JPH0297448A - Cement composition for placement by pouring - Google Patents

Abstract

PURPOSE:To provide the title compsn. having good workability without sacrificing the strength and durability of a completed floor by incorporating Portland cement, pozzolan, ZrO2 and/or MgO, alkaline (earth) metal salt of stearic acid, water-reducing admixture and polymer stabilizer respectively at prescribed ratios into the compsn. CONSTITUTION:The above-mentioned cement compsn. contains the compsn. of the following ratios in 100 pts.wt. The compsn. contains 85 to 95 parts Portland cement; 2 to 5 parts fine silica powder; 0.5 to 2 parts >=1 kinds of ZrO2 and MgO; 0.5 to 2 parts alkaline (earth) metal salt of the stearic acid; 1 to 6 parts cement quick-setting agent essentially composed of Na2CO3; 0.2 to 1 part water-reducing admixture such as lignin sulfonate; 0.1 part polymer stabilizer such as CMC. The above-mentioned cement compsn. is kneaded with a proper ratio of inorg. aggregate and water, by which mortar having 0cm slump value and excellent natural flowability is obtd. In addition, bleeding after the placement does not raise and both the strength and watertightness of hardened material after completion are excellent.

Description

[Detailed Description of the Invention] (Object of the Invention) When floor paving is performed by pouring cement mortar, the strength and durability of the completed floor will be great if the proportion of water is reduced and hard mortar is used. Construction workability is extremely poor. On the other hand, if you increase the proportion of water and use softer mortar, workability will be better, but the strength and durability of the floor will be sacrificed.

This invention provides such workability and strength in floor construction.
By overcoming the fact that there is a trade-off with durability, and by incorporating this into the mix, we can achieve this without sacrificing the strength and durability of the finished floor.
The object is to provide a cement composition with which a cement mortar with good workability can be prepared.

Conventionally, it has been said that mortar prepared for floor construction generally needs to have a slump value of 2.51 or more, but in this case the water/cement ratio is 0.1 or less. Since such hard mortar with a slump of 4M2.5ctx or more does not flow naturally on the surface into which it is driven, it is necessary to perform a leveling operation with a trowel immediately after driving. Needless to say, leveling the driving surface with a trowel requires skill and a great deal of effort.

If the water addition rate is increased in an attempt to reduce or omit the labor of this type of troweling work, the slump value will decrease and the fluidity of the mortar will improve, but at the cost of this, the poured mortar particles will coagulate. This causes the so-called breathing phenomenon in which the water settles and the separated water rises before the floor is finished, resulting in a deterioration in the strength and durability of the completed floor. The inventor has provided a means for reliably preventing the occurrence of such a breathing phenomenon, and has succeeded in overcoming the above-mentioned contradiction in casting cement mortar.

(Structure of the Invention) In other words, the cement a composition according to the present invention consists of 100 parts by weight (hereinafter, parts by weight are simply referred to as "Part J") ■ 85 to 95 parts of Bortland cement ■ Fine silica powder or fly ash At least one type 2 to 5 parts ■At least one type of zirconia or magnesia 0.5 to 2 parts ■At least I type of alkali metal stearate or alkaline earth metal stearate 0.5 to 2 parts 0
100 parts Sodium carbonate 70 parts Sodium fluorosilicide 10 parts Calcium chloride 10 parts Zinc white 10 parts Cement quick setting agent 1 to 6 parts Water reducing agent consisting of at least one of lignin sulfonate or alkylaryl sulfonate 0.2 to 1 part ■ Polymer stabilizer consisting of at least one of methylcellulose or CMC 0.2 to 1 part or more ■ to ■
Contains.

Below, the reasons for the composition of the composition according to the present invention will be described.Firstly, it is Bortland cement (2), but if it is less than the above-mentioned range, the compaction strength and durability of the mortar after hardening will decrease. is noticeable, and if it is too large, all or part of the ratios of (1) to (2) described above will decrease, resulting in an adverse effect.

Next, the pozzolan substance (2) has a favorable effect of imparting coagulation force to the fine non-solidifying substances that rise when breathing occurs, but when the amount is less than the above range, breathing occurs as a result. The strength of the mortar after hardening is markedly reduced, such as by about 50% in some cases, and on the other hand, if the amount exceeds the above range, there is an adverse effect due to a decrease in the proportion of other components.

Zirconia, magnesia (■), and stearate (■) are intended to increase the watertightness of the completed mortar and improve its durability. However, if the amount is less than the above range, the water absorption of the mortar after hardening will increase, resulting in poor durability. On the other hand, if the amount is too high, the proportions of other components will be reduced, which will have an adverse effect.

The quick setting agent (2) is used to stop the initial stage of setting of mortar and stop the settling of particles at an early stage. However, if the amount is less than the above range, the hardening speed of mortar decreases, causing an opportunity for breathing to occur, and causing damage to the mortar surface. The raintance increases and the strength and watertightness after curing deteriorate, while if it is too much, the smoothness of the floor surface is impaired due to excessive early curing.

The water reducing agent (2) is necessary to ensure fluidity with as little water as possible, but if it is less than the above range, the amount of water required to ensure a small slump value during driving will increase, and the mortar will have a stronger strength after hardening. , without any negative effect on durability. On the other hand, if the amount is too high, not only will it cause a decrease in other components, but it will also prolong the setting time of the cement, increasing the chance of bleeding occurring.

The polymer stabilizer (2) has the effect of suppressing sedimentation of particles in the composition, but if the amount is less than the above range, the effect will not be apparent, and if it is too much, the mortar will lack fluidity.

In order to prepare a mortar for poured pouring construction using the cement composition according to the present invention, it is necessary to follow a normal mortar preparation method, and add to the cement composition a total of silica sand, river sand and other inorganic materials conventionally used for mortar preparation. Blend and knead the aggregate and total water.

If the thoroughly mixed mortar is poured into the floor frame, there is no need to trowel it, and it will flow naturally and settle. If the mixing ratio of this cement composition, inorganic aggregate, and water is appropriate in the mixing and preparation of mortar, it will be 70 to 80% after completion of construction.
A hardened mortar bed appears with a strength (-axial compressive strength) of 0 kg r /cj.

The optimum mixing ratio to obtain the above strength is 1.2 to 1.7 parts of inorganic aggregate to 1 part of cement composition, and 1 part of water.
Experiments have shown that this is the case.

The compositions of Examples and Control Examples of the cement compositions of the present invention are shown in Table 1, and Table 2 shows the test results of mortars and cured products prepared using these Examples and Control Examples. The indications of ■ to ■ in the table correspond to the indications of ingredients ■ to ■ in the structure of the invention described above. However, in preparing the mortar, 150 parts of the inorganic aggregate listed in Table 3 (silica sand No. 6) and 100 parts of water are mixed with 100 parts of the cement composition, stirred and kneaded, and the prepared mortar is mixed into 4 cm
The mortar slump value, the strength of the cured product, etc. were measured by pouring into a double formwork in which three box frames of X4c and X16cm were connected. Note that the control examples were limited to those in which a slump value comparable to that obtained using the composition of the present invention was obtained.

Table 1 Table 2 However, Ex and Ref indicate examples and comparative examples of compositions according to the present invention, respectively.

In Table 2, the water absorption rate is the measured value obtained by measuring the amount of water absorbed after leaving the specimen in a room temperature room for 78 hours and then immersing it in water for 24 hours.

The bending strength, -axial compressive strength, and lead hardness are the measured values of the specimen after measuring the amount of water absorption.

Table 1 (Effects of the Invention) That is, as clearly shown by the test results described above, according to the present invention, by kneading with an appropriate amount of inorganic aggregate and water, a mortar with excellent natural fluidity and a slump value Oc layer can be produced. Moreover, there is no bleeding phenomenon after construction, and as a result, the cured product after completion has high strength and watertightness, and therefore it is possible to construct a highly durable mortar bed, making it an ideal choice for civil engineering and construction technology. It greatly contributes to development and improvement of construction economy.

Claims (1)

[Scope of Claims] [1] 85 to 95 parts by weight of Portland cement in 100 parts by weight [2] Pozzolanic material consisting of at least one of silica fine powder or fly ash 2 to 5
Weight part [3] At least one of zirconia or magnesia 0.
5 to 2 parts by weight [4] 0.5 to 2 parts by weight of at least one of alkali metal stearate or alkaline earth metal salt stearate [5] 70 parts by weight of sodium carbonate in 100 parts by weight 10 parts by weight of sodium silicofluoride 1 to 6 parts by weight of a cement quick setting agent consisting of 10 parts by weight of calcium chloride and 10 parts by weight of zinc white; 0.2 to 1 part by weight of a water reducing agent consisting of at least one of lignin sulfonate or alkylaryl sulfonate; 7] A cement composition for casting construction containing 0.2 to 1 part by weight of a polymer stabilizer consisting of at least one of methylcellulose and CMC.