JPS59192523A - Method of adding surface-active agent for mortar and concrete - 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 provides a method for adding a surfactant for the purpose of improving workability of mortar and concrete and improving slump loss due to elapsed time, and more specifically, encapsulating a powdered surfactant, It relates to a method of adding it to pre-mixed mortar or concrete.

Reducing the amount of water used by adding cement dispersants and air-entraining agents when mixing mortar and concrete is now an essential requirement for preventing cracks and improving the durability of structures. However, due to recent trends in the aggregates used, the unit water volume has been increased and mortar and concrete with relatively large slump have been used in many cases, even though workability has been ensured. Not good for improvement. Also, in general,
Mortar and concrete have a property that their slump decreases over time, so construction may become difficult due to transportation and other circumstances. A number of methods have been proposed to improve this problem, one of which is to transport hard kneaded mortar and comfleet to the construction site, where the unit water volume is small, and add a surfactant there to improve the slump and improve the workability. There are ways to improve this and obtain high-quality mortar and concrete that use less water per unit. However, since the surfactant added here is an aqueous solution with a concentration of 20% by weight to 40% by weight, there is a problem that the water-cement ratio changes. Furthermore, addition equipment such as a container and a pump is required, and even if such equipment is provided, there is a drawback that the amount added may vary or stagnate due to changes in viscosity due to changes in liquid temperature.

The purpose of the present invention is to solve these drawbacks caused by the oxidation of aqueous solutions of surfactants, and to provide a method for adding powdered surfactants.

That is, the present invention is characterized in that the encapsulated powder is added to a mortar or concrete surfactant mixture and mixed in advance into mortar or concrete, and the capsules are destroyed by stirring. This is an activator addition method.

To explain the present invention in more detail, the present invention involves charging the encapsulated powder surfactant with the capsules from the hopper of a truck agitator vehicle, which is a transport vehicle for ready-mixed concrete, and agitating the powder at a high speed in the drum of the truck agitator vehicle. By destroying the capsules and dispersing the powdered surfactant into mortar or concrete, mortar or concrete with increased slump and good workability is produced.

If you try to add a powdered surfactant without encapsulating it, it will not only stick to the hopper of the truck agitator and not get into the concrete, making it impossible to adjust the slump, but it also has drawbacks such as being a fine powder and causing a lot of scattering when measuring. .

To encapsulate powdered surfactants, e.g. polyvinyl alcohol, polyethylene oxide, amylose,
Methods of wrapping with water-soluble films such as methylcellulose, hydroxypropylcellulose, and starch, such as glass,
There are methods such as wrapping it in easily destructible materials such as paper and plastic. On the other hand, the surfactants included in this include condensates of β-naphthalene sulfonates, condensates of melamine sulfonates, lignosulfonates, oxycarboxylic acid bases, polycarboxylate salts, etc. for mortar and concrete. Surfactants, as well as their derivatives, complexes, co-condensates, etc. The size of the capsule is such that the required amount of surface active agent is divided into 1 or 2 or more, for example 3 to 5, portions.

In addition, when storing the encapsulated powder surfactant, wrap it in polyethylene film, etc., and when using it,
It can also be used with the exterior removed.

The present invention will be explained below with reference to Examples.

Example: 1 m with water-cement ratio of 57.0% and fine aggregate ratio of 43.7%
``279 kl of ordinary Portland cement, 1 liter of water
59kg, mir material 807X? , coarse aggregate 1.055 to 9
, lignin-based admixture (trade name [Hozolith, %'5LJ)]
0.697 k17 ready mixed concrete 5m
3 was loaded onto a truck agitator vehicle and transported to the pouring site. At the pouring site, divide the amount of powdered surfactant shown in the table into two, wrap it in a water-soluble polyvinyl alcohol film (“DF107#20” manufactured by Denki Kagaku Kogyo Co., Ltd.), and pour the particles into the concrete from a truck agitator. did. After that, the truck agitator drum was rotated at both speeds (12 to 15 r, p, m) for 1.5 minutes, and the comfried truck was discharged, and the physical properties shown in the table were obtained. As a comparative example,
Powdered surfactant, not wrapped in a water-soluble film, was added with a mug from a truck agitator vehicle hopper.

In addition, the slump of physical property measurement is: rxs A-1101
slump test method for concrete, air amount is J-8A
-1128 unhardened concrete test method using air volume pressure, compressive strength is 010CrrLX20c
Using the formwork No. m, molding was carried out in accordance with the method for making concrete strength test specimens specified in J Engineering 5A-1132 and the method for compressive strength testing of concrete specified in J Engineering 5A-1108.

From the table in the margin below, it can be seen that the Examples have a strong effect on increasing slump, while the Comparative Examples have only a slight effect.

Patent applicant: Denki Kagaku Kogyo Co., Ltd. <s)-119-

Claims (1)

[Claims] A method for adding surface active agents for mortar and concrete, which involves adding encapsulated powder to mortar or concrete that has been mixed in advance and stirring to destroy the capsules. .