133 / 2022-04-28 20:33:52

Using limestone calcined clay cement and recycle fine aggregate to make eco-friend ultra-high performance concrete: properties and environmental impact

Limestone calcined clay cement,Recycled fine aggregate,Mechanical properties,Microstructure,Eco-friendly,Ultra-high performance concrete

Limestone calcined clay cement has been used in concrete as a new type of low-carbon and environmentally friendly cement in many examples. Recycled fine aggregate is also widely used in concrete as a green aggregate. This paper uses Limestone calcined clay cement and Recycled fine aggregate to produce eco-ultra-high performance concrete with comparable mechanical properties to traditional ultra-high performance concrete. The experimental results show that the compressive strength of eco-ultra-high performance concrete made with Limestone calcined clay cement and Recycled fine aggregate is comparable to that of traditional ultra-high performance concrete (Fig. 1), while the tensile strength is slightly lower than that of traditional ultra-high performance concrete, and the ultimate tensile strain is increased (Fig. 2).

In this paper, seven days of Heat of hydration analysis with different mix-IDs were studied. The experimental results showed that due to the addition of Limestone calcined clay, in the induction period of 1–3 h heat flow increased. At 7th hour, LC315 and LC330 simultaneously appeared the first exothermic peak, while the second exothermic peak decreased, indicating that the early calcined clay had participated in the hydration reaction (Fig. 3).



The pore structure distribution of different mix-IDs was tested by MIP experiments (Fig. 4), and the experimental results showed that Limestone calcined clay cement can effectively reduce the proportion of macropores in the total pore volume and optimize the pore results. And the total pore volume of LC330 was smaller than that of the control group (Fig. 5).



The impact of different mix-IDs on the environment was analyzed through life cycle analysis (Fig. 6). The results show that Limestone calcined clay cement and Recycled fine aggregate can effectively reduce the impact on the environment, indicating that Limestone calcined clay cement and Recycled fine aggregate are feasible to make eco-ultra-high performance concrete.