JP2007022849A - Polymer cement mortar and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a most suitable method for producing a polymer cement mortar which contains an SBR and an epoxy resin being free of a curing agent and is particularly excellent in bending strength, and compression strength, while having characteristics of a polymer cement mortar and a hardened article therefrom. <P>SOLUTION: The polymer cement mortar contains cement, fine aggregate, SBR and an epoxy resin free of a curing agent, and the manufacturing method of a hardened body of the mortar comprises hardening the polymer cement mortar, that is not yet hardened, by using a combination of steam curing and heat curing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polymer cement mortar and a method for producing the same, and more particularly to a high-strength polymer cement mortar and a method for producing the same by accelerated curing.

  The polymer cement mortar is composed of cement hydrate whose binder is modified with a polymer admixture, which greatly improves the disadvantages of conventional cement mortar. That is, the polymer cement mortar is a mortar having excellent properties such as tensile strength, bending strength, adhesion, waterproofness, and chemical resistance. Therefore, it is often used as a concrete repair material or finishing material. It is also suitable for precast concrete products. Polymers are generally expensive and have not been used much, but in recent years, many polymer admixtures have been developed and used with a focus on performance. As polymer admixtures, resin emulsions such as rubber latex including SBR (abbreviation of styrene butadiene rubber) and polyacrylate are well known. Epoxy resins have also been developed. A mixed dispersion in which these are mixed has also been studied (Non-Patent Document 1). In recent research, examples of improved adhesion and waterproofing using polymer cement mortar using SBR as a joint material for precast concrete panels (Patent Document 1), polymer using polymer dispersion and epoxy resin in combination By curing and drying cement mortar, autoclaving polymer cement mortar with excellent bending strength, adhesive strength, waterproofness and durability (Non-patent Document 2), polymer cement mortar with blast furnace slag and SBR latex added A polymer cement mortar for precast products (Non-Patent Document 3), which is excellent in cured compressive strength and bending strength, has been reported.

Japanese Patent Laid-Open No. 11-350617 Japan Concrete Institute, Concrete Handbook, page 253, Gihodo Publishing Co., Ltd., issued November 20, 1989 Yoshihiko Otsuki et al. Proceedings of Concrete Engineering Annual Report 15-1 233 (1993) Yoshihiko Otsuki et al. Architectural Institute of Japan Structural Papers Collection No. 545 1 pages (2001)

  As described above, production of polymer cement mortar using a combination of a polymer dispersion including SBR latex and an epoxy resin has been attempted, but it is well balanced and can be used as a polymer cement mortar as a cured product. A method for producing polymer cement mortar has not yet been established. In the present invention, the polymer cement mortar containing the SBR latex excellent in bending strength and compressive strength and the epoxy resin without addition of a curing agent, and the most suitable method for producing the cured product, while maintaining the characteristics of the conventional polymer cement mortar. It is intended to provide.

Means for solving the problems of the present invention are as follows.
(1) A polymer cement mortar containing cement, fine aggregate, SBR, and a curing agent-free epoxy resin.
(2) A method for producing a cured polymer cement mortar, wherein the polymer cement mortar according to (1) is cured by combining steam curing and heat curing.
In the present invention, the mortar means both a mortar that has not yet hardened and a hardened mortar as usual. However, in particular, when referring only to the mortar before curing, it may be called a polymer cement mortar cured body when it refers to a mortar that has not yet hardened, and when referring only to a cured mortar. Therefore, the “polymer cement mortar described in (1)” in the above (2) is the “polymer cement mortar described in (1) which has not yet solidified”.

  The polymer cement mortar of the present invention is a mortar having excellent properties in bending strength, tensile strength, adhesion, waterproofness, chemical resistance and the like, as in the case of ordinary polymer cement mortar. Furthermore, the cured polymer cement mortar produced by curing according to the present invention not only has a very short curing period, but also has excellent bending strength, particularly compressive strength that cannot be improved by ordinary polymer cement mortar.

  The polymer cement mortar of the present invention contains cement, fine aggregate, SBR, and a curing agent-free epoxy resin. Cement may be used any kind of cement including ordinary Portland cement. Although the fine aggregate is not particularly limited, the fine aggregate defined in the RC specification or JASS 5 is suitable. There is no particular limitation on the production area and density. It may be selected considering the availability and the purpose of use, for example, the color and the roughness of the mortar surface. The SBR as the polymer dispersion may be an ordinary commercially available SBR latex. For example, those polymerized at a ratio of styrene 50-80 to butadiene 20-50 are easy to use. The solid content (SBR) in the SBR latex may be about 20 to 60%. There is no problem even if an additive such as an antifoaming agent or a stabilizer is added to the SBR latex. Additives and the like may be used according to the necessity of mortar manufacturing work. A commercially available epoxy resin may be used for the epoxy resin. Epoxy resins obtained by polymerizing bisphenol A with propylene oxide or ethylene oxide are common and easy to use. No curing agent is added to the epoxy resin. The epoxy resin is sufficiently cured by steam curing and heat curing even without a curing agent. Conversely, when a curing agent is added, only the epoxy resin may be cured during mixing of the mortar. These mortar production methods such as mixing and kneading are not completely different from conventional polymer cement mortar production methods. However, since the epoxy resin reacts and hardens when working at a high temperature, it is preferable to knead at 60 ° C. or lower. The polymer content is expressed in terms of% by weight of the SBR latex with respect to the cement 100, and is desirably 1 to 40% by mass, preferably 3 to 30% by mass (the polymer cement ratio is the mass of solids in the SBR latex with respect to the cement 100). (The same applies hereinafter.) Although depending on the curing conditions, the higher the polymer content, the better the properties of the polymer cement mortar. From an economic point of view, the polymer content may be selected between 5 and 20% by mass in accordance with the target performance. The epoxy resin content is 1 to 20% by mass, preferably 3 to 7% by mass, where the mass of the cement is 100 and the mass of the epoxy resin is expressed in% (the epoxy resin content is hereinafter the same expression).

  A method for producing a cured polymer cement mortar of the present invention by curing a polymer cement mortar that has not yet solidified will be described. In the present invention, the strength development of the polymer cement mortar is led by combining steam curing and heat curing. In general, in the production of precast concrete products, steam curing, autoclave curing, and heat curing may be performed. This can be expected to significantly shorten the curing time and improve the compressive strength. However, as a curing method for polymer cement mortar, steam curing and heat curing have not been studied so much because it is recognized that polymers are vulnerable to heat. In particular, combining them only complicates the work, and it was not thought that a special effect could be expected. The present inventors harden a polymer cement mortar, particularly a polymer cement mortar containing a curing agent-free epoxy resin that is a thermosetting polymer, and improve the compressive strength while taking advantage of the polymer cement mortar. I have studied the method. So far, wet-dry combination curing has been studied, but the polymer cement mortar containing SBR and epoxy resin was inferior in strength development compared to the polymer cement mortar to which only SBR was added (see FIG. 2). Therefore, a curing method using steam curing and heat curing has been studied, but a curing method for curing polymer cement mortar containing SBR latex and a curing agent-free epoxy resin by combining steam curing and heat curing is very effective. It has been found that this is a method for producing a cured polymer cement mortar. And the curing condition which the bending strength and compressive strength of the polymer cement mortar containing SBR and an epoxy resin improve dramatically was discovered. The order of steam curing and heat curing may be either, but it is usually preferable to perform steam curing first and then heat curing to reduce moisture. In addition, since steam curing is often higher in temperature than normal temperature, it is preferable to perform normal temperature curing for about 1 day (even if the humidity is close to 100%, this is not usually referred to as steam curing) before steam curing. . Steam curing may be performed at 50 to 150 ° C. for about 0.5 to 5 days, preferably at 55 to 95 ° C. for about 1 to 2 days. If the temperature is too low, the curing time will be long, and if the temperature is too high, the polymer may deteriorate and the strength development may be insufficient. Note that an autoclave is required under curing conditions of 100 ° C. or higher. In addition, it is possible to lengthen the curing time, but it is not preferable because it is economically wasteful. The heat curing is preferably performed after the cement reacts with water and takes in necessary crystal water and the like. The heating conditions may be 50 to 200 ° C. for about 0.5 to 5 days, preferably 70 to 130 ° C. for about 1 to 2 days. If the temperature is too low, the curing time will be long, and if the temperature is too high, the polymer may deteriorate and the strength development may be insufficient. In addition, when it cures combining steam curing and heat curing, the temperature and time which fully advance reaction by combining both are required. If it is the said temperature range, it is preferable that the total curing time shall be 2 days or more. By adopting such accelerated curing, the curing time usually required for 28 days or more can be set to about 3 days.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.
(Preparation of polymer cement mortar that has not yet hardened)
As the cement, ordinary Portland cement specified in JIS R 5210 was used. The general properties are shown in Table 1. Incidentally, MgO as a chemical composition: 1.5 _wt%, SO 3: 2.1 wt%, loss on heating: 1.9 wt%. The fine aggregate was Toyoura standard sand. As the polymer admixture, SBR latex and a bisphenol A propylene oxide type epoxy resin without addition of a curing agent were used. The SBR latex has a density of 1.02 g / cm ³ (20 ° C.), a pH of 9.22, a viscosity of 67 MPa · s (20 ° C.), and a total solid content of 44.6%. Thus, a silicone-based antifoaming agent (effective silicone 30%) is added so that the effective solid content is 0.7%. The epoxy resin has an epoxy equivalent of 184, an average molecular weight of 340, a density of 1.16 g / cm ³ (20 ° C.), a viscosity of 3800 MPa · s (20 ° C.), and no curing agent is used.

According to JIS A 1171 (Testing method for polymer cement mortar), 0 to 20% of SBR latex and 0.5% of epoxy resin were used under the conditions shown in Table 2 so that the flow value of the mortar, that is, the consistency was almost constant. 10 types of polymer cement mortar were prepared. The properties of the mortar that has not yet solidified are shown in Table 2 and FIG.
FIG. 1 shows the water cement ratio (A) and the air amount (B) with respect to the polymer cement ratio. It can be seen that as the polymer ratio increases, the water-cement ratio can be reduced but the air is sufficiently entrained. In addition, there was almost no change by addition of an epoxy resin.

(Mortar curing)
Ten types of the prepared mortars 1 to 10 were each molded into a prismatic shape of 40 × 40 × 160 mm and cured. The following three types of curing conditions were used.
Curing conditions (1): First curing at 20 ° C. and 90% humidity for 1 day, curing for 1 day in a steam atmosphere at 60, 75 and 90 ° C. respectively, and finally heating curing at 120 ° C. for 1 day, or heating curing There are 6 conditions without.
Curing conditions (2): First curing at 20 ° C. and 90% humidity for 1 day, curing in a steam atmosphere at 90 ° C. for 1 day, and finally heating curing at 80, 100, and 120 ° C. for 1 day, or heating curing, respectively. There are four conditions, none.
Each was allowed to cool to 20 ° C. in a desiccator after completion of curing, and 90 types of mortar specimens in total were produced.
In addition, the curing condition (3) corresponding to normal curing conditions is that the moisture curing is first performed at 20 ° C. and a humidity of 90% for 2 days, under water at 20 ° C. for 5 days, and at 20 ° C. and a humidity of 60% for 21 days. Ten types of mortar specimens were prepared for dry curing.

(Evaluation of cured polymer cement mortar)
In accordance with JIS A 1171, the bending strength and compressive strength of the produced mortar specimens were measured. Note that the variation of the test data of each specimen was within 5% of the coefficient of variation. The results are shown in Tables 3-6 and shown in FIGS.

  From the above results, by combining steam curing and heat curing, mortars with higher bending strength and compressive strength than steam curing alone can be obtained respectively, especially polymer cement added with SBR latex and epoxy resin with no hardener added. It turns out that the mortar hardened | cured material with very high intensity | strength can be manufactured by the said combination curing of mortar. The polymer cement mortar of the present invention thus obtained has a strength not inferior to that of a polymer cement obtained by ordinary wet-dry curing, and the strength is significantly increased as compared with a mortar only by steam curing. In addition, the polymer cement mortar to which the SBR latex and the epoxy resin without the addition of a curing agent were added had a lower strength than the polymer cement mortar to which only the SBR latex was added. Such defects were also improved, and if the curing conditions were selected on the high temperature side, the strength tended to improve rather, and the strongest mortar specimen was obtained.

A square column having a cross section of 5 × 5 mm was formed from the inside of the specimen after the bending strength test, and this was folded, and the surface was etched with 3% hydrochloric acid to obtain a surface observation sample, which was observed with an electron microscope.
As can be seen from the electron microscopic observation photograph shown in FIG. 9, compared to the polymer cement mortar mixed with cement with SBR alone (1) or the epoxy resin alone (2), the polymer cement mortar (3 ) To (5) are consistent with the fact that the structure of the transition zone formed at the interface of the fine aggregate becomes dense, and the adhesiveness of the fine aggregate and hence the bending strength is improved (in parentheses). Numbers represent photo numbers.) As can be seen from the photograph (3), even when the SBR mixing amount is as low as 5%, the transition zone is sufficiently dense.

FIG. 1 shows the relationship (A) between the polymer cement ratio and the water cement ratio of the prototype mortar and the relationship (B) between the polymer cement ratio and the air amount. FIG. 2 shows the relationship between the polymer cement ratio, bending strength (C), and compressive strength (D) of a prototype mortar specimen manufactured under curing conditions (3). FIG. 3 shows the relationship between the polymer cement ratio and bending strength at a steam curing temperature of 60 ° C. (E), 75 ° C. (F), and 90 ° C. (G) of a prototype mortar specimen manufactured under the curing condition (1). FIG. 4 shows the relationship between the polymer cement ratio and the compressive strength at a steam curing temperature of 60 ° C. (E), 75 ° C. (F), and 90 ° C. (G) of a prototype mortar specimen manufactured under the curing condition (1). FIG. 5 shows the relationship between the heat curing temperature and the bending strength of the prototype mortar specimen manufactured under curing condition (2) with and without epoxy resin addition (L) and without (K). FIG. 6 shows the relationship between the heat curing temperature and compressive strength of the prototype mortar specimen manufactured under curing condition (2) with and without epoxy resin addition (N) and without (M). FIG. 7 shows the polymer cement ratio and bending of the experimental mortar specimens manufactured under curing conditions (2) at heating curing temperatures of 80 ° C. (O), 100 ° C. (P), 120 ° C. (Q), and steam curing only (R). Represents the strength relationship. FIG. 8 shows the polymer cement ratio and compression of the experimental mortar specimens manufactured under curing conditions (2) at heating curing temperatures of 80 ° C. (S), 100 ° C. (T), 120 ° C. (U), and steam curing only (V). Represents the strength relationship. FIG. 9 is an electron micrograph of polymer cement mortar cured for one day at 90 ° C. for steam curing and 100 ° C. for heating curing under curing condition (2). (1) 0% polymer, 5% epoxy resin added, (2) 5% polymer, 0% epoxy resin added, (3) 5% polymer, 5% epoxy resin added, (4) 10% polymer, 5% epoxy resin added, (5) is a mortar containing 20% polymer and 5% epoxy resin.

Explanation of symbols

1: SBR mortar without addition of epoxy resin 2: SBR mortar with addition of 5% by weight of epoxy resin 3: SBR mortar without addition of epoxy resin with steam curing only 4: SBR mortar with addition of 5% by weight of epoxy resin with steam curing only 5: combination of heating and steam Curing epoxy resin-free SBR mortar 6: Heated, steam combined curing epoxy resin 5% by weight SBR mortar 7: Polymer cement ratio 20% SBR mortar 8: Polymer cement ratio 15% SBR mortar 9: Polymer cement ratio 10% SBR mortar 10 : Polymer cement ratio 5% SBR mortar 11: Polymer cement ratio 0% SBR mortar 12: Steam curing only epoxy resin-free SBR mortar 13: Steam curing only epoxy resin 5 mass% addition SBR mortar 14: Heating and steam combination curing No epoxy resin added BR Mortar 15: heating, steam combination curing epoxy resin 5 wt% added SBR mortar

Claims (2)

  A polymer cement mortar containing cement, fine aggregate, SBR, and a curing agent-free epoxy resin.   The manufacturing method of the polymer cement mortar hardening body which hardens the polymer cement mortar of Claim 1 combining steam curing and heat curing.

Images