The development of a new method for the proportioning of high-performance concrete mixtures (original) (raw)
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Mix Design of High Performance Concrete Using Silica Fume and Superplasticizer
High Performance Concrete (HPC) now a days used widely in the construction industry world wide. To produce HPC with normal ingradients we use mineral admixtures like Silica fume, fly ash and metakoline and workable agents Superplasticizers are also used. The usage of mineral admixtures in the concrete not only enhances its strength properties but also durability. The compressive strength are investigating finding the optimum use of mineral admixture(Silica fume of levels 0, 5, 10,15, 20 and 25% at 7 days and 28 days of curing). The present investigation aims to give design mix for HPC by using silica fume and superplasticizers.
Properties of Ultra High Performance Concrete Containing Superfine Cement and without Silica Fume
Journal of Advanced Concrete Technology, 2014
To avoid the disadvantages caused by using silica fume, by using superfine cement (SC) to substitute silica fume, a new kind of ultra high performance concrete (SC-UHPC) was prepared and introduced. The influence of component types and dosages on the mechanical properties of SC-UHPC was investigated. The results show that 40% ground granulated blast furnace slag (GGBFS) or 10% fly ash (FA) & 30% GGBFS replacing SC are the most appropriate proportions to get high strength with satisfied workability and low cost. A suitable amount of defoaming agent (DA) in superplasticizer (SP) effectively reduced the void ratio in the UHPC. To optimize the strength and fluidity, the rational natural sand distribution with lowest clay particles amount can be used. The small sized steel fibers added into the mixture effectively improved the flexural behavior of SC-UHPC. Multiple nonlinear analysis show that, with sufficient calcium silicate hydrate (C-S-H gel) and enough mixture fluidity, the compressive strength of UHPC is closely related to the water to binder ratio and void ratio, and increases linearly with the incremental fiber amount. Microstructure analysis proved that the microstructure of SC-UHPC has ultra high density and homogeneity.
Neutron
In this research, a lightweight concrete mixture was made with foam and made use of the remaining broken rock from the Crusher Machine process, which was washed ashes. Other added ingredients used in the mixture are Silica Fume, Superplasticizer (Admixture Type F) and Bonding. This reseach uses a mix design from Circular Letter Number: 44 / SE / M / 2015 Concerning Design Guidelines for Mixing Light Material with Foam Mortar for Road Construction, Ministry of PUPR. Trial mix variations carried out are in proportion (SF 5%; BO 0.5%), (SF 10%; BO 0.5%), (SF 5%; BO 1%), (SF 10%; BO 1% ), as well as foam agents with variations 1:20 and 1:40. The treatment process (curing) of the test object is immersed in a water bath, and the testing of the compressive strength of the test object is carried out at the age of 7 days, 14 days and 28 days. By using stone ash, lightweight concrete was obtained with an average specific gravity of 1722 kg / m3 to 1884 kg / m3. From the research results obtai...
The Compressive Strength of High-Performance Concrete and Ultrahigh-Performance
Advances in Materials Science and Engineering, 2012
The compressive strength of silica fume concretes was investigated at low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer. The results show that partial cement replacement up to 20% produce, higher compressive strengths than control concretes, nevertheless the strength gain is less than 15%. In this paper we propose a model to evaluate the compressive strength of silica fume concrete at any time. The model is related to the water-cementitious materials and silica-cement ratios. Taking into account the author's and other researchers’ experimental data, the accuracy of the proposed model is better than 5%.
Advances in materials research, 2018
In the present study, a special attention has been paid to the effects regarding the use of different superplasticizers in different dosages. To do so, 36 mixes of normal and self-compacting concrete with two water/binder ratios of 0.35 and 0.45, four different types of superplasticizer including melamine-formaldehyde, naphthalene-formaldehyde, carboxylic-ether and poly-carboxylate, four different superplasticizer/cement ratios of 0.4%, 0.8%, 1.2% and 1.6% and two silica fume/cement ratios of 0% and 10% have been cast. Moreover, the initial and final setting time of the pastes have been tested. For self-compacting mixes, flow time, slump flow, V-funnel, J-ring and L-box tests have been carried out as well as testing the compressive strength and rupture modulus. For normal concrete mixes, slump test has been conducted to assess the workability of the mix and then for each mix, the compressive strength and rupture modulus have been determined. The results indicate that in addition to ...
HBRC Journal, 2014
Heavy weight high performance concrete (HPC) can be used when particular properties, such as high strength and good radiation shielding are required. Such concrete, using ilmenite and hematite coarse aggregates can significantly have higher specific gravities than those of concrete made with dolomite and air-cooled slag aggregates. Four different concrete mixes with the same cement content and different w/c ratios were designed using normal dolomite aggregate, air-cooled slag by-product and two different types of iron ore aggregates. High performance concrete (grade-M60) can be achieved using superplasticizer to reduce the water/cement ratio; the effect of SF on the performance of concrete was studied by addition of 10% silica fume to the total cement content. The physico-mechanical properties of coarse aggregates and hardened concrete were studied. The results show that, Ilmenite coarse aggregate gives higher physical and mechanical properties than the other aggregates. Also, addition of 10% silica fume developed a stronger and a denser interfacial transition zone (ITZ) between concrete particles and the cement matrix. Crushed air-cooled slag can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with crushed hematite and ilmenite. Heavy density concrete made with fine aggregates of ilmenite and air-cooled slag are expected to be suitable as shielding materials to attenuate gamma rays.
The incorporation of silica fume and superplasticizers in high strength and high performance concrete, along with a low water-cement ratio, leads to significant changes in the workability and the energy needed to homogenize and compact the concrete. Moreover, several aspects of concrete production that are not criticai for conventional concrete are important for high strength concrete. This paper will discuss the need for controlling the humidity of the aggregates, optimizing the mixing sequence used in the fabrication, and the slump loss. The application of a silica fume concrete in typical building columns will be analyzed considering the required consolidation, the variability of the material strength within the structural element and the relation between core and molded specimen strength. Comparisons will also be ma de with conventional concrete. Resumo A incorporação de adições minerais e aditivos químicos nos concretos de alto desempenho e de alta resistência, aliados a baixa ...
Effect of Silica Fume on High Performance Concrete Strength
High Performance Concrete (HPC) is now a days used widely in the construction industry worldwide. To produce HPC with normal ingredients one use mineral admixtures like silica fume, fly ash and metakoline. In addition admixtures including Superplasticisers are also used. This paper investigates the effect of silica fume (SF), added in varying percentages (0, 3, 5, 7.5, 10, 12.5%), on concrete strength. Superplasticiser-(Viscocrete Tempo 12)-was added to the concrete mixtures as well. Compressive strength, shear strength and tensile strength tests were conducted, and the results were discussed. Results showed that the compressive strength changes with the varying percentage addition of silica fume. The highest compressive strength (88 MPa) was obtained when the percentage of silica fume was 7.5 % of the cement weight. Beyond 7.5 % silica fume, the compressive strength started descending. Tensile and shear strength were found to vary in an inverse relationship with the increasing percentage of silica fume. A significant reduction in tensile strength and shear strength were recorded when the silica fume percentage is increased. However, the 10% ratio between tensile and compressive strength for normal concrete, was not found to be, relevant for HPC with SF.
Cement and Concrete Research, 2019
High silica fume content used in ultra-high performance concrete (UHPC) can increase viscosity and render agglomeration issue, leading to reduction in mechanical properties, including bond to fibers. This study investigates the effect of silica fume content, ranging from 0 to 25%, by mass of cementitious materials, on rheological, fiber-matrix bond, and mechanical properties of non-fibrous UHPC matrix and UHPC made with 2% micro-steel fibers. Binary mixtures consisting of cement and silica fume with targeted mini-slump flow were specifically prepared. The involved mechanical properties include compressive, flexural, and tensile behavior. Rheology, fiber-matrix bond, flexural, and tensile strengths of UHPC were linked to each other using fiber dispersion and orientation analyses or the Composite Theory. Test results showed that UHPC made with 10% to 15% silica fume obtained the highest fiber-matrix bond, flexural, and tensile properties. Such silica fume content was found to result in lower viscosity and more uniformly distributed fibers as determined by image analysis. The flexural and tensile strengths of UHPC made with 5%-20% silica fume can be effectively predicted using the Composite Theory considering obtained fundamental inputs, such as flexural or tensile strengths of matrix, fiber characteristics, and fiber-matrix bond strength. The experimental-to-predicted tensile and flexural strength ratios were in the range from 0.9 to 1.1. However, the predicted strengths of UHPC mixtures with 0 and 25% silica fume were greatly lower than the experimental values due to high viscosity and low packing density.
Prediction of Strength and Slump of Silica Fume Incorporated High-Performance Concrete
This study describes the development of statistical models to predict strength and slump of silica fume incorporated High-Performance Concrete (HPC). Experimental data of silica fume incorporated HPC mixes were used to develop and validate models. The HPC having compressive strength range of 40-113 MPa and slump range of 180-250 mm were used. Statistical models were developed by regression analysis. The results of prediction by the models showed good agreement with those of experiments and other researchers. The developed models can be used to predict slump and 28 days compressive strength of silica fume incorporated HPC.