Synthesis And Properties Research Of Acrylic Acid Superplasticizers

Acrylic acid superplasticizer is a kind of polycarboxylate high range water-reducer. It is widely used in developed countries due to its good properties on improving the workability of fresh concrete and performances of hardened concrete. With the development of concrete technique and modern architecture, polycarboxylate-type superplasticizer will inevitablely replace the traditional water-reducers.In this paper, using acrylic acid, methyl acrylate and their derivants as main materials, and during the free radical polymerization, synthesize a series of acrylic acid superplasticizers with different chain structure and molecular weight distribution. Besides, the polymers are characterized with FT-IR spectrum to certify the structure, and they are mixed in cement and concrete to test their properties. Moreover, a kind of sodium sulfanilate-phenol-formaldehyde condensate is synthesized through condensation polymerization process for the contrast study. The processing parameters, including reaction temperature, mixture ratio of materials, reaction initiator and reaction time etc., and technique of synthesis are mainly confirmed by fluidity of cement paste. Superplasticizers with large fluidity are filtrated to test their concrete performances, such as the fluidity of fresh concrete, the slump-loss with time and mechanical properties of hardened concrete.Some products have higher performance. For example, when the blend ratio is only 0.3%, the fluidity of cement paste can reach 340mm. The products of superplasticizers can approximately be separated into two parts: gasifying-type agent and degasifying-type agent. The FT-IR spectra of them have unconspicuous differences. However, there are large distinctions between the influences of the two types to the workability of cement paste and fresh concrete, the mechanical properties and microstructure of hardened concrete. And the contrast study shows that the sodium sulfanilate-phenol-formaldehyde condensate and the acrylic acid superplasticizers are both better than commercial product of sulphonated naphthalene formaldehyde condensates. Further more, the mixture can get a fine fluidity with acrylic acid superplasticizers, at ultra low-volume, and sodium lignosulfonate.