JPS58110451A - Mixed cementitious material for grc - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to mixed cementitious materials used in the manufacture of glass fiber reinforced concrete feet.

Glass fiber reinforced concrete (hereafter “F” G RC
,! ) is expected to be widely used in construction materials and other applications due to its excellent performance, but the reinforcing glass fibers are eroded over a long period of time by the strong alkalinity of cement, and the impact strength in particular deteriorates significantly over time. It has the disadvantage that the effect of glass fiber reinforcement is weakened.

In order to solve this problem, according to the JP-A-Sho SS-experiments, it was found that if only the ultra-low alkaline cement was used, the impact strength would be lowered by the initial l
It was confirmed that the value decreased to less than /lt.

The purpose of the present invention is to further improve the prior art, and its gist is that calcium sulfoaluminate is 10-IIO weight %, calcium sulfate is 1 g weight % or more,
Contains free quicklime at most 7% by weight, and the molar ratio of calcium sulfate to calcium sulfoaluminate is /, t
-4,j, and 0 active silica substances are added to 1 part by weight of ultra-low alkaline cement that does not substantially contain tricalcium silicate.
．． A mixed cementitious material suitable for manufacturing GRO, characterized in that 23-1 parts by weight is added thereto.

The ultra-low alkaline cement used in the present invention is calcium sulfoaluminate (?CaO・JA1203ψCa
5Oa), calcium sulfate (CaSO3), and free quicklime (Cab), it reacts with water to produce ettrin guide and hardens, and hardly produces calcium hydroxide. Furthermore, since it does not substantially contain tricalcium silicate (joaO.5iO2), it does not produce calcium hydroxide even when hydrated. Therefore, unlike conventional Portland cement, there is far less excess calcium hydroxide formation, and therefore less erosion of glass fibers.

The activated silica material used in the present invention is a silica source for capturing residual calcium hydroxide, and is selected from fly ash, volcanic ash, clay, clay, silica powder, glass powder, blast furnace slump, etc., but contains CaO. Since less is better, fly ash, volcanic ash, clay, viscosity, silica powder, and glass powder are preferable. In particular, 7 lion ash has very little CaO and has a round particle shape, so it has excellent fluidity and can reduce the amount of added water.・It is particularly preferable because it can form a . The reason for limiting the range of addition of these active silica substances is that if the weight ratio to cement is less than 0.2j, it will not be effective in maintaining the impact strength (IS) after a long period of time after GRG is manufactured, and if it exceeds 1, the initial Bending proportional limit strength (LOP)
This causes problems in handling such as demolding and transportation.

There are many known attempts to maintain the long-term strength of GRC by adding active silica substances with a content of 110% or less, but in all of them, the outdoor exposure period tested was about 1 to 2 years, and Table 1 As shown in the figure, according to the inventor's experiments, GRO made by adding fly ash to ordinary Portland cement has a temperature of 70°C, which corresponds to 20 years of outdoor exposure.
1 after immersion test in water for 2g days. S is at most s'h/
cW? This can easily cause brittle fracture, especially in cement products such as GRC, which are often manufactured with thin walls.These GRC products are often used in buildings, etc., and from a safety point of view At least 20% considering the lifespan of the building etc.
It is necessary to maintain strength after long-term outdoor exposure of about 20 years.
Its performance should not be evaluated based on the results of only 1-2 years of outdoor exposure tests.

In addition, the present invention is based on the prior application filed by the inventor (Japanese Patent Application No. 1973-
? It is superior in long-term impact strength compared to FFJ No. 4 da), and is also superior in that the amount of active silica material added can be reduced.

That is, since the prior application uses ultra-fast hardening cement, it is not possible to maintain high long-term impact strength unless an extremely large amount of activated silica is added compared to the present invention, so the amount of cement must be reduced, and the long-term impact strength is the same as the present invention. In order to obtain the initial LOP value and bending fracture strength (MOR
), and as a result, we were forced to extend the mold release time. However, in the present invention, the above-mentioned disadvantages can be alleviated since up to 20% F can be removed by adding activated silica material.

Accordingly, the present invention specifically combines ultra-low A/L alkalinity cement with the addition of activated silica material to:1. G with high long-term impact strength unimaginable with conventional technology
It has been discovered that an RC product can be obtained.

Examples Table 1 shows the CR of the examples of the present invention and comparative examples other than the present invention.
This is a comparison of the initial strength of the O product and the strength after an accelerated deterioration test equivalent to over 20 years of outdoor exposure.

In preparing the sample, O0 parts by weight of sand and 0.33 parts by weight of water were used as aggregates for the mixed cement/overlapping part.

Parts by weight of water reducing agent O0OCoS, setting regulator (citric acid) 1st
Table l Table (continued) Table 3 Mineral composition of ultra-low alkaline cement (wt%) 3CaO・3A1203・Ca5o43/%CaSO4
22 cao g, r, zc
ao −Sio2 +2g1IC
aO-A1203・Fe2033q Others
Direct spraying of cement mortar obtained by mixing 0.003 parts by weight of activated silica material in accordance with the mixing ratio in Table 1 and chopped strands of alkali-resistant glass fiber at 5% by weight relative to the cement mortar. A glass fiber-containing cement mortar layer is formed by simultaneously spraying onto the formwork using a method, and the glass fibers are rolled over the glass fiber-containing cement mortar layer to defoam and blend the glass fibers into the cement mortar, resulting in a thickness of iommK. After smoothing it out, it was cured and demolded to obtain a GRO board. After curing this GRO board for two weeks, it was cut into a suitable size and used as a sample.

The cements used for sample preparation were ultra-low alkaline cement, ultra-fast hardening cement, and ordinary Portland cement with the chemical components shown in Table 2.
7 of the chemical components in the table was used. The mineral composition of the ultra-low alkaline cement is as shown in Table 3.

When measuring strength, LOP (proportional bending strength)
An autograph was used to measure MOR (bending rupture strength) at a displacement rate of 3 mm for 7 minutes, and IS (Izod impact strength) was measured using an Izod impact tester. Furthermore, in Table 7, the strength before the accelerated test is the strength of the sample prepared by the above method, and the strength after the accelerated test is the strength after being immersed in water at 70"C for 21 days after being cut and dried. O Sample &/~5 in Table 1 is a mixed cement in which ordinary Portland cement is used as cement, and the blending ratio of activated silica material and fly ash is gradually increased, Sample A6
-10 is a mixed cement in which fly ash is gradually increased in ultra-fast hardening cement, &//~/2 is a blending ratio outside of the present invention, and AI3~/za is an ultra-low alkaline cement with a blending ratio according to the present invention and fly ash. This is GRC manufactured using cement mixed with ash.

In order to discuss the superiority of ordinary cement and ultra-low alkaline cement, sample A/7. lt and 13~/zato, when comparing those with the same fly ash blending ratio, the LOP value is higher in the one using ordinary cement both before and after the accelerated test, but the NOR value and IS value after the accelerated test are especially extremely low. Those using alkaline cement are far superior. In addition, in order to discuss the superiority of ultra-fast hardening cement and ultra-low alkaline cement, when comparing samples A6-10 and 73-7g with the same fly ash blending ratio, the LOP
The values are higher for those using ultra-fast hardening cement, but the NOR and IS values after accelerated tests, especially the IS values, are significantly better for those using ultra-low alkaline cement, and the I after accelerated tests are significantly superior.
When comparing samples with fly ash blending ratios such that the S value is almost the same, the one using ultra-low alkaline cement is superior in terms of LOP value as well.

As is clear from the following, the CRC using the mixed cement of the present invention is excellent in impact strength, especially after a long period of time has elapsed after production.

Claims (1)

[Claims] +1) Calcium sulfoaluminate 10-11
0% by weight, calcium sulfate (g% by weight or more), free quicklime (7% by weight or less), and the molar ratio of calcium sulfate and calcium sulfoaluminate is /, 3 to t, S
0.2 of the active silica material per part by weight of ultra-low acalytic cement that does not substantially contain tricalcium silicate.
! A mixed cementitious material suitable for the production of GRC, characterized in that it contains i to da parts by weight. (2) A mixed cementitious material suitable for the production of GRC according to claim 7, in which at most 7 parts by weight of sand is added as aggregate to 1 part by weight of the cement and the activated silica material. (3) The weight ratio of the cement, the activated silica material, and the cement mortar prepared by adding water to the aggregate is 0.3 to
Mixed cementitious material suitable for the production of GRC according to claims 1 to 1, with the addition of IO% of alkali-resistant glass fibers. (4) A mixed cementitious material suitable for the production of GRC according to claims 1 to 3, wherein the activated silica material is 7-hianocy.