precast-tech

Concrete specimens mostly refer to concrete compressive strength test blocks, flexural strength test blocks, impermeability test blocks, and freeze-thaw resistant test blocks.

The unqualified test piece refers to the situation where the indicator value of the test piece that has reached the curing age does not reach 100% of the design value.

This type of nonconformity includes two aspects: the nonconformity of the specimens retained by the concrete supplier and the nonconformity of the specimens retained by the concrete user.

Once the test piece fails, it cannot be immediately determined that the concrete is unqualified.

A comprehensive investigation should be conducted to find the root cause.

Analyze possible influencing factors and eliminate them one by one.

Swift Lift Clutches

The following factors should be considered:.

The cement used is P · O42.

5 ordinary Portland cement, and the main performance indicators of the cement are shown in Table 1.

The slag powder is S95, with a moisture content of 0.

1% and a 28 day activity index of 100%.

Steel Chamfer

Limestone powder is obtained by washing, crushing, grinding, and screening limestone parent rock, with a MB value of 0.

2 and a specific surface area of 425 m2/kg.

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The physical properties of mechanism sand are significantly affected by its production process, and even after processing the same parent rock through different processes, its performance indicators vary greatly.

Precast Lifting Clutch

Mechanized sand has significant differences from natural sand in terms of grading, particle shape, and particle content below 0.

075mm.

In high-strength concrete, compared with natural sand, the use of machine-made sand is greatly restricted.

High strength concrete has stricter requirements for the parent rock, stone powder content, MB value, particle morphology, etc.

of machine-made sand.

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The impact of sudden cooling in autumn on concrete is not a single temperature change effect, but the result of the synergistic effect of climate factors such as dry winds and alternation of day and night.

Its mechanism of action presents the characteristics of “temperature stress dominance and multiple factors superposition”.

Ferrule Loop Insert

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As one of the most widely used building materials, the performance of concrete is directly related to the engineering quality and service life.

In recent years, the demand for high-performance concrete in engineering applications has been continuously increasing, but a single admixture is no longer sufficient to meet its performance requirements.

Although various admixtures such as fly ash, slag powder, and silica fume have their own characteristics in improving the performance of concrete, there is a relative lack of systematic research on the compounding effect of multiple admixtures.

Erection Anchor

Reasonably utilizing the synergistic effect of admixtures can not only improve the comprehensive performance of concrete, but also achieve energy conservation and emission reduction.

Therefore, studying the optimal ratio of various admixtures and their impact on concrete performance has important theoretical significance and engineering value.

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In addition, the surface state of the aggregate also has a certain influence on pumpability.

The smoother the surface of the aggregate, the smaller the relative friction between the aggregate particles, and under a certain slurry, the pumpability is better.

Crown Foot Anchor

The water absorption rate of aggregates also has a certain impact on the pumpability of the mixture.

Unsaturated water absorbing aggregates under pressure conditions will cause water to migrate to the internal pores of the aggregates, resulting in a decrease in the fluidity of concrete.

Therefore, aggregates with higher water absorption rates should be treated with moisture during construction.

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When selecting coarse aggregate for concrete, the following points should be noted: (1) The flexural strength of concrete with continuous gradation of coarse aggregate is better than that of concrete with single particle gradation.

(2) The flexural strength of concrete with a maximum particle size of 25mm is better than that of concrete with a maximum particle size of 31.

Lifting Socket

5mm.

(3) The worst strength is the mixture of single particle size grading with a maximum particle size of 31.

5mm.

Before pouring the concrete of the component, the prestressed steel bars are first tensioned and anchored on the pedestal, and then the concrete is poured.

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After the concrete reaches the specified strength value, the anchorage is released, the steel bars are relaxed, and the prestressing is applied to the concrete, which is called pre tensioning prestressing.

The pre tensioning method has a simple production process, few steps, high efficiency, and easy quality assurance.

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Concrete is the most widely used structural material in the construction industry, and its quality directly affects the safety and durability of buildings.

Ferrule Loop Insert

Concrete testing, as a crucial step in ensuring its performance meets design requirements, has become an indispensable part of engineering construction.

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