COMPARISON OF THE PROPERTIES OF MODIFIED EXPANDED CLAY LIGHTWEIGHT CONCRETE WITH VARIOUS TYPES OF SANDS

Abstract

The properties of expanded clay lightweight concrete on different types of sands were investigated. In the experiment, 50% and 100% of quartz sand in large fractions (1,25-2,5 mm and 2,5-5 mm) was replaced by light sand. Expanded clay sand and sand from granulated foam glass were used. The quartz sand had a packed density of 1580 kg/m³. Sand with 50% expanded clay granules in large fractions had a packed density of 1430 kg/m³, using 100% of expanded clay granules - 1290 kg/m³. Sand with 50% granular foam glass had a packed density of 1330 kg/m³, with 100% foam glass in large fractions – 1080 kg/m³. The amount of polycarboxylate plasticizer Coral ExpertSuid-5 also varied from 0,4 to 1% by weight to cement. All mixtures had equal concrete-mix consistency P5. It was found that when the amount of plasticizer is increased to 0.8% W/C mixtures wound mobility decreases. Further increase in the amount of the additive is ineffective. Lightweight concretes with an amount of plasticizer of 0,8% also have the highest strength.

The type of sand affects the compressive strength of expanded clay concrete more than the tensile strength. Expanded clay concrete with expanded clay sand has a 3-10% lower compressive strength compared to lightweight concrete on quartz sand. When using granular foam glass, the compressive strength is reduced by 17-32%. The strength of lightweight concrete on stretching using expanded clay sand is reduced by 4-9%, and when using granulated foam glass it is reduced by 5-19%. The main purpose of using light sands in expanded clay concrete was to reduce the average density of the material. When the amount of plasticizer varies, the average density of expanded clay concrete is not significant. When using expanded clay sand in large fractions, the average density of lightweight concrete is reduced by 4-7%. Sand of granulated foam glass is easier. Accordingly, when using granulated foam glass, the average density of expanded clay concrete decreases by 7-14%, respectively. The average density of lightweight concrete with expanded clay sand does not exceed 1572 kg/m³, and with granulated foam glass sand it does not exceed 1440 kg/m³. Modified expanded clay lightweight concrete on light sands can be used in thin-walled structures, for which it is important to reduce weight while ensuring the necessary strength of the material. When providing the necessary watertightness and frost resistance, such concretes can be used in reinforced concrete shipbuilding.