PSN-L Email List Message
Subject: Reinforced concrete base for Lehman instrument
From: beezaur beezaur@..........
Date: Fri, 07 Mar 2003 11:43:03 -0800
I am preparing to build a Lehman type seismograph and was wondering
about materials for the base. I am considering a slab of reinforced
concrete (R/C) about 20" by 40" max, but coffin-shaped, say 3-4" thick
and ~120 lbs @ 150 pcf. This is similar to the stuff parking garage
floors are made of. It is a very stable material and can be cast to
include mounting points for various hardware.
I have read about the unreinforced recipee 1:1 sand:cement for piers,
but this does not give the bending strength required for my slab. I am
thinking of a more conventional mix using ~1:2:3 cement:sand:pea gravel
and a lot of small reinforcement (#3 bar or welded wire fabric). If I
vibrate it well, I should be able to avoid air pockets.
My main concern is thermally induced noise from reinforcement
expanding/contracting differently than concrete.
Has anyone done or heard about this? Do you think it would produce
A day without math is like a day without sunshine.
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