Replacement of silica fume with thermally treated rice husk ash in Reactive Powder Concrete

2018 ◽  
Vol 188 ◽  
pp. 264-277 ◽  
Author(s):  
M. Vigneshwari ◽  
K. Arunachalam ◽  
A. Angayarkanni

Reactive Powder Concrete (RPC) is a special concrete with excellent mechanical and durability properties and it is differentiated with other forms of concrete in terms of production, mix proportion etc. Depending upon various parameters like composition and the curing temperature, its compressive strength ranges from 130 MPa to 750 MPa, bending strength varies as 29 to 51 MPa and Young's modulus results upto 50GPa to 75GPa.Though RPC possesses many outstanding properties, it has limited applications in the construction field. The usage of higher quantity of cement and Silica Fume causes the rise of production of RPC. In addition to that, the silica fume availability is also restricted. For a country like India, usage of SF is limited due to its high price. Also, mineral admixtures can be used as a suitable alternative. Hence in this research work, Rice Husk Ash (RHA) is used as a possible alternatives for replacing silica fume in RPC. RHA holds maximum amount of silica (approx. 96%) in amorphous form. In this research, an experimental research on mechanical and durability properties of RPC by partially replacing SF with RHA. The detailed literature survey on constituent materials, mix proportions and curing conditions of RPC were done. Also, the optimum temperature and duration for the thermal treatment of RHA were identified. The compressive strength of the specimens of partial replacement of Silica Fume using RHA were tested and the results were compared with control specimens compressive strength.


2018 ◽  
Vol 9 (4) ◽  
pp. 114 ◽  
Author(s):  
Mohamed Amin

Reactive Powder Concrete (RPC) is composed of very fine powders (cement, sand, and pozzolanic materials), and superplasticizers. A very dense matrix is found, and this tightness provides RPC with ultra-high strength and durability. Recently, using supplementary cementing materials associates greatly with ultra-high strength and the mix design of ultra-high performance concrete (UHPC). These materials could be natural, by-products or industrial wastes. They could be also less energy consuming and little time produced materials. Silica fume (SF), rice husk ash (RHA) and granulated blast furnace slag (GBFS) etc. are among the major supplementary cementing materials utilized. The detailed experimental investigation done to study the impact of partial alteration of cement with SF, RHA, and GBFS on concrete properties. This study aims to a minor replacement of Portland cement by SF, RHA and GBFS to reach UHPC. Twenty-five different concrete mixes (fc =150.1 to 188.2 MPa) with and without SF, RHA and GBFS were prepared with local materials in Egypt. Concrete mixes were cast with 0, 10, 15, 20, and 25% cement replaced by either SF or RHA, and another proportions taken combination between SF and RHA or SF and GBFS or RHA and GBFS about percentages from 10 to 15%. The mixes were tested for slump flow, air content, mechanical properties and water permeability. The findings of hardened properties indicate that optimum level for partial changing of cement by SF and RHA was 20% and it is observed that though the strengths of SF or RHA concrete goes on decreasing after the 20% addition of SF or RHA. Test results have indicated that RHA exhibits lower pozzolanic activity than SF.


InterConf ◽  
2021 ◽  
pp. 418-426
Author(s):  
Thi Ngoc Quyen Nguyen

The biggest disadvantage of conventional concrete is brittle and hard, in addition, its durability is not high. The low durability of concrete is due to the presence of calcium hydroxide at the intersection of coarse aggregate particles and hard cement powder. The introduction of coconut fiber and polyvinyl alcohol (PVA) fibers into the concrete to improve the durability and flexibility of the concrete. In addition, the article also considers the effects of other additives such as rice husk ash, silica fume to study the performance of the structure as well as its durability when joining concrete mixes to create flexible concrete movable and more flexible than conventional concrete.


2012 ◽  
Vol 174-177 ◽  
pp. 1090-1095 ◽  
Author(s):  
Kai Pei Tian ◽  
Yang Ju ◽  
Hong Bin Liu ◽  
Jin Hui Liu ◽  
Li Wang ◽  
...  

The explosive spalling of high-strength concrete due to fire is a problem that has garnered increasingly widespread attention, particularly the explosive spalling of reactive powder concrete (RPC). For years, based on the vapor pressure mechanism, the addition of fibers has been demonstrated to be somewhat effective in protecting against spalling. However, relevant experiments indicate that fibers are not effective for dense concrete, which is a challenge for the simple vapor pressure mechanism in providing spalling resistance for RPC. The authors found that silica fume plays an important role in the explosive spalling of RPC. Thus, four classes of RPCs with different ratios of silica fume were prepared, and the spalling phenomena and the inner temperature distribution during heating were investigated. The results show that silica fume content has a prominent effect on the spalling process of RPC.


Author(s):  
Aikot Pallikkara Shashikala ◽  
Praveen Nagarajan ◽  
Saranya Parathi

Production of Portland cement causes global warming due to the emission of greenhouse gases to the environment. The need for reducing the amount of cement is necessary from sustainability point of view. Alkali activated and geopolymeric binders are used as alternative to cement. Industrial by-products such as fly ash, ground granulated blast furnace slag (GGBS), silica fume, rice husk ash etc. are commonly used for the production of geopolymer concrete. This paper focuses on the development of geopolymer concrete from slag (100% GGBS). Effect of different cementitious materials such as lime, fly ash, metakaolin, rice husk ash, silica fume and dolomite on strength properties of slag (GGBS) based geopolymer concrete are also discussed. It is observed that the addition of dolomite (by-products from rock crushing plants) into slag based geopolymer concrete reduces the setting time, enhances durability and improves rapidly the early age strength of geopolymer concrete. Development of geopolymer concrete with industrial by-products is a solution to the disposal of the industrial wastes. The quick setting concrete thus produced can reduce the cost of construction making it sustainable also.


2018 ◽  
Vol 162 ◽  
pp. 02014
Author(s):  
Mazin Abdulrahman ◽  
Alyaa Al-Attar ◽  
Marwa Ahmad

Reactive Powder Concrete (RPC) is an ultra-high performance concrete which has superior mechanical and physical properties, and composed of cement and very fine powders such as quartz sand and silica fume with very low water/ binder ratio and Superplasticizer. Heat treatment is a well-known method that can further improve the performance of (RPC). The current research including an experimental study of the effect of different curing conditions on mechanical properties of reactive powder concrete (compressive strength, modulus of rupture and splitting tensile strength), the curing conditions includes three type of curing; immersion in water at temperature of 35 OC (which is considered as the reference-curing situation), immersion in water at temperature of 90 OC for 5 hours daily and curing with hot steam for 5 hours daily) until 28 days according to ASTM C684-99 [8]. This research includes also the study of effect of adding silica fume as percentage of cement weight on mechanical properties of reactive powder concrete for different percentage ratios (5%,10% and 15%). Super plasticizer is also used with ratio of (1.8%) by weight of cementitious material; constant water cement ratio (0.24) was used for all mixes. For each reactive concrete mix, it has been cast into a cubes of (150*150*150) (to conduct the compression test), a cylinders of 150mm diameter with 300mm height (to conduct split test) and prisms of (500*100*100)mm to conduct the modulus of rupture test. The results showed that the best method of curing (according to its enhancing the RPC mechanical properties) is the method of immersion in hot water at temperature 90 OC for the all silica fume percentages, and the best used silica fume percentage was (10%) for the all used curing methods.


Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1480
Author(s):  
Lili Cui ◽  
Hui Wang

In this paper, the slump flow and mechanical strengths (compressive and flexural strengths) of the reactive powder concrete (RPC) with rice husk ash (RHA) and waste fly ash (WFA) were investigated. The following corrosion resistance of steel bars-reinforced specimens was researched. The ultrasonic sound, the mass loss rate, the electrical resistance, and the electrical resistance time history curves were determined to reflect the corrosion resistance of steel bars. The influence of NaCl freeze–thaw cycles and dry–wet alternations was considered. Results showed that the addition of RHA and WFA demonstrated a negative effect on the fluidity of fresh RPC. The fluidity of fresh RPC with WFA was lower. Moreover, RHA and WFA could effectively improve the mechanical strengths of hardened RPC, and the enhancing effect of RHA was higher. The increasing dosage of RHA could improve the corrosion resistance of steel bars in RPC when the specimens were exposed to the environment of NaCl freeze–thaw cycles and dry–wet alternations. However, when WFA was added, the effect was the opposite. The steel bars in RPC corroded more seriously when the specimens were exposed to the environment of NaCl dry–wet alternations than the environment of NaCl freeze–thaw cycles.


2019 ◽  
Vol 4 (6) ◽  
pp. 74-83 ◽  
Author(s):  
Gamal I. K. ◽  
K. M. Elsayed ◽  
Mohamed Hussein Makhlouf ◽  
M. Alaa

Reactive Powder Concrete RPC is comprise of (cement, quartz powder, sand, and superplasticizer) mixture with low water/cement ratio. It has not coarse aggregates and characterized by highly dense matrix, high strength concrete, excellent durability, and economic. This study aims to investigate fresh and hardened properties of locally cast RPC with several available economical materials such as silica fume (SF), fly ash (FA), steel fiber (STF), and glass fiber (GF). Experimental investigation were performed to study the effectiveness of partial replacement of cement by SF or FA to reach ultra-high strength concrete, effect of additional materials STF or GF in order to improve the fracture properties of the RPC mixes, and influence of the treated with normal water as well as with hot water. Fifteen different RPC mixes were cast with 20, 25, 30, and 35% cement replacement by SF, 25% cement replacement by FA, and another proportions taken combination between SF and FA with percentages 15, 20, 25% FA and constant 10% SF. Varying fiber types (steel fiber or glass fiber) added to concrete by different percentages 1, 2, and 3%. Specimens were treated with normal water 25ᵒC and hot water at 60ᵒC and 90ᵒC by 2 mixes with silica fume content 25% of binder and steel fiber content 2% by total volume. Performance of the various mixes is tested by the slump flow, compressive strength, flexure strength, splitting tensile strength, and density. The production of RPC using local materials is successfully get compressive strength of 121 MPa at the age of 28 days at standard conditions and normal water curing 25°C with Silica fume content 25% of binder and steel fiber content 2% by total volume of RPC and water/binder ratio of 0.25.  The results also showed the effect of curing by hot water 60 and 90°C, it is observed that compressive strength increases proportionally with curing temperatures and a compressive strength of 149.1 MPa at 90°C for 1days was obtained.


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