Effects of Packing Degree and Calcium-Silicon Ratio of Cementitious Material on Strength of Reactive Powder Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1034-1037
Author(s):  
Tao Ji ◽  
Bao Chun Chen ◽  
Yi Zhou Zhuang ◽  
Zhi Bin Huang ◽  
Yong Ning Liang
Keyword(s):  
Silicon Dioxide ◽  
Cementitious Materials ◽  
Strength Test ◽  
Cementitious Material ◽  
Molar Ratio ◽  
Reactive Powder Concrete ◽  
Mix Proportion ◽  
Study Results ◽  
Calcium Silicon ◽  
Reactive Powder

Aim & Goff model was used to predict the packing degree of cementitious materials including cement and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing degree and calcium-silicon ratio of cementitious materials were designed and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing degree and calcium-silicon ratio of cementitious materials. For the mix proportion of RPC with the calcium- silicon molar ratio of 1.353 that is slightly less than the theoretical value of 1.42, where calcium hydroxide can react with silicon dioxide more fully, its strength of RPC approaches summit although its packing degree of cementitious material is not the largest one.

Effects of Packing Density and Calcium- Silicon Ratio of Ternary Cementitious Material System on Strength of Reactive Powder Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 197-201
Author(s):  
Tao Ji ◽  
Bao Chun Chen ◽  
Feng Li ◽  
Yi Zhou Zhuang ◽  
Zhi Bin Huang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Packing Density ◽  
Cementitious Material ◽  
Reactive Powder Concrete ◽  
Material System ◽  
Mix Proportion ◽  
Study Results ◽  
Calcium Silicon ◽  
Reactive Powder

Aim & Goff model was used to predict the packing density of cementitious material including cement, ultra-pulverized fly ash and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing density and calcium-silicon ratio of cementitious material were designed, and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing density and calcium-silicon ratio of cementitious material. For the mix proportion of RPC with the calcium-silicon ratio of 1.179, calcium hydroxide reacts with silicon dioxide fully, and the superfluous ultra-pulverized fly ash and silica fume fill the voids of RPC. The packing density of its cementitious material is the largest, and its strength approaches summit.

scholarly journals Influence of Partial Replacement of Micro-Silica by Fly-Ash on Strength Properties of Reactive Powder Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 2932-2937
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Reactive Powder Concrete ◽  
Experimental Investigations ◽  
Reactive Powder ◽  
Micro Silica

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.

scholarly journals Mechanical Testing of Composite Steel and Reactive Powder Concrete Structural Element

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3954
Author(s):  
Jan Bujnak ◽  
Peter Michalek ◽  
Frantisek Bahleda ◽  
Stefania Grzeszczyk ◽  
Aneta Matuszek-Chmurowska ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Composite Structures ◽  
Numerical Models ◽  
Concrete Slab ◽  
Initial Study ◽  
Cementitious Materials ◽  
Mechanical Tests ◽  
Reactive Powder Concrete ◽  
Structural Element ◽  
Reactive Powder

Reactive powder concrete (RPC), typically with higher compressive strength, is particularly attractive to structural engineers to apply them in infrastructures for enhancing their resistance under severe environments and loads. The main objective of the initial study presented in the paper was to investigate the behavior of two types of these new cementitious materials differing in the nature of microfibers. The RPC mixes were reinforced with steel and then with basalt microfibers. To evaluate the structural performance of developed unconventional materials, properties were investigated experimentally and compared with the control normal concrete mix. Mechanical tests indicated that dispersing fine fibers for making RPC, a mean compressive strength of 198.3 MPa and flexural strength 52.6 MPa or 23.2 MPa, respectively, were developed after 28 days of standard curing at ambient temperatures. In composite structures consisting of steel girders and a concrete slab, it is necessary to prevent the relative slip at the steel and concrete interface using shear connectors. The very high RPC strength enabled a material saving, weight-reduced application of precast construction, and particularly effective joint to steel beams. The investigation of such shear connection efficiency, in the case of the higher strength concrete deck, using standard push-out test specimens was executed. Finite element numerical models were developed. The outputs of the studies are presented in the paper.

scholarly journals Effect of Mix Proportion Parameters on Behaviors of Basalt Fiber RPC Based on Box-Behnken Model

2019 ◽  
Vol 9 (10) ◽  
pp. 2031 ◽  
Author(s):  
Hanbing Liu ◽  
Shiqi Liu ◽  
Shurong Wang ◽  
Xin Gao ◽  
Yafeng Gong
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Basalt Fiber ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Basalt Fibers ◽  
Factors Affecting ◽  
Remarkable Effect ◽  
Mix Proportion ◽  
Reactive Powder

Basalt fibers are widely used in the modification of concrete materials due to its excellent mechanical properties and corrosion resistance. In this study, the basalt fibers were used to modify reactive powder concrete (RPC). The effect of four mix proportion parameters on the working and mechanical properties of basalt fiber reactive powder concrete (BFRPC) was evaluated by the response surface methodology (RSM). The fluidity, flexural and compressive strength were tested and evaluated. A statistically experimental model indicated that D (the silica fume to cement ratio) was the key of interactions between factors, affecting other factors and controlling properties of BFRPC. The increase in basalt fiber content had a remarkable effect on increasing the flexural and compressive strength when D = 0.2. The addition of basalt fiber obviously improved the mechanical properties of RPC. While when D = 0.4, the decrease of fiber content and the increase of quartz sand content could increase the compressive strength.

Mix Proportion Optimization and Shrinking of New Developed Reactive Powder Concrete

2009 ◽  
Vol 405-406 ◽  
pp. 37-43 ◽  
Author(s):  
Heng Jing Ba ◽  
Ai Li Guo ◽  
Ying Zi Yan
Keyword(s):  
Raw Materials ◽  
Steel Fibers ◽  
Reactive Powder Concrete ◽  
Particle Sizes ◽  
Heat Curing ◽  
Mix Proportion ◽  
Binder Ratio ◽  
New Type ◽  
Dry Shrinkage ◽  
Reactive Powder

According to the theory of dense packing of particle, the theoretical particle size distribution of raw materials of RPC (Reactive Powder Concrete) was calculated. On the basis, the ratio of raw materials with different range of particle sizes of the RPC was determined by mechanical experiments. According to the determined ratio, a new type RPC was prepared by using flying ash and slag to replace part of cements and quartz flour, respectively. The workability, mechanical properties of the new RPC with different mix proportion and its shrinkage, cured at the normal temperature and 60°C, respectively, were studied. The results show that when water-binder ratio is 0.23, fly ash replaces 30% cements, slag replaces 50% quartz flour and superfine steel fibers percentage in volume is 2%, the compressive and flexural strength of prepared RPC are 160.1MPa and 25.3MPa, respectively, and after 3days heat curing (60°C), the dry shrinkage of it in 28days age reaches 299um/m. In addition, the fluidity of the new RPC is 258mm and meets requirements of workability of the pump concrete.

scholarly journals Effect of the Key Mixture Parameters on Shrinkage of Reactive Powder Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shamsad Ahmad ◽  
Ahmed Zubair ◽  
Mohammed Maslehuddin
Keyword(s):  
Empirical Equation ◽  
Cementitious Materials ◽  
Reactive Powder Concrete ◽  
Test Results ◽  
Total Period ◽  
Concrete Mixtures ◽  
Binder Ratio ◽  
Reactive Powder ◽  
Water To Binder Ratio ◽  
Different Levels

Reactive powder concrete (RPC) mixtures are reported to have excellent mechanical and durability characteristics. However, such concrete mixtures having high amount of cementitious materials may have high early shrinkage causing cracking of concrete. In the present work, an attempt has been made to study the simultaneous effects of three key mixture parameters on shrinkage of the RPC mixtures. Considering three different levels of the three key mixture factors, a total of 27 mixtures of RPC were prepared according to 33factorial experiment design. The specimens belonging to all 27 mixtures were monitored for shrinkage at different ages over a total period of 90 days. The test results were plotted to observe the variation of shrinkage with time and to see the effects of the key mixture factors. The experimental data pertaining to 90-day shrinkage were used to conduct analysis of variance to identify significance of each factor and to obtain an empirical equation correlating the shrinkage of RPC with the three key mixture factors. The rate of development of shrinkage at early ages was higher. The water to binder ratio was found to be the most prominent factor followed by cement content with the least effect of silica fume content.

Effects of Sand Particle Size and Gradation on Strength of Reactive Powder Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 208-211 ◽  
Author(s):  
Tao Ji ◽  
Bao Chun Chen ◽  
Yi Zhou Zhuang ◽  
Feng Li ◽  
Zhi Bin Huang ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Strength Test ◽  
Reactive Powder Concrete ◽  
Sand Particle ◽  
Particle Sizes ◽  
Test Results ◽  
Sand Mixture ◽  
Different Types ◽  
Reactive Powder

After modification, Toufar model was used to calculate the packing degrees of sand mixtures with different particle sizes. For four gradations of sands, the weight ratios of different types of sands with different size ranges, which achieve maximum packing degrees, have been obtained using the modified Toufar model. A strength test of reactive powder concretes (RPCs) with the four gradations of sands was reported. The test results show that the strength of RPC is related to both the maximum grain size and the packing degree of sand mixture. The smaller maximum grain size and larger packing degree of sand mixture can achieve the higher strength of RPC.

Thermodynamic Modelling of the Sorption of Radioelements onto Cementitious Materials

1995 ◽  
Vol 412 ◽  
Author(s):  
T. G. Heath ◽  
D. J. Ilett ◽  
C. J. Tweed
Keyword(s):  
Surface Chemistry ◽  
Calcium Ions ◽  
Cementitious Materials ◽  
Molar Ratio ◽  
Iodide Ions ◽  
Zeta Potentials ◽  
High Calcium ◽  
Cement Based Materials ◽  
Calcium Silicon ◽  
Modelling Approach

AbstractA model has been developed for the sorption of radioelements onto cementitious materials based on the diffuse-layer modelling approach. The model assumes that silicon sites (>SiOH) and calcium sites (>CaOH) dominate the surface chemistry and the sorption of radioelements onto the cementitious materials. Both types of site may undergo surface protonation and deprotonation reactions. Cement-based systems vary greatly in their chemistry depending on their calcium-tosilicon molar ratio, and the corresponding variation in the surface chemistry has been incorporated by allowing sorption of calcium ions onto silicon sites. This process results in a change from a silica-type surface, at very low calcium-silicon ratios, to a calcium hydroxide-type surface for high-calcium cement-based materials. The predicted variation in the surface chemistry is consistent with literature data on measured zeta potentials of cements. The model has been applied successfully to describe the sorption of simple caesium and iodide ions at varying calciumsilicon ratios. In a Nirex repository for low and intermediate level wastes, a high-calcium cementitious backfill would be specified. This model has allowed a consistent interpretation of experimental data for sorption of key radioelements, including uranium and plutonium, onto the backfill, under saline and non-saline conditions.

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