A Strength Model for Concretes Containing Fly Ash, Blast-Furnace Slag and Silica Fume

1985 ◽  
Vol 65 ◽  
Author(s):  
Edwin R. Dunstan

ABSTRACTThis paper describes preliminary a model for the strength of concretes containing industrial by-products such as fly ash, blast-furnace slag, and silica fume. A formula that describes the various strength production mechanisms of these by-products is developed. These materials produce strength by pozzolanic reaction, by latently hydraulic reactions and by self-cementing reactions similar to Portland cement. A method of separating the effect of each mechanism is proposed. A parameter for each of these strength producing mechanisms can be determined from concrete strength data.

2017 ◽  
Vol 865 ◽  
pp. 282-288 ◽  
Author(s):  
Jul Endawati ◽  
Rochaeti ◽  
R. Utami

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.


2013 ◽  
Vol 357-360 ◽  
pp. 1062-1065 ◽  
Author(s):  
Jeong Eun Kim ◽  
Wan Shin Park ◽  
Song Hui Yun ◽  
Do Gyeum Kim ◽  
Jea Myoung Noh

This paper presents the results of an experimental study on the compressive strength, splitting tensile strength and modulus of elasticity characteristics of high performance concrete. These tests were carried out to evaluate the mechanical properties of HPC for up to 7 and 28 days. Mixtures were prepared with water to binder ratio of 0.40. Two mixtures were containing fly ash at 25%, silica fume at 5% cement replacement, respectively. Another mixture was contains blast furnace slag and fly ash at 25%. Three standard 100¥a200 cylinder specimens were prepared. HPC showed improvement in the compressive strength and splitting tensile strength when ordinary Portland cement was replaced with silica fume. Compare with specimens FA25 and BS25FA25, specimen SF5 showed much more modulus of elasticity. It shows that the use of the blast furnace slag of 25% and fly ash of 25% cement replacement has caused a small increase in compressive strength and splitting tensile strength and modulus of elasticity compared to the only use of fly ash of 25% at 28days. The results indicated that the use of blast furnace slag or silica fume provided the good performance compare to fly ash when the mechanical properties of the high performance concretes were taken into account.


Author(s):  
Jan Pieter Vermeulen ◽  
Natalie Lloyd

This research examines an alternative binder, Alkali Activated Cement (AAC), examining the fresh and hardened mechanical properties of twelve AAC mortar mixes with varying mixture proportions of blast-furnace slag, fly ash, sodium silicate (the alkali activator), and additional water. In addition to the Slag-Fly Ash mortars, nine mixtures with blast-furnace slag, silica fume, aluminum hydrate, sodium silicate, and water were tested. For all mortars, the compressive strength was exponentially related to the water/activator-solids ratio. Mortar strengths at 28 days ranged from 5 MPa to 20 MPa. Increasing the slag to binder-solids ratio from 0.1 to 0.2 increased the strength with water to binder ratios from 0.2 to 0.4. However, rapid or almost instantaneous setting times were observed for a slag to binder-solids ratio of 0.2. The research concluded that using a carefully chosen mix design can prevent quick setting while still achieving high strength and acceptable workability. It is suggested the CaO to binder-solids ratio remain below 0.07; a sodium silicate to binder solids ratio of around 0.25 is optimal; a water to binder-solids ratio should be around 0.3. When replacing fly ash, a Si/Al ratio above 2 is recommended. This research concluded that other solids (Silica Fume and Aluminum Hydrate) could replace Slag and/or Fly Ash if the overall chemical balance of the system is maintained.


2011 ◽  
Vol 99-100 ◽  
pp. 758-761
Author(s):  
Yan Jun Hu ◽  
Yan Liang Du

In this study, concrete prisms were made with three mineral admixtures: fly ash, blast furnace slag or silica fume and with three water-to-binder ratios(w/b). Chloride penetration was measured by the rapid chloride permeability test (RCPT)-ASTM C1202, 150-days ponding test and alternate wetting and drying test by cyclic loading with salt solution and oven drying, and the results by the three test methods were compared. This paper discussed the effects of mineral admixtures and w/b on the concrete chloride permeability. Blending concrete with blast furnace slag, fly ash or silica fume was beneficial with regard to the resistance against chloride ion penetration. Concrete specimens with lower w/b showed lower chloride permeability.


Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 632
Author(s):  
Maléki Tagba ◽  
Shujin Li ◽  
Mingjie Jiang ◽  
Xu Gao ◽  
Mohamed Larbi Benmalek ◽  
...  

In this study, rubberized cementitious materials are produced with recycled rubber waste as an alternative to fine aggregate. Mixtures with different additions to rubber wastes (RW), silica fume (SF), and blast furnace slag (BFS) have been designed and characterized. Hardened properties including compressive and bond strength, shrinkage, water-accessible porosity, rapid chloride migration, and microstructure were investigated. The results show that the addition of SF and BFS improves the performances of rubberized mortars and reduces shrinkage. The incorporation of 5% RW with 20% BFS increases compressive strength and reduces water-accessible porosity. Ion chloride resistance was enhanced by a combination of 15% RW, 8% SF, and 20% BFS. The addition of SF and BFS as cement replacement improves the performance of mortars due to their filling effect and a pozzolanic reaction, which has been verified by a microstructural analysis.


2021 ◽  
Vol 13 (2) ◽  
pp. 873
Author(s):  
Numanuddin M. Azad ◽  
S.M. Samindi M.K. Samarakoon

There has been a significant movement in the past decades to develop alternative sustainable building material such as geopolymer cement/concrete to control CO2 emission. Industrial waste contains pozzolanic minerals that fulfil requirements to develop the sustainable material such as alumino-silicate based geopolymer. For example, industrial waste such as red mud, fly ash, GBFS/GGBS (granulated blast furnace slag/ground granulated blast furnace slag), rice husk ash (RHA), and bagasse ash consist of minerals that contribute to the manufacturing of geopolymer cement/concrete. A literature review was carried out to study the different industrial waste/by-products and their chemical composition, which is vital for producing geopolymer cement, and to discuss the mechanical properties of geopolymer cement/concrete manufactured using different industrial waste/by-products. The durability, financial benefits and sustainability aspects of geopolymer cement/concrete have been highlighted. As per the experimental results from the literature, the cited industrial waste has been successfully utilized for the synthesis of dry or wet geopolymers. The review revealed that that the use of fly ash, GBFS/GGBS and RHA in geopolymer concrete resulted high compressive strength (i.e., 50 MPa–70 MPa). For high strength (>70 MPa) achievement, most of the slag and ash-based geopolymer cement/concrete in synergy with nano processed waste have shown good mechanical properties and environmental resistant. The alkali-activated geopolymer slag, red mud and fly ash based geopolymer binders give a better durability performance compared with other industrial waste. Based on the sustainability indicators, most of the geopolymers developed using the industrial waste have a positive impact on the environment, society and economy.


2012 ◽  
Vol 450-451 ◽  
pp. 738-742
Author(s):  
Xue Fang Wang ◽  
Jian Lan Zheng

Influence of compounded mineral admixtures on shrinkage and early-age cracking behaviors of concrete was studied, based on the fellow factors: fly ash to blast furnace slag(denoted as BSF) ratio, fly ash-metakaolin ratio, BSF-silica fume ratio. Research shows that the Pozzolanic admixtures compounded with cementitious admixtures have complementary and synergistic effect for hydration progress of concrete, which can enhance the volume stability and cracking behaviors of concrete. However, the pozzolanic admixture compounded with other pozzolanic admixture, two pozzolanic admixtures will grab Ca(OH)2 resource. And then if the dosage of mineral admixture is higher, the compounding will result to decrease the volume stability and cracking behaviors of concrete.


2017 ◽  
Vol 266 ◽  
pp. 278-282 ◽  
Author(s):  
Jul Endawati

Pervious concrete primarily is used as a means of storm water management. Taking into consideration the environment issues, the binder can also be formed by partially replaced Portland cement by cementitious materials, such as blast furnace slag fine powder, fly ash and silica fume. The combination of the binder materials was determined based on previous work, which composed of 56% Portland Composite Cement, 15% fly ash Type F, 26% air-cooled blast furnace slag from a local steel Industry and 3% condensed silica fume. The compressive strength of specimens with coarser aggregate was lower compared with the control pervious concrete, but still within the range of the requirement compressive strength according to ACI 522R-2010. The difference of the aggregate size affected the enhancement of the compressive strength. The flexural strength of pervious concrete with aggregate size of 9.5mm-12.5mm tend to be higher compared with that of pervious concrete with smaller aggregate size. Furthermore, the addition of 6% natural fine aggregate while applying higher water/cement ratio could be a contribution to the enhancement of the compressive and the flexural strength.


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