scholarly journals Investigations of the Influence of Polystyrene Foamed Granules on the Properties of Lightweight Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Suman Kumar Adhikary ◽  
Zymantas Rudzionis ◽  
Marijus Zubrus
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Lightweight Concrete ◽  
Microscopic Analysis ◽  
Hydrated Lime ◽  
Curing Process ◽  
Polystyrene Foam ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio

Abstract This paper deals with the behaviour of cement paste upon the addition of crushed polystyrene foam. Crushed polystyrene foam waste with a fill density of 13.97 kg/m3 and hydrated lime were used to prepare the foam. Three different types of samples S-1, S-2, and S-3 were prepared to observe the behaviour of cement pastes after the addition of different doses of foam in constant water/cement ratio. The volumetric ratio of EPS and cement paste were 1: 1.294; 1: 0.863; and 1: 0.647. In each type of sample, 0.28 water/cement ratio is maintained. Slump test was carried out in the fresh state and it has been found slump value was decreasing by increasing foam content in concrete sample. On the 7th and 28th day of curing process, the compressive strength test was carried out. Compressive strength and density of concrete samples also decreasing by addition of higher foam content. In addition, water absorption test and microscopic analysis tests were carried out on the 28th day of curing process. It has been found from the study that samples thermal conductivity is working proportionally.

Microstructure of High Strength Cement Paste Systems

1984 ◽  
Vol 42 ◽  
Author(s):  
M. Regourd
Keyword(s):  
Cement Paste ◽  
Ultrafine Particles ◽  
High Strength ◽  
Interfacial Bond ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Composite Systems ◽  
Crystalline Hydrates ◽  
Low Porosity

AbstractHigh strength cement pastes include hot pressed, autoclaved, impregnated low water/cement ratio, macrodefect free, ultrafine particles arrangement systems. The densification of the microstrucure is mainly related to a low porosity and to the formation of poorly crystalline hydrates. In composite systems like mortars and concretes, the interfacial bond between the cement paste and aggregates is moreover less porous and more finely crystallized than the normal “auréole de transition”.

scholarly journals The Assessment of Strength of Cementitious Materials Impregnated Using Hydrophobic Agents Based on Near-Surface Hardness Measurements

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4583
Author(s):  
Martyna Nieświec ◽  
Łukasz Sadowski
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Concrete Structures ◽  
Surface Hardness ◽  
Cementitious Materials ◽  
Schmidt Hammer ◽  
Near Surface ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
The Impact

Recently, the surfaces of concrete structures are impregnated to protect them against the environment in order to increase their durability. It is still not known how the use of these agents affects the near-surface hardness of concrete. This is especially important for experts who use the near-surface hardness of concrete for estimating its compressive strength. The impregnation agents are colorless and, thus, without knowledge of their use, mistakes can be made when testing the surface hardness of concrete. This paper presents the results of investigations concerning the impact of impregnation on the subsurface hardness concrete measured using a Schmidt hammer. For this research, samples of cement paste with a water–cement ratio of 0.4 and 0.5 were used. The samples were impregnated with one, two, and three layers of two different agents. The first agent has been made based on silanes and siloxanes and the second agent has been made based on based on polymers. The obtained research results allow for the conclusion that impregnation affects the near-surface hardness of concrete. This research highlights the fact that a lack of knowledge about the applied impregnation of concrete when testing its near-surface hardness, which is then translated into its compressive strength, can lead to serious mistakes.

Pastes Prepared with Sulfonate, Chalcedony and Sugar

2012 ◽  
Vol 517 ◽  
pp. 338-341
Author(s):  
Ulisses Targino Bezerra ◽  
Normando Perazzo Barbosa
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Compression Strength ◽  
Cementitious Materials ◽  
Important Conclusion ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Good Workability ◽  
Portland Cement Paste

Papers presented at ICPIC 2010, Madeira Island, Portugal, dealing with the use of polymers in cementitious materials, show the need to combine different admixtures to optimize the properties of cement. This work is a continuation of a paper presented at NOCMAT 2010, Cairo-Egypt, about the incorporation of several materials in Portland cement to increase mechanical properties and workability. The best performance admixtures were chosen and they were combined considering the superposition of effects. Cement pastes were prepared with chalcedony and sulfonate (to increase compressive strength) and sugar (to increase workability). Two percent of cement was replaced by the admixtures. The water/cement ratio was constant and equal to 0.44. Results show that the combination of 0.05% of sugar and 1.95% of sulfonate and 0.10% of sugar and 1.90% of chalcedony produced a paste with the greatest compressive strength and good workability. Compression strength was respectively 27.4 MPa and 36.6 MPa, which represent increases of 33.5% and 78.6%, respectively, relative to the reference paste without admixtures. While increasing the paste compression strength with sulfonate has been significant, the results of the paste with chalcedony were the more surprising because the water/cement ratio of pastes was kept constant. The chalcedony is a type of crystalline silica, which shows deformation in their structure. So because of crystalline structure of chalcedony, there should be, probably, no significant reactivity of it with the cement hydrates, just the fact that its structure be deformed can explain this reactivity. The most important conclusion concerns is that the combinations of admixtures can improve a lot the properties of Portland cement paste.

scholarly journals A new approach to estimate compressive strength of concrete by the UPV method

2016 ◽  
Vol 9 (3) ◽  
pp. 395-402 ◽  
Author(s):  
M. A. P. Irrigaray ◽  
R. C. de A. Pinto ◽  
I. J. Padaratz
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Concrete Compressive Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Mixtures ◽  
Unique Relationship

ABSTRACT Although the ultrasonic pulse velocity (UPV) method has been extensively used to estimate concrete compressive strength, the relationship between UPV and concrete strength is mixture dependent. As a result, the applicability of this method to estimate strength is well known to be limited. Aggregate type, cement type, mixture proportions, and water-cement ratio influence such a relationship. Nevertheless, UPV and strength are both governed by cement hydration, and thus, a relationship between UPV in the cement paste phase and concrete compressive strength would be expected to exist. By not taking into account the type and volume content of aggregates, this relationship could be the same for concrete mixtures with same type of cement and water-cement ratio, regardless the aggregate type used. This study investigates the existence of such a relationship. Concrete mixtures with water-cement ratios of 0.48, 0.55 and 0.64, with different paste volumes were prepared in the laboratory. For each mixture, compressive strength and ultrasonic pulse velocity were evaluated at various ages. The UPV of each concrete phase: paste, fine aggregate, and coarse aggregate, was obtained through paste and mortar specimens. This study indicated that it is possible to establish a unique relationship between the UPV in cement paste phase and the concrete compressive strength. This unique relationship could be applied to several concrete mixtures, greatly expanding the use of the UPV method to estimate compressive strength.

scholarly journals Feasibility of Producing Lightweight Concrete Using Indigenous Materials Without Autoclaving

1970 ◽  
Vol 3 ◽  
Author(s):  
M Shamsuddoha ◽  
MM Islam ◽  
MA Noor
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Lightweight Concrete ◽  
Absorption Capacity ◽  
Appropriate Technology ◽  
Unit Weight ◽  
Sequential Approach ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Volumetric Expansion

This research shows the feasibility and sequential approach for producing lightweight concrete without autoclaving using indigenous ingredients and appropriate technology of Bangladesh. Ingredients were mixed chronologically using trial-and-error method to reduce unit weight. Specific volume principle was utilized to observe the effect of inclusion of cement, water, sand, lime and aluminium in the mixture to achieve the goal. Molds were used to accommodate volumetric expansion of mixture. Both 50 mm and 150 mm cubic specimens were prepared for tests. Density and compressive strength were determined for specimens. Absorption capacity and thermal conductivity were also determined to get the product performance. From the results, it was seen that density and compressive decreased with increased water-cement ratio. Volumetric expansion was high for higher volume surface ratio. Finally, lightweight concrete with density, compressive strength and thermal conductivity within range of 700-1000 kg/m3, 0.5-2.0 MPa and 0.2-0.5 W/m-k respectively was produced. KEY WORDS: Volumetric expansion; Lightweight concrete; Water-cement ratio; Mix design. DOI: http://dx.doi.org/10.3329/mist.v3i0.8049

Properties of Low Water/Cement Ratio and High Compressive Strength Pervious Concrete

2018 ◽  
Vol 932 ◽  
pp. 136-140
Author(s):  
Mao Chieh Chi ◽  
Jiang Jhy Chang ◽  
Wei Chung Yeih
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Pervious Concrete ◽  
Unit Weight ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Water Permeability Coefficient

The purpose of this study is to discuss the properties of low water/cement ratio and high compressive strength pervious concrete. Two sizes of air-cooling electric arc furnace slag (EAFS), for the same size of 0.24 - 0.48 cm and 0.48 - 0.96 cm, were prepared as the coarse aggregates. Two water-to-cement ratios and three filled percentages (70, 80, and 90%) of voids by cement pastes were selected as variables. The unit weight, connected porosity, water permeability coefficient, compressive strength, and flexural strength of pervious concrete were conducted. Test results show that the pervious concrete with higher filled percentage of voids by cement paste has higher unit weight, compressive strength, and flexural strength and smaller connected porosity and water permeability coefficient. The lower the water/cement ratio and EAFS size, the superior the properties. At the water/cement ratio of 0.25, pervious concrete with EAFS size of 0.24 – 0.48 cm and 90% filled percentage of voids by cement pastes had the highest compressive strength of 35 MPa and flexural strength of 7 MPa.

scholarly journals Role of Superplasticizer Additives Upon Hydration Process of Cement Pastes

2016 ◽  
Vol 14 (11) ◽  
pp. 23-26
Author(s):  
Nicolae Angelescu ◽  
Darius Stanciu ◽  
José Barroso de Aguiar ◽  
Hakim S. Abdelgader ◽  
Vasile Bratu
Keyword(s):  
Comparative Analysis ◽  
Cement Paste ◽  
Hydration Process ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
X Ray ◽  
Thermogravimetry Analysis

Abstract The article presents a comparative analysis on the hydration of cement paste without superplasticizer and water/cement ratio of 0.35 and a cement paste with the same water/cement ratio but has in its composition 2% superplasticizer additive Glenium Sky 526. For characterizing the hydration process of cement paste, both mixtures were subjected to X-ray diffraction and thermogravimetry analysis, at 3, 7, and 28 days passed since the initiation of hydration process.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Use of Nondestructive Testing of Ultrasound and Artificial Neural Networks to Estimate Compressive Strength of Concrete

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 44
Author(s):  
Fernando A. N. Silva ◽  
João M. P. Q. Delgado ◽  
Rosely S. Cavalcanti ◽  
António C. Azevedo ◽  
Ana S. Guimarães ◽  
...  
Keyword(s):  
Neural Networks ◽  
Compressive Strength ◽  
Artificial Neural Networks ◽  
Cross Sections ◽  
Influential Factors ◽  
Average Error ◽  
Ann Model ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Artificial Neural

The work presents the results of an experimental campaign carried out on concrete elements in order to investigate the potential of using artificial neural networks (ANNs) to estimate the compressive strength based on relevant parameters, such as the water–cement ratio, aggregate–cement ratio, age of testing, and percentage cement/metakaolin ratios (5% and 10%). We prepared 162 cylindrical concrete specimens with dimensions of 10 cm in diameter and 20 cm in height and 27 prismatic specimens with cross sections measuring 25 and 50 cm in length, with 9 different concrete mixture proportions. A longitudinal transducer with a frequency of 54 kHz was used to measure the ultrasonic velocities. An ANN model was developed, different ANN configurations were tested and compared to identify the best ANN model. Using this model, it was possible to assess the contribution of each input variable to the compressive strength of the tested concretes. The results indicate an excellent performance of the ANN model developed to predict compressive strength from the input parameters studied, with an average error less than 5%. Together, the water–cement ratio and the percentage of metakaolin were shown to be the most influential factors for the compressive strength value predicted by the developed ANN model.

Study on Preparation of Solid Concrete Brick with Recycled Aggregate

2013 ◽  
Vol 648 ◽  
pp. 108-111
Author(s):  
Qi Jin Li ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Mass Fraction ◽  
Recycled Aggregate ◽  
Preparation Process ◽  
Mass Ratio ◽  
Construction Waste ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Optimal Value

The construction waste was processed into recycled aggregate to produce solid construction waste brick with grade of MU20. The preparation process of recycled aggregate and the optimal value of mass ratio of water to cement (water cement ratio) and mass ratio of recycled aggregate to cement was studied. The results shows that when the water cement ratio is 0.86 and the mass ratio of recycled aggregate to cement is 5.5 and the dosage of activator is 0.25% (mass fraction with recycled aggregate), the compressive strength of sample is 22.5MPa and can be satisfied with the requirement of MU20 solid concrete brick.

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