High Efficiency Concrete Expansion Agent with Low Alkali Content
and Low Addition level ZY
ZY concrete expansion agent, is one of the important achievements
with patent right of China Building Material Academy (CBMA), which
was awarded the second prize of National Awards of Science and
Technology Progress and popularized as the key scientific payoffs
and the recommended products used to construct the Xiaokang
residential quarters by the Ministry of Construction. ZY is a kind
of water-resisting admixture coupled with crack resisting. It has
been used in thousands of water-resisting and crack-resisting
engineering in countrywide and came to the top since it adopted the
identification at ministry level in 1991.
Now the forth generation of ZY concrete expansion agent, the series
of ZY high efficiency concrete expansion agent with low alkali
content and low addition level, has been sold on the market. Its
patent number is ZL91110609X. The ZY has higher expansivity and
lower alkali content than general UEA sold on the market. The
series of ZY have 5 types: general type (Ⅰ), pumping and retarding
type (Ⅱ), pumping and high early strength type (Ⅲ), frost-resisting
type (Ⅳ), and high-performance type (Ⅴ). All of them accord with
the standard of building material industry Concrete Expansion
Agent” numbered JC476-1998 and others related to concrete additive.
Perhaps newer and better building materials are just what you need
and a wider market is expected for us. We are waiting for more
customers and friends and ZY will certainly become the link
contacting with each other.
New Concept of Waterproofing
The reasons causing crack in common concrete are complicated and
for materials, the main one is drying shrinkage of the concrete and
shrinkage due to temperature difference between surface and center
of the concrete. So a kind of expansion agent (ZY), with a main
function of compensating shrinkage, was successfully manufactured
in CBMA. When ZY, general cement concrete and water are blended and
stirred, a great deal of expansive crystalline hydrate, calcium
sulphoaluminate hydrate (C3A3CaSO
432H
2O), are produced and a tendency of expansion in the concrete is
visualized. Because of the compact confinement from the steel bar
and other parts in adjacent place, a compressive prestress of
0.2—0.7Mpa is produced in the construction, which balances the
tensile stress from the concrete shrinking in process of its
hardening. Now The Method of Compensating the Shrinkage of Concrete
in Engineering Application” has been listed as a national level
method in engineering application (YJGF22-92). This means that the
concrete with ZY is an important breakthrough in
self-water-resisting of the structure in our country.
By the stipulations of ministry of construction, water-resisting
engineering is divided into four grades according to the
importance. No matter which grade we choose, the
self-water-resisting of structure is essential, because the aging
and breaking phenomena after all is in existence for the
outer-layer water-resisting, used to coiled materials and coating
materials and the seepage caused in the construction is a
nonnegligible problem too. When general concrete is used as
structural materials, the construction will lose the final line of
defence in case it shrinks and cracks and this is a main reason
that buildings seep.
According to our practice for many years, we bring forward such a
new concept that for any water-resisting structure of concrete, the
crack-resistance is more important than the seep-resistance or
there will be no seeping if no cracking. The shrinkage compensating
concrete is a kind of ideal material that proves an important
ensurance to the self-water-resisting of structure.
The Physicochemical Properties and Alkali Content of ZY
1) Chemical elements and alkali contentTable 1. Chemical elements and alkali content:
Loss | SiO2 | Al2O3 | Fe2O3 | CaO | MgO | SO3 | K2O | Na2O |
1.70 | 15.20 | 16.50 | 0.90 | 32.60 | 2.35 | 29.55 | 0.30 | 0.10 |
* the alkali content R2O = Na
2O+0.658K
2O =0.3%
Fineness of ZY expansion agent is less than 10%, the density is
2.90, and the state is gray powder. Compare
