Development of Compressive Strength of Slag Based Cement Mortars Exposed to an Aggressive Sulphate Environment

2017 ◽  
Author(s):  
Adriana Estokova ◽  
Michaela Smolakova ◽  
Alena Luptakova
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Acid Corrosion ◽  
Partial Replacement ◽  
Conventional Concrete ◽  
Cement Mortars ◽  
Deterioration Process ◽  
Sulfuric Acid Corrosion ◽  
Furnace Slag

Sulfuric acid corrosion can cause severe damage to concrete and cement composites. There are a variety of approaches to enhancing the sustainability of concrete and mortar one of which is to enhance the durability of concrete using different cement replacement. Granulated blast furnace slag is used in mortar and concrete, as a partial replacement of Portland cement, and this use has resulted in significant savings in the cost of production of concrete. Moreover the use of conventional concrete is notoriously subject to durability and corrosion issues. Laboratory experiments were conducted to investigate the compressive strength of cement mortars samples with cement partially replaced by blast furnace slag. The samples with different share of slag (65, 75, 85 and 95 wt.%) were exposed to a bacterial sulphate environment for 90 days. A decrease in compressive strengths of reference samples by 8% as well as an increase in compressive strengths of all slag-based sampless up to 95 % have been observed. Surface structure and chemical com-positions of cement mortars´ leachates confirmed a deterioration process under the microbial exposure of Acidithioba-cillus thiooxidans.

scholarly journals Evolution of Mechanical Properties with Time of Fly-Ash-Based Geopolymer Mortars under the Effect of Granulated Ground Blast Furnace Slag Addition

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1135 ◽  
Author(s):  
Mateusz Sitarz ◽  
Izabela Hager ◽  
Marta Choińska
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Modulus Of Elasticity ◽  
Blast Furnace Slag ◽  
Energy Savings ◽  
Pulse Velocity ◽  
Partial Replacement ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Geopolymers are considered to alternatives to Portland cement, providing an opportunity to exploit aluminosilicate wastes or co-products with promising performances in the construction sector. This research is aimed at investigating the strength of fly-ash-geopolymers of different ages. The effect of granulated blast furnace slag (GGBFS) as a partial replacement of fly ash (FA) on the tensile (ft) and compressive strength (fc), as well as the modulus of elasticity, is investigated. The main advantage of the developed geopolymer mixes containing GGBFS is their ability to set and harden at room temperature with no need for heating to obtain binding properties, reducing the energy consumption of their production processes. This procedure presents a huge advantage over binders requiring heat curing, constituting a significant energy savings and reduction of CO2 emissions. It is found that the development of strength strongly depends on the ratio of fly-ash to granulated blast furnace slag. With the highest amount of GGBFS, the compressive strength of geopolymers made of fly-ash reached 63 MPa after 28 days of curing at ambient temperature. The evolution of compressive strength with time is correlated with the development of ultrasound pulse velocity methods, which are used to evaluate maturity. The modulus of elasticity changes with strength and the relationship obtained for the geopolymer is presented on the basis of typical models used for cement-based materials. The tensile to compressive strength ratios of the tested geopolymers are identified as higher than for cementitious binders, and the ft(fc) relationship is juxtaposed with dependencies known for cement binders, showing that the square root function gives the best fit to the results.

scholarly journals The Compressive Strength and Microstructure of Alkali-Activated Binary Cements Developed by Combining Ceramic Sanitaryware with Fly Ash or Blast Furnace Slag

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 337 ◽  
Author(s):  
Juan Cosa ◽  
Lourdes Soriano ◽  
María Borrachero ◽  
Lucía Reig ◽  
Jordi Payá ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Calcium Content ◽  
Partial Replacement ◽  
Alkali Activation ◽  
High Calcium ◽  
Furnace Slag ◽  
Alkali Activated

The properties of a binder developed by the alkali-activation of a single waste material can improve when it is blended with different industrial by-products. This research aimed to investigate the influence of blast furnace slag (BFS) and fly ash (FA) (0–50 wt %) on the microstructure and compressive strength of alkali-activated ceramic sanitaryware (CSW). 4 wt % Ca(OH)2 was added to the CSW/FA blended samples and, given the high calcium content of BFS, the influence of BFS was analyzed with and without adding Ca(OH)2. Mortars were used to assess the compressive strength of the blended cements, and their microstructure was investigated in pastes by X-ray diffraction, thermogravimetry, and field emission scanning electron microscopy. All the samples were cured at 20 °C for 28 and 90 days and at 65 °C for 7 days. The results show that the partial replacement of CSW with BFS or FA allowed CSW to be activated at 20 °C. The CSW/BFS systems exhibited better mechanical properties than the CSW/FA blended mortars, so that maximum strength values of 54.3 MPa and 29.4 MPa were obtained in the samples prepared with 50 wt % BFS and FA, respectively, cured at 20 °C for 90 days.

scholarly journals Effect of Polypropylene Fiber, GGBS and Fly Ash over the Strength Aspects of Concrete: A Critical Review

2021 ◽  
Vol 9 (VI) ◽  
pp. 978-983
Author(s):  
Khalid Bashir Mir
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Polypropylene Fiber ◽  
Synthetic Fiber ◽  
Partial Replacement ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In this review study the usage of three different kinds of constructional materials was discussed in detail. The three materials comprised of Ground Granulated Blast Furnace Slag, fly and polypropylene fiber. Ground Granulated Blast Furnace Slag is basically the slag derived after the quenching process of iron slag produced during the processing of iron in iron industry. Fly ash is the waste generated from the coal processing industries and is mainly used in the road constructions works. Polypropylene fiber is a synthetic fiber that has very high tensile strength and flexural strength. This fiber is also known as synthetic fiber as it is mainly used in the synthetic industry. Depending upon the results of previous studies over the usage of these materials various conclusions has been drawn which are as follows. The results of studies related to the usage of Ground Granulated Blast Furnace Slag as partial replacement of cement concluded that the most optimum usage percentage of Ground Granulated Blast Furnace Slag as partial replacement of cement was found to be between 20 percent and 30 percent and beyond this limit the strength of concrete was decreasing. The past studies related to the usage of fly ash as partial replacement of cement shoed that the most optimum usage percentage of fly ash was found to be between 15 percent to 20 percent and beyond this percentage the strength parameters of concrete such as compressive strength, flexural strength and split tensile strength starts declining up to a greater extent. The studies related to the usage of polypropylene fiber showed that the usage of this fiber increases the compressive strength of soil and the most optimum results were found between 1.0 percent to 1.5 percent usages of polypropylene fiber. Above this percentage there will be negative effect on the strength aspects and the compressive strength starts declining.

The Influence of the Properties of the Material Used for Obtaining Geopolymers on Their Structure and Compressive Strength

2017 ◽  
Vol 68 (6) ◽  
pp. 1182-1187
Author(s):  
Ilenuta Severin ◽  
Maria Vlad
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Wheat Straw ◽  
Red Mud ◽  
Blast Furnace Slag ◽  
Complex Structure ◽  
Point Of View ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Straw Ash

This article presents the influence of the properties of the materials in the geopolymeric mixture, ground granulated blast furnace slag (GGBFS) + wheat straw ash (WSA) + uncalcined red mud (RMu), and ground granulated blast furnace slag + wheat straw ash + calcined red mud (RMc), over the microstructure and mechanical properties of the synthesised geopolymers. The activation solutions used were a NaOH solution with 8M concentration, and a solution realised from 50%wt NaOH and 50%wt Na2SiO3. The samples were analysed: from the microstructural point of view through SEM microscopy; the chemical composition was determined through EDX analysis; and the compressive strength tests was done for samples tested at 7 and 28 days, respectively. The SEM micrographies of the geopolymers have highlighted a complex structure and an variable compressive strength. Compressive strength varied from 24 MPa in the case of the same recipe obtained from 70% of GGBFS + 25% WSA +5% RMu, alkaline activated with NaOH 8M (7 days testing) to 85 MPa in the case of the recipe but replacing RMu with RMc with calcined red mud, alkaline activated with the 50%wt NaOH and 50%wt Na2SiO3 solution (28 days testing). This variation in the sense of the rise in compressive strength can be attributed to the difference in reactivity of the materials used in the recipes, the curing period, the geopolymers structure, and the presence of a lower or higher rate of pores, as well as the alkalinity and the nature of the activation solutions used.

Effects of Fly Ash and Granular Blast-Furnace Slag on Development Rate of Strength of Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 371-375
Author(s):  
Ji Wei Cai ◽  
Si Jia Yan ◽  
Gong Lei Wei ◽  
Lu Wang ◽  
Jin Jin Zhou
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Development Rate ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Conventional Concrete ◽  
Enhancing Effect ◽  
Substitution Content ◽  
Furnace Slag

Fly ash (FA) and granular blast-furnace slag (GBFS) are usual mineral admixtures to conventional concrete, and their contents substituted for Portland cement definitely affect development rate of strength of concrete. C30 and C60 concrete samples with FA and/or GBFS were prepared to study the influence of substitution content of the mineral admixtures on 3 d, 7 d and 28 d strength. The results reveal that the development rate of strength in period from 3 d to 7 d gets slow with increasing content of mineral admixtures except for concrete with only GBFS less than 20%. In the case of substituting FA as the only mineral admixture for part of cement, the development rate of strength of C30 concrete in period from 7 d to 28 d keeps roughly constant even that of C60 concrete increases. When substituting mineral admixtures in the presence of GBFS for cement within experimental range, the development rate of strength in period from 7 d to 28 d gets fast with increasing substitution content. The enhancing effect of combining FA and GBFS occurs in period from 7 d to 28 d for both C30 and C60 concretes (FA+GBFS≤40%), even occurs in period from 3 d to 7 d for C60 concrete. Based on 7 d strength and the development rate, 28 d strength of concrete can be predicted accurately.

Optimization of Concrete Porous Mix Using Slag as Substitute Material for Cement and Aggregates

2017 ◽  
Vol 865 ◽  
pp. 282-288 ◽  
Author(s):  
Jul Endawati ◽  
Rochaeti ◽  
R. Utami
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Silica Fume ◽  
Blast Furnace Slag ◽  
Environmental Effect ◽  
Substitution Effect ◽  
Main Concern ◽  
Binder Material ◽  
Furnace Slag

In recent years, sustainability and environmental effect of concrete became the main concern. Substituting cement with the other cementitious material without decreasing mechanical properties of a mixture could save energy, reduce greenhouse effect due to mining, calcination and limestone refining. Therefore, some industrial by-products such as fly ash, silica fume, and Ground Iron Blast Furnace Slag (GIBFS) would be used in this study to substitute cement and aggregate. This substitution would be applied on the porous concrete mixture to minimize the environmental effect. Slag performance will be optimized by trying out variations of fly ash, silica fume, and slag as cement substitution material in mortar mixture. The result is narrowed into two types of substitution. First, reviewed from the fly ash substitution effect on binder material, highest compressive strength 16.2 MPa was obtained from mixture composition 6% fly ash, 3% silica fume and 17% grinding granular blast-furnace slag. Second, reviewed from slag types as cement substitution and silica fume substitution, highest compressive strength 15.2 MPa was obtained from mortar specimens with air-cooled blast furnace slag. It composed with binder material 56% Portland composite cement, 15% fly ash, 3% silica fume and 26% air-cooled blast furnace slag. Considering the cement substitution, the latter mixture was chosen.

scholarly journals Investigação da resistência à compressão e da resistividade elétrica de concretos com diferentes tipos de cimento

2014 ◽  
Vol 4 (2) ◽  
pp. 113-128 ◽  
Author(s):  
R. A. Medeiros-Junior ◽  
M. G. Lima ◽  
M. H. F. Medeiros ◽  
L. V. Real
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Direct Influence ◽  
Absolute Value ◽  
Furnace Slag

RESUMONesse estudo foi possível observar a influência de quatro tipos de cimento brasileiros na resistência à compressão e na Resistividade Elétrica Superficial (RES) de amostras de concreto. Foram analisadas três relações água/cimento, o que resultou em doze distintas dosagens. Os resultados mostraram que os tipos de cimentos tem influência direta em ambos os ensaios. De maneira geral, quando comparado com uma série de referência, os cimentos com adição de escória de alto forno e pozolanas apresentaram redução na resistência à compressão do concreto, porém ganho na RES. O cimento com adição de pozolana é o que apresenta o maior ganho de resistência à compressão no tempo, embora tenha o menor valor absoluto. Os resultados também indicaram que a RES cresce com o tempo de ensaio e diminui com o aumento da relação a/c do concreto. Foi encontrada uma boa correlação entre os ensaios, com R² variando de 0,823 a 0,999.Palavras chaves: resistência à compressão; resistividade elétrica superficial; cimentos; escória de alto forno; pozolana.ABSTRACTThis work studied the influence of four Brazilian types of cement on the compressive strength and electrical resistivity in samples of concrete. Three water/binder ratios were analyzed, which led to the preparation of twelve different samples. The results show that the types of cement has a direct influence on both tests. In general, compared to a reference, the cements with additions of blast furnace slag and pozzolans reduced the strength, but increased the electrical resistivity. It was also observed that the cement with pozzolan showed the highest gain in strength with time, although it resulted in the lowest absolute value. The results also indicated that the electrical resistivity increases with time and decreases with higher water/binder ratios. A good correlation was found between the mentioned tests with R2 ranging from 0.823 to 0.999.Keywords: compressive strength; electrical resistivity; cements; blast fumace slag; pozzolan.

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