Durability, service life prediction, and modelling for reinforced concrete structures – review and critique

Thermal performance of the building envelope integrated with phase change material for thermal energy storage: an updated review

Herein, we report a facile yet efficient strategy for fabricating a carbonized kapok fiber aerogel (CKF) based composite PCM, by incorporating magnetic guest of Fe3O4 nanoparticles and encapsulating thermal energy guest of lauric acid (LA). The obtained LA/CKF@Fe3O4 composite PCMs (CPM) shows an ultrahigh latent heat of 97.5% that of LA. Besides, the integration of Fe3O4 contributes to the CPM with excellent microwave absorption performance by achieving an optimal balance between the impedance matching and the high loss characteristics. The minimum reflection loss for CPM-30 is −17.3 dB at 8.4 GHz within thickness of 5.5 mm, far exceeding the practical demand of −10 dB. Furthermore, the CPM can also realize efficient solar/magnetic to thermal conversion. To the best of our knowledge, this is the first example of carbon aerogel based composite PCM prepared by facile yet renewable method that also exhibits ultrahigh thermal energy capacity, enhanced thermal conductivity, superior microwave absorption property and efficient solar/magnetic to thermal conversion performance. This study paves a way for designing of high-performance composite PCMs with numerous energy storage forms and functions by extending the reported system to other natural microtubules and functional guests.

Carbon aerogel based composite phase change material derived from kapok fiber: Exceptional microwave absorbility and efficient solar/magnetic to thermal energy storage performance

The excessive production of worn tires remaining from the transportation system and the lack of proper procedures to recycle or reuse these materials have caused critical environmental issues. Due to the rubber’s toughness, this material could be implemented to increase concrete toughness, and by crushing the tires concrete aggregates can be replaced proportionally with rubber crumbs and large quantities of scrapped rubber. However, this substitution decreases the concrete strength. In this study, crushed rubber with sizes from 1 to 3 mm and 3 to 6 mm were replaced by 5%, 10%, and 15% sand; the combination of two additives of nano silica and metakaolin additives with optimum values was used to compensate the degradation of the strength and improve the workability of the concrete. Moreover, the compressive strength, tensile behavior, and modulus of elasticity were measured and compared. The results indicate that the optimum use of nano silica and metakaolin additives could compensate the negative effects of the rubber material implementation in the concrete mixture while improving the overall workability and flowability of the concrete mixture.

https://www.mdpi.com/2673-4109/1/3/17/pdf

Nano Silica and Metakaolin Effects on the Behavior of Concrete Containing Rubber Crumbs

Development of flexible form-stable phase change material with enhanced electrical resistance for thermal management

Silica fume/capric acid-stearic acid PCM included-cementitious composite for thermal controlling of buildings: Thermal energy storage and mechanical properties

Thermal management performance and mechanical properties of a novel cementitious composite containing fly ash/lauric acid-myristic acid as form-stable phase change material

The main aim of this study is to investigate the possible effects of metakaolin on strength and durability properties of concrete. For this purpose, concrete mixtures are produced by substituting cement with metakaolin 0, 5, 10 and 20% by weight. The amount of binder for the concrete mixtures are 300 and 400 kg/m3 with a constant water to cement ratio of 0.6. Compressive and bending strengths, freeze-thaw and high-temperature resistances, capillary coefficients and rapid chloride permeability properties were determined and compared each other. Because of all the experiments conducted, it has been found that the use of metakaolin as a pozzolanic additive in concrete have positive effects especially on compressive and bending strengths, capillary, rapid chloride permeability, freeze-thaw resistance, and high temperatures, up to 800oC. The results indicated that the performance of concrete can be enhanced by metakaolin. Particularly, compressive strength and durability properties have found to be improved with increasing metakaolin content which is attributed to pozzolanic activity and filler effect. Furthermore, metakaolin has relatively positive impacts under elevated temperatures and freeze-thaw effects. However, almost all the strengths of entire concrete specimens are lost at 800

Durability properties of concrete containing metakaolin

Concrete is one of the most widely used construction materials in the world. Producing economical and durable concrete is possible by employing pozzolanic materials. The aim of this study is to underline the possibility of the utilization of natural zeolite in producing concrete and investigate its effects basically on the strength and durability of concrete. In the production of concrete mixes, Portland cement was replaced by the natural zeolite at ratios of 0%, 10%, 15%, and 20% by weight. Concretes were produced with total binder contents of 300 kg/m3 and 400 kg/m3, but with a constant water to cement ratio of 0.60. In addition to compressive and flexural strength measurements, freeze-thaw and high temperature resistance measurements, rapid chloride permeability, and capillary water absorption tests were performed on the concrete mixes. Compared to the rest mixes, concrete mixes containing 10% zeolite yielded in with the highest compressive and flexural strengths. The rapid chloride permeability and the capillary measurements were decreased as the natural zeolite replacement was increased. Freeze-thaw resistance also improved significantly as the replacement ratio of zeolite was increased. Under the effect of elevated temperature, natural zeolite incorporated concretes with lower binder content yielded higher compressive strength. However, the compressive strengths of concretes with higher binder content after elevated temperature effect were found to be
lower than the reference concrete.

Mechanical, durability and microstructure properties of concrete containing natural zeolite

Beton servis omru boyunca yangin ve yuksek sicaklik ve benzeri cesitli olumsuz cevresel etkilere maruz kalir. Betonun yangina karsi direnci belirli bir sicakliga kadar diger bircok yapi malzemesinden daha ustundur. 400 o C`nin uzerindeki sicakliklarda ciddi fiziksel ve mekanik hasarlar olusmaya baslar ve bu etkiler nedeniyle betonun performansi duser. Ucucu kul beton uretiminde mineral katki olarak kullanilan yapay puzolanik bir malzemedir. Ucucu kul kullanimi betonun performansi uzerinde olumlu bir etki olustururken termik santrallerin atik bir urunu oldugu icin betonda kullanilmasi ekonomik ve cevrecidir. Bu calismada, yuksek sicakliga maruz kalmis ucucu kul iceren betonun basinc dayanimi ve ultrases gecis hizi arastirilmistir. Olcumler 28 gun standart kur ve 28 gun standart kur ve ardindan 90 gun laboratuvar ortaminda kur edilmesi sonunda gerceklestirilmistir. Betonlar 300 kg/m 3 baglayici dozajinda ve ucucu kul cimento ile agirlikca %20, %30 ve %40 oranlarinda ikame edilerek uretilmistir. Ultrases ve basinc dayanimi deneyleri 100 mm kup numuneler uzerinde gerceklestirilmistir. Uygulanan sicakliklar sirasiyla 200 o C, 400 o C, 600 o C ve 800 o C’dir. Ucucu kul ikamesinin yuksek sicakliga maruz betonun hem ultrases gecis hizi hem de basinc dayanimina olumlu bir etki saglamadigi gorulmustur.

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Memduh Nas

Papers

Silica fume/capric acid-stearic acid PCM included-cementitious composite for thermal controlling of buildings: Thermal energy storage and mechanical properties

Thermal management performance and mechanical properties of a novel cementitious composite containing fly ash/lauric acid-myristic acid as form-stable phase change material

Durability properties of concrete containing metakaolin

Mechanical, durability and microstructure properties of concrete containing natural zeolite

Yüksek Sıcaklığa Maruz Uçucu Kül İçeren Betonun Ultrases Geçiş Hızı ve Basınç Dayanımının Değerlendirilmesi