Investigation on Micro Silica and Fly Ash as a Partial Replacement Material in Self Compacting Concrete

2011 ◽  
Vol 4 (8) ◽  
pp. 209-214
Author(s):  
Gajendra.L.Naik Gajendra.L.Naik ◽  
◽  
E.Ramesh Babu

Reactive powder concrete (RPC) is the ultra-high strength concrete made by cementitious materials like silica fumes, cement etc. The coarse aggregates are completely replaced by quartz sand. Steel fibers which are optional are added to enhance the ductility. Market survey has shown that micro-silica is not so easily available and relatively costly. Therefore an attempt is made to experimentally investigate the reduction of micro-silica content by replacing it with fly-ash and mechanical properties of modified RPC are investigated. Experimental investigations show that compressive strength decreases gradually with addition of the fly ash. With 10 per cent replacement of micro silica, the flexural and tensile strength showed 40 and 46 per cent increase in the respective strength, though the decrease in the compressive strength was observed to be about 20 per cent. For further percentage of replacement, there was substantial drop in compressive, flexural as well as tensile strength. The experimental results thereby indicates that utilisation of fly-ash as a partial replacement to micro silica up to 10 per cent in RPC is feasible and shows quite acceptable mechanical performance with the advantage of utilisation of fly-ash in replacement of micro-silica.


2018 ◽  
Vol 27 (3) ◽  
pp. 328-337
Author(s):  
Dorota Małaszkiewicz ◽  
Daniel Jastrzębski

The article presents the results of research assessing the possibility of making LWSCC from the locally produced sintered fly ash aggregate CERTYD. Two methods of preliminary LWA preparation were applied: pre-soaking with water and coating with a film of cement paste. The following properties of fresh LWSCC were evaluated: slump-flow, time T500 and passing ability using L-Box. Partial replacement of natural sand by fine LW sand (0/0.5 mm) improved filling and passing abilities of fresh concrete, reduced slightly the bulk density, but it resulted in compressive strength loss by 12-18%. In terms of both fresh and hardened concrete properties it is more favorable to use only fine LW sand as natural sand replacement. Considering fresh concrete properties paste impregnation of LW aggregate is more efficient than saturation with water.


2021 ◽  
Vol 2 (1) ◽  
pp. 13-16
Author(s):  
T.A. Buari

The ever increasing environmental challenge arising from improper waste management has been a great concern to researchers and the society. One of such industrial waste is micro silica; a bye-product of the Carbothermic reduction of high purity quartz at temperature of about 2000oC in the presence of coke. The finess of this material and its pozollanic nature makes it suitable for use in the production of self-compacting concrete. In this research micro silica was introduced in percentages of, 5, 10 and 15% as partial replacement of cement in the production of self-compacting concrete. The fresh properties were examined using slump flow, T50cm, slump flow, V-funnel and blockage ratio using L-Box. As the Micro silica were introduced, T50cm time increased, Slump flow reduced, V-funnel flow time increased and L-Box value reduced, due to increase in viscosity. Comparing the experimental results with European Federation of National Associations of Representing for Concrete EFNARC 2002, blockage ratio for 15% was below 0.8. The compressive stresses at 28days were higher than the control at 28days compressive stress with 8.6%, 19.04% and 11.9% for 5%, 10% and 15% respectively. Thus, cement can be partially substituted with micro silica up to 15% with improvement in compressive strength in self-compacting concrete.


2018 ◽  
Author(s):  
Khalid M. Breesem ◽  
Salim H. Jassam ◽  
Amar A. Hussein ◽  
Omar S. Dahham ◽  
N. Z. Noriman ◽  
...  

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 488
Author(s):  
Sylvia Kelechi ◽  
Musa Adamu ◽  
Abubakar Mohammed ◽  
Yasser Ibrahim ◽  
Ifeyinwa Obianyo

Waste tire disposal continues to pose a threat to the environment due to its non-biodegradable nature. Therefore, some means of managing waste tires include grinding them to crumb rubber (CR) sizes and using them as a partial replacement to fine aggregate in concrete. However, the use of CR has a series of advantages, but its major disadvantage is strength reduction. This leads to the utilization of calcium carbide waste (CCW) to mitigate the negative effect of CR in self-compacting concrete (SCC). This study investigates the durability properties of SCC containing CR modified using fly ash and CCW. The durability properties considered are water absorption, acid attack, salt resistance, and elevated temperature of the mixes. The experiment was conducted for mixes with no-fly ash content and their replica mixes containing fly ash to replace 40% of the cement. In the mixes, CR was used to partially replace fine aggregate in proportions of 0%, 10%, and 20% by volume, and CCW was used as a partial replacement to cement at 0%, 5%, and 10% by volume. The results indicate that the mixes containing fly ash had higher resistance to acid (H2SO4) and salt (MgSO4), with up to 23% resistance observed when compared to the mix containing no fly ash. In addition, resistance to acid attack decreased with the increase in the replacement of fine aggregate with CR. The same principle applied to the salt attack scenario, although the rate was more rapid with the acid than the salt. The results obtained from heating indicate that the weight loss was reduced slightly with the increase in CCW, and was increased with the increase in CR and temperature. Similarly, the compressive strength was observed to slightly increase at room temperature (27 °C) and the greatest loss in compressive strength was observed between the temperature of 300 and 400 °C. However, highest water absorption, of 2.83%, was observed in the mix containing 20% CR, and 0% CCW, while the lowest water absorption, of 1.68%, was found in the mix with 0% CR, 40% fly ash, and 10% CCW. In conclusion, fly ash is recommended for concrete structures immersed in water, acid, or salt in sulphate- and magnesium-prone areas; conversely, fly ash and CR reduce the resistance of SCC to heat beyond 200 °C.


2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Eluozo S.N. ◽  
Dimkpa K

Wood and fly ash were observed to have significant qualities that could improved the strength of self compacting concrete, the material were applied to increase the compressive strength of concrete strength, this material could be the demanding material for partial  replacement for cement, the study observed the behaviour of the material from experts that applied these material through experimental investigation, but the study monitored the behaviour of this material by applied modeling and simulation to determine other effect that could influence the behaviour of this materials in compressive strength, this was to determine the  significant effect on the addictive applied as partial replacement for cement, lots of experts has done works on fly ash through experiment concept, but the application of predictive concept has not be carried out, the  adoption of this concept has expressed other parameters that contributed to the efficiency of  wood and fly ash as partial replacement for cement on self compacting concrete. The study adopting modeling and simulation observed 10 and 20% by weight of cement as it is reflected on its performance in the simulation, from the simulation wood recorded 10% as it was observed from the growth rate of this self compacting concrete reflected from the trend, the simulation for model validation were compared with the works of the studies carried out [20]. And both values developed best fits correlation


Author(s):  
Aishwarya Dupaki

Abstract: This paper gives a review on self compacting concrete(SCC) to be made as partial replacing of cement by fly ash and metakaolin and partial replacing of fine aggregate with copper slag. Day by day production of concrete is increasing due to requirement of concrete is increasing with sufficient mechanical and durable properties in construction industry. Self compacting concrete is the special concrete which has ability of passing and filling of every corner of the congested area. So many researches are going on to increase mechanical and durable properties of SCC. Due to shortage of natural aggregates, researches are going on to use by-products or waste material as fine aggregate. Copper slag is a by-product produced during the process of production of copper. To achieve good mechanical and durable properties of self-compacting concrete cementitious material places an important role. Metakaolin and fly ash are used as the partial replacement of cement. In this paper an overview on the literature on mechanical behaviour of self-compacting concrete with partial replacement of cement by fly ash and metakaolin and partial replacement of fine aggregate with copper slag. Keywords: self compacting concrete, copper slag, fly ash, metakaolin, mechanical properties, durability


2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Eluozo S.N. ◽  
Dimkpa K

This paper monitors the growth rate of tensile strength under partial replacement of locally sourced materials, the study monitor the behaviour of tensile between seven and  twenty eight days of optimum curing age,  modeling and simulation were applied in the study, whereby parameters that generate the attained tensile strength from self compacting concrete were monitored considering various factors such as variation of compaction and water cement ratio, the reaction of these parameters were examined in the study through the simulation, the reflection of these parameters influence where observed in all the trend, the study examined the level of significances of tensile on concrete structure, therefore try to evaluate  various reflection effect from permeability and other parameters that were not considered in  experimental process, these are  developed from  self compacting concrete partially replace cement with fly ash and wood.  Tensile strength is an important property of concrete due its level of vulnerability to tensile cracking base on different kind of applied loading itself. The influence of permeability as a physical property has definitely affect the durability of concrete, these  where observed on the its reflection on tensile strength in all the trend, the rate of permeability effect on tensile were monitored to reflect its reaction through microstructural perspective influence from porosity, pore size, connectivity including its rates of bonding, these correlation includes  air content and capillarity, there rate of permeability coefficient on its reduction are determined by the decrease in porosity and void ratios from concrete compaction rate, it is  reflected on  its variation  of tensile strength in self compacting concrete, the rate of permeability reducing at constant rates determined the tensile strength through it microstructural  setting on the self compacting concrete, these condition were applied on the simulation to generates the predictive values compared with experimental values by an expert [22], while an improvement were made on it study, these include monitoring of concrete permeability and void ratios effect on tensile, the behaviour of porosity under the influence of permeability and variation concrete void were examined from the permeability influence on tensile strength.


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