Compressive Strength Of Foamed Concrete Research Articles

ВЛИЯНИЕ МИНЕРАЛЬНЫХ ДОБАВОК, ЛЕТУЧЕЙ ЗОЛЫ, ДОМЕННОГО ШЛАКА НА МЕХАНИЧЕСКИЕ СВОЙСТВА ПЕНОБЕТОНА

The present study evaluated the combined effects of organic-mineral additive based on a superplasticizer SR 5000F and the active mineral additive fly ash, blast furnace slag and silica fume SF-90 on properties of foam concrete. The calculation of mixture proportions of foam concrete is applied by the absolute volume method. Besides, the compressive strength and flexural strength of foam concrete are determined by Russian standard GOST 10180-2012. The porosity of the foamed concrete is determined by American standards ASTM C457-1998. The results from experiments show that flexural and compressive strength of the foam concrete obtained respectively, from 0.526 to 1.061 MPa and from 1.69 to 8.22 MPa. The relationship between compressive strength and curing age, compressive and flexural strengths of the FC were also determined in this investigation. The results of this study demonstrated that the use of fly ash and blast furnace slag to replace natural sand could produce foam concrete and environmental protection.

Development of a strength model for foam concrete based on water – cement ratio

Foam concrete is a lightweight concrete having many versatile features such as flowability, low density, self-compacting, thermal insulation properties, and adequate strength. However, the prediction of the compressive strength of foam concrete is always a challenge. There are various strength prediction models and relationships reported in the literature that are generally based on porosity, density, the volume of voids and space gel ratio, etc. In this paper, a new strength prediction model for the compressive strength of foam concrete is presented based on an effective water-cement ratio. Generally, the compressive strength of concrete is presented as a function of the water-cement (or binder) ratio. This model was developed by the inclusion of foam volume with water in w/c ratio which follows Abram’s strength-w/c law. This is a step ahead of the proposal of the equivalent water-cement ratio using the efficiency factor to include fly ash. The effectiveness of foam was considered as an important parameter for the precision of the model. In this paper, the proposed model was employed to predict the strength of foam concrete mixes reported in past studies. It was seen that this model is highly efficient compared to other models and easiness in predicting the strength since only water, foam, binder are involved.

EXPERIMENTAL INVESTIGATION ON FOAM CONCRETE WITH PARTIAL REPLACEMENT OF FINE AGGREATE BY FLY ASH AND CEMENT BY ALCCOFINE

As we know that Foam concrete has been successfully used and it has gained popularity due to its lower density than normal concrete. Globally the construction activities are rapid and using huge amount of fine aggregate and cement. Due to continuous usage of large amount of sand and cement we are creating natural imbalance by CONTINUOUS mining of sand, lime etc., from natural resources, which causes many natural hazards and become threat to humans. As a responsible citizen of world everyone think to stop the usage of sand and cement in huge quantity for infrastructural activities. Fly ash is one alternative solution as a partial replacement of sand and cement with Alccofine. In this investigation we are replacing fine aggregate with fly ash and cement with Alccofine by usage of Using additive materials in foam concrete which provides not only workability, strength but also reduce overall cost. As reducing the quantity of sand and cement in foam concrete we conserve Green House effect and also other raw materials used for cement. Foam concrete produced with uniform distribution of air bubbles thoughout the mass of concrete. The density of foam concrete is a function of the volume of foam added to the slurry and the strength decreases as decrease in densities. This experimental investigation was designed for density of 800 kg/m3. This study was compiled in determination of workability, plastic density, water absorption and compressive strength of foam concrete. The test specimens has been casted and tested at the age of 7,14 and 28 days.

Experimental investigation on foam concrete without and with recycled glass powder: A sustainable solution for future construction

This study investigates the potential of the use of recycled glass powder in foam concrete as a sustainable solution for future construction. The effects of cement and recycled glass powder contents, water to cement ratio and volume of foam on the plastic density, dry density, and compressive strength of foam concrete were investigated. The compressive strength of foam concrete without and with recycled glass powder increased with the increase in the plastic density and dry density of foam concrete. The direct replacement of cement with recycled glass powder (20% by mass) increased the compressive strength of foam concrete.

Effect of magnetized water on foam stability and compressive strength of foam concrete

It has been widely reported that the use of magnetized water to mix concrete can increase the workability of fresh concrete and its hardened strength. Meanwhile, the use of foam concrete in construction industry is gaining popularity because of its excellent properties, such as low self-weight and excellent thermal insulation properties. But the foam stability and relatively low compressive and splitting tensile strength of foam concrete are still the main challenges for engineers to use this material. This study intends to evaluate the influence of magnetized water on the foam stability, compressive strength, splitting tensile strength, water absorption and micro structure of foam concrete. A total of 9 mixes were prepared with water that passed through a permanent magnetic field for 1, 5 and 10 times at flow speeds of 0.75 m/s, 1.75 m/s and 2.75 m/s, respectively. The test results indicate that the foam stability, compressive and splitting tensile strength of foam concrete are significantly improved by using magnetized water, whereas the water absorption of hardened foam concrete decreases slightly.

Compressive Strength and Dimensional Stability of Palm Oil Empty Fruit Bunch Fibre Reinforced Foamed Concrete

Rapid drying shrinkage is an important factor in causing cracks of concrete. This research was aimed at studying the effects of Palm Oil Empty Fruited Bunch (POEFB) fibre on the drying shrinkage behaviour and compressive strength of foamed concrete (FC) under two different curing conditions. The adopted curing conditions were air curing and tropical natural weather curing. Two volume fractions of POEFB fibre were used, which were 0.25% and 0.50% based on dry mix weight with 1-2 cm in length. The dimensional stability of the control specimen and POEFB fibre reinforced FCs was obtained by cumulating the measured linear shrinkage or expansion due to different curing conditions. The results from the two different specimens were compared. The results showed that specimens reinforced with POEFB fibre and cured under tropical natural weather condition attained lesser variations of dimensional stability and higher 90-day strength performance index than the reference mix without POEFB fibre. This improvement was attributed to the ability of POEFB fibre to bridge the cement matrix, and irregular wetting process under tropical natural weather curing condition had enabled more production of Calcium Silicate Hydrate gels that gradually blocked the penetration of water into the specimens and increased the compressive strength. It is observed that 11.43% and 4.46% of improvement in 90-day strength performance index were obtained in natural weather cured 0.5% of POEFB fibre reinforced specimen, with corresponded to the reference mix and 0.25% of POEFB fibre reinforced specimens, respectively.

Mechanical properties of non-autoclaved foam concrete: analytical models vs. experimental data

In this paper, we focus on the mechanical characterisation of non-autoclaved foam concrete according to its macro porosity (foam volume fraction). Firstly, five densities of foam concrete ranging between 600 and 1400 kg/m3 have been designed and then made by varying the volume fraction of a pre-formed organic foam within the same mortar matrix. Secondly, this range of foam concrete has been characterised experimentally by measuring their Young’s moduli and their compressive and flexural tensile strengths. Based on these experimental results, it has been confirmed that foam concrete mechanical properties decrease with the increase of its macro porosity. Besides, analytical models have been identified to predict foam concrete mechanical properties according to its macro porosity. In fact, it has been found that the Young’s modulus and the compressive strength of foam concrete can be well predicted according to its macro porosity by Balshin type power laws. Moreover, it has been shown that a Shiller type exponential law gives a good prediction for the foam concrete flexural tensile strength. Finally, it has been observed that foam concrete tensile failure becomes less brittle when its macro porosity increases.

Development and characterization of amphiphilic hydroxyethyl starch derivatives

ABSTRACTNovel amphiphilic hydroxyethyl starch derivatives 2,4-bistertbutylphenoxy-[1,3,5] -triazine-6-yl)-hydroxyethyl starch with different degrees of substitution of hydrophilic triazine group and hydrophobic hydroxyethyl were prepared by reacting corn starch with chlorohydrin and 2,4-Ditertbutyl phenoxyl-6-chloro-[1,3,5]-triazine, successively. Their structure was characterized by FTIR, 1H NMR, and SEM. It exhibits ideal surfacial abilities and compressive strength. The surface tension of the amphiphilic hydroxyethyl starch derivatives (MS = 1.1, DS = 0.026) reached 33.35 mN · m−1 at the critical aggregation concentration (CAC) at 25°C. The compressive strength of foam concrete was 0.97 MPa when the amount of added starch derivatives (MS = 1.1, DS = 0.026) reached 0.1 wt% of the total weight.

Experimental Study of Ultralight (<300 kg/m3) Foamed Concrete

A type of ultralight (<300 kg/m3) foamed concrete (FC), which can be used as a new energy-conservation and environmental-protection building material and is particularly suitable for the thermal-insulation engineering of building external walls, was produced. The influences of different mixing amounts of fly ash, fly ash activator, WC (WC) ratio, and foaming agent (FA) on the compressive strength of FC were reported. The experimental study indicated that (1) the addition of fly ash reduced the strength of the FC and that the appropriate mixing amount of fly ash in this ultralight FC system should not exceed 45%; (2) with the increasing of fly ash activator, the strength of the FC sample is notably enhanced and the appropriate mixing amount of fly ash activator is 2.5%; (3) the optimized proportion of WC ratio is 0.45, and the FC that was produced according to this proportion has relatively high compressive strength; (4) by increasing the mixing amount of FA, the compressive strength of the FC notably decreases, and the optimal mixing amount of FA in this experiment is 3.5%.

The Effect of Sand/Cement Ratio and Cement Grade on the Compressive Strength of Foam Concrete

A series of experiments have been undertaken to investigate the effects, on compressive strength, of variable sand/cement ratios and cement grade. Ten mixtures of different s/c ratios used two kinds of cement were cast and the compressive strength at different curing ages was tested. The results indicate that the compressive strength gets lower as the s/c ratio increases for both 42.5R and 32.5R cement. For the mixtures used 32.5R cement, the 28-day compressive strength is pretty low for the s/c ratios of 1.5 and 2. The specimens used 42.5R cement have higher compressive strength than those with 32.5R cement. The compressive strength decreases from 42.5R to 32.5R cement are significantly smaller for the s/c ratios of 0.5 and 1 than the other three s/c ratios.

The Effect of Fly Ash and Red Mud Content on the Compressive Strength of Foam Concrete

A series of foam concrete with different content of fly ash or red mud were experimentally investigated in this study. The results indicated that the water-solids ratio of optimized material proportion and curing conditions were 0.5, and the compressive strength and density of the concrete compressive would fall with the addition of fly ash or red mud.

Models for strength prediction of foam concrete

There are several strength prediction relations developed for plain cement paste, mortar and concrete. In concrete where air voids contribute significantly to volume of voids (like aerated and foam concrete), more general expressions including the volume of air voids is to be developed as the better alternative. The objective of this paper is to propose prediction relations for the compressive strength of foam concrete by extending two of the well-known relations available for cement paste, mortar and normal concrete, viz., Balshin’s strength-porosity model and Power’s gel-space ratio equation. For this, theoretical equations were derived for porosity and gel-space ratio relating it to the density, proportion of ingredients in the mix and material characteristics like specific gravity. Foam concrete with fly ash showed lesser dependency on pore parameters than cement-sand mixes. As both the prediction relations developed in this study consider the effect of composition on the strength, it can serve as a simple tool for predicting the strength of foam concrete. But strength-porosity model stands out compared to gel-space model as it correlates well with the measured strength and also because of its ease in application since it employs the composition of constituents and easily measurable parameters.