Light-weight claydite and sawdust concrete based on supersulphated cement

Abstract

The paper gives coverage on the peculiarities of the properties of two types of lightweight concrete: claydite (light-weight expanded clay aggregate - LECA) concrete and sawdust (wood shavings) containing concrete. The first one is based on LECA produced in Western Ukraine and Moldova, for the second one sawdust of the common local coniferous trees was applied. There was used supersulphated cement composed of blast furnace granulated slag, phosphor-gypsum and Portland cement in the research. The calcium chloride was used to reduce retardation and superplasticizer for reduction of water demand in order to increase the compressive strength. High specific surface of supersulphated cement facilitates intensive hydration of CaO from slag glass and binding it into new formations. That increases the strength of light-weight concrete. With claydite, the process occurs with binding of free lime and gypsum with aluminates from slag and aggregate. The results obtained with the claydite concrete were varied within the range of average density from 960 to 1490 kg/m3 and compressive strength from 7 to 21.5 MPa. Such concrete can be applied for structural and thermal-insulating elements (walling blocks and panels). With sawdust concrete, the average densities were varied from 410 to 720 kg/m3 and compressive strength from 0.34 to 4.7 MPa, which can be used for structural and non-structural elements. As supersulphated cement had low operating pH due to the limited content of alkali, it led to a positive influence on sawdust aggregate and didn’t result to a significant extraction of tanning agents.