You must have the 2.4 version and use -s timeout option.
Edit:
https://www.wampserver.com/ – includes Apache 2.4.x Win32 and Win64.
Deprecated but still available however I not known until when and just not available:
You can use my win32-x86 binary (compiled under Visual Studio 2008 from trunk 8 Feb 2013):
http://mars.iti.pk.edu.pl/~nkg/ab-standalone.exe(no longer available)http://mars.iti.pk.edu.pl/~nkg/ab-standalone-src.zip(no longer available)
I was made it using: http://code.google.com/p/apachebench-standalone/wiki/HowToBuild and
http://ftp.ps.pl/pub/apache//apr/binaries/win32/apr-1.3.6-iconv-1.2.1-util-1.3.8-win32-x86-msvcrt60.zip (just not available).