldwide for the design of elevated water tanks incorporates the nonlinear response through reduction factor that considers overstrength, ductility and redundancy. The majority of these codes provide a value which incorporates the demand of their geological condition and construction industry. In Nepal, there is lack of own guidelines and codes for the seismic design of elevated water tanks. In the present work, seismic performance of elevated reinforced concrete (RC) Intze type water tank is evaluated and value of the response reduction factor (R) for the design of such tank is determined. In this research work 34 models of elevated reinforced water tank were analyzed using SAP 2000 to evaluate the seismic performance with varying tank filling condition and staging height for 450 cumec and 225 cumec capacity. Based on the results, it is concluded that single value of response reduction factor cannot be justified for all heights and capacity of elevated RC water tank. So, for economical design purpose, estimation of response reduction factor with exact analysis is preferred.

Methods of Test for Concrete Permeability: A Critical Review

Abstract The transport of liquids, gasses, and aggressive agents into concrete is responsible for a variety of durability issues. To obtain the low-permeability concrete required for long-lasting, sustainable infrastructure, stakeholders desire the ability to specify concrete based upon the permeability rating for specific uses. The mechanisms of moisture ingress into concrete are complex phenomena, and they are highly dependent on materials, mixture characteristics, curing conditions, and other factors. This review article provides an overview of the available permeability test methods and identifies existing gaps in the current field and knowledge. It discusses the mechanisms and key factors influencing moisture movement within concrete (capillary suction, absorption, water, and gas permeability) and outlines the procedures, advantages, and limitations of available permeability test methods. Despite a variety of tests available for water permeability, widespread acceptance for use of a single (or even a few) tests has not been achieved. No clear link exists between these tests and acceptable field performance. Additionally, several tests are viewed as problematic from a time, cost, or variability standpoint. Therefore, improved rapid permeability tests are needed to provide a pathway for agencies to move toward performance specifications with confidence. Recommendations regarding future work to support the development of improved test methods and, potentially, a model that would predict moisture ingress based on electrical resistivity, are also presented.

Collapse rates of reinforced concrete structures during large magnitude earthquakes: case study for Romania

This case study focuses on the evaluation of the collapse rates of various types of reinforced concrete structures (residential and industrial) as observed from the data collected in Romania after the Mw 7.4 Vrancea earthquake of March 4, 1977. The results of the analyses show that the largest collapse rates were attributed to elevated reinforced concrete silos and water tanks. Moreover, the majority of the collapsed elevated reinforced concrete water tanks were full at the moment of the seismic event. Very small collapse rates were observed for high-rise residential RC structures and for the multi-storey industrial RC structures.

Temporal analysis of the performance of an elevated concrete tank considering the corrosion of the steel reinforcement

Reinforced concrete water storage tanks are civil engineering structures subject to very aggressive atmospheric conditions that expose them to harmful corrosion risk. This dangerous phenomenon caused by the penetration of chloride ions causes pitting corrosion and leads to the reduction of the section of the reinforcements and consequently to the loss of strength and the structure performance. In this study, we are interested in analyzing the performance of an elevated storage tank, taking into account the corrosion of the reinforcements subjected to tensile stress, by considering environments with different rates of aggressiveness. A method based on Housner's model is used to evaluate the tension stresses in the reinforced concrete (RC) pedestal (supporting system) of the tank, subjected to the seismic actions. A pitting corrosion model is developed in order to determine the evolution in time of the reinforcements section in different environments. Several parameters influencing corrosion are taken into account, such as concrete cover and the concentration of chlorides ions.

Review on progress in concrete solar water collectors.

The solar-powered water heating method is the best way to use the available free solar radiation for thermal energy. Electrical water heating systems all over the world consume more electrical energy for their operation. The Solar Water Heating System (SWHS) has a higher efficiency than the electrical water heating system. As a result, SWHS plays an important role in the home, industry, hostel, and hotel. Various types of SWHS are published by different researchers. Concrete Collector Solar Water Heating (CCSWH) System used for dual purposes is one of the published works (space cooling and hot water production). The CCSWH system is discussed in this review, which includes both traditional and recent developments. Also, future research opportunities in this field are provided.

Investigation of the Effect of Seawater and Sulfate on the Properties of Cementitious Composites Containing Silica Fume

Concrete consumes over two billion tons of freshwater every year and 75 % of regions of the world will become water shortages in 2050. Because of increasing freshwater scarcity seawater may become reasonable as an alternative mixing and curing water for concrete. In this study, seawater (SW) was utilized for mixing and curing of concrete and investigated the seawater and sulfate on the properties of cementitious composites containing silica fume (SF). Hence, SF was replaced with the cement at ratios corresponding to 0 %, 2.5 %, 5 %, 7.5 %, 10 %, 12.5 %, and 15 % by weight of cement, and SW and tap water (TW) were used as mixing water in the production of cementitious composites. Thus, the effect of SW on the properties of fresh cement pastes and the flexural and compressive strengths of 7-day, 28-day, and 90-day old cementitious composites were examined. Additionally, the lengthening change values of cementitious composites containing SF that were kept in 5 % Na2SO4 solution for 7-day, 28-day, and 90-day were determined. The SF delayed the setting period while increasing the water requirement of the cement paste. It is determined that the SW accelerated the setting period of cement. In the case when 10 % SF in cementitious composites was used, the maximum compressive and flexural strengths were obtained for cementitious composites produced by mixing with SW and SF fume at an age corresponding to 28-day and 90-day. It was observed that the length change of the cementitious composites decreased due to the increase in the SF replacement ratio.

Influence of the formwork removal by polarization on the facing aesthetics in reinforced concrete

Formwork removal by means of polarization offers an alternative solution to compensate for some of the disadvantages and risks of using mineral-based oil due to its petrochemical origin. This technique consists of applying an electrical current between the steel reinforcing bars and the metal formwork wall in order to obtain a thin water film at the concrete/formwork interface and allow for formwork removal. This paper focuses on the facing quality of the reinforced concrete and formwork surface at various temperatures for both conventional and self-compacting concretes. A series of experimental tests have been conducted in the laboratory to determine the optimal polarization parameters (voltage value, time and duration of its application). On-site tests were then performed to observe the scaling effect. Results indicate that the proposed polarization technique can indeed provide an effective means to separate the concrete from its formwork without requiring demoulding oil. Concrete mixtures implemented both in the laboratory and on-site display high-quality facing without the presence of any attachment points. A chromatographic analysis of the concrete pore solution and water transported by electro-osmosis shows that ion concentrations remain unaffected. This polarization approach can thus be used as an alternative to avoid the use of oils of a chemical or petrochemical origin.

Beneficiation of concrete wash water with carbon dioxide

Wash water is generated as a by-product of ready mixed concrete production. Reuse of the water as mixture water is limited, in practice, by the negative material performance impacts associated with the water chemistry and suspended solids (i.e. hydrating binder phases and very fine aggregate); the effects are intensified with increasing content of suspended solids and water age. A novel carbon dioxide treatment to allow the use of high solids wash water as mixture water was examined through mortar and concrete testing. An industrially sourced wash water with a specific gravity of over 1.20 was treated with CO2. Seven batches of concrete were produced and compared: a reference mixture at three different w/b, and four batches with a 6% reduction in cement where wash water was used as mixture water (diluted to a specific gravity of 1.08, comparing untreated versus CO2 treated conditions, aged either 1 day or 5 days). The treatment mineralized CO2 at 27% by weight of the cement in the solids and reduced or eliminated negative aspects associated with the untreated water (set acceleration, workability loss, strength reduction with water age). The CO2-treated solids displayed latent hydraulicity. The approach allows three waste streams (CO2, wash water and wash water solids) to be reused to produce more sustainable concrete.

Evaluating durability parameters of concrete containing limestone powder and slag under bacterial remediation

Microbiological methods, in which bacteria serve as catalysts and contribute to urea hydrolysis by producing the urease enzyme, can be used to enhance concrete durability and repair the entrained pores and micro-cracks. The hydrolysis of urea in a calcium-rich environment leads to the formation of solid calcium carbonate that fills concrete pores and cracks. At least 7% of the total carbon dioxide available on a global scale originates from cement production. This has encouraged efforts to decrease cement consumption in concrete structures and to replace it with such cement-like materials as fly ash, blast furnace slag, micro silica, or limestone powder. Slag and fine limestone have nowadays gained wide applications as cement replacements for their technical, economic, and environmental advantages. The present study was designed and implemented to investigate concrete durability, water absorption, carbonation depth, and water penetration depth in specimens containing slag and fine limestone powder in their concrete mixes, where exposed to the bacterial treatment. For this study, 78 concrete cubes of 100 mm in size, 78 cubes of 70 mm, and 78 prisms of 120 × 200 × 200 mm3 were made using six concrete mix designs containing two limestone powder ratios of 0 and 15% and three slag ratios of 0, 20, and 40% as replacements for cement. The specimens were subsequently treated for 28 days in one of the curing media of tap water, seawater, and a solution of calcium lactate and urea. Finally, the surfaces of the specimens were treated for two weeks in one of the above media. Results showed improved durability in both concrete specimens with bacteria in their mix designs and those subjected to surface treatment with bacteria. Moreover, all the specimens with bacteria recorded lower values of water absorption, carbonation, and water penetration depths than those lacking bacteria. As regards the cement replacement materials, it was found that limestone powder served as a source of calcium for bacteria and that slag enhanced the compressive strength of concrete and reduced its permeability. Finally, the solution of calcium lactate and urea from among the curing media investigated was found to have better effects on the specimens either containing bacteria in their mix designs or subjected to surface remediation with bacteria.

A review on alternative binders, admixtures and water for the production of sustainable concrete

To keep its leading role, the concrete industry must face the environmental issues linked to the manufacturing, by increasing the energy efficiency and adopting alternative fuels or raw materials. The present work analyses physical, mechanical, and environmental performances of concrete products incorporating waste from four main sources (construction and demolition waste, residues from waste treatment, metallurgical industry by-products and other sources), as substitutes of one of the three main components of concrete (binder, admixtures and water). The binder is the easiest component to be replaced in terms of number of alternatives, with the highest impact on concrete properties, while water easily reaches a full replacement level. Ground granulated blast furnace slag (GGBFS) showed the highest potential for the overall performance, with positive effects on compressive strength, durability, and workability of concrete samples, along with electric arc furnace dust (EAFD) and ceramic powder.

Comparison of Compressive Strength of Concrete by Partial Replacement of Cement with GGBS and Silica Fume with Sea Water Curing and Addition with Fibers

In construction world concrete plays a vital role, around 60% of structure consists of Concrete. However, the production of Portland cement, an essential constituent of concrete, leads to the release of significant amounts of CO2, depletion of natural resources and environmental degradation. This paper investigates the compressive strength of concrete by replacing cement with GGBS and silica fume effect of glass fibers on performance of concrete is studied. In this present work a humble attempt had been made to evaluate and compare the compressive strengths of GGBS blended concrete cubes with controlled concrete cubes cured under sea water for 28 days. By conducting the tests on the cubes, conclusions were drawn after plotting and analyzing the results. Compressive strength test is conducted on the samples after 28 days. The optimum value is obtained at 15% replacement with GGBS and 5% with Silica fume. In this study again we trailed addition with Glass fibers with the percentage of 0.5%,1.0%,1.5%, compressive strength have been studied. Finally at 1.0% addition we get maximum strength compared to controlled mix.

The effects of using magnetized water in reactive powder concrete with different curing methods

The effects of using magnetized water in reactive powder concrete (RPC) under various curing procedures was investigated. The RPC samples were separated into four groups, cured with three different curing methods compared to normal curing (lab conditions) as a reference procedure, these methods were; autogenous curing, submersion in warm water (35 °C) and curing by applying high temperature (70 °C) cycles. A magnetic water device was used to produce magnetic water for use in the RPC mix. Where, the intended water was moving with flow rate equal to 0.1 m3/hr. passing through a magnetic field with an intensity of 0.9 Tesla. This circulation process was used for 60 minutes to produce the magnetized water utilised in this study. Test results showed some improvements in the compressive, flexural and splitting tensile strength for RPCs cured with different curing methods The percentage increases for compressive strength for RPC mixes containing magnetic water. Where, the enhancing percentage reached 7.66, 8.43, 8.86, and 9.15% for normal curing, autogenous curing, warm-water, and high temperature curing respectively at 28 days. The high temperature curing method showed the maximum improvement in compressive strength, with up to 34.4, 30.6, and 28.52% increases at 7, 28, and 90 days, respectively.

Study on Influence of High Activity Alkaline Electrolyzed Water on Sulfate Resistance Property of Concrete

In this study, a kind of alkaline electrolyzed waters with the pH of 10.5 was used to enhance the sulfate resistance properties of concrete with mineral admixture at different proportioning. The results showed that Alkaline electrolyzed water in concrete can activate the pozzolanic effect of mineral admixtures, leading to an increase of compressive strength. The compressive strengths of electrolyzed water concrete (DJ) were all high than those of natural tap water concrete (TW) at same mineral admixture proportion. Through 120 times of sulfate attack cycles, the sulfate resistance coefficients of TW concrete with different proportions were 90.4~93.7%, and those of DJ concrete is 94.7~96.8%. The sulfate corrosion resistance property of DJ concrete was improved. The corrosion products AFt and gypsum on the surface of concrete were formed by the reaction of Ca2+ in cement paste and free SO4 2- infiltrated into the solution, which would further deepen the internal Ca2+ migration. In order to maintain the overall charge balance, K+ ions in alkaline electrolyzed water moved in, so as to slow down the corrosion of concrete. The SEM micromorphology showed that the internal structure of alkaline electrolyzed water concrete was more dense and compact, the porosity is relatively lower, which was less affected by sulfate corrosion. The microstructure of DJ concrete with mineral admixtures was more developed and denser than TW concrete.

Investigation the Quality of the Treatment Sand from Sulfite using Magnetic Water in Reactive Powder Concrete

In this study, the effect of using magnetized water in fine aggregate treatment has been investigated. Three mixtures of reactive powder concrete (RPC) were prepared and caste within two molds so that the compressive and flexure strength can be tested when the samples are cured by ordinary, autogenous, warm water and high-temperature cycles curing procedure. All of the three mixtures consisted of the same primary material; the difference was in the sulfite content of the fine aggregate, where the intended sand samples have diverse sulfite content. The first mixture’s sulfite content was limited within the Iraqi specifications No.45/1984, and it was equal to 0.13%, the second mix contained sand with high sulfite content of 3.54%, and in the third; the latter sand was washed with magnetizing water before mixing. The test results pointed out a severe decrease in RPC properties when the high sulfite sand was used by taking the low sulfite content mixture as a reference mix. A decrease was recorded in the compressive strength by 8.6% and 16.8% when the samples were tested at the age of 28-days and 90-days, respectively, and cured with ordinary curing procedures. Similarly, the flexure strength decreases by 7.1% and 13.5% when the samples are tested at the age of 28-days and 90-days, respectively, and cured with an ordinary curing procedure. This decrease in RPC strength could be recovered, as the third mixture’s test results indicate; when the sand was treated with magnetized water before mixing, and the sulfite content was reduced down to (0.274%) accordingly.