Research method

Establishing Methods to Design Materials for
Polymer-Modified Cement Waterproofing Coating

X-ray diffraction/
scattering

Pursuit of hydration and hardening processes

Role of SPring-8

Achievements

Observing the cement hydration in polymer-modified cement waterproofing
coating materials* over time to clarify the process of cement hydrate
production
Realizing precise design method for materials suitable for each temperature andhumidity in a construction environment to improve the reliability of products
Adoption of the products in major facilities in Japan and overseas because of
their improved performance and reliability (Examples of adoption: Roppongi
Hills, Shanghai World Financial Center, Tokyo Urban Planning Group’s Nerima
Tunnel, etc.)
R&D facility: Ozeki Chemical Industry Co., Ltd.
*Polymer-modified cement waterproofing coating material: A kind of waterproofing material used in construction and engineering work.
When a polymer emulsion and cement admixture powder are mixed and kneaded at a construction site and applied to a base, the cement ishydrated to form a waterproofing coating. Polymer-modified cement waterproofing coatings are widely used as reliable and safe waterproofingmaterials because they combine the flexibility of polymers and the toughness and adhesiveness of cement and because they do not require the useof an organic solvent or open flame.

BackgroundResults

Polymer-modified cement waterproofing
coating materials must have characteristics that aresuitable for a wide range of environments because
they are used under various conditions, such as
high temperature and high humidity. In order toobtain materials with desirable properties under
all conditions, it is essential to understand theprocess of cement hydration in detail and designmaterials so that the properties of the final coating
can be predicted.
However,molecular-level
microscopic
measurement is needed to clarify the hydration
process. Such measurement was difficult withgeneral-purpose X-ray devices.

We traced the entire hydration process inpolymer-modified cement using high-brilliance
X-ray diffraction in SPring-8, and examined whenand how multiple cement hydrates are produced.
In addition, we collected data using materials withthe same combination ratio of cement andpolymer emulsion by varying the temperature andhumidity to quantitatively clarify the behavior of
the materials, including changes in the reaction
rate.
From these results, we made it possible todesign materials that form a waterproofing coatingeven in a closed underground environment with ahumidity of 100% by effectively using the water inthe polymer emulsion to hydrate the cement.

Publication: M. Kotera et al.; Journal of The Society of Materials Science, Japan 54 (7), 780-784 (2005)

Inorganic ceramic
containing alumina

Polymer emulsion

Hydration processes at room temperature and 35oC

1. Combine inorganic
ceramic containing alumina(alumina ceramics +aggregate) and polymeremulsion.

182. EVA resins, the alumina
ceramics, and theaggregate are uniformly
dispersed in the water inthe emulsion by kneading.

3. The cement components
are separated from thealumina ceramics in thewater in the emulsion.

4. The separated cement
components hydrate using
the water in the emulsion, andthus the water is consumed.
Simultaneously, the EVA
resins start fusing.

Cement hydrate (Solvent: water)

5. Moisture divergenceand fusion of the EVA
resins are promoted byfurther hydration, and acoupled waterproofing
coating is formed.

Temperature of sample

Nonhydrate Hydrate (C2AH8 and C3AH6+AH3)

RoomtemperatureoAlumina ceramics

Progress of cement hydration measured in SPring-8(at room temperature)

Temperature of sample( C)

Formation of polymer-modified cement waterproofing coating

EVA resin in polymer emulsion

Apparent reaction rate(%)

Aggregate

Hydrates are produced faster at 35oC than at room temperature. This
result revealed that hydration is promoted with increasing
temperature.

Time (min)35oC

Reaction time (min)19