Method for testing the water transport capacity of recycled aggregates in concrete

Abstract

The application relates to a test method for the moisture transmission capacity of recycled aggregate in concrete, which comprises the following steps: S10, humidity treatment is performed on dry to-be-tested recycled aggregate to obtain a first sample with a preset water content; S20, a first weight of the first sample is taken for mixing to obtain a first slurry, and the initial water content of the first sample after being coated with the slurry is determined; S30, dry to-be-tested recycled aggregate is subjected to humidity treatment to obtain a second sample with an initial water content; S40, a second weight of the second sample is taken, the second sample is placed in a curing container for curing, the temperature and humidity inside the curing container are controlled to change according to a preset temperature and humidity change curve; the third weight of the second sample at different ages is weighed, and the simulated water content of the second sample at the corresponding age is determined as a test result according to the third weight and the second weight. The test method can reflect the real state of the recycled aggregate in the concrete, and has higher measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a method for testing the water transport capacity of recycled aggregates in concrete. Background Technology

[0002] Traditional methods for disposing of construction waste such as waste concrete and bricks involve open dumping or direct landfilling. This simple approach not only occupies a large amount of land resources but also negatively impacts the aesthetics of cities. Implementing resource utilization of construction waste allows waste concrete to be crushed and screened to obtain recycled aggregates for reuse in construction projects. This not only reduces environmental pollution but also saves significant costs associated with construction waste disposal. Furthermore, it reduces the consumption of natural sand and gravel resources during the construction industry's development, protecting the natural environment and promoting the green and sustainable development of the construction industry, thus yielding significant economic, environmental, and social benefits.

[0003] Because recycled aggregates have a large amount of loose and porous old mortar adhering to their surface, their water absorption rate is often higher than that of ordinary natural aggregates (the water absorption rate of recycled aggregates is usually 2.3-4.6 times that of ordinary aggregates). The moisture content of recycled aggregates may vary depending on the storage environment. Studies have shown that the moisture content of recycled aggregates has a significant impact on the workability, mechanical properties, and durability of recycled concrete. This may be related to the water absorption and return characteristics of recycled aggregates with different moisture contents in concrete. However, at present, no scholars have conducted in-depth research on the water absorption and return characteristics of recycled aggregates in concrete and their impact on the macroscopic properties of concrete. This is mainly because it is difficult to quantitatively monitor the water transport capacity of recycled aggregates in concrete.

[0004] Existing technologies typically measure the water absorption rate of recycled aggregates directly in water or air through experiments. However, the water absorption capacity of recycled aggregates is easily affected by their environment. The water absorption characteristics of recycled aggregates in the experimental environment are completely different from their actual water absorption characteristics in the complex environment of concrete specimens. This makes the laboratory measurement results unable to reflect the true state of recycled aggregates in concrete, resulting in low accuracy of the measurement results. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a test method for the water transport capacity of recycled aggregate in concrete, which solves the technical problem of low accuracy of measurement results in the prior art.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] This invention provides a method for testing the water transport capacity of recycled aggregate in concrete, comprising:

[0010] S10. The dried recycled aggregate to be tested is subjected to moisture treatment to obtain a first sample with a preset moisture content.

[0011] S20. Take the first sample of the first weight, mix it with concrete according to the preset mix ratio to obtain the first slurry, and then remove the mortar from the first slurry to obtain the first sample after coating with slurry; determine the current initial moisture content of the first sample after coating with slurry.

[0012] S30. Take the dry recycled aggregate to be tested and perform moisture treatment according to the initial moisture content state described in S20 to obtain a second sample with the initial moisture content state.

[0013] S40. Take a second sample of a second weight and place it in a curing container for curing. Control the temperature and humidity inside the curing container to change according to a preset temperature and humidity change curve to simulate the temperature and humidity changes inside the concrete specimen. Weigh the second sample at different ages. Based on the third weight and the second weight, determine the simulated moisture content of the second sample at the corresponding age, which is used as the test result of the water transport capacity of the recycled aggregate to be tested in concrete with the preset moisture content state described in S10.

[0014] The temperature and humidity change curve is as follows: a sample of recycled aggregate to be tested is pre-treated for humidity to obtain a third sample with the preset water content state described in S10; the third sample is mixed according to the components of the first slurry and cured into a concrete specimen, and the temperature and humidity change curve inside the concrete specimen is measured over time during the curing period.

[0015] Optionally, in S10, obtaining the first sample having a preset water content includes:

[0016] The first sample is a sample with multiple preset water content states;

[0017] The samples with the various preset moisture content states include 100% saturated surface-dry samples, and also include one or more samples from 0% saturated surface-dry samples to 99% saturated surface-dry samples.

[0018] The moisture content of the 100% saturated surface-dry sample in the first sample is taken as the saturated surface-dry moisture content of the recycled aggregate to be tested.

[0019] Optionally, prior to S20, the following are also included:

[0020] S11. Take one sample from each of the first samples with each preset moisture content as the third sample, and mix them with concrete according to the preset mix ratio to obtain multiple portions of the second slurry.

[0021] Temperature and humidity sensors were inserted into each portion of the second slurry, and all the second slurries were cured under the same curing conditions to form concrete specimens. During this period, based on the temperature and humidity sensors, the temperature change curve and humidity change curve inside each concrete specimen were measured, which were used as the temperature and humidity change curves associated with the tested recycled aggregate contained in the concrete specimen and the preset moisture content.

[0022] Optionally, the step of curing all the second slurry into concrete specimens under the same curing conditions includes:

[0023] The curing conditions are: the temperature inside the curing container is [18℃, 22℃], and the humidity is [55%, 65%].

[0024] Optionally, in S20, a first sample of a first weight is taken, and concrete is mixed according to a preset mix ratio to obtain a first slurry. Then, the mortar in the first slurry is removed to obtain a first sample coated with slurry, including:

[0025] For each preset moisture content state of the first sample, the first weight is weighed and the concrete is mixed according to the preset mix ratio to obtain multiple portions of the first slurry.

[0026] The mortar in each of the multiple portions of the first slurry is removed to obtain the first sample after coating with slurry. The fourth weight of each portion of the first sample after coating with slurry is then measured.

[0027] Optionally, in S20, determining the current initial moisture content of the first sample after coating includes:

[0028] Based on the saturated surface dry moisture content of the recycled aggregate to be tested, determine the preset moisture content of the recycled aggregate to be tested under other preset moisture states;

[0029] The difference between the fourth weight and the first weight of the first sample, which is set to 100% saturated surface dry with a preset water content, is taken as the mortar error of the first sample.

[0030] For the first sample corresponding to other preset water content states, subtract the mortar error and the corresponding first weight from its fourth weight in sequence to obtain the water absorption of the first sample when it is coated with mortar.

[0031] The ratio of the water absorption during coating to the weight of the first sample in the dry state is taken as the moisture content increment of the first sample.

[0032] Calculate the sum of the preset moisture content and the moisture content increment corresponding to the first sample, and take the ratio of the obtained sum to the saturated surface dry moisture content as the initial moisture content of the first sample.

[0033] Optionally, in S40, the step of placing the second sample in a curing container for curing, and controlling the temperature and humidity inside the curing container to change according to a preset temperature and humidity change curve, includes:

[0034] The second sample for each initial water content state was placed in a different curing container;

[0035] For a second sample with a certain initial moisture content, a temperature and humidity change curve associated with the preset moisture content is determined based on the preset moisture content associated with the second sample, and loaded into the control module of the curing container to which the second sample belongs, so that the temperature and humidity inside the curing container change according to the temperature and humidity change curve associated with the preset moisture content.

[0036] Optionally, in S40, weighing the second sample at different ages includes:

[0037] For a second sample in a certain initial water content state, it is divided into multiple small samples. At each age, one small sample is taken out and weighed to obtain the third weight.

[0038] Optionally, in S40, determining the simulated moisture content of the second sample at the corresponding age based on the third weight and the second weight includes:

[0039] Based on the saturated surface dry moisture content of the recycled aggregate to be tested, the initial moisture content of the recycled aggregate to be tested in other initial moisture states is determined.

[0040] For a second sample in a certain initial water content state, the second weight of the second sample is divided by the number of its smaller portions to obtain the fifth weight;

[0041] For the second sample, the fifth weight obtained by weighing the corresponding small sample at a certain age is calculated. The difference between the fifth weight and the third weight is calculated. The ratio of the difference to the weight of the small sample in the dry state is used as the change in moisture content of the second sample at that age.

[0042] The sum of the change in moisture content of the second sample at this age and the initial moisture content is calculated. The ratio of the obtained sum to the saturated surface-dry moisture content is taken as the simulated moisture state of the second sample at this age.

[0043] Optionally, in S20, removing the mortar from the first slurry to obtain the first sample after coating includes:

[0044] The mortar in the first slurry is removed using a vibrating screen, and the slurry on the surface of the first sample is removed to obtain the first sample after coating with slurry.

[0045] (III) Beneficial Effects

[0046] The testing method steps of this invention include: S10, subjecting the dried recycled aggregate to be tested to moisture treatment to obtain a first sample with a preset moisture content; S20, taking a first weight of the first sample, mixing it with concrete according to a preset mix ratio to obtain a first slurry, then removing the mortar from the first slurry to obtain a first sample coated with slurry; determining the current initial moisture content of the coated first sample; S30, taking the dried recycled aggregate to be tested, subjecting it to moisture treatment according to the initial moisture content in S20 to obtain a second sample with the initial moisture content; S40, taking a second weight of the second sample, placing the second sample in a curing container for curing, and controlling the temperature inside the curing container. The temperature and humidity change according to a preset temperature and humidity change curve to simulate the temperature and humidity changes inside the concrete specimen; the third weight of the second sample at different ages is weighed, and the simulated water content of the second sample at the corresponding age is determined based on the third weight and the second weight, which is used as the test result of the water transport capacity of the recycled aggregate to be tested in concrete with the preset water content state described in S10; wherein, the temperature and humidity change curve is: a portion of the recycled aggregate to be tested is pre-treated for humidity to obtain a third sample with the preset water content state described in S10; the third sample is mixed according to the components of the first slurry and cured into a concrete specimen, and the temperature and humidity change curve inside the concrete specimen is measured over time during the curing period.

[0047] In other words, the testing method provided by this invention first experimentally determines the internal temperature and humidity change curve of a concrete specimen containing recycled aggregate under test with a preset moisture content during curing. Then, based on steps S10 and S20, the initial moisture content of the recycled aggregate under test in the freshly prepared slurry is measured. Finally, based on steps S30 and S40, a clean piece of recycled aggregate under test is taken and subjected to humidity treatment according to the initial moisture content to obtain a second sample. This sample is placed in a curing container, and the internal temperature and humidity environment changes of the concrete specimen during curing are simulated based on the measured internal temperature and humidity change curve. The changes in the simulated moisture content of the second sample are monitored, and this serves as the test result of the water transport capacity of the recycled aggregate under test in the concrete based on the preset moisture content. That is, the above testing process tests the water absorption characteristics of recycled aggregate by simulating the internal temperature and humidity changes of the concrete specimen during curing. Compared with the existing technology that directly measures the water absorption rate of recycled aggregate in water or air, this method can better reflect the true state of recycled aggregate in concrete and has higher measurement accuracy. Attached Figure Description

[0048] Figure 1 A schematic flowchart illustrating a method for testing the moisture transport capacity of recycled aggregate in concrete, provided as an example.

[0049] Figure 2 The data represents the temperature change data of the internal environment of the concrete specimens measured in the examples.

[0050] Figure 3 The data represents the relative humidity changes in the internal environment of the concrete specimens measured in the examples.

[0051] Figure 4 The results show the test results of the water transport capacity of the recycled aggregate in concrete. Detailed Implementation

[0052] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides a method for testing the moisture transport capacity of recycled aggregate in concrete, including steps S10 to S40, as detailed below:

[0056] S10. The dried recycled aggregate to be tested is subjected to moisture treatment to obtain a first sample with a preset moisture content.

[0057] Specifically, the preset moisture content of the recycled aggregate to be tested can be set to one or more states. Typically, to obtain more comprehensive data, the first sample is configured to have multiple moisture contents. Specifically, the multiple moisture contents include a 100% saturated surface-dry sample, and also include one or more samples selected from 0% saturated surface-dry to 99% saturated surface-dry samples. Preferably, the preset moisture contents of a group of first samples can be set to 0% saturated surface-dry, 50% saturated surface-dry, 80% saturated surface-dry, and 100% saturated surface-dry; or, the preset moisture contents of a group of first samples can be set to 0% saturated surface-dry, 30% saturated surface-dry, 70% saturated surface-dry, and 100% saturated surface-dry.

[0058] The aforementioned humidity treatment refers to the treatment operations performed on the moisture content of the recycled aggregate to be tested, specifically including: soaking, spraying, etc. to increase humidity, or hot air drying, centrifugal dehydration, etc. to reduce humidity.

[0059] S20. Take the first sample of the first weight, mix it with concrete according to the preset mix ratio to obtain the first slurry, and then remove the mortar from the first slurry to obtain the first sample after coating with slurry; determine the current initial moisture content of the first sample after coating with slurry.

[0060] Specifically, the preset mix proportion is the design mix proportion of each concrete component used in the production of concrete using this recycled aggregate. The concrete components typically include: aggregate, water, cement, and sand, etc.

[0061] For the first sample, after removing the slurry adhering to the surface of the first sample, the difference between the second weight and the first weight can be regarded as the amount of water absorbed by the first sample in the first slurry. The ratio of the amount of water absorbed to the first weight is added to the preset water content state, and the sum is the current initial water content state of the first sample.

[0062] To reduce errors, after screening the first sample, wipe the surface of the first sample with a wrung-out damp towel to remove the slurry adhering to the surface of the first sample, and then weigh the first sample to improve the accuracy of the initial moisture content.

[0063] S30. Take the dry recycled aggregate to be tested and perform moisture treatment according to the initial moisture content state described in S20 to obtain a second sample with the initial moisture content state.

[0064] The first sample corresponds to multiple preset water content states, and the initial water content state of the second sample is multiple, each corresponding to a preset water content state.

[0065] Although wiping removes some of the slurry from the surface of the recycled aggregate in the first sample, a small amount of slurry remains. If the first sample selected in S20 is used directly in step S40, the small amount of slurry remaining on its surface will absorb water, affecting the accuracy of the final test results. Therefore, preparing a second sample with no slurry on its surface and an initial water content in step S30 and using it in step S40 can further improve the accuracy of the test results.

[0066] S40. Take a second sample of a second weight and place it in a curing container for curing. Control the temperature and humidity inside the curing container to change according to a preset temperature and humidity change curve to simulate the temperature and humidity changes inside the concrete specimen. Weigh the second sample at different ages. Based on the third weight and the second weight, determine the simulated moisture content of the second sample at the corresponding age, which is used as the test result of the water transport capacity of the recycled aggregate to be tested in concrete with the preset moisture content state described in S10.

[0067] The temperature and humidity change curve is as follows: a sample of recycled aggregate to be tested is pre-treated for humidity to obtain a third sample with the preset water content state described in S10; the third sample is mixed according to the components of the first slurry and cured into a concrete specimen, and the temperature and humidity change curve inside the concrete specimen is measured over time during the curing period.

[0068] Based on the above steps, this embodiment first experimentally determines the internal temperature and humidity change curve of the concrete specimen containing the recycled aggregate under test with a preset moisture content during curing. Then, based on steps S10 and S20, the initial moisture content of the recycled aggregate under test in the freshly prepared slurry is measured. Finally, based on steps S30 and S40, another clean recycled aggregate under test is taken and subjected to humidity treatment according to the initial moisture content to obtain a second sample. This sample is placed in a curing container, and the internal temperature and humidity environment changes of the concrete specimen during curing are simulated based on the measured internal temperature and humidity change curve of the concrete specimen. The changes in the simulated moisture content of the second sample are monitored, serving as the test result of the water transport capacity of the recycled aggregate under test in the concrete based on the preset moisture content. That is, the above test process, by simulating the internal temperature and humidity changes of the concrete specimen during curing, tests the water absorption characteristics of the recycled aggregate. Compared with the existing technology of directly measuring the water absorption rate of the recycled aggregate itself in water or air, it can better reflect the true state of the recycled aggregate in the concrete and has higher measurement accuracy.

[0069] Example 2

[0070] To better understand Example 1, this example provides a detailed explanation of the specific steps of the testing method provided in Example 1 based on recycled aggregates with various preset moisture contents.

[0071] This embodiment provides a method for testing the moisture transport capacity of recycled aggregates in concrete, including steps A1 to A6, as follows:

[0072] A1. The dried recycled aggregate to be tested is subjected to moisture treatment to obtain a first sample with multiple preset moisture content states.

[0073] The first sample includes a 100% saturated surface-dry sample, and also includes one or more samples from 0% saturated surface-dry sample to 99% saturated surface-dry sample.

[0074] The moisture content of the 100% saturated surface-dry sample in the first sample is taken as the saturated surface-dry moisture content of the recycled aggregate to be tested.

[0075] Specifically, the saturated surface-dry moisture content refers to the moisture content of the recycled aggregate to be tested when it is 100% saturated surface-dry. For example, the test method can be as follows: take 1 kg of dry recycled aggregate to be tested, soak it in water for 24 hours, take it out and wipe off the surface moisture. At this time, the moisture content of the recycled aggregate to be tested is 100% saturated surface-dry, and its weight is measured to be 1.1 kg. Then, the saturated surface-dry moisture content of this batch of recycled aggregate to be tested is (1.1-1) / 1 = 10%.

[0076] A2. Take one sample from each of the first samples with each preset water content as the third sample, and mix them with concrete according to the preset mix ratio to obtain multiple portions of the second slurry.

[0077] Temperature and humidity sensors were inserted into each portion of the second slurry, and all the second slurries were cured under the same curing conditions to form concrete specimens. During this period, based on the temperature and humidity sensors, the temperature change curve and humidity change curve inside each concrete specimen were measured, which were used as the temperature and humidity change curves associated with the tested recycled aggregate contained in the concrete specimen and the preset moisture content.

[0078] The curing conditions are: the temperature inside the curing container is [18℃, 22℃], and the humidity is [55%, 65%].

[0079] More preferably, the maintenance conditions are: a temperature of 20°C and a humidity of 60% inside the maintenance container.

[0080] A3. For each preset moisture content state of the first sample, weigh the first weight, mix the concrete according to the preset mix ratio, and obtain multiple portions of the first slurry; remove the mortar from the multiple portions of the first slurry, and use a wet towel to remove as much slurry as possible from the surface of the first sample to obtain the first sample after slurry coating, and weigh the fourth weight of each portion of the first sample after slurry coating.

[0081] A4. Determine the current initial water content of the first sample.

[0082] Specifically, based on the saturated surface-dry moisture content of the recycled aggregate to be tested, the preset moisture content of the recycled aggregate to be tested in other preset moisture states is determined.

[0083] For the same batch of recycled aggregate to be tested, the preset moisture content is the product of the saturated surface-dry moisture content and the preset moisture state. For example, if the saturated surface-dry water absorption rate of the recycled aggregate to be tested has been measured to be 10% in step A1, then for the first sample with a preset moisture state of 80% saturated surface-dry, the preset moisture content is 10% × 80% = 8%.

[0084] The difference between the fourth weight and the first weight of the first sample, which is set to 100% saturated surface dry, is taken as the mortar error of the first sample.

[0085] For the first sample corresponding to other preset moisture content states, subtract the mortar error and the corresponding first weight from its fourth weight to obtain the water absorption of the first sample when it is coated with mortar; take the ratio of the water absorption when coated with mortar to the weight of the first sample in the dry state as the moisture content increment of the first sample; calculate the sum of the preset moisture content and the moisture content increment of the first sample, and take the ratio of the obtained sum to the saturated surface dry moisture content as the initial moisture content state of the first sample.

[0086] A5. Take the dried recycled aggregate to be tested and perform moisture treatment according to the initial moisture content state in A4 to obtain a second sample with the initial moisture content state.

[0087] A6. Take a second weight for each initial water content state of the second sample and place them in different curing containers.

[0088] For a second sample with a certain initial moisture content, a temperature and humidity change curve associated with the preset moisture content is determined based on the preset moisture content associated with the second sample, and loaded into the control module of the curing container to which the second sample belongs, so that the temperature and humidity inside the curing container change according to the temperature and humidity change curve associated with the preset moisture content.

[0089] Furthermore, the second sample, under a predetermined moisture content, is divided into multiple smaller samples. The second weight of the second sample is divided by the number of smaller samples to obtain the fifth weight.

[0090] A7. For a second sample in a certain initial water content state, a small sample is taken out and weighed at each age to obtain the third weight.

[0091] A8. Based on the third weight, second weight and fifth weight, determine the simulated water content of the second sample at the corresponding age.

[0092] Specifically, based on the saturated surface-dry moisture content of the recycled aggregate to be tested, the initial moisture content of the recycled aggregate to be tested in other initial moisture states is determined. The initial moisture content of the recycled aggregate to be tested in other initial moisture states is the product of the saturated surface-dry moisture content and the initial moisture state. For example, if the saturated surface-dry water absorption rate of the recycled aggregate to be tested has been measured to be 10% in step A1, then for the second sample with an initial moisture content of 96% saturated surface-dry, its initial moisture content is 10% × 96% = 9.6%.

[0093] For a second sample in a certain initial moisture content state, the second weight of the second sample is divided by the number of its subsamples to obtain the fifth weight; for the second sample weighing the corresponding subsample at a certain age, the fifth weight is subtracted from the third weight, and the ratio of the difference to the weight of the subsample in the dry state is taken as the change in moisture content of the second sample at that age; the sum of the change in moisture content of the second sample at that age and the initial moisture content is calculated, and the ratio of the sum to the saturated surface dry moisture content is taken as the simulated moisture content state of the second sample at that age.

[0094] A9. For a second sample with a certain initial moisture content, connect the simulated moisture content and the initial moisture content at all ages in chronological order to form a line graph. The line graph is the test result of the water transport capacity of the recycled aggregate under test in concrete associated with the initial moisture content and having a preset moisture content.

[0095] Example 3

[0096] This embodiment is based on the detailed steps provided in Embodiment 2, and uses specific devices and materials for specific description.

[0097] B0. Prepare several kilograms of the same batch of recycled aggregate required for testing, 4 sets of temperature and humidity sensors for testing the relative temperature and humidity inside the concrete, 4 curing containers that can be connected to an external temperature and humidity control system, several sets of temperature and humidity control systems that can encode temperature and humidity changes, and other materials required for preparing recycled concrete.

[0098] Specifically, the recycled aggregate was obtained from the same batch of waste concrete through crushing and screening, with a particle size of 5–25 mm and a continuous gradation. The moisture content of the recycled aggregate was measured to be 8% when it was 100% saturated and surface-dry.

[0099] The temperature and humidity sensor has a built-in data acquisition system with a sampling period of 5 minutes. Shorter sampling periods can also be used to obtain temperature and humidity data with finer time granularity.

[0100] The temperature and humidity control system can control the temperature and humidity changes inside the container through a program, with a temperature error not exceeding ±1℃ and a humidity error not exceeding ±2℃. More specifically, the temperature and humidity control system includes: (1) a data acquisition module, used to receive real-time temperature and humidity data inside the curing container collected by the temperature and humidity sensor. (2) a communication and network system, used to realize communication between the device and a mobile phone or cloud. (3) a display system, used to display real-time environmental parameters and system status inside the curing container. (4) a user input system, used to interact with the user, import the control program coded by the user in advance according to the expected temperature and humidity changes, and adjust relevant parameters and view the status by pressing the buttons. (5) a control module, used to analyze the collected real-time temperature and humidity data inside the curing container and generate control signals according to the expected temperature and humidity changes. (6) a temperature control device and a humidification device, which regulate the temperature and humidity inside the curing container according to the control signal. The water sprayed by the humidification device is in an atomized state to ensure a uniform humidification effect.

[0101] The curing container dimensions are: length 300mm–500mm, width 100–200mm, height 200–300mm. The container material is one of polycarbonate, acrylonitrile-butadiene-styrene, or polypropylene, and the curing container includes internal drainage measures.

[0102] B1. First, a portion of the recycled aggregate to be tested is subjected to humidity treatment according to a preset moisture content state to obtain the first sample. The preset moisture content states of the first sample are 0% saturated surface dry, 50% saturated surface dry, 80% saturated surface dry, and 100% saturated surface dry (hereinafter referred to as OD, 50% SSD, 80% SSD, and SSD, respectively). One sample from each of the first samples with each preset moisture content state is taken as the third sample. The four third samples with preset moisture content states are mixed with other concrete components according to the designed mix ratio to obtain four portions of second slurry. Temperature and humidity sensors are inserted into each portion of second slurry, and all second slurries are cured and formed into concrete specimens under the same curing conditions. During the curing period, the temperature and humidity inside each group of concrete specimens are monitored by temperature and humidity sensors at a frequency of 5 minutes / time to obtain the temperature and humidity change data inside the concrete specimens corresponding to the four preset moisture content states of the recycled aggregate to be tested.

[0103] Specifically, the measured temperature change data of the internal environment of the concrete specimens associated with each preset moisture content state are as follows: Figure 2 As shown, the humidity change data of the internal environment is as follows: Figure 3 As shown. From Figure 2 and Figure 3The temperature and humidity changes also show that the internal temperature of the concrete specimen rises first and then falls, while the relative humidity decreases slowly. Under these temperature and humidity changes, the water absorption characteristics of recycled aggregate are different from those in a stable temperature and humidity environment. This further demonstrates the superiority of the test method for simulating the internal environment of concrete specimens provided in this embodiment.

[0104] B2. Export the four sets of temperature and humidity change data that have been tested, and encode them according to the temperature and humidity change data corresponding to the four preset moisture content states to obtain four sets of control programs for controlling the temperature and humidity of the curing environment inside the curing container.

[0105] B3. For the first sample in step B1, take 12 kg of dried recycled aggregate and divide it into 4 portions, each weighing 3 kg. Perform a preset moisture content treatment on the 4 portions of recycled aggregate. After treatment, the OD, 50% SSD, 80% SSD, and SSD corresponding recycled aggregate masses (first weight) are 3.000 kg, 3.120 kg, 3.192 kg, and 3.240 kg, respectively. Each first sample was mixed with other concrete components according to a preset mix ratio for 10 minutes to obtain four first slurries. The slurry in each first slurry was removed using a vibrating screen, and the slurry on the surface of the recycled aggregate to be tested was wiped off as much as possible with a wrung-out damp towel. The fourth weight of each group of first samples was then measured. The weights (fourth weights) of the recycled aggregate with preset moisture contents of OD, 50% SSD, 80% SSD and SSD were 3.497 kg, 3.516 kg, 3.530 kg and 3.540 kg, respectively. According to the calculation step A4 in Example 2, the difference between the fourth weight and the first weight of the first sample with preset moisture contents of SSD, i.e. 3.540 kg - 3.240 kg = 0.3 kg, was taken as the mortar error caused by the mortar adhering to the surface of each group of recycled aggregates, which led to the increase in the mass of the recycled aggregate. For the first sample corresponding to other preset moisture content states, subtract the mortar error and the corresponding first weight from its fourth weight to obtain the water absorption of the first sample when it is coated with mortar. Then, based on the saturated surface dry moisture content of the recycled aggregate to be tested (8%) and the weight of the first sample in the dry state, the initial moisture content states of the four groups of recycled aggregates to be tested are calculated to be 82% SSD, 90% SSD, 96% SSD, and SSD, respectively.

[0106] B4. Take the same batch of dry recycled aggregate to be tested and perform moisture treatment to obtain the second sample. The initial moisture content of the second sample is 82% SSD, 90% SSD, 96% SSD and SSD. The second sample of each moisture content is divided into several small samples. The fifth weight of each small sample under the current initial moisture content is tested and recorded.

[0107] B5. Input the control program obtained in step B2 into the temperature and humidity control system of the four curing containers according to the preset correspondence of water content states, control the curing environment in the curing containers, and put the second sample processed in step B4 into the corresponding curing containers according to the preset correspondence of water content states.

[0108] B6. At curing ages of 1h, 6h, 12h, 1d, 3d, 7d, 14d, and 28d, a small sample is taken from each curing container and its third weight is tested at the corresponding age. Based on the third weight, second weight, and fifth weight, and according to the calculation steps in step A8 of Example 2, the current simulated moisture content of the sample is determined, which is the simulated moisture content of the recycled aggregate to be tested at the age associated with the sample and the preset moisture content.

[0109] B7. After completing the testing and statistics of simulated water content at all ages, for the second sample of each initial water content, connect its simulated water content at all ages and initial water content in chronological order to form a diagram as shown below. Figure 4 The line graph shown represents the test results of the water transport capacity of the recycled aggregate under test in concrete, which is associated with the initial moisture content.

[0110] from Figure 4 It can be seen that recycled aggregate absorbs a large amount of water in the early stage of curing and molding concrete specimens. Then, as the curing time progresses and the humidity inside the concrete specimen decreases, its water content also decreases synchronously, and gradually stabilizes at the end of curing. Figure 4 The line graph shown reflects the actual moisture transport capacity of recycled aggregates in concrete specimens, providing a reliable basis for designers to adjust the mix proportions of concrete.

[0111] Example 4

[0112] This embodiment is based on the detailed steps provided in Embodiment 2, and uses specific devices and materials for specific descriptions. The only difference between this embodiment and Embodiment 3 is that:

[0113] In step B1, the moisture content of the recycled aggregate after moisture treatment is 0% saturated surface dry, 30% saturated surface dry, 70% saturated surface dry and 100% saturated surface dry (hereinafter referred to as OD, 30% SSD, 70% SSD and SSD respectively).

[0114] In step B3, 12 kg of dried recycled aggregate was divided into four portions of 3 kg each. The four portions of recycled aggregate were subjected to a preset moisture content treatment. After treatment, the mass (first weight) of the recycled aggregate corresponding to OD, 30% SSD, 70% SSD, and SSD were 3.000 kg, 3.072 kg, 3.168 kg, and 3.240 kg, respectively. The fourth weight of each group of first samples was tested. The weight (fourth weight) of the recycled aggregate at the preset moisture content of OD, 30% SSD, 70% SSD, and SSD were 3.487 kg, 3.509 kg, 3.526 kg, and 3.540 kg, respectively. Based on the calculation steps in step A4 of Example 2, the initial moisture content of the four groups of recycled aggregates to be tested was calculated to be 78% SSD, 87% SSD, 94% SSD, and SSD, respectively.

[0115] In step B6, a small sample is taken from each curing container at 1h, 3h, 6h, 9h, 12h, 1d, 3d, and 7d curing periods, and the third weight of the sample at the corresponding curing period is tested. Based on the third and fifth weights, and according to the calculation steps in step A8 of Example 2, the current simulated moisture content of the sample is determined, which is the simulated moisture content of the recycled aggregate to be tested at the age associated with the sample and the preset moisture content.

[0116] It should be noted that any reference numerals placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims that enumerate several means, several of these means may be embodied by the same hardware. The use of the terms first, second, third, etc., is merely for convenience of expression and does not indicate any order. These terms can be understood as part of the component names.

[0117] Furthermore, it should be noted that in the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0118] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims should be interpreted to include both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0119] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

Claims

1. A method for testing the moisture transport capacity of recycled aggregate in concrete, characterized in that, include: S10. The dried recycled aggregate to be tested is subjected to moisture treatment to obtain a first sample with a preset moisture content. S20. Take the first sample of the first weight, mix it with concrete according to the preset mix ratio to obtain the first slurry, and then remove the mortar from the first slurry to obtain the first sample after coating with slurry; determine the current initial moisture content of the first sample after coating with slurry. S30. Take the dry recycled aggregate to be tested and perform moisture treatment according to the initial moisture content state described in S20 to obtain a second sample with the initial moisture content state. S40. Take a second sample of a second weight and place it in a curing container for curing. Control the temperature and humidity inside the curing container to change according to a preset temperature and humidity change curve to simulate the temperature and humidity changes inside the concrete specimen. Weigh the second sample at different ages. Based on the third weight and the second weight, determine the simulated moisture content of the second sample at the corresponding age, which is used as the test result of the water transport capacity of the recycled aggregate to be tested in concrete with the preset moisture content state described in S10. The temperature and humidity change curve is as follows: a sample of recycled aggregate to be tested is pre-treated for humidity to obtain a third sample with the preset water content state described in S10; the third sample is mixed according to the components of the first slurry and cured into a concrete specimen, and the temperature and humidity change curve inside the concrete specimen is measured over time during the curing process. In S10, obtaining the first sample having a preset water content includes: The first sample is a sample with multiple preset water content states; The samples with the various preset moisture content states include 100% saturated surface-dry samples, and also include one or more samples from 0% saturated surface-dry samples to 99% saturated surface-dry samples. Among them, the moisture content of the 100% saturated surface-dry sample in the first sample is used as the saturated surface-dry moisture content of the recycled aggregate to be tested. In S20, a first sample of the first weight is taken, and concrete is mixed according to a preset mix ratio to obtain a first slurry. Then, the mortar in the first slurry is removed to obtain a first sample coated with slurry, including: For each preset moisture content state of the first sample, the first weight is weighed and the concrete is mixed according to the preset mix ratio to obtain multiple portions of the first slurry. The mortar in the multiple portions of the first slurry is removed to obtain the first sample after coating with slurry. The fourth weight of each portion of the first sample after coating with slurry is weighed. In S20, determining the current initial moisture content of the first sample after coating includes: Based on the saturated surface dry moisture content of the recycled aggregate to be tested, determine the preset moisture content of the recycled aggregate to be tested under other preset moisture states; The difference between the fourth weight and the first weight of the first sample, which is set to 100% saturated surface dry with a preset water content, is taken as the mortar error of the first sample. For the first sample corresponding to other preset water content states, subtract the mortar error and the corresponding first weight from its fourth weight in sequence to obtain the water absorption of the first sample when it is coated with mortar. The ratio of the water absorption during coating to the weight of the first sample in the dry state is taken as the moisture content increment of the first sample. Calculate the sum of the preset moisture content and the moisture content increment corresponding to the first sample, and take the ratio of the obtained sum to the saturated surface dry moisture content as the initial moisture content of the first sample.

2. The test method according to claim 1, characterized in that, Prior to S20, it also included: S11. Take one sample from each of the first samples with each preset moisture content as the third sample, and mix them with concrete according to the preset mix ratio to obtain multiple portions of the second slurry. Temperature and humidity sensors were inserted into each portion of the second slurry, and all the second slurries were cured under the same curing conditions to form concrete specimens. During this period, based on the temperature and humidity sensors, the temperature change curve and humidity change curve inside each concrete specimen were measured, which were used as the temperature and humidity change curves associated with the tested recycled aggregate contained in the concrete specimen and the preset moisture content.

3. The test method according to claim 2, characterized in that, The process of curing all the second slurry into concrete specimens under the same curing conditions includes: The curing conditions are as follows: the temperature inside the curing container is [18]. ,twenty two The humidity is [55%, 65%].

4. The test method according to claim 2, characterized in that, In step S40, placing the second sample in a curing container for curing, and controlling the temperature and humidity inside the curing container according to a preset temperature and humidity change curve, includes: The second sample for each initial water content state was placed in a different curing container; For a second sample with a certain initial moisture content, a temperature and humidity change curve associated with the preset moisture content is determined based on the preset moisture content associated with the second sample, and loaded into the control module of the curing container to which the second sample belongs, so that the temperature and humidity inside the curing container change according to the temperature and humidity change curve associated with the preset moisture content.

5. The test method according to any one of claims 1 to 3, characterized in that, In S40, weighing the second sample at different ages includes: For a second sample in a certain initial water content state, it is divided into multiple small samples. At each age, one small sample is taken out and weighed to obtain the third weight.

6. The test method according to claim 5, characterized in that, In S40, determining the simulated moisture content of the second sample at the corresponding age based on the third weight and the second weight includes: Based on the saturated surface dry moisture content of the recycled aggregate to be tested, the initial moisture content of the recycled aggregate to be tested in other initial moisture states is determined. For a second sample in a certain initial water content state, the second weight of the second sample is divided by the number of its smaller portions to obtain the fifth weight; For the second sample, the fifth weight obtained by weighing the corresponding small sample at a certain age is calculated. The difference between the fifth weight and the third weight is calculated. The ratio of the difference to the weight of the small sample in the dry state is used as the change in moisture content of the second sample at that age. The sum of the change in moisture content of the second sample at this age and the initial moisture content is calculated. The ratio of the obtained sum to the saturated surface-dry moisture content is taken as the simulated moisture state of the second sample at this age.

7. The test method according to any one of claims 1 to 3, characterized in that, In step S20, removing the mortar from the first slurry to obtain the first sample after coating includes: The mortar in the first slurry is removed using a vibrating screen, and the slurry on the surface of the first sample is removed to obtain the first sample after coating with slurry.

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