GB/T 25176-2010Recycled fine aggregate for concrete and mortar (English PDF)

3.1 Recycled fine aggregate for concrete and mortar

Particles with a size not exceeding 4.75 mm, processed from construction and demolition waste - such as concrete, mortar, stone, and brick/tile - and used for the preparation of concrete and mortar.

3.2 Content of fine powder

The content of particles with a particle size of less than 75 µm in recycled fine aggregate.

3.3 Content of clay lump

The content of particles in recycled fine aggregate that initially have a size greater than 1.18 mm but break down into particles smaller than 600 µm after water immersion and manual kneading.

3.4 Fineness module

An indicator used to measure the fineness or coarseness of recycled fine aggregate.

3.5 Soundness

The ability of recycled fine aggregate to resist disintegration under the influence of natural weathering and other physical and chemical factors.

3.6 Light material

Material in recycled fine aggregate with an apparent density of less than 2000 kg/m³.

3.7 Methylene blue index

An index used to determine the kaolin content of particles smaller than 75 µm in recycled fine aggregate.

3.8 Recycled mortar

Mortar prepared using recycled fine aggregate, cement, and water in accordance with the methods specified in this Standard.

3.9 Reference mortar

Mortar prepared using standard sand, cement, and water in accordance with the methods specified in this Standard.

3.10 Water demand of recycled mortar

Water content for the recycled mortar with a flow of 130 mm ± 5 mm.

3.11 Water demand of reference mortar

Water content for the reference mortar with a flow of 130 mm ± 5 mm.

3.12 Water demand ratio of recycled mortar

The ratio of the water demand of recycled mortar to the water demand of reference mortar.

3.13 Compressive strength ratio of recycled mortar

The ratio of the compressive strength of recycled mortar to that of reference mortar.

4.1 Classification

Recycled fine aggregate for concrete and mortar (hereinafter referred to as recycled fine aggregates) are classified into Class I, Class II, and Class III based on performance requirements.

4.2 Specifications

Recycled fine aggregates are classified into coarse, medium, and fine grades based on their fineness modulus. Their respective fineness moduli Mx are.

Coarse. Mx = 3.7~3.1 Medium. Mx = 3.0~2.3 Fine. Mx = 2.2~1.6

5.1 Particle size distribution

The particle size distribution of recycled fine aggregate shall comply with the requirements of Table 1.

6.9 Sulfide and sulfate content

Conduct the test in accordance with the methods for determining sulfide and sulfate content specified in GB/T 14684.

6.10 Chloride content

Perform the test for chloride content in accordance with the method specified in GB/T 14684.

6.11 Soundness

The test shall be conducted in accordance with the sodium sulfate solution method specified in GB/T 14684, but the test results shall be accurate to 0.1%.

6.12 Crushing index

Perform the test in accordance with the crushing index method specified in GB/T 14684.

6.13 Water demand ratio of recycled mortar

6.13.1 Instruments, equipment and test materials

6.13.1.1 The instruments and equipment are as follows.

a) Oven. Forced-air oven capable of maintaining a temperature of 105°C ± 5°C;

b) Other instruments and equipment shall comply with the provisions of GB/T 2419.

6.13.1.2 The test raw materials are as follows.

a) The cement used shall be either reference cement complying with GB 8076 or Grade 52.5 Portland cement complying with GB 175;

b) The standard sand shall comply with the provisions of GB 178;

c) The water shall comply with the provisions of JGJ 63.

6.13.2 Test procedure

6.13.2.1 Dry a specimen of recycled fine aggregate weighing at least 5 kg to constant mass at 105°C ± 5°C. Determine the particle size distribution of the recycled fine aggregate in accordance with 6.3, and remove particles larger than 4.75 mm by sieving.

6.13.2.2 Weigh out 1350 g of standard sand and 540 g of reference cement (or Grade 52.5 Portland cement). Add an appropriate amount of water to prepare the reference mortar. Measure the flow of the mortar in accordance with the method specified in GB/T […]