The Influence Of Mineral Admixtures On Properties Of Thermal Insulation Material With Expanded And Vitrified Beads

As a lightweight aggregate, expanded and vitrified beads are used in constructions for energy conservation. Upon rapid heating, the surface of expanded perlite is vitrified and closed. After this process, it transforms into a cellular material of low bulk-density, and thus providing an advantage in terms of thermal insulation. Therefore, expanded and vitrified beads are generally used in the production of thermal insulation mortar. But in recent years, there have arised a few problems that could affect the process of application. Limited by the construction environment and technology, it is difficult to guarantee the uniformity of mortar, and thus affected the efficiency of energy saving. Therefore, it is necessary to improve the performance of mortar containing expanded and vitrified beads based mortar. With the utilization of lime and mineral admixture, the property of mortar will be studied.The influence on mortars with different dosages of cement, lime, mineral admixtures will be studied. When the weight ratio of cement content is 45%, the apparent density can reach to 320 kg/m3, with the compressive strength of 0.95 MPa. Replacing the cement with 20% content of lime, and then adjust the weight ratio of hydrated lime and unslaked lime to 3:1, the density can reach to 295 kg/m3, with the compressive strength of 0.74 MPa.The density of mortar is decreased with the addition of mineral admixture. With the increase of fly ash, the density and compressive strength is reduced gradually. When the content of fly ash is 20%, with the compressive strength of 0.65 MPa, the density is 285 kg/m3. When the cement content is replaced by 15% blast slag, the compressive can reach to 0.80 MPa, with the density of 290 kg/m3.Increasing the content of blast slag, the consistency of mortar is reduced, and then the density is increased correspondingly. When the silica fume is added as replacement for cement by decreasing the cement weight in the ratio of 10%.The density can reach to 280kg/m3, with the strength of 0.95 MPa. In accordance with the density, the lowest thermal conductivity of 0.063W/m.K was observed. Optimal strength-thermal conductivity combination was obtained by the replacement of 15% blast slag and 5% silica fume together. The mechanical properties are shown as follows: with the lowest apparent density of 280 kg/m3, the compressive strength can reach to 0.93 MPa and the corresponding thermal conductivity is 0.065W/m.K.With the addition of 20% lime, the specific absorption of water is 38.6%.Mixed the mortar with mineral admixtures and 0.3% dosage of water-repellent agent, the specific absorption of water is 26.3%. The surface of expanded perlite based mortar can be reinforced by the alkali-resistance mesh fabric and anti-crack mortar, the panel shows a better result at flexural test.