Search

The performance of completely recycled sand is significantly different from that of river sand, and the plastering mortar prepared with completely recycled sand cannot be calculated by the existing design method of plastering mortar mix ratio. A study was conducted on the effect of completely recycled sand on the performance of plastering mortar under different cement dosage. The results show that: under the same dosage of cement, the water demand and the compressive strength at 28d of completely recycled sand plastering mortar are higher than that of river sand mortar; the law of water consumption and 28d compressive strength of completely recycled sand plastering mortar changing with cement dosages are basically the same as that of river sand plastering mortar; according to the experimental results and referring to the existing mortar mix design methods, a mix design method of completely recycled sand plastering mortar is proposed. [ABSTRACT FROM AUTHOR]

A special air entraining agent was used to study the mix ratio of Non-autoclaved Ceramsite Lightweight Concrete (NCLC) under standard curing conditions, and the mechanism was analyzed by comparing it with the performance of NCLC foamed with foaming agent. Furthermore, the effect of air entraining agent and foaming agent on the area density, compressive strength and dry shrinkage of the NCLC partition wallboard under the dry-heat curing condition was carried out. The preferred NCLC mix ratio is sand-binder ratio 2.0, water-binder ratio 0.30, the absolute volume of ceramsite is 15%, concrete target wet density is 1650 kg/m³. The result shows that the area density, compressive strength and dry shrinkage performance of the air entrained NCLC and foamed NCLC partition wallboard under dry-heat curing conditions can meet the requirements of the General Technical Requirements of Light Weight Panel Used for Building Partition (JG/T 169-2016). It is more efficient to use air entraining agent to prepare NCLC because the compressive strength is higher at the same density, and the drying shrinkage is lower. [ABSTRACT FROM AUTHOR]

To reduce the cost of lightweight concrete (LWC) partition panels and to address recycling concrete waste, this work utilized completely recycled fine aggregate (CRFA) to replace the natural fine aggregate and ceramsite in the preparation of LWC and LWC partition panels. To this end, an autoclave-free curing process and an air-entraining agent were used to prepare the CRFA-LWC. The workability, compressive strength, drying shrinkage, and pore structure of the CRFA-LWC and the performance of the CRFA-LWC partition panels were then investigated. The results show that the optimal ratio of the CRFA to the cement is 2.2 for the lightweight concrete, and the optimal panel cross section is a rounded rectangular one. All the pores in the CRFA-LWC have a diameter of smaller than 0.17 mm, and the diameter of 89% of them is less than 0.05 mm. In order to satisfy the drying shrinkage requirements stipulated by Chinese code JC/T 169-2016, the CRFA-LWC should be cured for at least 10 days. The economic analysis concludes that the material cost of CRFA-LWC is 40% lower than that of the autoclaved ceramsite concrete. In addition, utilizing CRFA in lightweight concrete can ease the shortage of natural aggregate. Highlights: CRFA is used for preparing the lightweight concrete partition panels. The optimal ratio of the CRFA to the cement is 2.2 for the lightweight concrete. CRFA lightweight concrete needs to be cured for at least 10 days. The cost of lightweight concrete is reduced by 40% by using CRFA. [ABSTRACT FROM AUTHOR]