Strength Of Laterized Concrete Research Articles

Influence of Neem Seed Husk Ash (NSHA) on the Strength of Laterized Concrete

Influence of Neem Seed Husk Ash (NSHA) on the Strength of Laterized Concrete

Mechanical properties of concrete prepared using seawater, sea sand and spontaneous combustion coal gangue

This paper presents a method for preparing concrete using sea water, sea sand, and spontaneous combustion coal gangue (SCG). The splitting tensile strength, flexural strength, compressive strength, and stress–strain relationship were investigated and micro-structural analysis was performed. Results revealed that the mechanical properties of concrete were significantly influenced by the seawater, sea sand, and SCG. Seawater and sea sand increase the early strength of concrete and decrease the later strength, and the pore structure of SCG can form an internal curing effect, which improved the later strength of concrete. According to the test results obtained by this study and reported in the literature, the elastic modulus and peak strain of the concrete prepared using sea water, sea sand, and SCG were regressed to obtain the relationship with the axial compressive strength. Based on Carreira and Du Pan’s model, a predicted model of the stress–strain relationship is proposed.

Effect of calcium sulfoaluminate and MgO expansive agent on the mechanical strength and crack resistance of concrete

This work explored effects of calcium sulfoaluminate (CSA) and MgO blended expansive agent on the mechanical strength and deformation of concrete. What’s more, the mechanism was investigated using SEM and XRD analysis. Results show that the addition of MgO is beneficial to improve the later strength of concrete. When the MgO content exceeds 2%, the mechanical strength of concrete at the later stage increases significantly; however, it begins to reduce when the MgO content is more than 5%. All results illustrate that the optimum mass ratio of CSA and MgO is 2:1, and the concrete shows a certain expansion at all stages, which also reduces the drying shrinkage at the later stage. Meanwhile, with the optimum mass ratio of CSA and MgO, the crack resistance of concrete can be improved by 97–127 % compared with a single expansive agent.

Study on Compressive Strength of Concrete Mixed by Steel Slag Powder and Fly Ash

Using steel slag powder and fly ash to replace cement can promote the secondary utilization of industrial solid waste and protect the ecological environment. Besides, fly ash can save costs, improve workability and improve the later strength of concrete. Four groups of concrete test blocks were tested by the combination of the two to replace cement, and the concrete appearance and compressive strength of the test blocks in different periods were tested. The experimental results show that: 1. Under the premise that the total amount of composite substitution is 40%, increasing the content of steel slag powder can effectively improve the compressive strength of concrete, but excessive addition and substitution will make it counterproductive. 2. Steel slag is regarded as overburned Portland cement clinker, which can be used as auxiliary cementing material to improve the activity of cement, while fly ash can improve the workability of concrete and improve the later strength of concrete. 3. The recommended optimal composite substitution ratio is cement: steel slag powder: fly ash = 12:5:3.

Influence of Curing Media and Mixing Solution on the Compressive Strength of Laterized Concrete

Concrete has been a major building material over the centuries due to its strength, durability and versatility. However, despite the numerous advantages of concrete, it is still plagued with several limitations in addition to its high use of raw materials. In order to improve the resilience of concrete mixtures, this study was carried out to investigate the effect of curing media and mixing solution on the compressive strength of concrete mixtures incorporating different proportions of laterite as partial replacement of the conventional fine aggregate. The laterite content in the concrete was varied at 0%, 15% and 30% of fine aggregate, and mixed with bacteria solution or water. The compressive strength of the mixtures was evaluated at 7, 14 and 28 days for concrete mixtures cured in water, bacteria solution, nutrient broth and combined bacteria and nutrient broth. Results from this study indicate concrete mixtures cured in nutrient broth plus bacteria solution have the highest compressive strength followed by bacteria, nutrient broth and water. The improvement in compressive strength due to Bacillus sp. CT-5 (i.e. bacteria used in this study) can be attributed to the precipitation of CaCO3 at the cell surface as well as within the concrete matrix. This provided a nucleation site which made it to become less porous and permeable and thereby increasing the compressive strength of the concrete cubes. The results of this study can be used to understand how various solutions incorporating bacteria can be used to enhance the performance of concrete. In addition, this study exhibits the viability of using locally available materials such as laterite in concrete mixtures.

Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

This study examined the relative strength-maturity relationship of high-strength concrete (HSC) specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1) isothermal curing conditions of 5°C, 20°C, and 40°C and (2) terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

Compressive Strength Development of High-Strength Concrete under Different Curing Temperatures

The present study examined the in-place strength of high-strength concrete based on the relative strength-maturity relationship. The measured strength gain of high-strength concrete was compared with the predictions obtained from the modified maturity function to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. This study demonstrates that the compressive strength gain of concrete cured at the reference temperature (20°C) for an early age of 3 days is little affected by the subsequent curing temperature histories.

Laboratory Investigation on the Short-Term Compressive Strength of Microbial Laterized Concrete

This study investigates the effect of Bacillus subtilis JC3 on the compressive strength of laterized concrete. Taguchi method of experimental design which involved the use of orthogonal tables with three levels and three factors was employed. In all, 108 samples of 150mm×150mm×150mm concrete cubes cured in two media (water and nutrient broth) with a mix ratio of 1:2:4 were tested for compressive strength at 7, 14 and 28 days. The factors used were water/cement ratio, percentage laterite replacement for fine aggregate and concentration level of bacterial medium (added in different proportions as liquid for mixing the composite material). The results showed that Bacillus Subtilis JC3 generally enhanced the compressive strength and durability of the conventional concrete studied. The observed optimum values for water/cement ratio and bacterial medium for the constitution of concrete were found to be 0.50 and 20% respectively, however a negative trend was observed for laterite replacement for sand.

Influence of the MB Value of Manufactured Sand on the Mechanical Property of Concrete

In this paper, influence of micro-fines on the manufactured sand and influence of manufactured sand containing micro-fines on concrete is studied. Using the MB value of manufactured sand to control the content of micro-fines in manufactured sand. The experimental results show that if MB value is less than 1.0, content of micro-fines is less than 15%, concrete keeps a high level of compressive strength ; both the content and property of micro-fines have a certain influence on the compressive strength of concrete; the fineness of micro-fines has influence on the early strength of concrete, but little influence on the later strength of concrete.

Research on the Basic Mechanical Properties of Fly Ash Fiber Reinforced Concrete

The basic mechanical properties of fly ash fiber concrete were tested. The influences to the compressive strength, splitting tensile strength and compressive modulus of elasticity of fiber concrete by water-cement ratio, dosage of fly ash and other factors were analyzed. The influence mechanism of fly ash to concrete is discussed. The results indicate that with the increase of the dosage of fly ash, the early strength of double-doped concrete is reduced, while the later strength of concrete was obviously increased.

Durability Improvement of Concrete in the Environment of Compound Salt and Freeze-Thaw Cycles by Incorporating Mineral Additives

Durability improvement of concrete in the complex environments of chloride, sulfate and freeze-thaw, by incorporating compound mineral additives of fly ash, slag, diatomite and zeolite in concrete, was studied through the approach of orthogonal array testing and related analysis. The results show that zeolite and diatomite play a dominant role in improving the durability of concrete in the complex environments, but the role of fly ash and slag should not be ignored. A reasonable combination of the mineral additives can effectively improve the durability of concrete in the complex conditions without lowering or even increasing the early and later strength of concrete.

The Effect of Water Content on the Compressive Strength of Laterized Concrete

Abstract Laterized concrete is defined as concrete in which laterite fines replace sand. A previous paper highlighted only the salient points of difference between laterized and normal concrete. The results reported in this paper are mainly on the effect of water content on the compressive strength of laterized concrete. Other properties such as durability, resistance to frost action, and creep need to be investigated to decide whether or not laterized concrete would be usable in all climates. It is the aim of the author that this paper and his earlier paper will generate research interest in other parts of the world where facilities and climatic conditions are more favorable for the investigations of properties which are not easily investigated in the tropics. The mix design showed that laterized concrete mixes require more water than normal concrete for equal proportions and weights of dry normal concrete and of dry laterized concrete mix. The water/cement ratio recommended for structural laterized concrete mixes of 1:1:2 and 1:1½:3 by weight is 0.65. This water/cement ratio would yield compressive strength of about 23.59 MPa (3425 psi) for 1:1:2 and 21.45 MPa (3110 psi) for 1:1½:3 by weight in 28 days. The water/cement ratio recommended for 1:2:4 mix by weight is 0.75. This would yield about 18.50 MPa (2682 psi) in 28 days. Graphs showing the variation of compressive strength with water/cement ratio and independently with age are presented. A schematic map of the world showing laterite deposits is included. It is suggested that the paper may generate interest in reinforced laterized concrete structural elements and that laterized concrete may eventually be used for structural works in those parts of the world where suitable sharp sand is not available, just as lightweight concrete is now being slowly introduced into major construction works.