WO2022158640A1 - Eco-friendly mortar composition employing blast furnace slag fine aggregates and ready-mixed concrete recovered water - Google Patents

Abstract

The present invention relates to an eco-friendly mortar composition, which leads to an increase in recycling rate of recovered water, a by-product in the ready-mixed concrete industry, and employs blast furnace slag fine aggregates generated as an industrial by-product after the extraction of metals from ore during a steelmaking procedure and ready-mixed concrete recovered water generated during a ready-mixed concrete producing procedure. More specifically, the present invention relates to a method in which blast furnace slag fine aggregates are incorporated at an increased ratio into mortar employing ordinary Portland cement and natural pit sad fine aggregates, thereby promoting the fluidity, strength, and durability performance of the mortar. The present invention provides an eco-friendly mortar composition employing blast furnace slag fine aggregates and ready-mixed concrete recovered water, the mortar composition comprising 330-360 parts by weight of cement, 80-320 parts by weight of fine aggregates, and 160-180 parts by weight of combined water, wherein: the fine aggregates are composed of 60-90 vol% of natural fine aggregates and 10-40 vol% of blast furnace slag fine aggregates; the combined water contains 5.0-10,0 wt% of solids obtained from ready-mixed concrete recovered water, the solids promoting the reactivity of the blast furnace slag fine aggregates.

Description

Eco-friendly mortar composition applied with blast furnace slag fine aggregate and ready-mixed concrete recovery

The present invention relates to a mortar composition that improves fluidity, compressive strength, tensile strength, drying shrinkage, and neutralization inhibitory performance by using blast furnace slag fine aggregate and ready-mixed concrete recovery as raw materials for the mortar composition,

More specifically, it relates to a technique for improving the hardening performance and durability of mortar by activating the reactivity of the blast furnace slag fine aggregate by the solid obtained from the ready-mixed concrete recovery.

Recently, the importance of environmental issues has been greatly emphasized, and regulations to prevent environmental pollution are being strengthened. In the construction industry, efforts to prevent environmental pollution and research for recycling by-products of the construction industry are being actively conducted.

Meanwhile, in the production of ready-mixed concrete, the recovery of ready-mixed concrete, which is generated in the form of equipment washing, concrete mixing, and surplus water, is a process by-product that inevitably occurs during the manufacture of large-scale ready-mixed concrete, and is generated over 20 million tons annually, and some concrete secondary Although it is applied in the form of an additive to the product, the amount is not reduced because the amount used is very small.

In addition, in order to avoid the burden of treatment costs in some workplaces, the recovery of ready-mixed concrete is discharged or buried in rivers without permission, so an eco-friendly recycling management technique of recovered water, sludge, symbol water, and sludge is required in the field.

On the other hand, natural fine aggregates used in construction sites are essential for a stable supply as a basic material for the construction industry, but difficulties in on-site supply and demand are increasing.

The amount of natural fine aggregates stored is continuously decreasing, and the difficulty in collecting aggregates is increasing due to indiscriminate development of stone mountains, environmental regulations caused by sea sand extraction, and opposition from residents.

The shortage of natural fine aggregates leads to an increase in prices in the construction material market, which is currently the cause of the high price of 40,000 won per cubic meter.

In addition, the aggregate price is expected to rise to the level of 45,000 won per 1m3 within the next three years, and it is urgent to secure alternative fine aggregates as a countermeasure against this.

As described above, blast furnace slag fine aggregate is being researched and developed as a substitute for natural fine aggregate that is difficult to supply. Blast furnace slag fine aggregate is made from industrial by-products generated in steel mills as the main raw material. More than 70% of slag is a water material that is rapidly cooled by rapidly spraying molten slag generated in the blast furnace with water. It is mainly used as a raw material in the manufacture of fine powder of blast furnace slag.

The present invention is for increasing the recycling rate of the ready-mixed concrete recovery, and for increasing the problem of aggregate supply and demand and the utilization of industrial by-products. An object of the present invention is to provide a mortar composition that exhibits excellent inhibitory performance and the like.

For solving the above-mentioned problems, the present invention is "330 to 360 parts by weight of cement; 80-320 parts by weight of fine aggregate; and 160 to 180 parts by weight of a compounding water; Including, but the fine aggregate is composed of 60 ~ 90 vol% of natural fine aggregate and 10 ~ 40 vol% of fine aggregate of blast furnace slag, and the blending water contains 5.0 ~ 10.0 wt% of the solid obtained from the ready-mixed concrete recovery, the solid is the blast furnace It provides an eco-friendly mortar composition applied with blast furnace slag fine aggregate and ready-mixed concrete recovery, characterized in that it promotes the reactivity of the slag fine aggregate.

The blast furnace slag fine aggregate has a particle diameter of 5 mm or less, A granulation ratio of 2.3 to 3.1 and a specific gravity of 2.5 to 2.8 g/cm 3 can be applied, and by composing the fine aggregate with 70 to 90 vol% of natural fine aggregate and 10 to 30 vol% of blast furnace slag fine aggregate, the dry shrinkage rate is 6 compared to natural fine aggregate alone. It can be reduced by ~10%.

In addition, by composing the fine aggregate at 60 vol% of natural fine aggregate and 40 vol% of blast furnace slag fine aggregate, the accelerated neutralization depth can be reduced by 10% or more compared to the natural fine aggregate alone blending.

The solid material may be applied to a CaO containing 35 wt% or more.

Effects that can be obtained through the present invention are as follows.

1. By substituting some of the natural fine aggregates (stone aggregates, sea sand, etc.) applied to the mortar composition with fine blast furnace slag aggregates and using the mixing water mixed with the recovered ready-mixed concrete, physical properties equal to or higher than that of mortar using only natural fine aggregates ( fluidity, compressive strength, tensile strength, drying shrinkage, etc.) are expressed.

2. The compressive strength and tensile strength of the mortar composition are improved by the amorphous crystal structure and latent hydraulic properties of the blast furnace slag fine aggregate.

3. In the case of including 5.0 to 10.0 wt% of recovered ready-mixed concrete solids in the mixing water applied to the mortar composition and 10 to 40 vol% of blast furnace slag fine aggregate among the fine aggregates, the physical properties such as fluidity, initial strength and long-term strength are generally is improved

4. When 10-30 vol% of blast furnace slag fine aggregate is included among the fine aggregates applied to the mortar composition, the drying shrinkage rate is reduced by 6-10% compared to the natural fine aggregate alone formulation.

5. When 40vol% of blast furnace slag fine aggregate is included among the fine aggregates applied to the mortar composition, the accelerated neutralization depth is reduced by more than 10% compared to the natural fine aggregate alone formulation.

1 shows the XRD component analysis result of the ready-mixed concrete recovered solid.

Figure 2 is a schematic diagram of the mechanism of densification and surface reaction of fine aggregate of blast furnace slag by ready-mixed concrete recovery solids.

Figure 3 shows the flow change of the mortar using the solid content and blast furnace slag fine aggregate in the blending water.

4 shows the change in the compressive strength of the mortar at the age of 7 days, 28 days and 56 days by fixing the same amount of mixing water containing 5 wt% of solids and increasing the replacement rate of fine aggregate in blast furnace slag.

5 shows the change in tensile strength of the mortar at 28 days of age according to the fixing of the same amount of mixing water containing 5 wt% of solids and increasing the replacement rate of blast furnace slag fine aggregate.

6 shows the change in drying shrinkage length up to 56 days of age of the mortar by fixing the same amount of mixing water containing 5 wt% of solids and increasing the replacement rate of blast furnace slag fine aggregate.

7 shows the measurement result of the accelerated neutralization penetration depth of the mortar at the age of 28 days by fixing the same amount of mixing water containing 5 wt% of solids and increasing the replacement rate of blast furnace slag fine aggregate.

330 to 360 parts by weight of cement;

80-320 parts by weight of fine aggregate; and

Blending water 160-180 parts by weight; including,

The fine aggregate is composed of 60 ~ 90 vol% of natural fine aggregate and 10 ~ 40 vol% of blast furnace slag fine aggregate,

The mixing water contains 5.0 to 10.0 wt% of the solids obtained from the ready-mixed concrete recovery,

An eco-friendly mortar composition to which the blast furnace slag fine aggregate and ready-mixed concrete recovery are applied, characterized in that the solid material promotes the reactivity of the blast furnace slag fine aggregate.

The present invention "330-360 parts by weight of cement; 80-320 parts by weight of fine aggregate; and 160 to 180 parts by weight of a compounding water; However, the fine aggregate is composed of 60 ~ 90 vol% of natural fine aggregate and 10 ~ 40 vol% of blast furnace slag fine aggregate, and the mixing water contains 5.0 ~ 10.0 wt% of the solids obtained from the ready-mixed concrete recovery (hereinafter 'solids') , provides an eco-friendly mortar composition applied with blast furnace slag fine aggregate and ready-mixed concrete recovery, characterized in that the solid material promotes the reactivity of the blast furnace slag fine aggregate.

The ready-mixed concrete recovery is water generated by washing in the recovery water process, and is a generic term for the sludge number ^** and symbol water ^*** obtained by purifying the washing waste ^* (KS F 4009).

- Washing drainage ^* : Water that washes concrete and spilled concrete attached to transport vehicles, plant mixers, hoppers, etc.

- Sludge number ^** : Suspension water remaining after separating and collecting coarse and fine aggregates in the washing drainage of concrete

- Symbol water ^*** : Water from which sludge solids have been removed from the sludge water by sedimentation or other methods

Sludge ^* exists in the ready-mixed concrete recovery excluding symbol water, Solids ^** can be extracted from the sludge.

- Sludge ^* : The sludge is concentrated and the fluidity is lost.

- Sludge solid content ^** : obtained by drying sludge at 105~110℃

In the present invention, when the sludge of the ready-mixed concrete recovery water is diluted with the mixing water, the solid component contained in the mixing water is referred to as “solid material”. The components of "solid content" and "solid matter" are the same, but the "solid content" contains the concept of "powder collected through a drying process", whereas "solid matter" as defined in the present invention is related to the collection process and properties. It is an ingredient-oriented concept that does not exist.

That is, in the present invention, when sludge is extracted from the ready-mixed concrete recovery and the sludge is diluted in the mixing water as it is, the solids contained in the mixing water can be collectively referred to as "solids", In the case of preparing the blended water in this way, separate energy consumption such as the solid content drying process is not required.

The solid material contains components such as CaO, Al ₂ O ₃ , and MgO, and thus Ca(OH) ₂ may be formed as a hydrate.

Specifically, by adding the sludge obtained from the ready-mixed concrete recovery to the mixing water of the mortar composition, the resulting solids become 5.0 to 10.0 wt% of the mixing water, and the solids contain more than 35 wt% of CaO. It activates the latent hydraulic properties of the blast furnace slag fine powder while the pH of the water exhibits strong alkalinity of 12 or higher.

Table 1 below shows the chemical composition ratio (unit: wt%) of the recovered ready-mixed concrete solids satisfying the above conditions, and FIG. 1 shows the XRD component analysis results of the recovered ready-mixed concrete solids. It can be seen from FIG. 1 that the main hydration product of the ready-mixed concrete recovery is Ca(OH) ₂ .

SiO 2	Al 2 O 3	Fe 2 O 3	CaO	MgO	SO 3	Insol.	S 2 O	Na 2 O	Ig.loss
21.53	4.04	2.78	36.7	2.03	5.03	10.67	0.23	0.05	2.5

On the other hand, the recovery of the ready-mixed concrete can be used that contains 0.2 ~ 0.9kg of the polymer coagulant per 1000ℓ. The solids obtained from the recovery of the ready-mixed concrete contain the polymer coagulant component, so that the polymer coagulant can serve as a thickener in the lightweight mortar composition.

Aluminum sulfate (Al ₂ (SO ₄ ) ₃₎ to shorten the settling time by aggregating the cement suspension material dispersed in the process of generating ready-mixed concrete recovery by purifying the washing waste into sludge particles (floc), A polymer coagulant prepared from raw materials such as ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (Fecl ₃ ), and polyaluminum chloride (PAC: Polyaluminium Chloride) may be used. Accordingly, when the solid obtained from the ready-mixed concrete recovery is added to the mixing water according to the present invention, the polymer coagulant is diluted and components such as methyl cellulose and HPMC (Hydroxypropyl methylcellulose, Hydromellose) act as a thickener in the lightweight mortar composition . Conventionally, expensive starch-based thickeners have been added to increase the viscosity of lightweight mortar, but through the present invention, without adding a separate thickener, the polymer coagulant contained in the ready-mixed concrete recovery serves as a thickener, thereby reducing the mortar manufacturing cost. have

The blast furnace slag fine aggregate has a particle diameter of 5 mm or less, A granulation ratio of 2.3 to 3.1 and a specific gravity of 2.5 to 2.8 g/cm 3 can be applied, and by composing the fine aggregate with 70 to 90 vol% of natural fine aggregate and 10 to 30 vol% of blast furnace slag fine aggregate, the dry shrinkage rate is 6 compared to natural fine aggregate alone. It can be reduced by ~10%.

In addition, by composing the fine aggregate at 60 vol% of natural fine aggregate and 40 vol% of blast furnace slag fine aggregate, the accelerated neutralization depth can be reduced by 10% or more compared to the natural fine aggregate alone blending.

The above effect is due to the densification of the blast furnace slag fine aggregate and the surface reaction (refer to FIG. 2).

However, if the solid content is less than 5.0 wt%, the hydrate production amount is small, so the reaction effect with cement is insignificant. can cause difficult problems.

1. Specimen (Formulation Table)

Table 2 below is a formulation table of mortar composition test specimens used to evaluate the performance of the present invention.

For each specimen, natural fine aggregate was replaced with blast furnace slag fine aggregate (replacement rate increased by 10 vol%), and water containing the solid was used. The solid material contains components such as CaO, Al ₂ O ₃ , and MgO, and thus hydrate Ca(OH) ₂ is produced.

Mix	BS (S×wt%)	W/C (wt%)	S/a (vol%)	Unit weight(kg/㎥)					Sludge (W×wt%)
				W	C	S	BS	G
Plain	0	50	42	170	340	739	0	1041	0
RW5BS0	0			170	340	739	0	1041	5
RW5BS10	10			170	340	665	80	1041
RW5BS20	20			170	340	591	160	1041
RW5BS30	30			170	340	513	240	1041
RW5BS40	40			170	340	444	320	1041

BS : Blast Furnace Slag Fine Aggregate

The fixed and variable values of each test sample formulation are as follows.

(1) fixed value

1) 5wt% of the solid content in the blending water (fixed to 5wt%, which is the content that minimizes the effect of hydrate formation within the appropriate solid content range, provided that Plain does not include the solids)

2) Water-cement ratio 50% (cement amount 340kg/㎥, mixed water amount 170kg/㎥)

(2) Variation value

1) Fine aggregate content of blast furnace slag among fine aggregates (vol%)

-RW5BS0 : Blast furnace slag fine aggregate 0vol%

-RW5BS10 : Blast furnace slag fine aggregate 10vol%

-RW5BS20 : Blast furnace slag fine aggregate 20vol%

-RW5BS30 : Blast furnace slag fine aggregate 30vol%

-RW5BS40 : Blast furnace slag fine aggregate 40vol%

2. Materials used

The materials used for the test are as follows.

(1) binder

As a binder, CaO 64wt% or _more and SiO2 17wt% or more, specific gravity 3.1~3.2g/cm3, and powderyness 3500~3600cm2/g of type 1 ordinary Portland cement were applied.

(2) mixing water

In the test example, mixing water having the above solid content of 5.0 wt% was used. It is preferable to use 150-180 kg/m ³ per unit volume (m ³ ) as the amount of mixing water, and in this test example, the water-cement ratio was specified as 50%.

(3) fine aggregate

Table 3 below shows the physical properties of the natural fine aggregate and the blast furnace slag fine aggregate used to evaluate the performance of the present invention.

The natural fine aggregate used in the present invention was used with a specific gravity of less than 2.6g/cm3 and a granulation ratio of 2.45 or less. The weight per unit volume (m ³ ) corresponds to 80 to 320 kg.

The fine aggregate of blast furnace slag is a blast furnace slag impurity generated during the smelting of high-temperature molten pig iron in the ironmaking process, and is limited to particles of 5 mm or less generated by rapid cooling by cold water or cold air.

Type	FM	Density (g/㎤)	Water absorption ratio(%)
S	2.45	2.60	1.0
BS	2.3	2.80	2.1

3. Test methods and results

In order to examine the flow characteristics and hardening characteristics of mortar according to the change in the replacement rate of blast furnace slag fine aggregate, the flow, compressive strength, and tensile strength of the mortar were measured according to the KS L 5105 and KS F 2423 test methods, respectively.

In addition, drying shrinkage and accelerated neutralization depth were evaluated to examine the durability characteristics of the mortar.

Drying shrinkage was measured using a contact gauge in accordance with KS F 2424 “Test Method for Length Change of Mortar and Concrete”.

In the neutralization test, in accordance with KS F 2584 “Test Method for Accelerated Carbonation of Concrete”, the neutralization depth was measured using a phenolphthalein solution after accelerating neutralization to the required age using an accelerated neutralization test chamber under a CO ₂ concentration of 5% environment.

(1) Review of mortar flow properties

3 shows the results of testing the mortar flow, regardless of whether or not solids are included in the mixing water, the mortar flow value is 180-200 mm as the mixing rate of fine aggregate in blast furnace slag increases. was shown.

Specifically, in the case of Plain containing no solids in the mixing water, the flow value was less than 182 mm.

On the other hand, the flow value of the RW5BS0 specimen was about 184.5 mm, indicating a flow value similar to that of Plain.

On the other hand, in the case of the RW5BS40 test specimen, the flow value was about 203 mm, which was about 12% higher than that of Plain.

(2) Review of mortar hardening properties

Compressive strength and splitting tensile strength were measured to examine the hardening performance of mortars with different solids content of 5.0 wt% and blast furnace slag fine aggregate mixing ratio in the mixing water.

4 shows the amount of change in compressive strength. At 7 days of age, the RW5BS0 specimen shows a value 4% lower than that of Plain.

Overall, the compressive strength of the RW5BS20, RW5BS30 and RW5BS40 specimens is about 38.3~39.5MPa, which is similar to Plain (38.5MPa).

At 28 days of age, Plain and RW5BS0 specimens show similar values of about 43 MPa, but RW5BS40 specimens are about 52.7 MPa, which is about 18% higher than that of RW5BS0 specimens.

At 56 days of age, Plain and RW5BS0 specimens are 60.5 MPa and 63.0 MPa, respectively, and 4% higher compressive strength value can be obtained through the inclusion of solids in the mixing water.

In addition, in the case of RW5BS10, RW5BS20, RW5BS30 and RW5BS40 specimens, about 3~8% higher level of compressive strength can be obtained compared to RW5BS0 specimens.

5 shows the amount of change in the tensile strength of the mortar in which the solids content of 5.0 wt% and the mixing ratio of blast furnace slag fine aggregates in the silver mixing water were changed.

Plain is 3.7 MPa, RW5BS0, RW5B10, RW5B20 specimen is about 3.8 MPa, and RW5BS30 and RW5BS40 specimen are 3.93 MPa and 4.24 MPa, respectively. Compared to Plain, about 5-14% higher tensile strength can be obtained.

(3) Review of mortar durability

6 shows the change in drying shrinkage of the mortar in which the solids content of 5.0 wt% and the mixing ratio of blast furnace slag fine aggregates in the mixing water were changed.

Plain is 0.142% and RW5BS50 specimen shows similar shrinkage rates of 0.144%, and RW5BS10, RW5BS20 and RW5BS30 specimens have about 0.128-0.133% shrinkage, which is about 6-10% lower than Plain, and RW5BS30 specimen shows about With a shrinkage rate of 0.128%, the highest drying shrinkage reduction effect can be obtained.

7 shows the accelerated neutralization depth of the mortar in which the solids content of 5.0 wt% and the mixing ratio of blast furnace slag fine aggregates in the mixing water were changed.

Plain is 0.97mm, RW5BS0 specimen is 0.86mm, which is about 11% lower than Plain, and RW5BS40 specimen is 0.56mm, so the highest neutralization inhibitory effect can be obtained.

Although the physical properties and effects of the present invention have been reviewed through the test results above, the present invention is not limited to the above test examples, and some modifications and changes are possible within the scope without departing from the technical spirit of the present invention. will say that

The present invention can be applied to the field of mortar compositions for construction.

Claims (5)

1. 330 to 360 parts by weight of cement;

   80-320 parts by weight of fine aggregate; and

   Blending water 160-180 parts by weight; including,

   The fine aggregate is composed of 60 to 90 vol% of natural fine aggregate and 10 to 40 vol% of blast furnace slag fine aggregate,

   The mixing water contains 5.0 to 10.0 wt% of the solids obtained from the ready-mixed concrete recovery,

   An eco-friendly mortar composition to which the blast furnace slag fine aggregate and ready-mixed concrete recovery are applied, characterized in that the solid material promotes the reactivity of the blast furnace slag fine aggregate.
2. In claim 1,

   The fine aggregate is composed of 70 ~ 90 vol% of natural fine aggregate and 10 ~ 30 vol% of blast furnace slag fine aggregate,

   An eco-friendly mortar composition to which blast furnace slag fine aggregate and ready-mixed concrete recovery is applied, characterized in that the drying shrinkage rate is reduced by 6 to 10% compared to the natural fine aggregate alone formulation.
3. In claim 1,

   The fine aggregate is composed of natural fine aggregate 60vol% and blast furnace slag fine aggregate 40vol%,

   An eco-friendly mortar composition to which blast furnace slag fine aggregate and ready-mixed concrete recovery is applied, characterized in that the accelerated neutralization depth is reduced by more than 10% compared to the blending of natural fine aggregate alone.
4. In claim 1,

   The blast furnace slag fine aggregate has a particle diameter of 5 mm or less, An eco-friendly mortar composition to which blast furnace slag fine aggregate and ready-mixed concrete recovery is applied, characterized in that the granulation ratio is 2.3 to 3.1 and specific gravity is 2.5 to 2.8 g/cm3.
5. 5. In any one of claims 1 to 4,

   The eco-friendly mortar composition to which the blast furnace slag fine aggregate and ready-mixed concrete recovery is applied, characterized in that the solids contain more than 35 wt% of CaO.

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