scholarly journals إيجاد مقاومة الضغط المستقبلية الناتجة تحت تأثير محتوى الكلوريدآت والكبريتات بالخرسانة

2021 ◽  
Vol 9 (2) ◽  
pp. 95-99
Author(s):  
ابوالقاسم يحي ابوصبيع ◽  
الطيب حسن اونسة

The compressive strength of concrete is the primary characteristic of concrete quality, as the high durability of concrete is one of the characteristics that gave concrete its position, and low durability is the most important problem facing concrete. This study aims to lay the foundations for forming a preliminary idea on knowing the compressive strength of future concrete other than destroying concrete and following up on it without doing destructive tests for it. In order to obtain results that simulate reality to a great degree. In this research, a laboratory study was conducted where a concrete mixture was made and after conducting experiments on the materials included in the mixture and preparing concrete cubes of ordinary Portland cement and sulfate-resistant cement and compressive strength testing on them in times of 28 days and 60 days and 90 days and 180 days and 365 days and subjected to conditions Treating (water and air) and performing chemical analyzes on it to determine the percentage of chlorides and sulfates in the concrete. From the results of the research, an engineering program was designed using Mat lab program to obtain future strength. And reached by the program to know the compressive strength of future concrete under the influence of the chlorides and sulfate content of concrete and the results were good.  

Author(s):  
Oluwatosin Babatola

This paper discusses the findings of an experimental study on the effect of various curing procedures on the compressive strength of concrete produced by partially substituting portland cement with Palm Kernel Shell Ash (PKSA). Palm kernel shell ash was utilized in a 1:2:4 mix ratio as a partial substitute for ordinary Portland cement (OPC) at percentage levels of 0%, 10%, and 15%. River sand with particles passing a 4.75 mm BS sieve was used, as well as crushed aggregate with a maximum size of 20 mm, and palm kernel shell ash with particles passing a 212 μm sieve. The compressive strength of the test cubes (150 mm x 150 mm x 150 mm) was determined after 7, 28, and 56 days of curing. The results demonstrated that test cubes containing Palm kernel shell ash developed strength over a longer curing period than ordinary Portland cement concrete samples and that the strength changes depending on the amount of PKSA in the cube samples. The findings showed that at 28 days, test cubes with 5%, 10%, and 15% PKSA content in all curing procedures utilized obtained a greater compressive strength. Curing by immersion produced the highest compressive strength in all replacement level while the concrete cured by sprinkling and spraying gives a lower strength in all replacement leve


2014 ◽  
Vol 894 ◽  
pp. 342-348
Author(s):  
Abdoullah Namdar ◽  
Fadzil Mat Yahaya

The quality of a construction material satisfies stability of structure. Several additives have been innovated for improve quality of compressive strength of concrete. In this paper for enhancement of compressive strength of concrete, a simple method has been proposed. The kaolin and bentonite have been treated by heat for duration of 1 hour, with constant temperature. For kaolin 200 oC, 400 oC, 600 oC, 800 oC, 1000 oC and 1200 oC of heat, and for bentonite 200 oC, 400 oC, 600 oC, 800 oC of heat has been subjected. The kaolin and bentonite treated by heat have been proposed as additive for concrete. The objective is to introduce an additive to improve compressive strength of concrete. The microstructure of modified Ordinary Portland Cement (OPC) paste has been investigated by using Field Emission Scanning Electron Microscopy (FESEM) and X-ray diffractometry (XRD). The results indicate that the best level of heat for produce additives from kaolin and bentonite, and illustrate quantity of additives for replace a portion of cement in concrete application. Modification of nanoparticles of cement paste during hydration has been discussed.


2013 ◽  
Vol 312 ◽  
pp. 377-381
Author(s):  
Qing Fang Zhang

This study used ordinary portland cement of 42.5 strength grade, mixed with various minerals and water reducer for the preparation of concrete C30 by means of four schemes, for each of which a specific mix proportion was employed. Accordingly the compressive strength of concrete with different preparations at different ages were compared. No matter which scheme was employed, single or double doping, with or without superplasticizer, the compressive strength of concrete at different ages was maximized when slag amount was 30% or maximum. Hence it can be concluded that the reasonable content of slag should be 30% for the preparation of concrete C30. It is suggested that the above results can be better applied to large-volume concrete, underground, harbor, road and bridge and civil engineering as well.


2012 ◽  
Vol 476-478 ◽  
pp. 1585-1588
Author(s):  
Hong Pan ◽  
Guo Zhong Li

The comprehensively modified effect of cement, VAE emulsion and self-made acrylic varnish on mechanical and water-resistant properties of gypsum sample was investigated and microstructure of gypsum sample was analyzed. Experimental results exhibit that absolutely dry flexural strength, absolutely dry compressive strength, water absorption and softening coefficient of gypsum specimen with admixture of 10% ordinary Portland cement and 6% VAE emulsion and acrylic varnish coated on its surface can respectively reach to 5.11MPa , 10.49 MPa, 8.32% and 0.63, respectively.


Author(s):  
Kotaro Kawamura ◽  
Joe Takemura ◽  
Shigenobu Iguchi ◽  
Tsutomu Yoshida ◽  
Masashi Kobayashi

<p>We are carrying out a construction project of new railroad viaducts. These new railroad viaducts are constructing using about 110,000 m<span>3</span> volume concrete. In this construction place, it is difficult for us to get low ASR-reactive aggregates and it is expected to be supplied with snowmelt water on the viaducts in winter. Then we tested ASR-reactive these local aggregates and found an effective mixed ratio of fly-ash is 20% of cement. On the other hand, various side effects were also expected by using fly-ash. For example, initial cracking due to contraction, early strength concrete, bleeding, etc. Therefore, we repeated various tests and examined and carried out a method that could ensure the same construction method and quality as when using ordinary Portland cement, even with fly-ash. Also, we adopted a structure that is unlikely to be affected by rainwater as a structural measure. For example, the entire adoption of a ramen type viaduct that has eliminated bearings, adoption of FRP sound barrier, etc. Then we made it possible to build highly durable railway viaducts by these various measures of materials and structures.</p>


2013 ◽  
Vol 6 (1) ◽  
pp. 50-61
Author(s):  
Amer M. Ibrahem ◽  
Shakir A. Al-Mishhadani ◽  
Zeinab H.Naji

This investigation aimed to study the effect of nano metakaolin ( NMK ) on some properties (compressive strength ,splitting tensile strength & water absorption ) of concrete. The nano metakaolin (NMK) was prepared by thermal activation of kaolin clay for 2 hours at 750 Ċ. The cement used in this investigation consists of ordinary Portland cement (OPC). The OPC was partially substituted by NMK of ( 3, 5 & 10%) by weight of cement. The C45 concrete was prepared , using water/cement ratio ( W/c) of (0.53) .The Water absorption was tested at 28 days while the tests (compressive strength ,splitting tensile strength) were tested at ages of (7, 28, 60,& 90) days . The compressive strength and splitting tensile strength of concrete with NMK were higher than that of reference concrete with the same W/c ratio.The improvement in the compressive strength when using NMK was (42.2, 55.8 , 63.1% ) at age 28 days for ( 3%, 5%, &10% ) replacement of NMK respectively whereas the improvement in the splitting tensile strength was (0% , 36% & 46.8 %) at age of 28 days when using (3%, 5%, &10% ) NMK respectively. The improvement in the water absorption was (16.6%, 21.79%, &25.6 ) when using (3, 5, &10% )NMK.


Author(s):  
Safiki Ainomugisha ◽  
Bisaso Edwin ◽  
Bazairwe Annet

Concrete has been the world’s most consumed construction material, with over 10 billion tons of concrete annually. This is mainly due to its excellent mechanical and durability properties plus high mouldability. However, one of its major constituents; Ordinary Portland Cement is reported to be expensive and unaffordable by most low-income earners. Its production contributes about 5%–8% of global CO2 greenhouse emissions. This is most likely to increase exponentially with the demand of Ordinary Portland Cement estimated to rise by 200%, reaching 6000 million tons/year by 2050.  Therefore, different countries are aiming at finding alternative sustainable construction materials that are more affordable and offer greener options reducing reliance on non-renewable sources. Therefore, this study aimed at assessing the possibility of utilizing sugarcane bagasse ash from co-generation in sugar factories as supplementary material in concrete. Physical and chemical properties of this sugarcane bagasse ash were obtained plus physical and mechanical properties of fresh and hardened concrete made with partial replacement of Ordinary Portland Cement. Cost-benefit analysis of concrete was also assessed. The study was carried using 63 concrete cubes of size 150cm3 with water absorption studied as per BS 1881-122; slump test to BS 1881-102; and compressive strength and density of concrete according to BS 1881-116. The cement binder was replaced with sugarcane bagasse ash 0%, 5%, 10%, 15%, 20%, 25% and 30% by proportion of weight. Results showed the bulk density of sugarcane bagasse ash at 474.33kg/m3, the specific gravity of 1.81, and 65% of bagasse ash has a particle size of less than 0.28mm. Chemically, sugarcane bagasse ash contained SiO2, Fe2O3, and Al2O3 at 63.59%, 3.39%, and 5.66% respectively. A 10% replacement of cement gave optimum compressive strength of 26.17MPa. This 10% replacement demonstrated a cost saving of 5.65% compared with conventional concrete. 


2020 ◽  
Vol 20 (01) ◽  
pp. 61-68
Author(s):  
Siska Apriwelni ◽  
Nugraha Bintang Wirawan

(ID) Penelitian ini membahas pengaruh kuat tekan beton mutu tinggi dengan memanfaatkan limbah fly ash dan limbah kaca. Tujuan dari penelitian ini untuk mengetahui kuat tekan beton pada masing-masing variasi, mengetahui persentase campuran beton untuk menghasilkan kuat tekan maksimum, dan mengetahui apakah fly ash dan serbuk kaca efektif digunakan secara bersamaan sebagai bahan campuran beton. Komposisi fly ash terdiri dari 5 variasi yaitu persentase 0%, 5%, 10%, 15%, dan 20%. Sedangkan untuk komposisi serbuk kaca terdiri dari 2 variasi yaitu persentase 5% dan 10%. Jumlah benda uji 30 buah silinder berukuran diameter 15 cm dan tinggi 30 cm dengan 3 benda uji untuk setiap variasi. Perencanaan campuran beton menggunakan SNI 03-2834-2000 yang dimodifikasi. Pengujian kuat tekan diuji pada umur beton 28 hari. Beton dengan fly ash 0% dan serbuk kaca 10% memiliki kuat tekan paling tinggi dibandingkan dengan beton dengan tambahan fly ash, yaitu 46,77%. Selain itu, dapat disimpulkan bahwa semakin bertambahnya jumlah persentase serbuk kaca yang digunakan menunjukkan bahwa kuat tekan beton semakin bertambah juga. Penambahan fly ash pada campuran beton mempengaruhi kuat tekan beton yang dihasilkan. Pada variasi fly ash 0% memiliki kuat tekan tertinggi baik pada saat campuran serbuk kaca 5%dan 10%. Variasi fly ash 15% adalah kondisi optimum campuran beton dengan kuat tekan beton yaitu 43,31 Mpa. Kedua limbah ini dapat dikombinasikan dan dimanfaatkan dengan baik dan digunakan dalam pembuatan beton mutu tinggi. (EN) This study discusses the effect of high quality concrete by utilizing fly ash and glass waste. The purpose of this study is to determine the compressive strength of concrete in each variation, to determine the contribution of concrete to produce compressive strength, and to find out that fly ash and glass powder are effectively used in full as a concrete admixture. Fly ash composition consists of 5 variations, namely the percentage of 0%, 5%, 10%, 15%, and 20%. While for the composition of glass powder consists of 2 variations, namely the percentage of 5% and 10%. The number of specimens is 30 cylinders with a diameter of 15 cm and a height of 30 cm with 3 specimens for each variation. Concrete mixture planning using SNI 03-2834-2000 was developed. Compressive strength testing on concrete age 28 days. Concrete with 0% fly ash and 10% glass powder have the highest compressive strength compared to concrete with additional fly ash, which is 46.77%. In addition, it can increase the amount of glass powder addition that is used to show the concrete compressive strength is increasing as well. The addition of fly ash in the concrete mixture has an effect on the compressive strength of the concrete produced. In the variation of 0% fly ash has the highest compressive strength when the glass powder mixture of 5% and 10%. The 15% fly ash variation is the optimal concrete mixture with compressive strength of 43.31 MPa. These two wastes can be combined and utilized properly and are used in making high quality concrete.  


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