Influence of freeze-thaw cycles on capillary absorption and chloride penetration into concrete
TL;DR: In this article, the influence of freeze-thaw cycles on capillary water absorption and chloride penetration into ordinary concrete with two different water-cement ratios and air-entrained concrete was investigated.
About: This article is published in Cement and Concrete Research.The article was published on 2017-10-01. It has received 289 citations till now. The article focuses on the topics: Air entrainment & Chloride.
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TL;DR: In this paper, the authors reviewed the published literatures on the use of CO2 curing to enhance the properties of the recycled aggregate (RA) and prepared RAC, and the results showed that the RA properties, CO2 concentration and pressure, relative humidity and curing time all had a significant impact on the CRA.
Abstract: In recent years, the CO2 curing technique has been developed to enhance the properties of recycled aggregate (RA) and recycled aggregate concrete (RAC), materials that can absorb the CO2 gas and are more sustainable for the construction industry. A body of literature on the CO2 curing of RA and RAC is currently available, but a systematic review is lacking. Therefore, this paper reviewed the published literatures on the use of CO2 curing to enhance the properties of the RA and prepared RAC. The studies on CO2 curing technology, the properties of carbonated recycled aggregate (CRA), and the micro-properties, workability, mechanical properties and durability performance of concrete with CRA are respectively reviewed. The results showed that the RA properties, CO2 concentration and pressure, relative humidity and curing time all had a significant impact on the properties of CRA. Carbonation treatment improved the pore structure of RA and reduced its porosity, and the workability, mechanical properties and durability performance of prepared RAC were also improved. In addition, an outlook on the CO2 curing of RA and prepared concrete was presented, and we expected that this work may inform further investigation of the use of CO2 curing to enhance the properties of concrete and cement products.
205 citations
TL;DR: In this paper, a coupling effect of pressure load with stress ratio of 0, 0.3 and 0.5 and freeze-thaw cycles was found to play an important role in the water absorption and chloride penetration of concrete.
146 citations
TL;DR: The findings revealed that ANN can be an effective tool to identify the discrepancies in the experimental findings, and would be particularly useful for evaluating the chloride resistance of RC structures serving in complex or harsh environment.
135 citations
TL;DR: In this paper, a review of applications of both two-dimensional neutron radiography and three-dimensional Neutron tomography to investigate specific aspects of durability and deterioration of cement-based materials is presented.
124 citations
TL;DR: In this paper, the feasibility of utilizing low-quality desulfurization ash from semi-dry flue gas desulurization by mixing with α-hemihydrate gypsum was investigated.
116 citations
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TL;DR: In this paper, the spallation neutron source SINQ had its first proton beam on the target, achieving a steady-state proton output of 850 KilA, the strongest of its kind in the world.
Abstract: At December 3rd 1996, the spallation neutron source SINQ had its first proton beam onthe target. With a steady-state proton beam of 850 IlA this facility is now the strongest of its kind in the world. One of the first experimental facilities in operation was theradiography station NEUTRA (for NEUtron Transmission Radiography). The designwas described at earlier meetings [1,2] and the first validation measurements werereported [3]. There are some advantages in comparison to other radiography stations atresearch reactors. This will be demonstrated in detail by means of the measured valuesand examples of practical applications. The use as reference facility will be envisagedwithin an European project (COST-524).
211 citations
TL;DR: In this paper, the authors present three basic possibilities to increase the sustainability of a structure, i.e., methods to assess and reduce the environmental impact of concrete, means to increase concrete performance, and design concepts which increase the possible lifetime of a concrete structure.
205 citations
TL;DR: In this paper, the application of the sorptivity test to determine the capillary water absorption properties of cement mortars is described, and the measured sorptivities of mortars vary markedly with water/cement ratio, cement/sand ration and plasticizer content, and ranges in the materials studied from 0.15 to 2mm min−12 approximately.
143 citations
TL;DR: In this paper, the authors applied neutron radiography to study the process of water penetration into cracked steel reinforced concrete and the effectiveness of integral water repellent concrete to prevent ingress of water and salt solutions.
Abstract: Service life and durability of reinforced concrete structures have become a crucial issue because of the economical and ecological implications. Service life of reinforced concrete structures is often limited by penetration of water and chemical compounds dissolved in water into the porous cement-based material. By now it is well-known that cracks in reinforced concrete are preferential paths for ingress of aggressive substances. Neutron radiography was successfully applied to study the process of water penetration into cracked steel reinforced concrete. In addition, the effectiveness of integral water repellent concrete to prevent ingress of water and salt solutions was investigated. Results are described in detail in this contribution. It will be shown that neutron radiography is a powerful method to visualize the process of water penetration into cracked and uncracked cement-based materials. On the basis of the obtained experimental data, it is possible to quantify the time-dependent water distributions in concrete with high accuracy and spatial resolution. It is of particular interest that penetration of water and salt solutions into damaged interfaces between concrete and steel can be visualized by means of neutron radiography. Deteriorating processes in cracked reinforced concrete structures can be studied in a completely new way. This advanced technology will help and find adequate ways to improve durability and service life of reinforced concrete structures. This will mean at the same time an essential contribution to improved sustainability.
116 citations
TL;DR: Neutron transmission tomography (NT) as mentioned in this paper is a technique that provides two- or three-dimensional maps of the attenuation coefficient distribution within an object by this means, the inner macroscopic structure and material composition can be visualized.
Abstract: Neutron transmission tomography is a technique providing two- or three-dimensional maps of the attenuation coefficient distribution within an object By this means, the inner macroscopic structure and material composition can be visualized Although basic principles are known since decades, this technique became more used in recent time, due to the availability of digital neutron area detectors and increased power of computers Modern neutron imaging detectors provide at the same time high sensitivity and sufficient spatial resolution Thus, objects in the size of a few millimeters up to tens of centimeters can be scanned in reasonable time Neutron tomography (NT) complements other computed tomography (CT) techniques like X-ray CT or nuclear magnetic resonance, due to the specific attenuation characteristics of thermal or cold neutrons NT can preferably be applied in cases where thick layers of (heavy) metals have to be transmitted and small amounts of light elements like hydrogen, boron, have to be detected We present methodological aspects specific for neutron transmission tomography Some recent results of NT investigations of scientific and technical relevance are given
106 citations