阅读说明：本技术 一种复合缓凝材料及其制备方法 (Composite retarding material and preparation method thereof ) 是由 李瑞青 朱永清 陈跃龙 邹琳 郑宾 杨阳 田坤 于 2020-05-25 设计创作，主要内容包括：本发明涉及一种复合缓凝材料,以质量百分比计包括以下组分：单糖类缓凝材料20-80％；多糖类缓凝材料0-60％；无机酸类缓凝材料0-52％；有机酸类缓凝材料0-14％。本发明的复合缓凝材料实现了不受水胶比限制,不受混凝土外掺料影响,在添加入混凝土后,可以控制混凝土初凝时间在60h到90h间自由选择,终凝时间控制在70h到100h之间,不出现单糖缓凝剂造成混凝土假凝现象,不发生多糖缓凝剂造成混凝土坍落度损失过快的情况,克服了无机酸类缓凝剂缓凝时间短的问题,不影响混凝土后期强度增长。本发明还涉及所述的复合缓凝材料的制备方法：将单糖类缓凝材料、多糖类缓凝材料、无机酸类缓凝材料及有机酸类缓凝材料按照固体质量比例混合均匀,制成粉剂。(The invention relates to a composite retarding material which comprises the following components in percentage by mass: 20-80% of monosaccharide retarding material; 0-60% of polysaccharide retarding material; 0-52% of inorganic acid retarding material; 0-14% of organic acid retarding material. The composite retarding material is not limited by water-cement ratio and is not influenced by concrete admixture, after the composite retarding material is added into concrete, the initial setting time of the concrete can be controlled to be freely selected from 60h to 90h, the final setting time is controlled to be 70h to 100h, the pseudo-setting phenomenon of the concrete caused by monosaccharide retarder is avoided, the condition that the slump loss of the concrete is too fast caused by polysaccharide retarder is avoided, the problem of short retarding time of inorganic acid retarder is solved, and the later strength increase of the concrete is not influenced. The invention also relates to a preparation method of the composite retarding material, which comprises the following steps: and uniformly mixing monosaccharide retarding materials, polysaccharide retarding materials, inorganic acid retarding materials and organic acid retarding materials according to a solid mass ratio to prepare powder.)

1. The composite retarding material is characterized by comprising the following components in percentage by mass: 20-80% of monosaccharide retarding material; 0-60% of polysaccharide retarding material; 0-52% of inorganic acid retarding material; 0-14% of organic acid retarding material.

2. The composite set retarding material of claim 1, wherein: the monosaccharide retarding material is one or a combination of glucose and sodium gluconate.

3. The composite set retarding material of claim 1, wherein: the polysaccharide retarding material is sucrose.

4. The composite set retarding material of claim 1, wherein: the inorganic acid retarding material is one or the combination of more of sodium hexametaphosphate, sodium dihydrogen phosphate, sodium pyrophosphate, boric acid and borate.

5. The composite set retarding material of claim 1, wherein: the organic acid retarding material is one or a combination of more of tartaric acid, citric acid and salts thereof.

6. The composite set retarding material of claim 1, wherein: the monosaccharide retarding material is sodium gluconate, the polysaccharide retarding material is sucrose, the inorganic acid retarding material is sodium hexametaphosphate, sodium dihydrogen phosphate, sodium pyrophosphate and boric acid, and the organic acid retarding material is tartaric acid and sodium citrate.

7. The composite set retarding material of claim 6, wherein: the mass percentages of the materials are as follows: 20-80% of sodium gluconate, 0-60% of sucrose, 0-20% of sodium hexametaphosphate, 0-10% of sodium dihydrogen phosphate, 0-10% of sodium pyrophosphate, 0-12% of boric acid, 0-8% of tartaric acid and 0-6% of sodium citrate.

8. The composite set retarding material of claim 1, wherein: the dosage of the material is 0.12 to 0.2 percent of the total mass of the cementing material in the doped concrete.

9. A method for preparing a composite set retarding material as claimed in claims 1 to 8, characterized in that: and uniformly mixing monosaccharide retarding materials, polysaccharide retarding materials, inorganic acid retarding materials and organic acid retarding materials according to a solid mass ratio to prepare powder.

Technical Field

The invention relates to a retarding material, in particular to a composite retarding material for concrete and a preparation method thereof.

Background

The slow setting material is one of common additives of concrete, and can delay the hydration rate of cement, adjust the setting time of concrete and improve the construction performance of concrete. At present, the retarding materials on the market are mainly single retarding materials which are mainly divided into four categories of monosaccharide retarding materials, polysaccharide retarding materials, inorganic acid retarding materials and organic acid retarding materials, but when concrete with the retarding time of 60 hours and meeting the use requirement of an underwater cast-in-place pile needs to be prepared, the four categories of single retarding materials have obvious defects.

The monosaccharide retarding material is mainly represented by sodium gluconate, and the sodium gluconate is also the most commonly used retarder at present. Referring to fig. 1, fig. 1 shows the effect of the sodium gluconate content on the initial setting time of concrete. With the increase of the dosage of the sodium gluconate, the initial setting time of the concrete can be prolonged from 10 hours to more than 20 days, and the retarding effect is good. However, when the amount of the sodium gluconate exceeds 0.12% of the gelled material in the concrete, the concrete can generate a pseudo-coagulation phenomenon, the fluidity of the concrete is lost after the concrete is taken out of the machine for 5-10min, and then the concrete is gradually recovered after 30min, and the higher the sodium gluconate is, the faster the fluidity is lost, the longer the required recovery time is, the working performance of the concrete can be seriously influenced, and the construction pouring requirement cannot be met. When the mixing amount of the sodium gluconate is 0.12 percent of the concrete cementing material, the initial setting time of the concrete is 45-50 hours, so that when the mixing amount of the sodium gluconate is less than 0.12 percent, the initial setting time of the concrete cannot be longer than 60 hours, and when the mixing amount exceeds 0.12 percent, the working performance of the concrete cannot meet the requirements of transportation and pouring.

The polysaccharide retarder mainly comprises sucrose, starch, dextrin and the like, wherein the most commonly used sucrose. The cane sugar is disaccharide which is a retarding material with obvious effect, and when the use amount of the cane sugar reaches 0.3 percent of the concrete cementing material, the initial setting time of the concrete can be delayed to more than 10 days. However, when the amount of the sucrose is more than 0.1%, the slump loss of the concrete is accelerated, and the slump loss is irreversible, thereby seriously affecting the performance of the concrete. However, the initial setting time of the concrete is only about 40 hours when the sucrose content is 0.1 percent.

The inorganic acid retarding material mainly comprises phosphates (sodium hexametaphosphate, sodium dihydrogen phosphate, sodium pyrophosphate and the like) in different polymerization states, boric acid and borate; the organic acid retarding material mainly comprises citric acid, tartaric acid and the like. These materials are characterized by a short retardation time, but the retardation effect is evident at an earlier stage. Taking sodium hexametaphosphate as an example, when the doping amount of the sodium hexametaphosphate is 0.08 percent of the cementing material in the concrete, the initial setting time is about 20 hours, and when the doping amount is enlarged to 0.15 percent, 0.3 percent and 0.5 percent of the cementing material in the concrete, the initial setting time is 40 to 48 hours, and the setting time of the concrete is not prolonged along with the increase of the using amount of the sodium hexametaphosphate. The retardation time of such retarding materials is limited.

The engaged row pile is used as a foundation pit enclosure structure and is divided into a hard cutting engaged pile and a soft cutting engaged pile according to the construction process. Wherein the construction mode of soft cutting secant pile is: firstly constructing I-sequence piles (interlocked concrete cast-in-place piles constructed at intervals in advance), then constructing II-sequence piles (concrete cast-in-place piles which are constructed subsequently and interlocked with the adjacent I-sequence piles), cutting off the concrete of the intersection part of the I-sequence piles and the II-sequence piles before the concrete of the I-sequence piles is hardened, and then completing the concrete casting of the II-sequence piles, thereby realizing the interlocking. The key of the construction of the soft cutting secant pile is to cut before concrete of the I-sequence pile is hardened, the cutting is usually completed before the concrete is initially set, the soft cutting of the I-sequence pile is smoothly completed, besides reasonably arranging construction organization, the setting time of the concrete must be prolonged enough to ensure that the II-sequence pile has sufficient construction time, if the concrete is hardened during the cutting, a drill cylinder of the soft cutting cannot complete the cutting, at the moment, the drill cylinder with a cutter edge needs to be replaced to perform hard cutting, the construction cost is greatly increased, and the construction efficiency is greatly reduced. Therefore, whether the hardening time of the concrete of the I-sequence pile can meet the soft cutting requirement or not plays an important role in the whole construction organization.

The design of the foundation pit enclosure of the Shenzhen subway 14 # line large transportation city comprehensive transportation hub project mostly adopts the form of meshed piles + inner supports, wherein the meshed piles of the foundation pit of the large transportation station all adopt the soft cutting construction process, the site conditions have a lot of restrictions on construction, the concrete delayed coagulation time of the I-sequence pile is required to be longer, and the process has the following three points in concrete requirements by combining the actual conditions of the project itself:

1. the initial setting time of the first-order pile concrete is not less than 60 hours;

2. the concrete needs to have good working performance so as to meet the requirement of pouring self-compacting concrete into a pile foundation;

3. the delayed coagulation of concrete cannot affect the later strength of the concrete.

However, in the existing single retarding material, if the monosaccharide retarding material and the polysaccharide retarding material are used for realizing 60 hours of retarding time of the concrete, the working performance of the concrete is damaged, and the inorganic acid retarding material and the organic acid retarding material cannot realize 60 hours of retarding time.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a composite retarding material which can ensure that the initial setting time of concrete is long, the working performance is good and the later strength is high.

The composite retarding material comprises the following components in percentage by mass: 20-80% of monosaccharide retarding material; 0-60% of polysaccharide retarding material; 0-52% of inorganic acid retarding material; 0-14% of organic acid retarding material.

Compared with the prior art, the composite retarding material is compounded by monosaccharide, polysaccharide, inorganic acid and organic acid retarding agents, the respective effects of the retarding materials are researched, and different combinations of the retarding materials are combined to make up for deficiencies, so that the composite retarding material is not limited by water-cement ratio and is not influenced by concrete admixture, after the concrete is added, the initial setting time of the concrete can be controlled to be freely selected from 60h to 90h, the final setting time is controlled to be 70h to 100h, the pseudo-setting phenomenon of the concrete caused by the monosaccharide retarding agents is avoided, the condition that the slump retarding loss of the concrete is too fast caused by the polysaccharide retarding agents is avoided, the problem that the inorganic acid retarding agents are short in time is solved, and the later strength increase of the concrete is not influenced. The slow-release water reducing agent has the advantages that the slow-release water reducing agent can play a role in retarding uniformly and continuously, the condition of segregation and bleeding caused by strong slow-release effect at a certain stage can be avoided, and the slow-release water reducing agent is matched for use, so that the mixed concrete has good workability.

Further, the monosaccharide-based retarding material is a combination of one or more of glucose and sodium gluconate. The delayed coagulation time can be prolonged.

Further, the polysaccharide retarding material is sucrose. The delayed coagulation time can be prolonged.

Further, the inorganic acid retarding material is one or a combination of more of sodium hexametaphosphate, sodium dihydrogen phosphate, sodium pyrophosphate, boric acid and borate. Can play a role in retarding early so as to reduce the using amount of the carbohydrate retarder.

Further, the organic acid retarding material is one or a combination of more of tartaric acid, citric acid and salts thereof. Can play a role in retarding at early and middle stages, and the inorganic acid retarder and the carbohydrate retarder are lapped, so that the retarding process is continuously and stably.

Further, the monosaccharide retarding material is sodium gluconate, the polysaccharide retarding material is sucrose, the inorganic acid retarding material is sodium hexametaphosphate, sodium dihydrogen phosphate, sodium pyrophosphate and boric acid, and the organic acid retarding material is tartaric acid and sodium citrate.

Further, the mass percentages of the materials are as follows: 20-80% of sodium gluconate, 0-60% of sucrose, 0-20% of sodium hexametaphosphate, 0-10% of sodium dihydrogen phosphate, 0-10% of sodium pyrophosphate, 0-12% of boric acid, 0-8% of tartaric acid and 0-6% of sodium citrate. Is a composite retarding material proportioning completely suitable for the occlusion type row pile soft cutting process.

Furthermore, the dosage of the concrete cementing material is 0.12 to 0.2 percent of the total mass of the cementing material in the doped concrete. The retardation time can be controlled by controlling the incorporation ratio.

The invention also comprises a preparation method of the composite retarding material, namely, monosaccharide retarding material, polysaccharide retarding material, inorganic acid retarding material and organic acid retarding material are uniformly mixed according to the mass proportion of solids to prepare powder.

Drawings

FIG. 1 shows the effect of sodium gluconate on the initial setting time of concrete.

Detailed Description

Uniformly mixing 20-80% of monosaccharide retarding material, 0-60% of polysaccharide retarding material, 0-52% of inorganic acid retarding material and 0-14% of organic acid retarding material in percentage by mass, and preparing into powder to obtain the composite retarding material. When the composite concrete material is used, the composite concrete material can be added into concrete according to the proportion of 0.12-0.2% of the concrete cementing material, or the composite concrete material can be added into water to prepare a water agent and then added into the concrete, or the water agent and the water reducing agent are added into the concrete.