Indranil Goswami’s Civil Engineering All-In-One PE Exam Guide: Breadth And Depth is probably the best reference book for PE exam. The book comes with the actual format of the exam, so you can familiarize yourself with the structure of the exam. It does not cover only things that you will need to know to pass the exam, but it also serves as an essential on-the-job reference. The book covers important civil engineering topics such as structures, geotechnics, and construction.
Civil PE Professional Engineering Exam Construction Module by Ruwan Rajapakse is a practice book that contains sample problems that are similar to what you might find on the actual exam. It also has examples and step-by-step worked solutions, complete with illustrations. The book covers various topics such as horizontal curves and vertical curves of highway constructions, multi-storey buildings, construction grade stake markings, machine horsepower computation, and many others.
If you want a good reference book that you can use on daily basis, Analysis and Behavior of Structures by Edwin Rossow would be a good choice. This is an excellent reference book for civil engineering students because it emphasizes assumptions and limitations that they have to take into account when creating mathematical models for analysis. The book will also help you distinguish the differences between nonlinear and linear problems.
Environmental technology is also an integral part of civil engineering, thus Jerry Nathanson’s Basic Environmental Technology: Water Supply, Waste Management & Pollution Control is a good choice for students or engineers who want to gain a better understanding of chemistry, geology, biology, and hydraulics. It is an easy-to-read book, providing introduction on related topics such as pollution control, waste management, or water supply. This book is also a good reference book for professionals working in the public health protection or environmental quality control field.
There are other books that cover specific areas of civil engineering. And since this branch of engineering is a very broad field, it would be better if you can identify the areas you need to improve and you can online for the most suitable books for you.