Strength improvement additives for cement bitumen emulsion mixture Jian Ouyang a,⇑ , Lijun Hu a , Wenting Yang b , Baoguo Han b a School of Transportation and Logistics, Dalian University of Technology, Dalian 116024, China b School of Civil Engineering, Dalian University of Technology, Dalian 116024, China highlights Effect of water content on the indirect tensile strength and air void content of CBEM is studied. The microstructure of CBE paste and the interface between CBE paste and aggregate are studied. The deficiency in strength about CBEM is discussed through analyzing the microstructure of CBEM. Superplasticizer and JFC are proposed to increase the indirect tensile strength of CBEM. article info Article history: Received 2 September 2018 Received in revised form 28 November 2018 Accepted 29 November 2018 Keywords: Cement bitumen emulsion mixture Indirect tensile strength Interface Superplasticizer Wetting agent abstract To increase the strength of cement bitumen emulsion mixture (CBEM), the effect of water and cement content on the volumetric properties and strength of CBEM was firstly studied to find the deficiency in strength about CBEM, and then two additives were added to overcome this deficiency. Results indicates that CBEM at maximum indirect tensile strength (ITS) has much lower water content than that at min- imum air void content. This is because the strength of CBEM is not only dependent on the air void content of CBEM, but also it is related to the microstructure of cement bitumen emulsion (CBE) paste and the interface between CBE paste and aggregate. Low water content can help to form a dense microstructure of CBE paste, which is beneficial to the strength of CBEM. However, CBE paste has a poor bonding inter- face with aggregate at low water content, and the air void content of CBEM is relative high in this con- dition. The addition of superplasticizer and wetting agent (JFC, a fatty alcohol–polyoxyethylene ether) can efficiently overcome the two deficiencies of CBEM and greatly increase the strength of CBEM. The air void content of CBEM at low water content can be decreased by adding superplasticizer and JFC. Meanwhile, superplasticizer and JFC can improve the wetting ability of fresh CBE paste, thus the coating state of aggregate with fresh CBE paste and the bonding interface between hardened CBE paste and aggre- gate are greatly improved. Accordingly, the failure surface of CBEM is changed from ‘‘adhesive failure” to ‘‘cohesive failure” and ‘‘fine aggregate fracture” after adding superplasticizer and JFC. The maximum ITS can increase by 21.5% and 29.1% for CBEM with superplasticizer and CBEM with superplasticizer and JFC, respectively. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction With the growing health, safety and environmental awareness, significant efforts have been carried out to save non-renewable fossil fuels, conserve energy and reduce emissions in various industries. The pavement industry is aware that reduction in the production and operation temperatures of hot mix asphalt (HMA) can contribute in a positive way to these efforts [1]. Accordingly, many new environmental friendly technologies (e.g., warm and cold mix asphalt technologies) were invented to reduce the ther- mal generation of bitumen mixture [1]. Among these technologies, cement bitumen emulsion mixture technology has been gaining increasing interest in recent years. Cement bitumen emulsion mix- ture (CBEM) is a typical cold mix asphalt whose mixing, laydown and compaction can be carried out at ambient temperature because of the low viscosity of bitumen emulsion [2]. As a result, CBEM greatly reduces energy consumption, dust and gaseous emissions and is more cost effective compared to conventional hot mix asphalt (HMA) [3,4]. Moreover, CBEM has a higher rutting resistance and lower temperature sensitivity than HMA due to the effect of cement hydration [5,6]. For these benefits, CBEM is believed to be a promising pavement material. https://doi.org/10.1016/j.conbuildmat.2018.11.280 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: [email protected] (J. Ouyang). Construction and Building Materials 198 (2019) 456–464 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Strength improvement additives for cement bitumen emulsion mixture
Jun 28, 2023
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Related Documents
