Effects of metakaolin, silica fume and slag on pore structure, interfacial transition zone and compressive strength of concrete

2013 ◽  
Vol 44 ◽  
pp. 1-6 ◽  
Author(s):  
Ping Duan ◽  
Zhonghe Shui ◽  
Wei Chen ◽  
Chunhua Shen
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Transition Zone ◽  
Silica Fume ◽  
Interfacial Transition Zone ◽  
Compressive Strength Of Concrete

The Interfacial Transition Zone: “Direct” Evidence on Compressive Response

1994 ◽  
Vol 370 ◽  
Author(s):  
David Darwin
Keyword(s):  
Compressive Strength ◽  
Transition Zone ◽  
Cement Paste ◽  
Direct Evidence ◽  
Indirect Evidence ◽  
Interfacial Strength ◽  
Interfacial Transition Zone ◽  
Compressive Response ◽  
Heterogeneous Nature ◽  
Compressive Strength Of Concrete

AbstractThere is little question that the strength of the interfacial transition zone (MTZ) between cement paste and aggregate affects the compressive strength of concrete. The key question, rather, is to what degree? It is difficult to directly measure the response of the overall composite to changes in interfacial properties, since it is difficult to isolate interfacial strength as the only variable.Research on the effects of interfacial strength on the compressive response of concrete that comes the closest to providing direct evidence is summarized. The studies, dating to the 1950's, include both experimental and analytical efforts aimed at isolating the effects of the ITZ, as well as experimental efforts that are considered to provide strong indirect evidence. The research shows that the ITZ plays a measurable role in the response of concrete to compressive stress, but that its role is overshadowed by the properties of the cement paste and aggregate constituents of concrete and the heterogeneous nature of the composite.

scholarly journals Experimental study on the compressive strength, damping and interfacial transition zone properties of modified recycled aggregate concrete

2019 ◽  
Vol 6 (12) ◽  
pp. 190813
Author(s):  
Bin Lei ◽  
Huajian Liu ◽  
Zhimin Yao ◽  
Zhuo Tang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Transition Zone ◽  
Loss Factor ◽  
Steel Fibre ◽  
Interfacial Transition Zone ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Damping Properties ◽  
Aggregate Concrete

At present, many modification methods have been proposed to improve the performance of recycled aggregate concrete (RAC). In this study, tests on the compressive strength and damping properties of modified RAC with the addition of different proportions of recycled coarse aggregate (RCA) (0, 50, 100%), rubber powder (10, 15, 20%), steel fibre (5, 7.5, 10%) and fly ash (15, 20, 5%) are carried out. To elucidate the effect of the modification method on the interfacial transition zone (ITZ) performance of RAC, model ITZ specimens are used for push-out tests. The results show that when the replacement rate of RCA reaches 100%, the loss factor of the RAC is 6.0% higher than that of natural aggregate concrete; however, the compressive strength of the RAC decreases by 22.6%. With the addition of 20% rubber powder, the damping capacity of the modified RAC increases by 213.7%, while the compressive strength of the modified RAC decreases by 47.5%. However, with the addition of steel fibre and fly ash, both the compressive strength and loss factor of the RAC specimens increase. With a steel fibre content of 10 wt%, the compressive strength and loss factor of the RAC increase by 21.9% and 15.2%, respectively. With a fly ash content of 25 wt%, the compressive strength and loss factor of the RAC increase by 8.6% and 6.9%, respectively. This demonstrates that steel fibre and fly ash are effective in improving both the damping properties and compressive strength of RAC, and steel fibre is more effective than fly ash. Two methods were used for modification of the RAC: reinforcing the RCA through impregnation with a 0.5% polyvinyl alcohol (PVA) emulsion and nano-SiO 2 solution, and strengthening the RAC integrally through the addition of fly ash as an admixture. Both of these techniques can improve the ITZ bond strength between the RAC and new mortar. Replacing 10% of the cement with fly ash in the new mortar is shown to be the best method to improve the ITZ strength.

scholarly journals Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

2019 ◽  
Vol 8 (2S8) ◽  
pp. 883-887
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Before And After ◽  
Alkaline Conditions ◽  
Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

The Contribution of the Transition Zone to the Strength of High Quality Silica Fume Concretes

1987 ◽  
Vol 114 ◽  
Author(s):  
A. Bentur ◽  
A. Goldman ◽  
M. D. Cohen
Keyword(s):  
Pore Structure ◽  
Transition Zone ◽  
Silica Fume ◽  
Fresh Concrete ◽  
High Strength ◽  
High Quality ◽  
The One

ABSTRACTThe strength of high strength silica fume concretes is usually attributed to the reduction in w/c ratio and the refinement of the pore structure. A study of concretes and pastes, with and without silica fume, suggests that the contribution of the silica fume to strength is also the result of the densification of the transition zone. It is argued here that this influence is as important as the one due to the reduction in w/c ratio. It is suggested that the densification of the transition zone is the result of the effect of the silica fume on the nature of the fresh concrete.

scholarly journals Influence of Graphene Oxide on Interfacial Transition Zone of Mortar

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hongfang Sun ◽  
Zhili Ren ◽  
Li Ling ◽  
Shazim Ali Memon ◽  
Jie Ren ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Graphene Oxide ◽  
Prediction Model ◽  
Transition Zone ◽  
Cement Mortar ◽  
Interfacial Transition Zone ◽  
Backscattered Electron ◽  
The Difference

In this paper, the influence of graphene oxide (GO) on the microstructure of interfacial transition zone (ITZ) in cement mortar was investigated through image analysis (IA) of backscattered electron (BSE) micrographs. The results showed that the incorporation of GO significantly reduced the thickness of ITZ. The porosity in ITZ and bulk paste decreased due to the introduction of GO; meanwhile, the compressive strength of the mortar samples was improved. The addition of GO also narrowed the gap between the porosity of ITZ and bulk paste, and therefore, the entire microstructure of mortar became more homogenous. Based on the above results, the model to predict the compressive strength of mortar was modified for better precision. The improved prediction model indicated that the difference between the compressive strength of ITZ and bulk paste was reduced upon the refinement of ITZ by GO.

scholarly journals Thermal and mechanical properties of PCM-incorporated normal and lightweight concretes containing silica fume

2019 ◽  
Vol 46 (7) ◽  
pp. 643-656 ◽  
Author(s):  
Amin Moshtaghi Jafarabad ◽  
Morteza Madhkhan ◽  
Naser P. Sharifi
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Mechanical Characteristics ◽  
Lightweight Aggregate ◽  
Salt Hydrate ◽  
Promising Strategy ◽  
Compressive Strength Of Concrete ◽  
Physical And Mechanical Characteristics

Improving the thermal performance of concrete, as an important construction and pavement material, by incorporating phase change materials (PCMs) has been the topic of much research. Also, various carrier agents such as lightweight aggregate (LWA) have been introduced to incorporate PCMs into concrete. However, incorporation of PCM-impregnated LWA reduces the compressive strength of concrete. In this study, the application of silica fume to improve the compressive strength of PCM-incorporated concrete is investigated. Two types of PCMs, salt hydrate PCM and polyethylene glycol PCM, were incorporated into concrete via scoria LWA, and different physical and mechanical characteristics of the concrete were studied when silica fume was incorporated into the mix. The results show that incorporation of silica fume increases the compressive strength of PCM-incorporated concrete, and at the same time does not diminish the thermal performance of the incorporated PCM. Therefore, incorporation of silica fume was found to be a promising strategy to improve the compressive strength of PCM-incorporated concrete.

Literature Review: Properties of Silica Fume Concrete

2014 ◽  
Vol 1004-1005 ◽  
pp. 1516-1522
Author(s):  
Xi Xi He ◽  
Qing Wang
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Silica Fume ◽  
Water Demand ◽  
Interfacial Transition Zone ◽  
Normal Concrete ◽  
Plastic Shrinkage ◽  
Micro Level

Silica fume (SF) modifies interfacial transition zone between cement paste and aggregate at the micro level. Properties of both fresh and hardened silica fume concrete are affected significantly compared to normal concrete. Experiments indicate that concretes become more cohesive and less prone to segregation in the presence of silica fume, moreover, performance of water demand, setting of time, plastic shrinkage varies respectively from concretes without silica fume. Obvious mechanical enhancement of concrete is observed in the aspects of compressive strength tensile strength, elastic modulus as well as fracture toughness.

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