CN110818360A - A kind of expanded perlite foam light soil and preparation method thereof - Google Patents

Abstract

An expanded perlite foam lightweight soil belongs to the technical field of building materials and comprises the following components by weight: 9-27 parts of expanded perlite, 420 parts of cementitious material, 155-195 parts of water, 20-60 parts of latex powder , 1.25~2.1 parts of foaming agent, 1.5 parts of thickener, 0.5 part of water reducing agent. In the foam light soil prepared by the invention, due to the addition of light aggregate expanded perlite, the phenomena such as pumping defoaming, segregation and bleeding that are easy to occur in construction are improved, and the skeleton acts as a skeleton to reduce its density while ensuring strength; Add dispersible polymer powder to improve the toughness, impact resistance of the material and reduce water absorption to improve durability.

Description

A kind of expanded perlite foam light soil and preparation method thereof

technical field

The invention belongs to the technical field of building materials, and particularly relates to an expanded perlite foam lightweight soil and a preparation method thereof.

Background technique

As an inorganic porous material, foamed lightweight soil is applied to highway subgrade, and it is a new technology that changes the filling method of conventional highway subgrade. The production process of foam lightweight soil reflects the characteristics of new technology, new technology, environmental protection and secondary utilization of resources, and has a very broad application prospect. Foamed lightweight soil material has the advantages of low density, light weight, greater strength than conventional backfill, forming a whole after filling, no lateral pressure, and small load on the foundation. After filling with foam light soil, the highway is in an over-consolidated state, thereby reducing settlement and uneven settlement, reducing post-construction settlement of highway subgrade filler itself, and avoiding bridge head jumping disease, which has obvious technical advantages.

At present, the preparation technology and performance of the main researches are carried out. However, the degree of influence of various factors on stable preparation and performance is not clear, and the preparation technology also has many problems to be solved, such as poor construction stability, high density grade, poor pore structure, etc.; due to the poor toughness and impact resistance of materials It has multiple functions when it affects engineering applications such as low performance and poor durability.

The Chinese patent with the publication number of CN 109020614 A discloses a foamed light soil, including the following components in the following mass ratios: 268-401 parts of red mud, 13-20 parts of desulfurized gypsum, 382-256 parts of cement, and 329-329 parts of water. 337 parts, 32-33 parts foam. The red mud is sintered red mud, and the fineness of desulfurized gypsum is required to pass through a 4.75mm square-hole sieve, and the foam is diluted by a composite foaming agent into a foaming liquid. The wet density of the red mud-based foam lightweight soil is 780～820kg/m ³ , and the 28d unconfined compressive strength is 0.81～1.20MPa. Crackability is poor. It is easy to segregate and volume deformation during construction.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a kind of expanded perlite foam light soil and a preparation method thereof, the technical problem to be solved by the present invention: the construction stability of the foam light soil is poor in highway application, and there are poor cracking toughness and impact resistance. In order to improve the strength, toughness and impact resistance of foam lightweight soil while retaining the advantages of lightweight, thermal insulation and environmental protection of foam lightweight soil materials, it can have multiple functions in engineering applications. Improve its constructability.

For achieving the above object, the present invention provides the following technical solutions:

An expanded perlite foam lightweight soil, comprising the following components in parts by weight: 9-27 parts of expanded perlite, 420 parts of cementitious materials, 155-195 parts of water, 20-60 parts of latex powder, 1.25-2.1 parts of hair Foaming agent, 1.5 parts thickener, 0.5 part water reducing agent.

Preferably, the cementitious material is composed of cement and fly ash, wherein the mass percentage of cement in the cementitious material is 80%, and the mass percentage of fly ash in the cementitious material is 20%.

Preferably, the latex powder is a water-soluble dispersible latex powder, which is a mixture based on an acrylate copolymer or an ethylene-vinyl acetate copolymer or an acrylic acid copolymer.

Preferably, the thickener is one or both of polyvinyl alcohol and carboxymethyl cellulose.

Preferably, the foaming agent is a cement foaming agent.

Preferably, the water reducing agent is a polycarboxylate water reducing agent.

Preferably, the particle size range of the expanded perlite is 1-2 mm, and the bulk density of the expanded perlite is 100-120 kg/m ³ .

By adopting the above technical solution, the expanded perlite is a light aggregate, wherein the ultra-light weight and high thermal insulation properties of the expanded perlite make it widely used in the field of construction engineering; on the other hand, the expanded perlite has the advantages of light weight, Porous, good chemical stability, improved construction stability and other advantages, improving construction is prone to pumping defoaming, segregation and bleeding. Adding an appropriate amount of perlite can not only reduce the density of lightweight concrete, but also its strength and pumping performance can meet the specification requirements; redispersible polymer powder can improve the foam lightweight soil, and the rubber powder can be used in the hydration of foamed cement. The surface of the product forms a polymer film and becomes a part of the pore wall, which increases the cohesion and improves the ability to resist stress and strain damage. It can effectively prevent the plastic shrinkage of the foam lightweight soil and improve the crack resistance and impact resistance of the foam lightweight soil; water reduction It can further increase the dispersion uniformity between the particles in the concrete mixture, so that the amount of water used can be reduced. The foaming agent produces abundant and uniform foam under the mechanical action, and mixes the foam and the slurry evenly, which has the effect of preparing the foamed lightweight soil; the waterproofing agent can further increase the waterproof performance of the foamed lightweight soil.

The preparation method of the expanded perlite foam light soil, comprises the following steps:

S1. Pre-wet treatment of expanded perlite. At room temperature, according to the set mixing ratio, weigh the corresponding amount of expanded perlite and add one-third of the proportion of water for pre-wetting treatment for 5-10 minutes;

S2. Preparation of expanded perlite cement slurry. First, weigh the corresponding components of cement, fly ash, thickener and latex powder and put them into the mixer for initial mixing for 20-30s; secondly, put the treated expanded perlite into the mixer and continue to mix for 40 seconds. ~60s; Finally, add the remaining water and water reducing agent, and continue stirring for 10~15min to make expanded perlite cement slurry;

S3. Mix the foam and the slurry, weigh the corresponding amount of foaming agent and water to dilute at 1:50, start the foaming machine for foaming after stirring for 2~3 minutes, and then add the prepared foam to the expanded perlite cement slurry In the material, continue to stir for 2~3 minutes to form a mixed slurry. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.

By adopting the above technical scheme, the cement is stirred and mixed with fly ash, thickener and latex powder, which helps to improve the mixing uniformity; the pre-wetted expanded perlite is added to the pre-mixed dry mixture and stirred, so as to improve the mixing uniformity. Disperse the admixture evenly, add water to stir and fuse, thus form a uniform slurry; inject foam into the slurry, so that the foam and the slurry are stirred and mixed to form a foam light soil mixture.

Further, the foaming agent is a cement foaming agent, which has low foam bleeding rate, good affinity with cement-based materials, and can improve the workability of the slurry. times diluted.

By adopting the above technical scheme, the hydroxypropyl methyl cellulose ether used in the test is a white or off-white powder, which has a fast dissolving speed and good dispersibility. It is soluble in water and some solvents, soluble in water and some solvents, HPMC also has thickening ability to prevent segregation, good dispersibility and good water retention.

The particle size range of the expanded perlite is 1-2 mm, and the bulk density of the expanded perlite is 100-120 kg/m ³ . It is characterized by light apparent density, low thermal conductivity, good chemical stability, non-toxic and tasteless, and many other excellent properties. It can improve the phenomena such as pumping defoaming, segregation and bleeding that are easy to occur in construction, and play a skeleton role while ensuring strength. reduce its density.

The present invention has the following beneficial effects:

1. In the present invention, the expanded perlite is introduced into the foam lightweight soil, and the porous structure of the expanded perlite utilized can improve the large-volume construction and is prone to pumping defoaming and bleeding while controlling the lightweight characteristics of the foam lightweight soil. Segregation and other phenomena, so that its strength and pumping performance can also meet the requirements of the specification.

2. In the present invention, adding latex powder with high bonding ability and film-forming performance into the foam lightweight soil mixture can improve the flexural strength, waterproofness, wear resistance and ease of construction of the mortar, and has a stronger flexibility, improving its crack resistance and durability. Prevent segregation, defoaming and volume deformation that are easy to occur during construction. Improve the toughness and impact resistance of foam lightweight soil, and prevent cracks and other phenomena that are prone to occur under impact load and dynamic load.

Detailed ways

The present invention will be further explained below in conjunction with the examples.

An expanded perlite foam lightweight soil, comprising the following components in parts by weight: 9-27 parts of expanded perlite, 420 parts of cementitious materials, 155-195 parts of water, 20-60 parts of latex powder, 1.25-2.1 parts of hair Foaming agent, 1.5 parts thickener, 0.5 part water reducing agent;

The cementitious material is composed of cement and fly ash, wherein the mass percentage of cement in the cementitious material is 80%, and the mass percentage of fly ash in the cementitious material is 20%.

Preferably, the cement is 42.5 ordinary Portland cement, and the fly ash is grade II composite Portland cement with a label of 32.5 MPa, which conforms to the standard "General Portland Cement" GB1752007.

The latex powder is a redispersible latex powder, which is a water-soluble redispersible powder based on an acrylate copolymer or an ethylene-vinyl acetate copolymer or a mixture based on an acrylic acid copolymer. Vinyl alcohol as protective colloid.

Before the test, the immersion method was used to modify the expanded perlite, and a pre-wet treatment was required for 5-10 minutes.

Prepared as follows:

Step 1: Proportion of Foam Lightweight Soil Raw Materials

In parts by weight, 9-27 parts of expanded perlite, 420 parts of cementitious materials, 155-195 parts of water, 20-60 parts of latex powder, 1.25-2.1 parts of foaming agent, 1.5 parts of thickener, 0.5 parts of parts of water reducing agent;

The cementitious material is composed of cement and fly ash, wherein the mass percentage of cement in the cementitious material is 80%, and the mass percentage of fly ash in the cementitious material is 20%.

Step 2: Preparation of expanded perlite foam lightweight soil

S1. Pre-wet treatment of expanded perlite. At room temperature, according to the set mixing ratio, weigh the corresponding amount of expanded perlite and add one-third of the proportion of water for pre-wetting treatment for 5-10 minutes;

S2. Preparation of expanded perlite cement slurry. First, weigh the corresponding components of cement, fly ash, thickener and latex powder and put them into the mixer for initial mixing for 20-30s; secondly, put the treated expanded perlite into the mixer and continue to mix for 40 seconds. ~60s; Finally, add the remaining water and water reducing agent, and continue stirring for 10~15min to make expanded perlite cement slurry;

S3. Mix the foam and the slurry, weigh the corresponding amount of foaming agent and water to dilute at 1:50, start the foaming machine for foaming after stirring for 2~3 minutes, and then add the prepared foam to the expanded perlite cement slurry In the material, continue to stir for 2~3 minutes to form a mixed slurry. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.

Example 1

An expanded perlite foam lightweight soil, comprising the following steps:

S1. Weigh 155kg of water, add one third of the proportion of water to 9kg of expanded perlite for pre-wetting for 5~10min.

S2, first, weigh 335kg of cement, 85kg of fly ash, 1.5kg of hydroxypropyl methylcellulose and 40kg of redispersible latex powder and put them into the mixer for preliminary mixing for 20 to 30s, and secondly, put the treated expanded perlite into the mixer Continue stirring for 40~60s. Finally, stir the remaining water and 0.5kg of polycarboxylate superplasticizer into the mixer, and continue to stir for 10~15min.

S3. Weigh 1.25kg of cement foaming agent and water to dilute at 1:50 at the same time. After stirring for 2~3min, start the foaming machine for foaming, and then add the prepared foam to the expanded perlite cement slurry and continue stirring. After 2~3 minutes, the mixed slurry is formed. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.

Example 2

An expanded perlite foam lightweight soil, comprising the following steps:

S1. Weigh 178kg of water, add one-third of the proportion of water to 18kg of expanded perlite for pre-wetting for 5~10min.

S2, first, weigh 335kg of cement, 85kg of fly ash, 1.5kg of hydroxypropyl methylcellulose and 20kg of redispersible latex powder and put them into the mixer for preliminary mixing for 20 to 30s, and secondly, put the processed expanded perlite into the mixer Continue stirring for 40~60s. Finally, stir the remaining water and 0.5kg of polycarboxylate superplasticizer into the mixer, and continue to stir for 10~15min.

S3. Weigh 1.68kg of cement foaming agent and water to dilute at 1:50 at the same time. After stirring for 2~3min, start the foaming machine for foaming, and then add the prepared foam to the expanded perlite cement slurry and continue stirring. After 2~3 minutes, the mixed slurry is formed. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.

Example 3

An expanded perlite foam lightweight soil, comprising the following steps:

S1. Weigh 193kg of water, add one-third of the proportion of water to 27kg of expanded perlite for pre-wetting for 5-10min.

S2, first, weigh 335kg of cement, 85kg of fly ash, 1.5kg of hydroxypropyl methylcellulose and 40kg of redispersible latex powder and put them into the mixer for preliminary mixing for 20 to 30s, and secondly, put the treated expanded perlite into the mixer Continue stirring for 40~60s. Finally, stir the remaining water and 0.5kg of polycarboxylate superplasticizer into the mixer, and continue to stir for 10~15min.

S3. Weigh 2.1kg of foaming agent and water to dilute at 1:50 at the same time. After stirring for 2~3 minutes, start the foaming machine for foaming. Then add the prepared foam to the expanded perlite cement slurry, and continue to stir for 2 It takes ~3 minutes to form a mixed slurry. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.

Comparative Example 1

Basically the same as Example 1, the difference is that no latex powder is added.

Comparative Example 2

Basically the same as Example 2, the difference is that no latex powder is added.

Comparative Example 3

Basically the same as Example 3, the difference is that no latex powder is added.

Comparative Example 4

Basically the same as Example 1, the difference is that no expanded perlite is added.

Comparative Example 5

It is basically the same as Example 1, except that no latex powder and expanded perlite are added.

Performance testing

The samples were prepared according to the methods of Examples 1-3 and Comparative Examples 1-3, and the properties of the standard sample blocks were tested according to the following methods. The test results of each group of sample blocks were averaged, and the test results were shown in Table 1. shown:

1. Dry density: according to the JG/T266-2011 "foamed concrete" standard, test the dry density of the test block;

2. 28-day compressive strength: According to GB/T 11969-2008 "Autoclaved Aerated Concrete Performance Test Method", make standard test blocks, and measure the compressive strength of the standard test blocks after curing for 28 days;

3. 28-day flexural strength: According to GB/T 11969-2008 "Autoclaved Aerated Concrete Performance Test Method", make standard test blocks, and measure the compressive strength of the standard test blocks after curing for 28 days;

4. 28-day impact resistance test: refer to the method recommended by ACI (American Concrete Institute) Committee 544 to carry out the drop weight test;

5. Moisture content: measure the moisture content according to GB/T 11969-2008 "Test method for performance of autoclaved aerated concrete".

Table 1 The performance test results of the standard concrete test blocks prepared by the above examples

The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims (8)

1. an expanded perlite foam light soil is characterized in that: comprise the component of following weight part: 9～27 parts of expanded perlite, 420 parts of cementitious materials, 155～195 parts of water, 20～60 parts of latex powders , 1.25~2.1 parts of foaming agent, 1.5 parts of thickener, 0.5 part of water reducing agent. 2. A kind of expanded perlite foam light soil according to claim 1, is characterized in that: described cementitious material is made up of cement and fly ash, and wherein the mass percentage of cement in cementitious material is 80%, The mass percentage of fly ash in the cementitious material is 20%. 3 . The expanded perlite foam light soil according to claim 1 , wherein the latex powder is a water-soluble dispersible latex powder, based on acrylate copolymer or ethylene-vinyl acetate. 4 . Copolymer based or acrylic copolymer based blends. 4. a kind of expanded perlite foam light soil according to claim 1, is characterized in that: described thickener is one or both in polyvinyl alcohol, carboxymethyl cellulose. 5 . The expanded perlite foam light soil according to claim 1 , wherein the foaming agent is a cement foaming agent. 6 . 6 . The expanded perlite foam light soil according to claim 1 , wherein: the water reducing agent is a polycarboxylate water reducing agent. 7 . 7. a kind of expanded perlite foam light soil according to claim 1, is characterized in that: described expanded perlite particle size range is 1～2mm, and the bulk density of described expanded perlite is 100～120kg/m ³ . 8. the preparation method of a kind of expanded perlite foam light soil according to any one of claim 1-7, is characterized in that: may further comprise the steps: S1. Pre-wet treatment of expanded perlite. At room temperature, weigh the corresponding amount of expanded perlite according to the proportion and add one-third of the proportion of water for pre-wet treatment for 5-10 minutes; S2. Preparation of expanded perlite cement slurry. First, weigh the corresponding components of cement, fly ash, thickener and latex powder and put them into the mixer for initial mixing for 20-30s; secondly, put the treated expanded perlite into the mixer and continue to mix for 40 seconds. ~60s; Finally, add the remaining water and water reducing agent, and continue stirring for 10~15min to make expanded perlite cement slurry; S3. Mix the foam and the slurry, weigh the corresponding amount of foaming agent and water to dilute at 1:50, start the foaming machine for foaming after stirring for 2~3 minutes, and then add the prepared foam to the expanded perlite cement slurry In the material, continue to stir for 2~3 minutes to form a mixed slurry. After the mixed slurry is poured and cured, the expanded perlite foam light soil will be formed.