I. Equipment Introduction

The soil compaction tester was developed by the Highway Research Institute of the Ministry of Transport as a rapid detection tool for the deformation modulus of subgrade soil. It played a significant role in soil strength surveys and subgrade compaction quality inspections at the time. After being widely adopted by highway research institutions, highway departments, and other construction units, years of practice have led to the application of this rapid detection method in the quality control of lime soil base construction, serving as a quick method to measure the rebound modulus of lime soil bases.

II. Usage Method

(1) Clean the surface of the lime soil base that has been cured for more than 7 days. If the surface is soft or has a hard crust, scrape it off to expose a representative lime soil surface.

(2) Place the penetrometer on the leveled lime soil surface. Hold the handle with one hand and lift the hammer to the lower end of the handle with the other hand, then release to allow the hammer to fall freely, driving the penetration needle into the lime soil.

(3) When the penetration needle is fully embedded in the lime soil, record the number of penetration impacts. Parallel penetration tests are generally conducted at 2-3 locations, and the average penetration value N is taken. For silty sand lime soil, the number of impacts should be no less than 25-50 times, while for clayey lime soil, it should be no less than 50-100 times. The lower limit applies to shorter curing periods, and the upper limit applies to longer curing periods.

(4) The empirical formula for calculating the rebound modulus is as follows:

E1 = 1.7 × 26N

Where: E1 - Rebound modulus of lime soil (Kg/Cm2)

N - Average number of penetration impacts

In the formula, 1.7 is the relationship coefficient between rebound modulus and deformation modulus.

26 is the relationship coefficient between penetration impacts and deformation modulus.

O - Average number of impacts

III. Technical Parameters:

Measurement range: 0MPa - 10MPa;